FILE: <bc-58.htm> GENERAL INDEX [Navigate to MAIN MENU ]
MANAGEMENT OF THE ENVIRONMENT
TO FAVOR PEST
CONTROL
(Contacts)
-----Please CLICK on desired
underlined categories [to search for Subject
Matter, depress Ctrl/F ]:
|
[Please refer also to Related
Research #1, #2, #3 ] |
|
Introduction Managing the environment is important to increase the
efficacy of natural enemies, which depend on production technologies such as
varietal development, cropping systems, tillage practices and chemical
inputs. Late trends in agriculture have, nevertheless, been toward decreasing
environmental heterogeneity, increasing fertilizer and pesticide input,
increasing mechanization and decreasing genetic diversity (USDA 1973,
Bottrell 1980, Whitham 1983, Altieri & Anderson 1986, Altieri &
Letourneau 1999). Such creates agricultural environments that impede pest
population regulation by natural enemies. The current emphasis on IPM, the
increasing restrictions on various pesticides and growing public concern
about pesticide contamination, as well as increased production costs, justify
increased research efforts for long term alternatives to the current trends.
Although agroecosystems devoted food and fiber production have been stressed,
these same systems frequently generate pests that are of human and veterinary
health concern, such as mosquito, gnat and fly outbreaks. Numerous research
has been conducted to document the importance of manipulating environmental
properties of crop fields to make them more favorable to natural enemies and
less amenable for insect pests, since van den Bosch & Telford (1964)
presented their classical chapter that encouraged biological control in
agroecosystems (van Emden & Williams 1974, Perrin 1980, Cromartie 1981,
Thresh 1981, Altieri & Letourneau 1982, 1984; Price & Waldbauer 1982,
Risch et al. 1983, Herzog & Funderburk 1985). For pests of medical and
veterinary importance environmental management is essential to the maximized
performance of parasitoids and predators (Please refer to Selected Reviews &
Detailed
Research ) Since the
mid 1970's most effort has been directed to analyzing the effects of reduced
tillage and vegetational diversification of agroecosystems. Research on other
types of cultural manipulation such as strip-harvesting, trap cropping, use
of nests or artificial shelter, etc., has been scarce, except for the use of
food sprays (Hagen 1986) and kairomones (Lewis et al. 1976, Nordlund et al.
1981a,b, 1987) that enhance the activity of specific natural enemies. There has been much research on multiple cropping systems and their effect on
insect dynamics (Root 1973, Litsinger & Moody 1976, Perrin 1977, Altieri
et al. 1978, Perrin & Phillips 1978, Bach 1980a,b; Risch 1980, 1981;
Andow 1983b, Letourneau & Altieri 1983, Altieri & Liebman 1986).
These studies provide a basis for designing crop systems with vegetational
attributes that enhance reproduction, survival and efficacy of natural
enemies. However, because agricultural land use is driven principally by
economic forces, pest control plans are seldom made on the basis of habitat
management. In developed countries farmers reduce unit production costs by
increasing farm size and becoming more specialized, with the consequence that
environmental manipulation strategies with demonstrated effectiveness under
experimental conditions, such as cotton/alfalfa strip cropping for Lygus management in cotton
(Stern et al. 1964), or the use of Rubus
plantings around vineyards for conservation of grape leafhopper parasitoids
(Doutt & Nakata 1973), have not been adopted on a regional scale. The
political and economic context of modern farming does not support the
maintenance of landscape diversity, which is one of the main obstacles to the
implementation of many of the alternative strategies to pesticides. The effective
environment of an organism has been characterized by Rabb et al (1976) as
weather, food, habitat (shelter, nests) and other organisms. Environmental
management for biological control is concerned with the functional
environment, i.e., the physical and biotic elements that directly or
indirectly impact survival, migration, reproduction, feeding and the
behaviors associated with these life processes. Although pest populations can
be controlled directly through cultural control methods that modify the
habitat, the main thrust of this section is conservation (maintenance of
natural enemy abundance and diversity) and enhancement (increased
immigration, tenure time, longevity, fertility and efficiency) strategies
that can be used to manipulate natural enemies in agroecosystems. Habitat
management is directed at (1) enhancing habitat suitability for immigration
and host finding, (2) providing alternative prey/hosts during times when
pests are scarce, (3) providing supplementary food (food sprays, nectar and
pollen for predators/parasitoids), (4) maintenance of noneconomic levels of
the pest or alternative hosts over long periods to ensure continued survival
of natural enemies and (5) providing refugia for mating or overwintering.
Cropping techniques that enhance parasitoids through these five processes
have been reviewed by Powell (1986) and shown in table form by Altieri &
Letourneau (1999). Approaches to manipulating natural enemies include
several levels, from agroecosystem processes to eco-physiological features of
individual organisms. The number of elements that can be manipulated and
their degree of flexibility depend on characteristics of the agroecosystem.
The role, methods and future directions of environmental management as a preventative
control strategy are detailed after Vandermeer & Andow (1986) in the
following sections. A unique set of agroecosystems are found in different regions,
which result from local climate, topography, soil, economic relations, social
structure and history. A number of farming features can be modified and some
can impact the dynamics of insect populations. The agroecosystems of a region
often include both commercial and local use agricultures, which rely on
technology to a different extent depending on the availability of land,
capital and labor. Some technologies in modern systems aim at efficient land
use, such as reliance on biochemical inputs, while others reduce labor or
mechanical inputs. On the other hand, resource poor farmers usually adopt low
technology, labor intensive practices that optimize production efficiency and
recycle scarce resources (Mattson et al. 1984). Area wide environmental
management techniques are difficult to design and implement because of
differences in climate, agricultural products and economic and political
structure of each agricultural system. Many farming systems are in
transition, with changes forced by shifting resource needs, unequal resource
availability, environmental degradation, economic growth or stagnation,
political change, etc. Strategies amenable to labor intensive operations will
be radically different from those designed for mechanized, large scale
operations. Specialization and concentration of crops are the most important
factors limiting the application of many environmental management options for
a particular region. Farms may be classified by type of agriculture or agroecosystem
even though there are many individual differences among farms in a region.
Functional grouping is essential for devising areawide habitat management
strategies. Norman (1979) listed five criteria that can be used to classify
agroecosystems in a region: (1) the types of crop and livestock, (2) the
methods used to grow the crops and produce the stock, (3) the relative
intensity of use of labor, capital and organization, and the resulting output
of product, (4) the disposal of the products for consumption (whether used
for subsistence or supplement on the farm or sold for cash or other goods),
and (5) the structures used to facilitate farming operations. Using these
criteria Giggs (1974) recognized seven main types of agricultural systems in
the world: (1) shifting cultivation systems, (2) semi-permanent rain-fed
cropping systems, (3) permanent raid-fed cropping systems, (4) arable
irrigation systems, (5) perennial crop systems, (6) grazing systems, and (7)
systems with regulated farming (alternating arable cropping and sown
pasture). Systems 4 and 5 evolved into habitats which are much simpler in
form and poorer in species than the others, which can be considered more
diversified, permanent and less disturbed and consequently inherently
containing elements of natural pest control. It is obvious that modern
systems require more radical modifications of their structure to approach a
more diversified, less disturbed state. If it is argued that such
modifications are not possible in large scale agriculture due to technical or
economic factors, then there is a strong conservative argument in favor of
small, multiple use farms. Types of Environmental Management An obvious form of environmental management concerns vegetational
designs across appropriate levels of scale. AT the regional level landscape
vegetation mosaics influence the distribution of food and shelter resources
and consequently, colonization patterns of insects (Andow 1983b). At a
smaller scale, herbivores and their natural enemies respond to localized
patterns of plant spacing, plant structure and plant species (or varietal)
diversity. Environmental components and their management in agroecosystems
have three main dimensions: temporal, spatial and biological. Other means of
biotic management through inundative releases and classical biological
control are considered in other sections. Mechanical modes of environmental
management, such as cultivating, mowing and harvesting affect the structure
and permanence of the habitat and thus the life processes of insects in
agroecosystems. Chemical inputs, such as the periodic application, water,
fertilizers, behavior modifying agents and the pesticides affect the rates of
growth and survival of pests and natural enemies. Biotic, physical/chemical
and mechanical manipulations are imposed upon agroecosystems often as means
to achieve objectives unrelated to insect pest management, but the possible
range of environmental manipulations designed for higher yields can be broad
enough to incorporate tactics which simultaneously improve pest control. Management of Vegetation.--Monocultures which are frequently disturbed often favor
the rapid colonization and growth of herbivore populations. Initial
conditions of natural enemy-free space and high abundance of pests further
reduces the ability of natural enemies to regulate them (Price 1981). These
negative factors can be minimized or eliminated by providing continuity of
vegetation (and the associated food and shelter) in time and space, thereby
aiding natural enemies. Studies documenting direct behavioral and
physiological effects of plants on natural enemies are numerous (e.g., van
Emden 1965, Leius 1967, Campbell & Duffey 1979, Nettles 1979, Altieri et
al. 1981, Letourneau & Altieri 1983, Boethel & Eikenbary 1986,
Letourneau 1987). Entomophages are sometimes more abundant in the presence of
certain plants, even in the absence of hosts or prey, or they are attracted
or arrested by chemicals released by the herbivore's host plant or other
associated plants. Some parasitoids prefer particular plants over others
(Monteith 1960, Shahjahan 1974, Nettles 1979). Other authors recognized that
parasitism of a pest was higher on some crops than on others (Read et al.
1970, Martin et al. 1976, Nordlund et al. 1985, Johnson & Hara 1987). Noncrop plants within and around fields can also benefit
biological control agents (Altieri & Whitcomb 1979a,b; Barney et al.
1984, Norris 1986). Rapidly colonizing, fast growing plants offer many
important requisites for natural enemies such as alternate prey or hosts,
pollen or nectar, and microhabitats which are not available in weed free
monocultures (van Emden 1965, Doutt & Nakata 1973) but these interactions
can be difficult to define and to implement in control programs (Flaherty et
al. 1985). Outbreaks of some kinds of crop pests are more apt to occur in
weed free fields than in weed diversified crop systems (Dempster 1969,
Flaherty 1969, Root 1973, Smith 1976a, Altieri et al. 1977). Crop fields with
dense weed cover and high diversity usually have more predaceous arthropods
than do weed free fields (Pimentel 1961, Dempster 1969, Flaherty 1969,
Pollard 1971, Root 1973, Smith 1976b, Speight & Lawton 1976). Carabids
(Dempster 1969, Speight & Lawton 1976, Thiele 1977), syrphids (Pollard
1971, Smith 1976b), and coccinellids (Bombosch 1966, Perrin 1975) are abundant
in weed diversified systems. Relevant examples of cropping systems in which
the presence of specific weeds has enhanced the biological control of
particular pests are numerous. The potential for managing weeds as useful
components of agroecosystems is great, but not all weeds promote biological
control (see Powell et al. 1986). Leius (1967) found that the presence of wild flowers in apple
orchards resulted in an 18X increase in parasitism of tent caterpillar pupae
over nonweedy orchards; parasitism of tent caterpillar eggs increased 4X, and
parasitism of codling moth larvae increased 5X. A cover crop of bell beans, Vicia faba L. in rain fed apple orchards in northern California
decreased infestations by codling moth. This lower moth infestation was correlated
significantly with increased numbers of predators in the Aranae,
Coccinellidae, Syrphidae and Chrysopidae, which were present on the trees
(Altieri & Schmidt 1985). Similar observations were made by Dickler
(1978) in Germany. In New Jersey peach orchards, control of the oriental
fruit moth increased in the presence of ragweed, Ambrosia sp., smart weed, Polygonum sp., lambsquarter, Chenopodium album
L., and goldenrod, Solidago
sp. Such weeds provided alternate hosts for the parasitoid Macrocentrus ancylivorus Rohwer (Bobb 1939).
O'Connor (1950) suggested the use of a cover crop in coconut groves in the
Solomon Islands to improve the biological control of coreid pests by an ant, Oecophylla smaragdina subnitida
Emery. In Ghana, coconut served this purpose by providing sufficient shade
for cocoa to support high populations of Oecophylla
longinoda Latreille which
maintained the cocoa crop free of cocoa caspids (Leston 1973). Annual crops
diversified with cover crops also suffer less damage. Brust et al. (1986)
reported dramatically higher predation rates of Lepidoptera larvae (black
cutworms, Agrotis ipsilon (Hufnagel), armyworms, Pseudaletia unipunctata Haworth, stalk
borers, Papaipema nebris (Guenée) and European
corn borers, Ostrinia nubilalis (Hübner) tethered to
corn sown into a grass/legume mixture than to corn in monoculture. Carabid
beetles were more abundant to the living mulch system and were among the
larval predators in both systems. Because farming in a region differs in energy inputs, levels of
crop diversity and successional stages, variations in insect dynamics may
occur that are difficult to predict. However, low pest potentials may be
expected in agroecosystems that show traits as follows: (1) high crop
diversity through mixtures in time and space (Cromartie 1981, Altieri &
Letourneau 1982, Risch et al. 1983, Andow & Risch 1985, Nafus &
Schreiner 1986). (2) Discontinuity of monoculture in time through rotations,
use of short maturing varieties, use of crop-free or host free periods, etc.
(Stern 1981, Lashomb & Ng 1984). (3) Small scattered fields creating a
structural mosaic of adjoining crops, and uncultivated land which potentially
provide shelter and alternative food for natural enemies (van Emden 1965,
Altieri & Letourneau 1982). Pests also may proliferate in these
environments depending on plant species composition (Altieri & Letourneau
1984, Collins & Johnson 1985, Levine 1985, Slosser et al. 1985, Lasack
& Pedigo 1986). But the presence of low levels of pest populations and/or
alternate hosts may be necessary to maintain natural enemies in the area. (4)
Farms with a dominant perennial crop component. Orchards are considered to be
more stable as permanent ecosystems than are annual crop systems. Because
orchards suffer less disturbance and are characterized by greater structural
diversity, possibilities for the establishment of biological control agents
are generally higher, especially if floral undergrowth diversity is
encouraged (Huffaker & Messenger 1976, Altieri & Schmidt 1985). Sometimes
orchard sanitation practices may interfere with the performance of natural
enemies, as is the case with sanitation to remove mummied almond fruit from
almond and walnut trees that serve as overwintering reservoirs for
parasitized hosts (Legner 1983a). (5) High crop
densities and the presence of tolerable levels of weeds (Shahjahan &
Streams 1973, Altieri et al. 1977, Sprenkel et al. 1979, Mayse 1983, Andow
1983a, Buschman et al. 1984, Ali & Reagan 1985). (6) High genetic
diversity resulting from the use of variety mixtures or several lines of the
same crop (Perrin 1977, Whitham 1983, Gould 1986, Altieri & Schmidt
1987). The above generalizations can serve in the planning of a
vegetation management strategy in agroecosystems; but they must take into
account local variations in climate, geography, crops, local vegetation,
inputs, pest complexes, etc., which might cause increases of decreases in the
potential for pest development under some conditions. The selection of
component plant species also can be critical. Systematics studies on the
quality of plant diversification with respect to the abundance and efficiency
of natural enemies are needed. While 59% of the 116 species of entomophages
in documented studies reviewed by Andow (1986) exhibited increased abundance
when plant species were added to the system, 10% decreased in abundance and
20% were variable, sometimes increasing and other times decreasing. Nafus
& Schreiner (1986) found lower parasitism rates in intercropped corn. The
addition to squash decreases the abundance of Coleomegilla maculata
(DeGeer) on squash because of a nonuniform distribution of prey (Andow &
Risch 1985). However, Orius tristicolor (White), a
generalist predator, is more abundant on squash when corn is interplanted,
and plant architecture and the nonuniform distribution of prey are beneficial
(Letourneau 1988). Plant density and diversity may interact negatively to
determine ground beetle emigration rates (Perfecto et al. 1986). Mechanistic
studies to determine the underlying elements of plant mixtures that enhance
or disrupt colonization and population growth of natural enemies allow a more
precise planning of cropping schemes and increase the chances of a desired
effect beyond the current levels. Management of Crops With Mechanical
Devices.--Manipulating the environment with mechanical devices may
disturb the system depending on its severity and frequency. Low input, perennial
systems would present an extreme contrast to mechanized annual crop
production systems, for example. But slight modifications in cultural
practices for sowing, maintaining and harvesting annual crops can effect
substantial changes in natural enemy populations which bring them nearer to
those observed in less disturbed perennial counterparts (Arkin & Taylor
1981, Barfield & Gerber 1979, Blumberg & Crossley 1983, Herzog &
Funderburk 1985). Cultivation & Habitat Disturbance.--Modern tillage practices reflect attempts to limit
mechanical disturbance of the soil; and there is an emphasis on surface
tillage and no tillage as alternative to plow tillage in order to control
soil erosion, enhance crop performance, use energy more efficiently (Sprague
1986) and reduce soil breeding chloropid eye gnats (Legner 1970 ). Minimum tillage systems can conserve and enhance
natural enemies of important pests (Legner 1970 , House & All 1981, Luff 1982, Blumberg & Crossley
1983, All & Musick 1986), altho each case must be considered
independently. Plowing, disking and other manipulations of the soil or breeding
habitat can affect ground or waste-dwelling arthropods, whether they inhabit
the soil consistently or intermittently (Legner 1970 , Legner et al. 1973-1980). The extent of
direct mortality depends on their distribution with respect to soil depth and
their phenologies. Less directly put potentially as important effects are
caused by the removal of resources and natural enemies associated with living
undergrowth and plant residues. The impact of natural enemies on crop pests
in such systems, and the casual links between tillage practices, numbers of
natural enemies, and level of biological control has been shown in only a few
cases (Risch et al. 1983, Letourneau 1987). Significantly higher densities of carabids, including Amara spp., Pterostichus spp. and Amphasia spp occurred in no
tillage systems and were the major factor reducing black cutworm damage below
that achieved in conventional corn systems (Brust et al. 1985). Other studies
show that herbivore damage is reduced in no tillage fields despite similar
predator abundance in tilled and nontilled fields. For example, reduced
rootworm, Diabrotica spp.,
damage to corn in nontilled fields compared to plowed fields reflected lower
herbivore densities (Stinner et al. 1986). Although spider density was
highest in nontilled systems, predators in general did not exhibit higher
densities. Probably efficiency rather than abundance of predators/parasitoids
are enhanced and the vegetative component may be important by providing
alternative resources to entomophages. Foster & Ruesink (1984) showed
that the flowering weeds associated with reduced tillage in corn are
important nectar sources that increase survival and fecundity of Meteorus rubens (Nees) an important parasitoid of the black
cutworm. Ants are generalist
predators sensitive to tillage practices in agroecosystems (Risch &
Carroll 1982). Altieri & Schmidt (1984) reported greater species
richness, abundance and predation pressure in uncultivated orchard systems
than in those cultivated twice in six weeks. Both lack of nest disturbance
and habitat suitability due to vegetational cover may be important causes of
greater ant abundance. Similar results were predicted for a highly effective
predator of bollworm, Iridomyrmex
pruinois (Rogers) in
Arkansas cotton fields (Kirkton 1970) based on field observations. Carroll
& Risch (1983) and Letourneau (1983) sampled ant activity in lowland
tropical Mexico where farming practices are in transition between
slash-and-burn and mechanized cropping practices. The number of ant species at
tuna baits in maize fields was similar whether they had been plowed or sown
into slash (20-23 spp.). But in central Texas, spring plowing decreased ant
species richness from 12 species to 2 species. Among the species that were no
longer present at baits after plowing were those that prey on Solenopsis invicta Buren queens. Pests can be suppressed directly by plowing the soil (Watson
& Larsen 1968) and burying stubble (Holmes 1982). Talkington & Berry (1986)
significantly reduced the adult emergence of the pyralid moth pest Fumibotys fumalis (Guenée), in peppermint fields by burying the
prepupae into the soil; tillage depth was directly correlated with control.
In locations where natural enemies are not effective, deep burial of infested
stubble may be necessary (Umeozor et al. 1985). However, a study by Telenga
& Zhigaev (1959) on the beet weevil, Bothynoderes
punctiventris Germer, shows
how differential effects on pests and their natural enemies can be achieved
through carefully planned tillage practices. Although >90% of the weevil
eggs were destroyed by deep plowing, surface tillage with a disk increased
the survival of a parasitoid on the eggs, which caused a greater level of
pest control. Nilsson (1985) found that an average of 4X as many parasitoids
of Meligethus sp. pollen
beetles emerged from fallow fields or from plots of rape that had direct
drilling of winter wheat than emerged from disk harrowed or plowed plots.
Although the effect of these practices on parasitization were not studied, a
regional use of direct-drilling was recommended. Studies in northern Florida
by Altieri & Whitcomb (1979a,b) have shown that weed species composition
changes markedly according to the date of plowing. Early winter plowing
stimulated populations of golden rod, Solidago
altissima L. and 58 predator
species which feed on the aphids, Uroleucon
spp, and other herbivores associated with this weed. However, plowing in
mid-autumn caused camphor weed populations to be enhanced along with the 30
predator species associated with herbivores of this weed. Mowing, Harvesting & Weed Control.--When crops are pruned or mowed, arthropods may move from
the cut plant material and there will be a period of new growth. These can
have important consequences on the performance and synchrony of natural
enemies. Weeding can also stimulate crop colonization by associated
arthropods, the extent to which movement will occur depending on distance and
arthropod mobility, but some weeding operations leave associated arthropods
intact and promote such movement. When patches of stinging nettle, Urtica dioica L., are cut in late spring, predators are forced to
move into crop fields (Perrin 1975). Also Coccinellidae have been observed to
move to orchard trees in southeastern Slovakia when grass weed cover was cut
(Hodek 1973). Alfalfa strip-cutting systems typically
illustrate how natural enemy movement prompted by vegetation cutting can
occur. Van den Bosch & Stern (1969) compared densities of several
predators, including Geocoris
pallens Stal, Nabis americoferus Caryon, Orius
tristicolor, Chrysoperla carnea (Stephens), and Hippodamia spp. in strip-cut
and solid cut fields. Movement out of the field was uncommon even for these
mobile predators in strip-cut fields; most moved onto adjacent plants so that
on a field wide basis these predators were conserved. Strip cutting also
reduced mortality of Aphidius
smithi Sharman & Rao by
providing shelter from adverse physical conditions and host scarcity. Host availability
for the parasitoid, Cotesia medicaginis (Muesebeck) in
alfalfa was altered through a different mechanism, however. Oviposition rates
of the alfalfa butterfly, Colias
philodice eurytheme Godart, peak on new
growth following harvest, which causes periodicity in the availability of
early instar larvae. Strip cropping can spread the vulnerable stages more
evenly over time and thus favor the maintenance of A. medicaginis
populations over the season. When fire is used to prepare land for cropping by the "slash and burn" practice or to reduce crop
residue, the affects on resident natural enemies and incoming colonists can
be serious. Burning of old fallow vegetation in a tropical slash and burn
system decreased ant abundance and foraging activity for more than four
months (Saks & Carrol 1980). Although fire has been used as a tool for
direct control of pests (Komareck 1970), generalizations on its effect on
natural enemies are not possible. An isolated study showed that controlled
burning increased spider and ant densities and biomass due to increased food
supply for herbivores in the form of succulent plant growth after the burn
(Hurst 1970). Chemical Usage.--Although the influence of water and fertilizer applications on
herbivores is complex (Scriber 1984, Louda 1986), fertilizer and herbivory
levels may be causally related through changes in plant quality or phenology
that affect the dynamics of predator/prey and host/parasitoid interactions.
However, pesticides have direct detrimental effects on natural enemies and
their use in environmental management must be limited to situations where
they are timed carefully or selectively applied. Perhaps the use of behavior
modifying chemicals (Lewis & Nordlund 1985) will provide new tools for
the manipulation of biological control agents, but to date practical
deployment has not resulted (Chiri & Legner 1983, 1986). Fertilizer.--Changes on the physiological conditions of crops caused
by soil amendments may have consequences for pest management, which depend on
soil variability, the growth, developmental and biochemical responses of the
plant, the direct effects of such changes on herbivores and the secondary
impact on natural enemies. Much work has been done on herbivore response to
fertilizers that increase nitrogen levels in plants. Mattson (1980) believed
that foliage N-level is a major regulator of herbivory rate. Although insects
often improve their survival, fecundity and growth rates when plant quality
is increased (higher N), general statements on the direct responses of
herbivores to nitrogen fertilizer are not possible because of the array of
responses by different species (Scriber 1984). Experiments on links between
soil amendments and pest management relate to the effects on the pest via
their response to resistant and susceptible varieties under conditions of
different sources or levels of Ca, Mg, N, P, K or S (Kindler & Staples
1970, Culliney & Pimentel 1986, Shaw et al. 1986, Manuwoto & Scriber
1984). Thus the natural enemy's environment is affected by soil amendments
through changes in plant quality as well as by the concomitant changes in the
herbivores. The direct effects of fertilizer on biological control are not
well known. Many herbivores exhibit marked increases in population growth on
nitrogen enriched hosts. There is an obvious concern for the ability of
natural enemies to track their prey/hosts under conditions. There were no
differences in biological control of mites detected on apple trees treated
with three levels of nitrogen fertilizer (Huffaker et al. 1970). Although the
fecundity of Panonychus ulmi (Koch) increased with the
nitrogen level up to a 4X increase, when Amblyseius
potentillae (Garman)
predators were not present, the predators were able to compensate for most of
the increased prey density. However, fertilized cotton plots exhibited higher
levels of Heliothis zea (Boddie) than did controls
despite significantly higher population densities of Hippodamia convergens
Guerin-Meneville, Coleomegilla
maculata langi Timberlake and Orius insidiosus (Say) in fertilized cotton (Adkisson 1958).
Chiang (1970) showed that fertilized corn fields (50 tons manure/acre) had
significantly fewer (ca. 1/2) corn rootworms than did unfertilized controls.
Although ground beetles and spiders were not affected, the populations of
phytophagous and predaceous mites were 3X higher in manure treatment plots.
Through three seasons of field and laboratory experiments Chiang (1970) concluded
that mit predation accounted for 20% control of corn rootworm under natural
field conditions and 63% control when manure was applied. Other effects of
fertilizers on natural enemies may be predicted based on the combined
information of relevant studies. For example it is known that the parasitoid Diaretiella rapae (McIntosh) attacks the
green peach aphid Myzus persicae (Sulzer) more readily
when the aphid is associated with Brassica
spp. (Read et al. 1970), the mustard oils in crucifers serving as attractants.
It has also been shown that some glucosinolates are inversely related to
nitrogen level (Wolfson 1980), and thus soil fertility may have profound
effects on pest control by limiting the production of semiochemicals that
play an important role in mediating interactions between plants, herbivores
and natural enemies. The frequency and levels of fertilizer applications can modify
the synchrony of predators with their prey. Low nutritive quality of host
plants may cause immature herbivores to develop more slowly, and thus
increase their availability to natural enemies (Feeny 1976, Moran &
Hamilton 1980, Price et al. 1980). A predaceous pentatomid was found to
regulate more efficiently the Mexican bean beetles on nutritionally poor
plants than on highly fertilized ones (Price 1986). Host plant phenology can
also be driven by fertilizer inputs, and Hogg (1986) suggested that the
timing of square availability was one factor influencing predation and
parasitism rates of H. zea in cotton. Changes in nutritive quality of host plants as influenced by
fertilizer may indirectly affect the survival and reproduction of natural
enemies by determining prey quality. Although direct examples of fertilizer
effects have not been demonstrated, nitrogen content is known to be an
important aspect of prey quality. Nitrogen content may be responsible for
higher egg production by H. convergens when fed apterate
instead of alate green peach aphids (Wipperfürth et al. 1987). Analagous
effects may occur in the case of prey of different quality due to host plant
conditions. Zhody (1976) observed that size, fecundity and longevity of Aphelinus asychis (Walker) was dependent on the food composition of
the host Myzus persicae. But low quality food
can also impair the ability of a host to encapsulate a parasitoid (El-Shazley
1972a,b). Nutrients in the host plant can also modify toxic effects to
parasitoids (Duffey & Bloem 1986) and influence their sex ratio
(Greenblatt & Barbosa 1981). Host size is often an important determinant
of egg fertilization by ovipositing females (Charnov 1982). Although studies
on direct effects of nitrogen on crop architecture and subsequent effects on
searching efficiency are not available, some studies indicate that these
interactions can occur. The sex ratio of Diadegma
reared from larvae of Plutella
xylostella L. from field
plots over a wide range of nitrogen fertilizer inputs showed a significant
trend for female bias in heavy fertilized plots. Soil nutrient levels are known to influence plant size, leaf area,
canopy closure and crop architecture, and these conditions define searching
area for natural enemies (Kemp & Moody 1984). Predator/prey or
parasitoid/host contact rates are a function of habitat preference, searching
area, prey density and dispersion patterns. Fye & Larsen (1969) found
that the searching efficiency of Trichogramma
spp. was dependent on structural complexity. Hutchison & Pitre (1983) did
not find this effect with Geocoris
punctipes (Say) on H. zea, however. Shady conditions resulting from overgrowing
vegetation reduce parasitism levels of Pieris
spp. (= Artogeia spp.) by Cotesia glomerata (L.) (Sato & Ohsaki 1987) by deterring the
parasitoid. The levels of key chemical constituents in the soil can
indirectly affect natural enemies by influencing weed composition in a field.
In Alabama fields with low soil potassium were dominated by buckhorn
plantain, Plantiago lanceolata L. and curly dock, Rumex crispus L., while fields with low soil phosphorus were
dominated by showy crotalaria, Crotalaria
spectabilis Roth, morning
glory, Ipomoea purpurea Roth, sicklepod, Cassia obtusifolia L., Geranium
carolinianum L. and coffee
senns, Cassia occidentalis L. (Hoveland et
al. 1976). Soil pH can influence the growth of weeds, e.g., weeds of the
genus Pteridium occur on
acid soils while Cressa sp.
inhabits only alkaline soils. Other species of Compositae and Polygonaceae
are found growing in saline soils (Anon. 1969). Water.--Plant quality and RH at the field level can be
influenced by flooding fields, draining land and furrow, drip or sprinkler
irrigation. The desert valleys of southeastern California are suitable
habitat for the predaceous earwig Labidura
riparia (Pallas) due to
favorable conditions produced by irrigation (van den Bosch & Telford
1964). Much of the experimental work on the effects of plant stress from
water conditions has targeted herbivores (Miles et al. 1982, Bernays &
Lewis 1986, Louda 1986). Water availability can affect palatability, feeding
duration, developmental time, migration, survival and fecundity of
plantfeeders. Therefore, many important effects of water conditions on
natural enemies are indirect and are mediated through changes in host/prey
abundance and dispersion or through qualitative changes. For example, rape
plants under drought conditions had increased proline levels and an
associated shift in the balance of free amino acids (Miles et al. 1982).
Cabbage aphids reached adulthood faster on stressed plants, and availability
of suitable hosts for parasitoids might thus be decreased both by the
duration of vulnerable stages and if the parasitoids require slower
development than the host, if plants are water stressed. The direct effects of water include mortality during irrigation
and impacts of RH. Ferro & Southwick (1984) and Ferro et al. (1979)
reviewed the importance of RH on small arthropods. Crop architecture and
watering regimes cause large deviations from ambient temperature and humidity
levels (Ferro & Southwick 1984) within foliage boundary layer
microhabitats. Irrigation of soybean caused a substantial decrease in canopy
temperature and a 16% increase in RH at 15 cm above the ground (Downey &
Caviness 1973). Prolonged periods of such irrigation effects can have
important consequences for natural enemies because developmental time and
therefore population growth and synchrony are related to temperature and RH.
This may be illustrated in the case of the tachinid Eucelatoria armigera
(Coquillett), which completes development at different rates depending on
temperature and host species (Jackson et al. 1969). Holmes et al. (1963)
showed that parasitism levels of the wheat stem sawfly by Bracon cephi (Gahan) were enhanced by soil moisture and
temperature levels that slow plant ripening. Force & Messenger (1964)
showed that a few degrees dramatically affect changes of the innate capacity
for increase (r) in parasitoids under laboratory conditions. Cotesia medicaginis reaches its maximum longevity at 55% RH;
longevity decreased markedly at levels above and below this value (Allen
& Smith 1958). However, it was not deemed an important factor in
determining parasitism levels of Colias
spp. larvae in alfalfa. But it is known that armored scale parasitoids in
arid citrus groves require irrigated conditions for maximum biological
control (DeBach 1958b). The vertical profile and general microclimate depend
not only on water inputs but on mulching, row direction, windbreaks and crop
spacing (Hatfield 1982). The severity of effects caused by drought conditions
depends on many factors, including availability of free water and nectar in
the habitat. Bartlett (1964) reported that caged Microterys flavus
(Howard) was able to function well at extremely low RH if provided with honey
and water. Semiochemicals.--The knowledge that parasitic insect behavior is
influenced by chemicals produced by their hosts stimulated considerable
interest in the use of semiochemicals for manipulating predators and
parasitoids in the field, especially for aggregating and/or retaining
released parasitoids in target areas (Gross 1981). The various opportunities
for and limitations of manipulating natural enemies with semiochemicals were
reviewed by Vinson (1977), Nordlund et al. (1981a,b, 1988), Powell (1986) and
Hagen (1986). Lewis et al. (1976) suggest that host or prey selection is the
most important step in the searching behavior of entomophagous insects that
can be manipulated to improve biological control. Semiochemicals should be
used to increase effective establishment of imported species, improving
performance and uniform distribution of released species throughout a target
area and optimizing abundance and performance of naturally occurring natural
enemies (Greenblatt & Lewis 1983). It is possible to devise three main habitat
management technique with semiochemicals: (1) strategies directed at
improving habitat characteristics such as the use of semiochemicals to make
crops more attractive or to define a more complex mosaic of local search
areas (Altieri et al. 1981). Gardner & van Lenteren (1986) nevertheless
give an exception. (2) Enhancing host plant characteristics; breeding
programs directed at improving chemical attractiveness of crops or crops with
extrafloral nectaries. (3) Mimicking high pest densities through applications
of diatomaceous earth or artificial eggs impregnated with kairomones (Gross
1981). Drift of Pesticides.--Low level inputs of insecticides to nontarget areas
result from aerial applications. Half the material applied to a field under
ideal conditions can drift a considerable distance downwind (Ware et al.
1970). Although a great deal is known about the effects of direct spraying of
various insecticides on natural enemies, there is not much experimental work
to determine the effects of low level inputs. Biological control can be
disrupted given sufficient frequency, intensity and toxicity of sprays
(Ridgway et al. 1976, Riehl et al. 1980). The ratio of natural enemies to
herbivores was increased by low, drift-level concentrations of carbaryl, and
arthropod abundance dropped significantly more in an old field than it did in
a corn monoculture. It was suggested that low concentrations of insecticides
have different effects on herbivores and natural enemies depending on whether
the nontarget habitat is a crop field or a field of natural vegetation which
serves as a source of colonizers. However, such impacts cannot be predicted
from knowledge of effects at high concentrations (Risch et al. 1986). Drift
of chemicals may be minimized by making applications when winds are less than
2 m/sec, using adjuvants, formulating inert emulsions and using large droplet
sizes (Gebhardt 1981). Windbreaks surrounding field and regional wide spray
synchrony are forms of cooperative efforts for drift reduction of the effects
of low level pesticide applications. The application of herbicides to crop fields can have nontarget
effects similar to low-level insecticide application. Baker et al. (1985)
showed that Orius spp. and Nabis spp. densities were
decreased by monosodium methanearsenate, but not the abundance of spiders, Geocoris spp., Hymenoptera and
coccinellids. Herbicides may also modify weed species composition in fields
and thereby affect natural enemies. Other Pollutants (Dust).--Dust and pollutants of different kinds may influence the
efficiency of predators and parasitoids. Environmental management includes
consideration of the placement of the sources and control of pollutant influx
with respect to agricultural fields. It has long been known that some pest
outbreaks are caused or enhanced by dust on crop foliage. Bartlett (1951)
found that many inert dusts rapidly killed Aphytis chrysomphali
(Mercet) and Metaphycus luteolus (Timberlake). DeBach
(1985a) demonstrated an increase in California red scale populations on
citrus trees in response to road dust. Mechanisms may be mechanical
interference or desiccation (Edmunds 1973). It is possible also that leaf
temperature, which can be raised 2-4°C by dust cover (Eller 1977) is a factor.
Planned placement of roads and timing of cultivation can reduce the level of
dust on crops. Strawberry growers in California profit from daily or twice
daily watering of roadways through the reduction in losses from mites, as
predaceous mites are apparently inhibited by dust. Gaseous air pollutants are more difficult to detect and to control. Sulphur dioxide is
a common effluent that has known negative effects on a variety of organisms
(Petters & Mettus 1982), including honeybees (Ginevan et al. 1980). But
acute exposure of female Bracon
hebetor (Say) to sulphur
dioxide in air causes no reduction in fertility and fecundity. Petters &
Mettus (1982) suggested that damage to parasitic wasps may develop in the
earlier stages or behavioral avoidance of contaminated areas may explain
reports of lower parasitoid and higher herbivore levels near sources of
sulphur dioxide pollution. Melanic morphs of the generalist coccinellid
predator Adalia bipunctata (L.) occur
disproportionately often in the vicinity of coal processing plants in Great
Britain. Although earlier investigators suggested a mechanism involving
selective toxicity of air pollutants, Muggleton et al. (1975) attributed the
differences to sunshine levels. Whether or not the coloration of such
predators affects their efficiency as biological control agents is unknown.
Other sources of contamination include auto traffic, drainage from selenium
rich soils (Gerling 1984), and ozone (Trumble et al. 1987). Literature
stresses effects on herbivores, and little is known about effects on natural
enemies. Lead as a contaminant from auto exhaust has been shown to
concentrate in higher trophic levels (Price et al. 1974). Some pollutants are
inadvertently added to the crop with soil amendments, such as sludge, manure and
chemical fertilizer (Wong 1985). Culliney et al. (1986) found a general
response of low arthropod diversity when sludge containing heavy metals and
toxic chemicals was applied to cole crops. Mechanisms Involved in Enhancing
Natural Enemies Insights into the biological mechanisms for environmental
management that enhances biological control can be obtained from an
examination of host selection processes of entomophages, which includes host
or prey habitat location, host or prey location and host or prey acceptance
(Vinson 1981). Designing crop habitats for effective biological control
requires an understanding of such mechanisms. During migration and habitat
location the effective environment may be the local area, a regional
landscape or a series of distant habitat patches with long distances between
them. The interplay of colonizer source location, wind patterns, vegetation
texture and host or prey density becomes important on a large scale. Maximum
levels of natural control require at the onset both sufficient numbers of
natural enemies and temporal synchrony of these invasions. Regional
environmental management for enhancing the success of habitat location by
natural enemies should focus on the arrangement of colonizer sources in
relation to target sites of potential pest problems as well as on timing of
natural enemy colonization. Rabb (1978) addressed these needs when he
criticized the propensity of single commodity, closed system approaches to
pest management in research and decision making as deficient for problems
which demand attention to large unit ecosystem heterogeneity. Natural enemies vary in their dispersal range, and migration
often occurs in high currents along paths of turbulent convection. Even weak
flying insects can disperse over long distances and across wide areas by
exploiting the ephemeral but very structured nature of air movement
(Wellington 1983). For example, robust hosts and minute parasitoids can
exhibit coupled displacement in long distance migration, as shown by the
Australian plague locust Chortoicetes
terminifera Walker and its
egg parasitoid Scelio fulgidus Crawford which
disperse independently on wind currents to the same location (Farrow 1981).
Cumulative numbers over a growing season may be irrelevant if immigration
rates of natural enemies are very slow in relation to rising levels of the
pest (Doutt & Nakata 1973, Letourneau & Altieri 1983, Williams 1984).
Information on source constitution, phenology and flight patterns are
necessary to design and manage regional scale agroecosystems for optimal
biological control. Flight capacity studies and mathematical models to
describe movement patterns based on continuous diffusion or discrete random
walk equations have focused on predicting dispersal and migration of
herbivores (Okubo 1980, Stinner et al. 1983, 1986). Biological information
coupled with predictive models of natural enemy movement may aid in
predicting synchrony (Duelli 1980), but many times synchronies are difficult
to achieve because local species are adapted to exploit natural conditions of
prey or host phenologies. For example, coccinellid beetles in California
estivate during times of prey availability; irrigated crops provide a
continuous food supply that was not available in an area before agricultural
expansion had occurred (Hagen 1962). While locating hosts or prey, factors such as the physical
texture of plant surfaces, structural attributes of plants, microclimatic
conditions and patch heterogeneity interplay. Flaherty (1969) showed enhanced
control of herbivorous mites on grape vines with Johnson grass cover. The
grass acted as a source of predaceous mites. In this study involving prey
location, and in the habitat location phase study of Doutt & Nakata
(1973), the cumulative total number of natural enemies was not as important
as the temporal synchrony with growing herbivore populations. During host or
prey acceptance and predation or parasitism, environmental factors operate
indirectly through their effects on host or prey behavior, host or prey
quality and alter levels of vulnerability of natural enemies to mortality
factors. Examples of the mechanisms of host or prey selection on all levels
of natural enemy behavior were given by many authors. Activities other than those directly associated with predation or
parasitism are migration to overwintering sites, mating, and the acquisition
and use of resources other than the primary prey or hosts. The
interdependence and variability of resource needs and factors such as
proximity and availability of resources in time become vital aspects of the
environment. These are factors of habitat suitability for natural enemies. A
reduction of the relative energy expenditure needed, in a particular
environment, to fulfill the resource needs of a particular parasitoid/predator
will increase its efficiency as a biological control agent. Conservation of
natural enemies through habitat management techniques adapted to the
prevailing agronomic schemes can be of great benefit. Small changes in
agricultural practices may increase natural enemy populations or enhance
efficiency. But predators and parasitoids are extremely diverse and each
family represents a particular range of responses to environmental
modification. There are numerous examples of habitat management techniques
that have been shown to increase the effectiveness an abundance of specific
predator groups. Theoretical Aspects of Management Natural Enemy-Free Space.--Probably the most general level of theory to guide
habitat management for biological control is that of ecological and/or
evolutionary escape from predators/parasitoids. Price (1981) acknowledged in
his theory of natural enemy-free space, that pest irruption is a likely
consequence of agricultural practices that foster the spatial and temporal
isolation of herbivores from their natural enemies. Pest introduction to a
novel environment is a classic example (Price 1981, Altieri & Letourneau
1982, 1984; Risch 1987). Temporary release of pests also occurs under
conditions of insecticide caused pest resurgence and secondary pest
outbreaks. Evolutionary changes in native crop pests (Host shifts) is still
another process that may result in a reduction of predation/parasitism. Island Biogeographic Theory.--Cultivated areas are insular in nature, which has
motivated several analogies regarding crops as islands available for
colonization by arthropods (Strong 1979, Price & Waldbauer 1982,
Simberloff 1985). The development of arthropod communities in crops was
analyzed using MacArthur & Wilson's (1967) theory of island biogeography,
which allows the prediction of colonization rates and mortality/emigration
rates, on a comparative basis, with respect to crop area, distance from the
sources of colonizers, and crop longevity (assuming that the system has
aspects of equilibrium). The species composition, structure and abundance of
arthropods colonizing a crop field are the result of highly dynamic processes
and the assumption of equilibrium is often inappropriate, however. But some
predictions from the theory seem possible. One example is that species richness is positively correlated to
size on oceanic islands. Similarly in mainland communities, the number of
herbivores associated with a plant is a positive function of the local area
planned to or covered by that species (Strong 1979). Larger host islands
probably collect more individuals by random probability of encounter. Also,
patch detection by dispersers may increase with size. The effect of an
increase in the number of herbivores with an increase in size is important for
consideration in pest management strategies. But any increase in species
diversity must be defined by the proportion in each trophic level, and if
possible by the component species' biologies before it can be analyzed for
pest management potential. MacArthur & Wilson's (1967) model treated all
members of s species source pool as equivalent colonizers. The application of
this theory to dynamic and temporary crop islands requires the consideration
not only of the number of species and pattern of occurrence, but the order of
colonizer establishment by trophic level (Altieri & Letourneau 1984,
Robinson & Dickerson 1987). Extinction rates depend upon resource availability in a system.
Because the plants are supplied to the system or reset at certain intervals (Levins
& Wilson 1980), the resource base may be more predictable for herbivores
at least early in the season. The immigration rates of natural enemies to
large expanses of monoculture may be similarly increased, though spread from
the edges may be slow and thus favor the development of herbivore
populations. The equilibrium theory of biogeography does not allow for
comparisons of single, large crop fields versus a network of several small
fields of the same total area, yet the contrasting designs are likely to
differ in terms of suitability for biological control (Price 1976). Even though most theory based on island community development
poses questions and organizes thought on crop design, the barriers to its
application are (1) frequent disturbance of most crop fields reduces the
rigor and applicability of equilibrium models; (2) the few current empirical
data available on diversity, size and distance relationships do not
constitute a sufficient basis for environmental design recommendations
(Simberloff 1985); (3) the theory does not distinguish pests and beneficial
organisms (Stenseth 1981); (4) economic impact of changing island size must
be viewed as exceedingly risky until demands for more certainty in the theory
are met (Simberloff 1985). However, Liss et al. (1986) presented a
modification of the MacArthur & Wilson (1967) model that incorporates
colonizer source composition and changes in island habitats over time. Consumer Dynamics.--Studies of consumer dynamics become important after the
natural enemies are within the habitat of their prey or hosts, in order to
predict the outcome of their interactions. Trophic interaction studies in
manipulated and natural systems have focused on two trophic levels, such as
plant-herbivore, host-parasitoid and predator-prey. Theory and data both
demonstrate the regulation of populations at the lower trophic level (plant,
prey or host) by natural enemies (Clark & Dallwitz 1975, Mattson &
Addy 1975, Murdoch & Oaten 1975, Podoler & Rogers 1975, Morrow 1977,
Gilbert 1978, Hassell 1978, May & Anderson 1978, Clark & Holling
1979, Murdoch 1979, McClure 1980, Kareiva 1982). On the other hand, natural
enemies have been ineffective in other cases studied (Southwood & Comins
1976, Strong et al. 1984, Walker et al. 1984). The effectiveness of natural
enemies as regulators of herbivore populations depends not only on behavioral
and developmental responses of individual predators and on responses of the
entire population to changes in prey or host densities (Murdoch 1971, Murdoch
& Oaten 1975, Fox & Murdoch 1978), but also on variation in plant
parameters such as density, secondary compounds and associated plants
species. The ability of natural enemies to regulate the herbivores depends on
the herbivore population's intrinsic growth rate (r), which in turn reflects
the quality of the plant diet. Small changes in r caused by slight
differences in plant quality, such as variety, secondary chemistry,
nutrients, may determine whether or not parasitoids or predators can control
the herbivore populations (Lawton & McNeill 1980, Price et al. 1980). The
effectiveness of regulation also reflects subtle differences in the timing of
population events in both predator and prey populations (Hassell 1978, May
& Anderson 1978). Theory and data on interactions involving three trophic
levels in a complex habitat are ultimately more suitable as a basis for
environmental management strategies (Price 1986, Duffey & Bloem 1986,
Barbosa & Letourneau 1988). Therefore, the goal of such preemptive measures
of pest control is to avoid the provision of enemy-free space in agricultural
environments and instead to present pests simultaneously with deleterious
effects caused by their natural enemies and with selectively defensive or
suboptimal properties of their food plants. Studying systems as communities
of at least three trophic levels can contribute an understanding of complex
interactions that is different from that likely to be gained purely as a
byproduct of results from two level studies (Orr & Boethel 1986). Vegetation Diversity & Patch Size.--Two hypotheses were proposed by Root (1973) to explain
the tendency for low herbivore abundance in diverse vegetation. The Resource
Concentration hypothesis, which predicts that many herbivores, especially those
with a narrow host range, are more likely to find, survive and reproduce on
hosts that are in pure or nearly pure stands. The Enemies hypothesis
incorporates the third trophic level that Root (1973) predicted that
vegetation would provide more resources for natural enemies (e.g., alternate
hosts, refugia, nectar and pollen) and thus herbivore irruption would be
rapidly checked by a higher diversity and abundance of natural enemies.
Sheehan (1986) extended the resource concentration concept to predict that
specialist natural enemies will respond to mixed vegetation differently, and
probably less favorably, than will generalist predators and parasitoids,
because of the importance of alternate prey for generalists. The designation
of host/prey specialization categories, however, tends to rely only on one
aspect of the resource spectrum of parasitoids and predators (Letourneau
1987). A range of species characteristics, such as relative vagility,
resource needs, and habitat location cues may determine the response of
parasitoids and predators to vegetational diversity. Maintaining heterogeneity within an agroecosystem may also affect
the success of establishment of imported biological control agents. The
debate over the degree to which ultimate levels of regulation are attained by
single versus multi species releases in classical biological control
continues, but analyses of environmental factors as raw materials or as
constraints are rarely considered (Beirne 1985). Factors such as species
richness, climatic gradients and disturbance levels are important in
assessing the susceptibility of large scale communities to biological
invasion (Fox & Fox 1986). Optimal Foraging.--During the host/prey selection process, natural enemies
exhibit a chain of responses to stimuli. The objectives of biological control
are to exploit natural processes that allow maximum prey encounter and
foraging rates by natural enemies, and therefore, this body of theory is
useful for predicting enhancement mechanisms and for evaluating the consequences
of under and overexploitation. The aggregation of foraging parasitoids in patches of higher host
density has been a critical feature thought to be responsible for successful
biological control (Beddington et al. 1978, may & Hassell 1981). Models
of optimal patch use predict predation/parasitism levels between patches,
based on host/prey densities (see Cook & Hubbard 1977, Waage 1979, Iwasa
et al. 1984), but the power of these models varies. Murdoch et al. (1985)
examined the importance of this searching behavior using the successful olive
scale/Aphytis paramaculicornia DeBach &
Rosen - Coccophagoides utilis Doutt system. These
parasitoids do not aggregate in areas of high host density. Waage (1983) did
find that Diadegma spp.
attacking Plutella xylostella (L.) aggregated in
patches with greater host density, yet the proportion of hosts parasitized at
high host densities was not greater. Roland (1986) found similar results with
Cyzenis albicans; whether or not the eggs are clumped, the level
of parasitism is similar. Predictive models can be used to clarify the
mechanisms involved in natural enemy behavior and their importance. It might
be possible to take advantage of the simple rules that foragers use for
decisions on how long to remain in a patch, which hosts or prey to seek and
accept, when and where they will oviposit and especially for hymenopterous
parasitoids, what the sex ratio will be. If these decisions are made in
response to environmental cues, then they are potential field tools (Kareiva
& Odell 1987). Dicke et al. (1985) found that searching eucoilid
parasitoids remained longer in a patch with moderately higher kairomone
concentrations regardless of the actual density of Drosophila melanogaster
Meigen. Charnov & Skinner (1985) recommended careful reflection of both
the proximate causes of such responses and the evolutionary causes as
complementary approaches that enhance theory and application. It is also necessary to consider the
ultimate population effects on natural enemies given habitat manipulations
that exploit behavioral cues and maximize prey reduction. A recent example
giving particular attention to predator fitness shows that although juvenile
mantids exhibit a strong Type II functional response, such behavior rapidly
increases beyond the maximum gain in characteristics related to fitness (Hurd
& Rathet 1986). In any case, natural enemy response to environmental
manipulation should benefit through life table studies over many generations
(Hassell 1986) and optimal foraging modes that include longer term population
changes. REFERENCES: [Additional references
may be found at MELVYL Library ] Adkisson, P. L.
1958. The influence of fertilizer applications on populations of Heliothis zea (Boddie), and certain insect predators. J. Econ. Ent.
51: 757-59. Ali, A. D. &
T. E. Reagan. 1985. Vegetation manipulation impact on predator and prey
populations in Louisiana sugarcane ecosystems. J. Econ. Ent. 78: 1409-14. All, J. N. &
G. J. Musick. 1986. Management of vertebrate and invertebrate pests. p.
347-88. In: M. A. Sprague
& G. B. Triplett (eds.), No-tillage and Surface Tillage Agriculture. John
Wiley & Sons, New York Allen, W. W.
& R. F. Smith. 1958. Some factors influencing the efficiency of Apanteles medicaginis Muesebeck (Hymenoptera: Braconidae) as a
parasite of the alfalfa caterpillar Colias
philodice eurytheme Boisduval. Hilgardia
28: 1-42. Altieri, M. A.
1984. Patterns of insect diversity in monocultures and polycultures of
brussels sprouts. Pract. Ecol. 6: 227-32. Altieri, M. A.
& M. K. Anderson. 1986. An ecological basis for the development of
alternative agricultural systems for small farmers in the third world. Amer.
J. Alternat. Agric. 1: 30-8. Altieri, M. A.
& D. K. Letourneau. 1982. Vegetation management and biological control in
agroecosystems. Crop. Protect 1(4): 405-30. Altieri, M. A.
& D. K. Letourneau. 1984. Vegetation diversity and insect pest outbreaks.
CRC Crit. Rev. Plant Sci. 2: 131-69. Altieri, M. A.
& D. K. Letourneau. 1999. Environmental management to enhance biological
control in agroecosystems. In
Fisher, T. W. & T. S. Bellows, Jr. (eds) 1999. Handbook of Biological
Control: Principles and Applications. Academic Press, San Diego, CA 1046 p. Altieri, M. A.
& M. Liebman. 1986. Insect, weed, and plant disease management in
multiple cropping systems. p. 183-218. In:
C. A. Francis (ed.), Multiple Cropping Systems. MacMillan Publ., New York. Altieri, M. A.
& L. L. Schmidt. 1984. Abundance patterns and foraging activity of ant
communities in abandoned, organic and commercial apple orchards in northern
California. Agric. Ecosyst. Environ. 11: 3441-52. Altieri, M. A.
& L. L. Schmidt. 1985. Cover crop manipulation in northern California
apple orchards and vineyards: effects on arthropod communities. Biol. Agric.
Hortic. 3: 1-24. Altieri, M. A.
& L. L. Schmidt. 1986. Population trends, distribution patterns, and
feeding preferences of flea beetles (Phyllotreta
cruciferae Goeze) in
collard-wild mustard mixtures. Crop Protect. 5(3): 170-75. Altieri, M. A.
& L. L. Schmidt. 1987. Mixing cultivars of broccoli reduced populations
of the cabbage aphid, Breviocoryne
brassicae (Linnaeus). Calif.
Agric. 41(11-12): 24-6. Altieri, M. A.
& W. H. Whitcomb. 1979a. Manipulation of insect populations through
seasonal disturbance of weed communities. Prot. Ecol. 1: 185-202. Altieri, M. A.
& W. H. Whitcomb. 1979b. The potential use of weeds in the manipulation
of beneficial insects. Hort. Sci. 14: 12-18. Altieri, M. A.,
A. Schoonhoven & J. D. Doll. 1977. The ecological role of weeds in insect
pest management systems: a review illustrated with bean (Phaseolus vulgaris
L.) cropping systems. PNAS 23: 185-206. Altieri, M. A.,
R. C. Wilson & L. L. Schmidt. 1985. The effects of living mulches and
weed cover on the dynamics of foliage and soil arthropod communities in three
crop systems. Crop Protect. 4: 201-13. Altieri, M. A.,
C. A. Francis, A. Schoonhoven & J. Doll. 1978. Insect prevalence in bean
(Phaseolus vulgaris) and maize (Zea mays) polycultural systems. Field Crops Res. 1: 33-49. Altieri, M. A.,
W. J. Lewis, D. A. Nordlund, R. C. Gueldner & J. W. Todd. 1981. Chemical
interactions between plants and Trichogramma
sp. wasps in Georgia soybean fields. Prot. Ecol. 3: 259-63. Andow, D. 1983a.
Plant diversity and insect populations: interactions among beans, weeds and
insects. Ph.D. dissertation, Cornell University, Ithaca, New York. 201 p. Andow, D. 1983b.
The extent of monoculture and its effects on insect pest populations with
particular reference to wheat and cotton. Agric. Ecosyst. Environ. 9: 25-35. Andow, D. 1986.
Plant diversification and insect population control in agroecosystems. In: D. Pimentel (ed.), Some
Aspects of Integrated Pest Management. Dept. Ent., Cornell Univ., Ithaca, New
York. Andow, D. A.
& S. J. Risch. 1985. Predation in diversified agroecosystems: relations
between a coccinellid predator Coleomegilla
maculata and its food. J.
Appl. Ecol. 22: 357-72. Anonymous. 1969.
Principles of plant and animal control, Vol. 3, p. 100-69. Insect-pest
Management and Control, NAS, Washington, D.C. Arkin, G. F.
& H. M. Taylor (eds.). 1981. Modifying the Root Environment to Reduce
Crop Stress. Amer. Soc. Agric. Eng., St. Joseph, Missouri. 407 p. Bach, C. E.
1980a. Effects of plant density and diversity on the population dynamics of a
specialist herbivore, the striped cucumber beetle, Acalymma vittatta
(Fab.). Ecology 61: 1515-30. Bach, C. E.
1980b. Effects of plant diversity and time of colonization on an
herbivore-plant interaction. Oecologia (Berlin) 44: 319-26. Baker, R. S., M.
L. Laster & W. F. Kitten. 1985. Effects of the herbicide monosodium methanearsonate
on insect and spider populations in cotton fields. J. Econ. Ent. 78: 1481-84. Barbosa, P. &
D. K. Letourneau (eds.). 1988. Novel Aspects of Insect-plant Interactions.
John Wiley & Sons, New York. (in press). Barfield, B. J.
& J. F. Gerber (eds.). 1979. Modification of the Aerial Environment of
Plants. Amer. Soc. Agric. Eng., St. Joseph, Missouri. 538 p. Barney, R. J.
& B. C. Pass. 1986. Ground beetle (Coleoptera: Carabidae) populations in
Kentucky alfalfa and influence of tillage. J. Econ. Ent. 70: 511-17. Barney, R. J., W.
O. Lamp, E. J. Ambrust & G. Kapusta. 1984. Insect predator community and
its response to weed management in spring-planted alfalfa. Prot. Ecol. 6:
23-33. Bartlett, B. R.
1951. The action of certain "inert" dust materials on parasitic
Hymenoptera. J. Econ. Ent. 44: 891-96. Bartlett, B. R.
1964. Patterns in the host-feeding habit of adult parasitic Hymenoptera. Ann.
Ent. Soc. Amer. 57: 344-50. Beddington, J.
R., C. A. Free & J. M. Lawton. 1978. Characteristics of successful natural
enemies in models of biological control of insect pests. Nature 273(5663):
513-19. Beirne, B. P.
1985. Avoidable obstacles to colonization in classical biological control of
insects. Canad. J. Zool. 63: 743-47. Bellows, T. S.,
Jr. & T. W. Fisher, (eds) 1999. Handbook of Biological Control:
Principles and Applications. Academic Press, San Diego, CA. 1046 p. Bernays, E. A.
& A. C. Lewis. 1986. The effect of wilting on palatability of plants to Schistocerca gregaria, the desert locust. Oecologia
70: 132-35. Blumberg, A. Y.
& D. A. Crossley, Jr. 1983. Comparison of soil surface: arthropod
populations in conventional tillage, no-tillage and old field systems.
Agro-Ecosyst. 8: 247-53. Bobb, M. L. 1939.
Parasites of the oriental fruit moth in Virginia. J. Econ. Ent. 32: 605-09. Boethel, D. J.
& R. D. Eikenbary (eds.). 1986. Interactions of Plant Resistance and
Parasitoids and Predators of Insects. Ellis Horwood, Ltd., Chichester, Great
Britain. Bombosch, S.
1966. Occurrence of enemies on different weeds with aphids. p. 177-79. In: I. Hodek (ed.), Ecology of
Aphidophagous Insects. Czechoslovak Academic Printing House, Prague. Bottrell, D. R.
1980. Integrated Pest Management. Council on Environmental Quality. U. S.
Govt. Printing Off., Washington, D. C. 120 p. Brust, G. E., B.
R. Stinner & D. A. McCartney. 1985. Tillage and soil insecticide effects
on predator - black cutworm (Lepidoptera: Noctuidae) interactions in corn
agroecosystems. J. Econ. Ent. 78: 1389-92. Brust, G. E., B.
R. Stinner & D. A. McCartney. 1986. Predation by soil inhabiting
arthropods in intercropped and monoculture agroecosystems. Agric. Ecosyst.
Environ. 18: 145-54. Buren, W. F.
& W. H. Whitcomb. 1977. Ants of citrus: some considerations. Proc.
Intern. Soc. Citriculture 2: 496-98. Buschman, L. L.,
H. N. Pitre & H. F. Hodges. 1984. Soybean cultural practices: effects on
populations of geocorids, nabids, and other soybean arthropods. Environ. Ent.
13: 305-17. Campbell, B. C.
& S. S. Duffey. 1979. Tomatine and parasitic wasps: potential
incompatibility of plant antibiosis with biological control. Science 205:
700-02. Carroll, C. R.
1978. Beetles, parasitoids and tropical morning glories: a study in host
discrimination. Econ. Ent. 3: 79-86. Carroll, C. R.
& S. J. Risch. 1983. Tropical annual cropping systems: ant ecology.
Environ. Manag. 7: 51-7. Chandler, A. E.
F. 1968. The relationship between aphid infestations and oviposition by
aphidophagous Syrphidae (Diptera). Ann. Appl. Biol. 61: 425-34. Charnov, E. L. 1982. The Theory of Sex Allocation.
Princeton Univ. Press, Princeton, New Jersey. 355 p. Charnov, E. L. & S. W. Skinner. 1985. Complementary
approaches to the understanding of parasitoid oviposition decisions. Environ.
Ent. 14: 383-91. Chiang, H. C. 1970. Effects of manure applications and mite
predation on corn rootworm populations in Minnesota. J. Econ. Ent. 63:
934-36. 1982 Chiri, A. A. & E. F.
Legner. 1982. Host-searching kairomones alter behavior
of Chelonus sp. nr. curvimaculatus, a hymenopterous parasite of the pink bollworm, Pectinophora gossypiella (Saunders).
Environ. Entomol. 11(2):
452-455. 1983 Chiri, A. A. &
E. F. Legner. 1983. Field applications of host-searching kairomones
to enhance parasitization of the pink bollworm (Lepidoptera: Gelechiidae).
J. Econ. Entomol. 76(2):
254-255. 1986 Chiri, A. A. &
E. F. Legner. 1986. Response of three Chelonus (Hymenoptera: Braconidae) species to kairomones in
scales of six Lepidoptera. Canad.
Entomol. 118(4): 329-333. Clark, L. R. & M. J. Dallwitz. 1975. The life system of
Cardiaspina albitextura (Psyllidae),
1950-74. Aust. J. Zool. 23: 523-61. Clark, W. C. &
C. S. Holling. 1979. Process models, equilibrium structures and population
dynamics: on the formulation and testing of realistic theory in ecology.
Fortschr. Zool. 25: 29-52. Collins, F. L.
& S. J. Johnson. 1985. Reproductive response of caged adult velvetbean
caterpillar and soybean looper to the presence of weeds. Agric. Ecosyst.
Environ. 14: 139-49. Cook, R. M. &
S. F. Hubbard. 1977. Adaptive searching strategies in insect parasites. J.
Anim. Ecol. 46: 115-25. Cromartie, W. J.
1981. The environmental control of insects using crop diversity. p. 223-50. In: D. Pimentel (ed.), CRC
Handbook of Pest Management in Agriculture, Vol. 1. CRC Handb. Ser. In
Agric., CRC Press, Boca Raton. Florida. 597 p. Culliney, T. W.
& D. Pimentel. 1986. Ecological effects of organic agricultural practices
on insect populations. Agric. Ecosyst. Environ. 15: 253-66. Culliney, T. W.,
D. Pimentel & D. J. Lisk. 1986. Impact of chemically contaminated sewage
sludge on the collard arthropod community. Environ. Ent. 15: 826-33. DeBach, P. 1958a.
Application of ecological information to control citrus pests in California.
Proc. 10th Intern. Congr. Ent. 3: 187-94. DeBach, P. 1958b.
The role of weather and entomophagous species in the natural control of
insect populations. J. Econ. Ent. 51: 474-84. DeLima, J. O. G.,
& T. F. Leigh. 1984. Effect of cotton genotypes in the western bigeye bug
(Heteroptera: Miridae). J. Econ. Ent. 77: 898-902. DeLoach, C. J.
1970. The effect of habitat diversity on predation. Proc. Tall Timbers Conf.
Ecol. Anim. Control Habitat Management, Vol. 2: 223-41. Dempster, J. P.
1969. Some effects of weed control on the numbers of the small cabbage white
butterfly (Pieris rapae L.) on brussels sprouts.
J. Appl. Ecol. 6: 339-45. Dempster, J. P.
& T. H. Coaker. 1974. Diversification of crop ecosystems as a means of
controlling pests. p. 106-14. In:
D. P. Jones & M. E. Solomon (eds.), Biology in Pest and Disease Control.
John Wiley & Sons, New York. Dicke, M., M. C.
van Lenteren, J. G. F. Boskamp & R. van Voorst. 1985. Intensification and
elongation of host searching in Leptopilina
heterotoma (Thomson)
(Hymenoptera: Eucoilidae) through a kairomone produced by Drosophila melanogaster. J. Chem. Ecol. 11: 125-36. Dickler, E. 1978.
Influence of beneficial arthropods on the codling moth in an orchard with
green covered and clean cultivated soil. p. 16-18. In: Summaries of Papers Presented at the Joint FAO/IAEA
and IOBC/WPRS Research Coordination Meetings. Heidelberg, Germany. Paul
Parey, Berlin & Hamburg. Doutt, R. L.
& J. Nakata. 1973. The Tubus
leafhopper and its egg parasitoid: an endemic biotic system useful in grape
pest management. Environ. Ent. 2: 381-86. Downey, D. A.
& C. E. Caviness. 1973. Temperature, humidity and light studies in
soybean canopies. Bull. 784, Agric. Expt. Sta., University of Arkansas. 43 p. Duelli, P. 1980.
Adaptive and appetitive flight in the green lacewing, Chrysopa carnea.
Ecol. Ent. 5: 213-20. Duffey, S. S.
& K. A. Bloem. 1986. Plant defense-herbivore-parasite interactions and
biological control. p. 135-84. in:
M. Kogan (ed.), Ecological Theory and Integrated Pest Management Practice.
John Wiley & Sons, New York. Edmunds, G. F.,
Jr. 1973. Ecology of black pine leaf scale (Homoptera: Diaspididae). Environ.
Ent. 2: 765-77. Ehler, L. E.
& R. W. Hall. 1982. Evidence for competitive exclusion of introduced
natural enemies in biological control. Environ. Ent. 11: 1-4. Eller, B. M.
1977. Road dust induced increase leaf temperature. Environ. Pollut. 13:
99-107. El-Shazly, N. Z.
1972a. Der Einfluss aussere Faktoren auf die hämocytare Abwehrreaktion von Neomyzus circumflexus (Buck.) (Homoptera: Aphididae). Z. angew.
Ent. 70: 414-36. El Shazly, N. Z.
1972b. Der Einfluss von Ernahrung und alterbder Muttertieres auf die
hämocytare Abwehrreaktion von Neomyzus
circumflexus (Buck.).
Entomophaga 17: 203-09. Elzen, G. E., H.
J. Williams & S. B. Vinson. 1983. Response by the parasitoid Campoletis sonorensis (Hymenoptera: Ichneumonidae) to chemicals
(synomones) in plants: implications for host habitat location. Environ. Ent.
12: 1873-77. Farrow, R. A.
1981. Aerial dispersal of Scelio
fulgidus (Hym.:
Scelionidae), parasite of eggs of locusts and grasshoppers (Orth.:
Acrididae). Entomophaga 26: 349-55. Feeny, P. P.
1976. Plant appearance and chemical defense. Rec. Adv. Phytochem. 10: 1-40. Ferguson, H. J.
& R. M. McPherson. 1985. Abundance and diversity of adult Carabidae in
four soybean cropping systems in Virginia. J. Ent. Soc. Amer. 20: 163-71. Ferguson, H. J.,
R. M. McPherson & W. A. Allen. 1984. Effect of four soybean cropping
systems on the abundance of foliage-inhabiting insect predators. Environ.
Ent. 13: 1105-12. Ferro, D. N.
& E. E. Southwick. 1984. Microclimates of small arthropods: estimating
humidity within the leaf boundary layer. Environ. Ent. 13: 926-29. Ferro, D. N., R.
B. Chapman & D. R. Penman. 1979. Observations on insect microclimate and
insect pest management. Environ. Ent. 8: 1000-03. Flaherty, D.
1969. Ecosystems trophic complexity and Willamette mite Eotetranychus willametei
(Acarina: Tetranychidae) densities. Ecology 50: 911-16. Flaherty, D., C.
Lynn, F. Jensen & M. Hoy. 1971. Influence of environment and cultural
practices on spider mite abundance in southern San Joaquin Thompson seedless
vineyards. Calif. Agric. 25(11): 6-8. Flaherty, D. L.,
L. T. Wilson, W. M. Stern & H. Kido. 1985. Biological control in San
Joaquin Valley Vineyards. p. 501-20. In:
M. A. Hoy & D. C. Herzog (eds.), Biological Control in Agricultural IPM
Systems. Academic Press, San Diego, CA. Flanders, S. E.
1973. Habitat selection by Trichogramma.
Ann. Ent. Soc. Amer. 30: 208-10. Flint, H. M., J.
R. Merkle & M. Sledge. 1981. Attraction of male Collops vittatus
in the field by caryophylline alcohol. Environ. Ent. 10: 301-04. Flint, H. M., S.
S. Salter & S. Walters. 1979. Caryophyllene: an attractant for the green
lacewing. Environ. Ent. 8: 1123-25. Force, D. C.
& P. S. Messenger. 1964. Duration of development, generation time, and
longevity of three hymenopterous parasites of Therioaphis maculata,
reared at various constant temperatures. Ann. Ent. Soc. Amer. 54: 405-13. Foster, M. A.
& W. G. Ruesink. 1984. Influence of flowering weeds associated with
reduced tillage in corn on a black cutworm (Lepidoptera: Noctuidae)
parasitoid, Metorus rubens (Nees). Environ. Ent.
13: 664-68. Fox, L. R. &
W. W. Murdoch. 1978. Effects of feeding history of short-term and long-term
functional responses in Notonecta
hoffmanni. J. Anim. Ecol.
47: 945-59. Fox, M. D. &
B. J. Fox. 1986. The susceptibility of natural communities to invasion. p.
57-66. In: R. H. Groves
& J. J. Burdon (eds.), Ecology of Biological Invasions. Cambridge Univ.
Press, Sydney, Australia. Fye, R. E. &
D. J. Larsen. 1969. Preliminary evaluation of Trichogramma minutum
as a released regulator of lepidopterous pests of cotton. J. Econ. Ent. 62:
1291-96. Gardner, S. M.
& J. C. van Lenteren. 1986. Characterisation of the arrestment responses
of Trichogramma evanescens. Oecologia 68:
265-70. Gebhardt, M. R.
1981. Methods of pesticide application. p. 87-102. In: D. Pimentel (ed.), Handbook of Pest Management in
Agriculture, Vol. II. CRC Press, Inc., Boca Raton, Florida. Gerling, C. A.
1984. Selenium in agriculture and the environment. Agric. Ecosyst. Environ.
11: 37-65. Gilbert, L. E.
1978. Development of theory in the analysis of insect plant interactions. p.
116-54. In: D. J. Horn, et
al. (eds.), Analysis of Ecological Systems. Ohio State Univ. Press, Columbus,
Ohio. Ginevan, M. E.,
D. D. Lane & L. Greenberg. 1980. Ambient air concentration of sulfur
dioxide affects flight activity in bees. Proc. Nat. Acad. Sci. U.S.A. 77:
5631-33. Gould, F. 1986.
Simulation models for predicting durability of insect-resistant germ plasm:
Hessian fly (Diptera: Cecidomyiidae) in resistant winter wheat. Environ. Ent.
15: 11-23. Gould, W. P.
& R. L. Jeanne. 1984. Polistes
wasps (Hymenoptera: Vespidae) as control agents for lepidopterous cabbage
pests. Environ. Ent. 13: 150-56. Greenblatt, J. A.
& P. Barbosa. 1981. Effect of host's diet on two pupal parasitoids of the
gypsy moth: Brachymeria intermedia (Nees) and Coccygominus turionellae (L.). J. Appl.
Ecol. 18: 1-10. Greenblatt, J. A.
& W. J. Lewis. 1983. Chemical environment manipulation for pest insects
control. Environ. Management 7: 35-41. Grigg, D. B.
1974. The Agricultural Systems of the World. Cambridge Univ. Press, London.
358 p. Gross, H. R.
1981. Employment of kairomones in the management of parasitoids. p. 137-50. In: D. A Nordlund, R. L. Jones
& W. J. Lewis (eds.), Semiochemicals: Their Role in Pest Control. John
Wiley & Sons, New York. Gross, J. R.,
Jr., S. D. Pair & R. D. Jackson. 1985. Aggregation response of adult
predators to larval homogenates of Heliothis
zea and Spodoptera frugiperda
(Lepidoptera: Noctuidae) in whorl-state cotton. Environ. Ent. 14: 360-64. Hagen, K. S.
1962. Biology and ecology of predacious Coccinellidae. Ann. Rev. Ent. 7:
289-326. Hagen, K. S.
1986. Ecosystem analysis: plant cultivars (HPR), entomophagous species and
food supplements. p. 151-97. In:
D. J. Boethel & R. D. Eikenbary (eds.), Interactions of Plant Resistance
and Parasitoids and Predators of Insects. Ellis Horwood, Ltd., Chichester,
Great Britain. 244 p. Hamai, J. &
C. B. Huffaker. 1978. Potential of predation by Metaseiulus occidentalis
in compensating for increased, nutritionally induced, power of increase of Tetranychus urticae. Entomophaga 23:
225-37. Harris, V. E.
& J. W. Todd. 1980. Male-mediated aggregation of male, female and
5th-instar green stink bugs and concomitant attraction of a tachinid
parasite, Trichopoda pennipes. Ent. Expt. Appl. 27:
117-26. Hassell, M. P.
1978. The Dynamics of Arthropod Predator-prey Systems. Princeton Univ. Press,
Princeton, New Jersey. Hassell, M. P.
1986. Parasitoids and population regulation. p. 202-24. In: J. Waage & D. Greathead (eds.), Insect
Parasitoids. Academic Press, New York. Hatfield, J. L.
1982. Modification of the microclimate via management. p. 147-70. In: J. L. Hatfield & I. J.
Thomason (eds.), Biometerology in Integrated Pest Management. Academic Press,
New York. Hemenway, R.
& W. H. Whitcomb. 1967. Ground beetles of the genus Lebia latreilla
in Arkansas (Coleoptera: Carabidae): ecology and geographic distribution.
Proc. Arkansas Acad. Sci. 21: 15-20. Herzog, D. C.
& J. E. Funderburk. 1985. Plant resistance and cultural practice interactions
with biological control. p. 67-88. In:
M. A. Hoy & D. C. Herzog (eds.), Biological Control in Agricultural IPM
Systems. Academic Press, Orlando, Florida. Hislop, R. G.
& R. J. Prokopy. 1981. Mite predator responses to prey and
predator-emitted stimuli. J. Chem. Ecol. 7: 895-904. Hodek, I. 1973.
Biology of Coccinellidae. Czechoslovak Academic Publishing Co., Prague. Hogg, D. B. 1986.
Interaction between crop phenology and natural enemies: evidence from a study
of Heliothis population
dynamics on cotton. p. 98-124. In:
D. J. Boethel & R. D. Eikenbary (eds.), Interactions of Plant Resistance
and Parasitoids and Predators of Insects. Ellis Horwood, Ltd., Chichester,
Great Britain. Holliday, N. J.
& E. A. C. Hagley. 1984. The effect of sod type on the occurrence of
ground beetles (Coleoptera: Carabidae) in a pest management apple orchard.
Canad. Ent. 116: 165-71. Holmes, N. D.
1982. Population dynamics of the wheat stem sawfly, Cephus cinctus
(Hymenoptera: Cephidae) in wheat. Canad. Ent. 114: 775-88. Holmes, N. D., W.
A. Nelson, L. K. Peterson & C. W. Farstad. 1963. Causes of variations in
effectiveness of Bracon cephi (Gahan) (Hymenoptera:
Braconidae) as a parasite of the wheat stem sawfly. Canad. Ent. 95: 113-26. Horn, D. J. 1981.
Effects of weedy backgrounds on colonization of collards by green peach
aphid, Myzus persicae, and its major
predators. Environ. Ent. 10: 285-89. House, C. J.
& J. N. All. 1981. Carabid beetles in soybean agroecosystems. Environ.
Ent. 10: 194-96. House, G. J.
& B. R. Stinner. 1983. Arthropods in no-tillage soybean agroecosystems:
community composition and ecosystem interactions. Environ. Management 7:
23-8. Hoveland, C. S.,
G. A. Buchanan & M. C. Harris. 1976. Response of weeds to soil phosphorus
and potassium. Weed Sci. 24: 144-201. Huffaker, C. B.
& P. S. Messenger (eds.). 1976. Theory and Practice of Biological
Control. Academic Press, New York. 788 p. Huffaker, C. B.,
M. van de Vrie & J. A. McMurtry. 1970. Ecology of tetranychid mites and
their natural enemies: a review. II. Tetranychid populations and their
possible control by predators: an evaluation. Hilgardia 40: 391-458. Hulspas-Jordaan,
P. M. & J. C. van Lenteren. 1978. The relationship between host-plant
leaf structure and parasitization efficiency of the parasitic wasp, Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Med. Fac.
Landbouww. Rijksuniv. Gent 43: 431-40. Hurd, L. E. &
I. H. Rathet. 1986. Functional response and success in juvenile mantids.
Ecology 67: 163-67. Hurst, G. A. 1970.
The effects of controlled burning arthropod density and biomass in relation
to bobwhite quail brood habitat on a right-of-way. Proc. Tall Timbers Conf.
on Ecol. Anim. Contr. Habiata Management 2: 173-83. Hutchison, W. D.
& H. N. Pitre. 1983. Predation of Heliothis
virescens (Lepidoptera:
Noctuidae) eggs by Geocoris punctipes (Hemiptera:
Lygaeidae) adults on cotton. Environ. Ent. 12: 1652-56. Iwasa, Y., Y.
Suzuki & H. Matsuda. 1984. Theory of oviposition strategy of parasitoids.
I. Effect of mortality and limited egg number. Theor. Pop. Biol. 26: 205-27. Jackson, C. G.,
D. E. Bryan & R. Patana. 1969. Laboratory studies of Eucelatoria armigera,
a tachinid parasite of Heliothis
spp. J. Econ. Ent. 62: 907-09. Johnson, M. W.
& A. H. Hara. 1987. Influence of host crop of parasitoids (Hymenoptera)
of Liriomyza spp. (Diptera:
Agromyzidae). Environ. Ent. 16: 339-44. Jones, R. L., W.
J. Beroza, M. B. A. Bierl & A. N. Sparks. 1973. Host seeking stimulants
(Kairomones) for the egg parasite Trichogramma
evanescens. Environ. Ent. 2:
593-96. Kareiva, P. 1982.
Experimental and mathematical analyses of herbivore movement: quantifying the
influence of plant spacing and quality on foraging discrimination. Ecol.
Mono. 52: 261-82. Kareiva, P. &
G. Odell. 1987. Swarms of predators exhibit "preytaxis" if
individual predators are area-restricted search. Amer. Nat. 130: 233-70. Kemp, W. P. &
U. L. Moody. 1984. Relationships between regional soils and foliage
characteristics and western spruce budworm (Lepidoptera: Tortricidae) outbreak
frequency. Environ. Ent. 13: 1291-97. Kindler, S. D.
& R. Staples. 1970. Nutrients and the reaction of two alfalfa clones to
the spotted alfalfa aphid. J. Econ. Ent. 63: 939-40. Kirkton, R. M.
1970. Habitat management and its effects on populations of Polistes and Iridomyrmex. Proc. Tall Timbers
Conf. Ecol. Anim. Cont. Habitat Management 2: 243-46. Komareck, E. V.,
Sr. 1970. Insect control-fire for habitat management. Proc. Tall Timbers
Conf. Ecol. Animal Control Habitat Management 2: 157-71. Lasack, P. M.
& L. P. Pedigo. 1986. Movement of stalk borer larvae (Lepidoptera:
Noctuidae) from noncrop areas into corn. J. Econ. Ent. 79: 1697-1702. Lashomb, J. H.
& Y.-S. Ng. 1984. Colonization by Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera:
Chrysomelidae), in rotated and nonrotated potato fields. Environ. Ent. 13:
1352-56. Laster, M. L.
& R. E. Furr. 1972. Heliothis
populations in cotton-sesame interplantings. J. Econ. Ent. 65: 1524-25. Lawson, F. R., R.
L. Rabb, R. E. Guthrie & T. G. Bowery. 1961. Studies of an integrated
control system for hornworms in tobacco. J. Econ. Ent. 54: 93-97. Lawton, J. H. & S. McNeill. 1979. Between the devil and
the deep blue sea: on the problem of being a herbivore. p. 223-44. In: R. M. Anderson, B. D. Turner
& L. R. Taylor (eds.), Population Dynamics. Blackwell Scientific Publ.,
Oxford. 1970 Legner, E. F. 1970.
Contemporary considerations on the biological suppression of noxious
brachycerous Diptera that breed in accumulated animal wastes.
Proc. Calif. Mosq. Contr. Assoc., Inc. 38: 88-89. 1971 Legner, E. F. 1971.
Some effects of the ambient arthropod complex on the density and
potential parasitization of muscoid Diptera in poultry wastes. J.
Econ. Entomol. 64(1): 111-115. 1977 Legner, E. F. 1977.
Response of Culex spp.
larvae and their natural insect predators to two inoculation rates with Dugesia dorotocephala
(Woodworth) in shallow ponds. J.
Amer. Mosq. Contr. Assoc. 37(3):
435-440. 1979 Legner, E. F. 1979.
Considerations in the management of Tilapia for biological aquatic weed control. Proc. Calif. Mosq. & Vector Contr. Assoc., Inc. 47:
44-45. 1983a Legner, E. F. 1983.
Influence of residual Nonpareil almond mummies on densities of the
navel orangeworm and parasitization.
J. Econ. Entomol. 76(3): 473-475. 1983b Legner, E. F. 1983.
Imported cichlid behaviour in California. Proc. Intern. Symp. on Tilapia
in aquaculture, Nazareth, Israel, 8-13 May, 1983. Tel Aviv Univ. Publ. 59-63. 1986 Legner, E. F. 1986.
The requirement for reassessment of interactions among dung beetles,
symbovine flies and natural enemies.
Entomol. Soc. Amer. Misc. Publ. 61:
120-131. 1973 Legner, E. F.
& W. R. Bowen. 1973. Influence of available poultry manure
breeding habitat on emergence density of synanthropic flies (Diptera). Ann. Entomol. Soc. Amer. 66(3): 533-538. 1989 Legner, E. F.
& E. J. Dietrick. 1989. Coexistence of predatory Muscina stabulans and Ophyra aenescens [Dipt.: Muscidae] with dipterous prey in poultry manure. Entomophaga 34(4): 453-461. 1970 Legner, E. F.
& G. S. Olton. 1970. Worldwide survey and comparison of adult
predator and scavenger insect populations associated with domestic animal manure where
livestock is artificially congregated.
Hilgardia 40(9): 225-266. 1966 Legner, E. F., G.
S. Olton & F. M. Eskafi.
1966. Influence of physical
factors on the developmental stages of Hippelates
collusor in relation to the activities of its natural
parasites. Ann. Entomol. Soc. Amer.
59(4): 851-861. 1971 Legner, E. F., L.
Moore & R. A. Medved. 1971. Observations on predation of Hippelates collusor and distribution in southern California of associated fauna. J. Econ. Entomol. 64(2):
461-468. 1973 Legner, E. F., W.
R. Bowen, W. D. McKeen, W. F. Rooney & R. F. Hobza. 1973.
Inverse relationships between mass of breeding habitat and
synanthropic fly emergence and the measurement of population densities with sticky
tapes in California inland valleys.
Environ. Entomol. 2(2): 199-205. 1975 Legner, E. F., G. S.
Olton, R. E. Eastwood & E. J. Dietrick.
1975. Seasonal density,
distribution and interactions of predatory and scavenger arthropods in accumulating poultry wastes in coastal
and interior southern California.
Entomophaga 20(3): 269-283. 1980 Legner, E. F., R.
D. Sjogren & L. L. Luna.
1980. Arthropod fauna
cohabiting larval breeding sites of Leptoconops
foulki Clastrier & Wirth in the
Santa Ana River, California. J. Amer.
Mosq. Contr. Assoc. 40(1): 46-54. Leius, K. 1976. Influence of wild flowers on parasitism of
tent caterpillar and codling moth. Canad. Ent. 99: 444-46. Leston, D. 1973. The ant mosaic-tropical tree crops and the
limiting of pests and diseases. PANS 19: 311-41. Letourneau, D. K. 1983. The effects of vegetational
diversity on herbivorous insects and associated natural enemies: examples
from tropical and temperate agroecosystems. Ph.D. dissertation, University of
California, Berkeley. 109 p. Letourneau, D. K.
1987. The enemies hypothesis: tritrophic interactions and vegetational
diversity in tropical agroecosystems. Ecology 68: 1616-22. Letourneau, D. K.
& M. A. Altieri. 1983. Abundance patterns of a predator Orius tristicolor (Hemiptera: Anthocoridae), and its prey, Frankliniella occidentalis (Thysanoptera:
Thripidae): habitat attraction in polycultures versus monocultures. Environ.
Ent. 122: 1464-69. Levine, E. 1985.
Oviposition by the stalk borer, Papaipema
nebris (Lepidoptera:
Noctuidae), on weeds, plant debris, and cover crops in cage tests. J. Econ.
Ent. 78: 65-8. Levins, R. &
M. Wilson. 1980. Ecological theory and pest management. Ann. Rev. Ent. 25:
7-29. Lewis, W. J.
& D. A. Nordlund. 1985. Behavior-modifying chemicals to enhance natural
enemy effectiveness. p. 89-101. In:
M. A. Hoy & D. C. Herzog (eds.), Biological Control in IPM Systems.
Academic Press, San Diego, California. Lewis, W. J., R.
L. Jones, D. A. Nordlund & H. R. Gross, Jr. 1976. Kairomones and their
role in pest management. p. 7-14. In:
Proc. Northeastern Forest Inst. Work Conf. Gen. Tech. Rept. NE-27. U. S.
Dept. Agric. Liss, W. J., L.
J. Gut, P. H. Westigard & C. E. Warren. 1986. Perspectives on arthropod
community structure, organization and development in agricultural crops. Ann.
Rev. Ent. 31: 455-78. Litsinger, J. A.
& K. Moody. 1976. Integrated pest management in multiple cropping
systems. p. 293-316. In: G.
B. Triplett, P. A. Sanchez & R. I. Papendick (eds.), Multiple Cropping.
ASA Special Publ. No. 27, Madison, Amer. Soc. Agronomy. Louda, S. M.
1986. Insect herbivory in response to root-cutting and flooding stress on
native crucifers under field conditions. Acta Oecol. 7: 37-53. Luff, M. L. 1982.
Population dynamics of Carabidae. Ann. Appl. Biol. 101: 164-70. MacArthur, R. H.
& E. O. Wilson. 1967. The Theory of Island Biogeography. Princeton Univ.
Press, Princeton, New Jersey. 203 p. Manuwoto, S.
& J. M. Scriber. 1985. Differential effects of nitrogen fertilization of
three corn genotypes on biomass and nitrogen utilization by the southern
armyworm, Spodoptra eridania. Ecosyst. Environ.
14(1-2): 25-40. Martin, P. B., P.
D. Lingren, G. L. Greene & R. L. Ridgway. 1976. Parasitization of two
species of Plusiinae and Heliothis
spp. after release of Trichogramma
pretiosum in seven crops.
Environ. Ent. 5: 991. Mattson, P. C.,
M. A. Altieri & W. C. Gagne. 1984. Modification of small farmer practice
for better pest management. Ann. Rev. Ent. 29: 303-402. Mattson, W. J.,
Jr. 1980. Herbivory in relation to plant nitrogen content. Ann. Rev. Ecol.
Syst. 11: 119-67. Mattson, W. J.,
Jr. & N. D. Addy. 1975. Phytophagous insects as regulators of forest
primary production. Science 190: 515-22. May, R. M. &
R. M. Anderson. 1978. Regulation and stability of host-parasite interactions.
II. Destabilizing processes. J. Anim. Ecol. 47: 279-67. May, R. M. &
M. P. Hassell. 1981. The dynamics of multiparasitoid-host interactions. Amer.
Nat. 117: 234-61. Mayse, M. A.
1983. Cultural control in field crop fields: habitat management technique.
Environ. Management 7: 15. McCaffrey, J. P.
& R. L. Horsbargh. 1986. Functional response of Orius insidiosus
(Hemiptera: Anthocoridae) to the European red mite, Panonychus ulmi
(Acari: Tetranychidae) at different constant temperatures. Environ. Ent. 15:
532-35. McClure, M. S.
1980. Foliar nitrogen: a basis for host suitability for elongate hemlock
seeds, Fiorinia externa (Homoptera:
Diaspididae). Ecology 61: 72-9. McMurtry, J. A.
& G. T. Scriven. 1966. The influence of pollen and prey density on the
number of prey consumed by Amblyseius
hibisci (Chant) (Acarina:
Phytoseiidae). Ann. Ent. Soc. Amer. 59: 147-49. McMurtry, J. A.
& G. T. Scriven. 1968. Studies on predator-prey interactions between Amblyseius hibisci and Oligonychus
punicae: effects of
host-plant conditioning and limited quantities of alternate food. Ann. Ent.
Soc. Amer. 61: 393-97. Miles, P. W., D.
Aspinall & L. Rosenberg. 1982. Performance of the cabbage aphid, Brevicoryne brassicae (Linnaeus), on
water-stressed rape plants, in relation to changes in their chemical
composition. Aust. J. Zool. 30: 337-45. Monteith, L. G.
1960. Influence of plants other than the food plants of their host on
host-finding by tachinid parasites. Canad. Ent. 92: 641-52. Moran, N. &
W. D. Hamilton. 1980. Low nutritive quality as defense against herbivores. J.
Theoret. Biol. 86: 247-54. Morrow, P. A.
1977. The significance of phytophagous insects in the Eucalyptus forests of Australia. p. 19-29. In: W. J. Mattson (ed.), The
Role of Arthropods in Forest Ecosystems. Springer-Verlag, New York. Muggleton, J., D.
Lonsdale & B. R. Benham. 1975. Melanism in Adalia bipunctata
Linnaeus (Col.: Coccinellidae) and its relationship to atmospheric pollution.
J. Appl. Ecol. 12: 451-64. Murdoch, W. W.
1971. The developmental response of predators to changes in prey density.
Ecology 52: 133-37. Murdoch, W. W.
1979. Predation and the dynamics of prey populations. Fortschr. Zool. 25:
295-310. Murdoch, W. W.
& A. Oaten. 1975. Predation and population stability. Adv. Ecol. Res. 9:
2-131. Murdoch, W. W.,
J. Chesson & P. L. Chesson. 1985. Biological control in theory and
practice. Amer. Nat. 125: 344-66. Nafus, D. & I.
Schreiner. 1986. Intercropping maize and sweet potatoes. Effects on
parasitization of Ostrinia furnacalis eggs by Trichogramma chilonis. Agric. Ecosyst.
Environ. 15: 189-200. National Academy
of Sciences (NAS). 1969. Principles of plant and animal control. Vol. 3., p.
100-69. Insect-pest Management and Control. NAS, Washington, D. C. 508 p. Neetles, W. C.
1979. Eucelatoria sp.
females: factors influencing responses to cotton and okra plants. Environ.
Ent. 8: 619-23. Neuenschwander,
P. & K. S. Hagen. 1980. Role of the predator Hemerobius pacificus
in a non-insecticide treated artichoke field. Environ. Ent. 9: 492-95. Nilsson, C. 1985.
Impact of ploughing on emergence of pollen beetle parasitoids after
hibernation. Z. ang. Ent. 100: 302-08. Nordlund, D. A., R.
B. Chalfant & W. J. Lewis. 1985. Response of Trichogramma pretiosum
females to extracts of two plants attacked by Heliothis zea.
Agric. Ecosyst. Environ. 12: 127-33. Nordlund, D. A.,
R. L. Jones & W. J. Lewis. 1981a. Semiochemicals: Their Role in Pest Control.
John Wiley & Sons, New York. Nordlund, D. A.,
W. J. Lewis & H. R. Gross. 1981b. Elucidation and employment of
semiochemicals in the manipulation of entomophagous insects. p. 463-75. In: E. R. Mitchell (ed.),
Management of Insect Pests With Semiochemicals: Concepts and Practice. Plenum
Press, New York. Nordlund, D. A.,
W. J. Lewis & M. A. Altieri. 1988. Influences of plant produced
allelochemicals on the host and prey selection behavior of entomophagous
insects. In P. Barbosa &
D. K. Letourneau (eds.), Novel Aspects of Insect-plant Interactions. John
Wiley & Sons, New York. Norman, M. J. T.
1979. Annual cropping systems in the tropics: an introduction. Univ. of
Florida Press, Gainesville, Florida. Norris, R. F.
1986. Weeds and integrated pest management systems. Hort. Sci. 21: 402-10. Obrycki, J. J.
& M. J. Tauber. 1984. Natural enemy activity on glandular pubescent
plants in the greenhouse: an unreliable predictor of effects in the fields.
Environ. Ent. 13: 679-83. O'Connor, B. A.
1950. Premature nutfall of coconuts in the British Solomon Islands
Protectorate. Agric. J. (Fiji Dept. Agric.) 21(1-2): 21-42. Okuba, A. 1980.
Diffusion and Ecological Problems: Mathematical Models. Springer-Verlag, New
York. 254 p. Orr, D. B. &
D. J. Boethel. 1986. Influence of plant antibiosis through four trophic
levels. Oecologia 70: 242-49. Perfecto, I., B.
Horwith, J. Vandermeer, B. Schultz, H. McGuiness & A. Dos Santos. 1986.
Effects of plant diversity and density on the emigration rate of two ground
beetles, Harpalus pennsylvanicus and Evarthrus sodalis (Coleoptera: Carabidae), in a system of tomatoes
and beans. Environ. Ent. 15: 1028-31. Perrin, R. M.
1975. The role of the perennial stinging nettle Urtica dioica,
as a reservoir of beneficial natural enemies. Ann. Appl. Biol. 81: 289-97. Perrin, R. M.
1977. Pest management in multiple cropping systems. Agro-Ecosyst. 3: 93-118. Perrin, R. M.
1980. The role of environmental diversity in crop protection. Prot. Ecol. 2:
77-114. Perrin, R. M.
& M. L. Phillips. 1978. Some effects of mixed cropping on the population
dynamics of insect pests. Ent. Expt. Appl. 24: 385-93. Petters, R. M.
& R. V. Mettus. 1982. Reproductive performance of Bracon hebetor
females following acute exposure to SO2 in air. Environ. Poll.,
Ser. A27: 155-63. Pimentel, D.
1961. Species diversity and insect population outbreaks. Ann. Ent. Soc. Amer.
54: 76-86. Podoler, M. &
D. Rogers. 1975. A new method for the identification of key-factors from
life-table data. J. Anim. Ecol. 44: 85-114. Pollard, D. G.
1971. Hedges VI: habitat diversity and crop pests-- a study of Brevicoryne brassicae and its syrphid
predators. J. Appl. Ecol. 8: 751-80. Powell, W. 1986.
Enhancing parasitoid activity in crops. p. 319-35. In: J. Waage & D. Greathead (eds.), Insect
Parasitoids. Academic Press, London. Powell, W., G. J.
Dean & N. Wilding. 1986. The influence of weeds on aphid-specific natural
enemies in winter wheat. Crop. Protect. 4: 182-89. Price, P. W.
1976. Colonization of crops by arthropods: non-equilibrium communities in
soybean fields. Environ. Ent. 5: 605-11. Price, P. W.
1981. Relevance of ecological concepts to practical biological control. p.
3-19. In: G. C. Papavizas et
al. (eds.), Biological Control in Crop Protection. Beltsville Symp. Agric.
Res. #5. U. S. A. Price, P. W.
1986. Ecological aspects of host plant resistance and biological control:
interaction among three trophic levels. p. 11-30. In: D. J. Boethel & R. D. Eikenbary (eds.),
Interactions of Plant Resistance and Parasitoids and Predators of Insects.
Ellis Horwood, Ltd., Chichester, Great Britain. Price, P. W.
& G. P. Waldbauer. 1975. Ecological aspects of pest management. p. 33-68.
In: R. L. Metcalf & W.
H. Luckman (eds.), Introduction to Insect Pest Management, 2nd ed. John Wiley-Interscience,
New York. Price, P. W., B.
J. Rathke & D. A. Gentry. 1974. Lead in terrestrial arthropods: evidence
for biological concentration. Environ. Ent. 3: 370-72. Price, P. W., C.
E. Bouton, P. Gross, B. A. McPheron, J. N. Thompson & A. E. Weis. 1980.
Interactions among three trophic levels: influence of plants on interactions
between insect herbivores and natural enemies. Ann. Rev. Ecol. Syst. 11:
41-65. Putman, W. L.
& D. C. Herne. 1966. The role of predators and other biotic factors in
regulating the population density of phytophagous mites in Ontario peach
orchards. Canad. Ent. 98: 808-20. Rabb, R. L. 1978.
A sharp focus on insect populations and pest management from a wide-area
view. Bull. Ent. Soc. Amer. 24: 55-61. Rabb, R. L, R. E.
Stinner & R. van den Bosch. 1976. Conservation and augmentation of
natural enemies. p. 233-54. In:
C. B. Huffaker & P. S. Messenger (eds.), Theory and Practice of
Biological Control. Academic Press, New York. Raros, R. S.
1973. Prospects and problems of integrated pest control in multiple cropping.
IRRI Saturday Seminar. Los Baños, Philippines. 20 p. Rasmy, A. H.
1977. Predatory efficiency and biology of the predatory mite Amblyseius gossipii (Acarina: Phytoseiidae) as affected by physical surfaces
of the host plant. Entomophaga 2: 421-23. Rasmy, A. H.
& E. M. Elbanhawy. 1974. Behaviour and bionomics of the predatory mite Phytoseius plumifer (Acarina: Phytoseiidae) as affected by physical
surfaces of the host plant. Entomophaga 19: 255-57. Read, D. P., P.
P. Feeny & R. B. Root. 1970. Habitat selection by the aphid parasite Diatreiella rapae (Hymenoptera: Braconidae)
and hyperparasite Charips brassicae (Hymenoptera:
Cynipidae). Canad. Ent. 102: 1567-78. Ridgway, R. L.,
E. G. King & J. L. Carrillo. 1976. Augmentation of natural enemies for
control of plant pests in the western hemisphere. p. 379-416. In: R. L. Ridgway & S. B.
Vinson (eds.), Biological Control by Augmentation of Natural Enemies. Plenum
Press, New York. Riechert, S. E.
& T. Lockley. 1984. Spiders as biological control agents. Ann. Rev. Ent.
29: 299-320. Riehl, L. A., R.
F. Brooks, C. W. McCoy, T. W. Fisher & H. A. Dean. 1980. Accomplishments
toward improving integrated pest management for citrus. p. 319-63. In: C. B. Huffaker (ed.), New
Technology of Pest Control. John Wiley, New York. Risch, S. J.
1980. The population dynamics of several herbivorous beetles in a tropical
agroecosystem: the effect of intercropping corn, beans and squash in Costa
Rica. J. Appl. Ecol. 17: 593-612. Risch, S. J.
1981. Insect herbivore abundance in tropical monocultures and polycultures:
an experimental test of two hypotheses. Ecology 62: 1325-40. Risch, S. J.
1987. Agricultural ecology and insect outbreaks. p. 217-33. In: P. Barbosa & J. C.
Schultz (eds.), Insect Outbreaks. Academic Press, New York. Risch, S. J., D.
Andow & M. A. Altieri. 1983. Agroecosystem diversity and pest control:
data, tentative conclusions and new directions. Environ. Ent. 12: 625-29. Risch, S. J., D.
Pimentel & H. Grover. 1986. Corn monoculture versus old field: effects of
low level of insecticides. Ecology 67: 505-15. Risch, S. J., R.
Wrubel & D. Andow. 1982. Foraging by a predaceous beetle, Coleomegilla maculata (Coleoptera:
Coccinellidae), in a polyculture: effects of plant density and diversity.
Environ. Ent. 11: 949-50. Robinson, J. V.
& J. E. Dickerson. 1987. Does invasion sequence affe4ct community
structure? Ecology 68: 587-95. Rogers, D. J.
& M. J. Sullivan. 1986. Nymphal performance of Geocoris punctipes
(Hemiptera: Lygaeidae) on pest-resistant soybeans. Environ. Ent. 15: 1032-36. Roland, J. 1986.
Parasitism of winter moth in British Columbia during build-up of its
parasitoid Cyzenis albicans: attack rate on oak
vs. apple. J. Anim. Ecol. 55: 215-34. Root, R. B. 1973.
Organization of plant-arthropod association in simple and diverse habitats:
the fauna of collards (Brassica
oleraceae). Ecol. Monogr.
43: 95-124. Ruberson, J. R.,
M. J. Tauber & C. A. Tauber. 1986. Plant feeding by Podisus maculivintris
(Hymenoptera: Pentatomidae): effect on survival, development and
preoviposition period. Environ. Ent. 15: 894-97. Saks, M. E. &
C. R. Carroll. 1980. Ant foraging activity in tropical agroecosystems.
Agro-Ecosyst. 6: 177-88. Sato, Y. & N.
Ohsaki. 1987. Host-habitat location by Apanteles
glomeratus and effects of
food-plant on host-parasitism. Ecol. Ent. 12: 291-97. Schlinger, E. I.
& E. J. Dietrick. 1960. Biological control of insect pests aided by
strip-farming alfalfa in experimental programs. Calif. Agric. 14: 15. Scriber, J. M.
1984. Nitrogen nutrition of plants and insect invasion. p. 441-60. In: R. D. Hauck (ed.), Nitrogen
in Crop Production. Amer. Soc. Agronomy. Shah, M. A. 1981.
The influence of plant surfaces on the searching behavior of coccinellid
larvae. Ent. Expt. Appl. 31: 377-80. Shahjahan, M.
1974. Erigeron flowers as
food and attractive odor source for Peristenus
pseudopallipes, a braconid
parasitoid of the tarnished plant bug. Environ. Ent. 3: 69-72. Shahjahan, M.
& A. S. Streams. 1973. Plant effects on host-finding by Leiphron pseudopallipes (Hymenoptera: Braconidae), a parasitoid of
the tarnished plant bug. Environ. Ent. 2: 921-25. Shaw, M. C., M.
C. Wilson & C. L. Rhykerd. 1986. Influence of phosphorous and potassium
fertilization on damage to alfalfa, Medicago
sativa Linnaeus, by the
alfalfa weevil, Hypera postica (Gyllenhall) and potato
leafhopper, Empoasca fabae (Harris). Crop Protection
5: 245-49. Sheehan, W. 1986.
Response by specialist and generalist natural enemies to agroecosystem
diversification: a selective review. Environ. Ent. 15: 456-61. Simberloff, D.
1985. Island biogeographic theory and integrated pest management. p. 19-35. In: M. Kogan (ed.), Ecological
Theory and Integrated Pest Management Practice. John Wiley & Sons, New
York. Slosser, J. E.,
P. W. Jacoby & J. R. Price. 1985. Management of sand shinnery oak for
control of the boll weevil (Coleoptera: Curculionidae) in the Texas rolling
plains. J. Econ. Ent. 78: 383-89. Smith, J. G.
1976a. Influence of crop background on natural enemies of aphids on brussels
sprouts. Ann. Appl. Biol. 83: 15-29. Smith, R. F.
& H. T. Reynolds. 1972. Effects of manipulation of cotton agroecosystems
on insect populations. p. 373-406. In:
M. T. Farvar & J. P. Milton (eds.), The Careless Technology: Ecology and
International Development. Natural History Press, Garden City, New York. Solomon, M. G.
1981. Windbreaks as a source of orchard pests and predators. p. 273. In: J. M. Thresh (ed.), Pests,
Pathogens and Vegetation. Pitman Publ. Co., Boston, Massachusetts. Southwood, T. R.
E. & N. H. Comins. 1976. A synoptic population model. J. Anim. Ecol. 45:
949-65. Speight, H. R.
& J. H. Lawton. 1976. The influence of weed cover on the mortality
imposed on artificial prey by predatory ground beetles in cereal fields.
Oecologia 23: 211-33. Sprague, M. A.
1986. Overview. p. 1-18. In:
M. A. Sprague & G. B. Tiplett (eds.), No-tillage and Surface-tillage
Agriculture. John Wiley & Sons, New York. Sprenkel, R. K.,
W. M. Brooks, J. W. van Duyn & L. L. Deitz. 1979. The effects of three
cultural variables on the incidence of Nomuroea
rileyi, phytophagous
Lepidoptera, and their predators on soybeans. Environ. Ent. 8: 337-39. Stenseth, N. C.
1981. How to control pest species: application of models from the theory of
island biogeography in formulating pest control strategies. J. Appl. Ecol.
18: 773-94. Stern, V. M.
1981. Environmental control of insects using trap crops, sanitation,
prevention and harvesting. p. 199-207. In:
D. Pimentel (ed.), CRC Handbook of Pest Management in Agriculture, Vol. 1.
CRC Press, Boca Raton, Florida. Stern, V. M., R.
van den Bosch & T. F. Leigh. 1964. Strip cutting of alfalfa for Lygus bug control. Calif.
Agric. 18: 4-6. Stinner, R. E.,
M. Saks & L. Dohse. 1986. Modeling of agricultural pest displacement. p.
235-41. In: W.
Danthanarayana (ed.), Insect Flight: Dispersal and Migration.
Springer-Verlag, New York. Stinner, R. E.,
C. S. Barfield, J. L. Stimac & L. Dohse. 1983. Dispersal movement of insect
pests. Ann. Rev. Ent. 28: 319-35. Strong, D. R.
1979. Biogeographical dynamics of insect-host plant communities. Ann. Rev.
Ent. 24: 89-119. Strong, D. R., J.
H. Lawton & T. R. E. Southwood. 1984. Insects on plants. Blackwell
Scientific, Great Britain. 313 p. Syme, P. D. 1975.
The effects of flowers on the longevity and fecundity of two native parasites
of the European pine shoot moth in Ontario. Environ. Ent. 4: 337-46. Talkington, M. L.
& R. E. Berry. 1986. Influence of tillage in peppermint on Fumibotys fumalis (Lepidoptera: Pyralidae), a common groundsel, Senicio vulgaris, and soil chemical components. J. Econ. Ent. 79:
1590-94. Tamaki, G. &
R. W. Weeks. 1972. Biology and ecology of two predators, Geocoris pallens
Stal and G. fullatus (Say). USDA Tech.
Bull. 1446. 46 p. Telenga, N. A.
1958. Biological method of pest control in crops and forest plants in the
USSR. p. 1-15. In: Report of
the Soviet Delegation, Ninth International Conference on Quarantine Plant
Protection. Moscow, USSR. Telenga, N. A.
& G. N. Zhigaev. 1959. The influence of different soil cultivation on
reproduction of Caenocrepis bothynoderis, an egg parasite
of beet weevil. Nauch. Tr. Ukr. Nauch. Issled. Inst. Zashch. Rast. 8: 68-75. Theuinissen, J.
& H. den Ouden. 1980. Effects of intercropping with Spergula arvensis
on pests of Brussels sprouts. Ent. Expt. Appl. 27: 260-68. Thiele, H. V.
1977. Quantitative investigations on the distribution of carabids. In: Carabid Beetles in Their
Environment. Springer-Verlag, Berlin. Thorpe, K. W.
1985. Effects of height and habitat type on egg parasitism by Trichogramma minutum and T. pretiosum (Hymenoptera: Trichogrammatidae). Agric.
Ecossyt. Environ. 12: 117-26. Thorpe, W. H.
& H. B. Caudle. 1938. A study of the olfactory responses of insect
parasites to the food plant of their host. Parasitology 30: 523-28. Thresh, J. M.
1981. Pests, Pathogens and Vegetation: The Role of Weeds and Wild Plants in
the Ecology of Crop Pests and Diseases. Putman Publ., Inc., Massachusetts.
517 p. Topham, M. &
J. W. Beardsley. 1975. An influence of nectar source plants on the New Guinea
sugarcane weevil parasite, Lixophaga
sphenophori (Villeneuve).
Proc. Hawaiian Ent. Soc. 22: 145-55. Treacy, M. F., G.
R. Zummo & J. H. Benedict. 1985. Interactions of host-plant resistance in
cotton with predators and parasites. Agric. Ecosyst. Environ. 13: 151-57. Trumble, J. T.,
J. D. Hare, R. C. Musselman & P. M. McCool. 1987. Ozone-induced changes
in host-plant suitability: interactions of Keiferia lycopersicella
and Lycopersicon esculentum. J. Chem. Ecol. 13:
203-18. Tukahirwa, E. M.
& T. H. Coaker. 1982. Effect of mixed cropping on some insect pests of
Brassicas: reduced Brevicoryne
brassicae infestations and
influences of epigeal predators and the disturbance of oviposition behaviour
in Delia brassicae. Ent. Expt. Appl. 32:
129-40. Turnbull, A. L.
1967. Population dynamics of exotic insects. Bull. Ent. Soc. Amer. 13:
333-37. Umeozor, O. C.,
J. W. van Duyn, J. R. Bradley, Jr., & G. G. Kennedy. 1985. Comparison of
the effect of minimum-tillage treatments on the overwintering emergence of
European corn borer (Lepidoptera: Pyralidae) in cornfields. J. Econ. Ent. 78:
937-39. USDA. 1973.
Monoculture in agriculture: extent, causes and problems: report of the task
force on spatial heterogeneity in agricultural landscapes and enterprises.
Washington, D. C., USDA. 64 p. van den Bosch, R.
1968. Comments on population dynamics of exotic insects. Bull. Ent. Soc.
Amer. 14: 112-15. van den Bosch, R.
& V. M. Stern. 1969. The effect of harvesting practices on insect
populations in alfalfa. p. 47-54. In:
Proc. Tall Timbers Conf. Ecol. Animal Control Habitat Management.
Tallahassee, Vol. 1. Tall Timbers Res. Sta., Tallahassee, Florida. van den Bosch, R.
& A. D. Telford. 1964. Environmental modification and biological control.
p. 459-88. In: P. DeBach
(ed.), Biological Control of Insect Pests and Weeds. Reinhold Publ. Co., New
York. Vandermeer, J.
& D. A. Andow. 1986. Prophylactic and responsive components of an
integrated pest management program. J. Econ. Ent. 79: 299-302. van Emden, H. F.
1965. The role of uncultivated land in the biology of crop pests and
beneficial insects. Sci. Hort. 17: 121-36. van Emden, H. F.
& K. S. Hagen. 1976. Olfactory reactions of the green lacewing, Chrysopa carnea, to tryptophan and certain breakdown points.
Environ. Ent. 5: 469-73. van Emden, H. F.
& G. F. Williams. 1974. Insect stability and diversity in agroecosystems.
Ann. Rev. Ent. 19: 455-75. Vet, L. E. M.
1983. Host habitat location through olfactory cues by Leptopilina clavipes
(Hartig) (Hym.: Eucoilidae), a parasite of fungivorous Drosophila: the influence of conditioning. Neth. J. Zool.
33: 225-48. Vinson, S. B.
1977. BEhavioural chemicals in the augmentation of natural enemies. p.
237-79. In: R. L. Ridgway
& S. B. Vinson (eds.), Biological Control by Augmentation of Natural
Enemies. Plenum Press, New York. Vinson, S. B.
1981. Habitat location. p. 51-77. In:
D. A. Nordlund, R. L. Jones & W. J. Lewis (eds.), Semiochemicals: Their
Role in Pest Control. John Wiley & Sons, New York. Waage, J. K.
1979. Foraging in patchily-distributed hosts by the parasitoid, Nemeritis canescens. J. Anim. Ecol. 48: 353-71. Waage, J. K.
1983. Aggregation in field parasitoid populations: foraging time allocation
by a population of Diadegma
(Hymenoptera: Ichneumonidae). Ecol. Ent. 8: 447-53. Walker, G. P., L.
R. Nault & D. E. Simonet. 1984. Natural mortality factors acting on
potato aphid 9Macrosiphum euphorbiae) populations in
processing-tomato fields in Ohio. Environ. Ent. 13: 724-32. Wallin, H. 1985.
Spatial and temporal distribution of some abundant carabid beetles
(Coleoptera: Carabidae) in cereal fields and adjacent habitats. Pedobiologia
28: 19-34. Ware, G. W., W.
P. Cahill, P. O. Gerhardt & J. M. Witt. 1970. Pesticide drift. IV.
On-target deposits from aerial application of insecticides. J. Econ. Ent. 63:
1982-83. Watson, T. F.
& W. E. Larsen. 1968. Effects of winter cultural practices on the pink
bollworm in Arizona. J. Econ. Ent. 61: 1041-44. Way, M. J. &
G. Murdie. 1965. An example of varietal variations in resistance of Brussels
sprouts. Ann. Appl. Biol. 56: 326-28. Wellington, W. S.
1983. Biometeorology of dispersal. Bull. Ent. Soc. Amer. 29: 24-9. Whitham, T. G.
1983. Host manipulation by parasites: within-plant variation as a defense against
rapidly evolving pests. p. 15-42. In:
R. F. Denno & M. S. McClure (eds.), Variable Plants and Herbivores in
Natural and Managed Systems. Academic Press, New York. Wilbert, H. 1977.
Der Honigtau als Resz und Engergiequelle für Entomophage Insekten. Apidologie
8: 393-400. Williams, D. W.
1984. Ecology of the blackberry-leafhopper-parasite system and its relevance
to California grape agroecosystems. Hilgardia 52: 1-33. Wipperfürth, T.,
K. S. Hagen & T. E. Mittler. 1987. Egg production by the coccinellid Hippodaemia convergens fed on two morphs of
the green peach aphid, Myzus
persicae. Ent. Expt. Appl.
44: 195-98. Wolfson, J. L.
1980. Oviposition response of Pieris
rapae to environmentally
induced variation in Brassica
nigra. Ent. Expt. Appl. 27:
223-32. Wong, M. H. 1985.
Heavy metal contamination of soils and crops from auto traffic, sewage
sludge, pig manure and chemical fertilizer. Agric. Ecossyt. Environ. 13:
139-49. Zhody, N. Z. M.
1976. On the effect of food of Myzus
persicae Sulz. on the
hymenopterous parasite Aphelinus
asychis Walker. Oecologia
26: 185-91. |