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SPOTTED  ALFALFA  APHID

 

Therioaphis maculata  (Buckton) -- Aphididae

(Contacts)

 

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This aphid, indigenous to the Old World where it attacks alfalfa and some clovers (Manglitz & Russell 1974), spread through the southwestern United States and California rapidly causing much damage to alfalfa (Smith 1959).  The presence in alfalfa of native aphid predators capable of reproducing during the summer months and the availability of a selective insecticide made possible the evolution of an integrated control program that has proved highly satisfactory in control of the spotted alfalfa aphid (Smith & Hagen 1959, Stern et al. 1959, Stern & van den Bosch 1959, Hagen et al. 1969).  Most aphid predators reproduce in the spring and fall months in California, but relatively few are reproductive during the summer months, probably because during their evolutionary history aphids have been scarce on low vegetation during the hot dry California summers.  The main aphid predators in California are ladybird beetles in the genus Hippodamia, and in most valleys of California H. convergens and H. quinquesignata are the two most important species (Hagen 1962, Hagen & van den Bosch 1968, Smith & Hagen 1965, 1966).  In the Imperial Valley, in addition to H. convergens, Cycloneda sanguinea L. is active against T. trifolii throughout the year (Dickson et al. 1955).

 

Three exotic parasitoids were introduced from the Old World into California in 1955-56:  Aphelinus asychis Walker, Praon exsoletum and Trioxys complanatus.  By 1959 all three species were established in most of the alfalfa districts, and were contributing significantly to biological control of the aphid (van den Bosch et al. 1959).  Trioxys complanatus was generally dominant over the other two species.  Phenologically, Trioxys is very active during spring, autumn and winter, while P. exsoletum largely confines its activity to the spring and fall.  Aphelinus is most active during the cooler, more humid times of the year (van den Bosch et al. 1964).  In total they greatly supplement one another, relative to the whole range of the aphid in California.  Bioclimatic studies by Messenger (1972) suggested that climate is the key feature in their pattern of distribution.  In areas of overlap, competition between the parasitoids can occur, the outcome of which can be influenced by climate.

 

The three parasitoids were also released in Arizona during 1955-57, and recoveries of each species were made and T. complanatus became well established in southern Arizona where it is a substantial control factor (Barnes 1960).  In Kansas, either the native A. semiflavus of A. asychis from France and India were colonized in 1956.  Aphids on alfalfa in greenhouses became heavily parasitized by this culture, but it is not certain if the Aphelinus involved was the native or the introduced A. asychis (Simpson et al. 1959). 

 

In the eastern United States, the three parasitoids were cultured in the USDA Moorestown laboratory in 1956 and released against the yellow clover aphid, Therioaphis trifolii (Monell), which mainly attacks red clovers.  The original stock of P. exsoletum came from France, A. asychis from Israel, and T. complanatus from the yellow clover aphid in New Jersey.  It is believed that the latter parasitoid had already been accidentally introduced into the United States (Mackauer & Stary 1967).  Angalet (1970) reported all three species as parasitizing spotted alfalfa aphid in New Jersey, Delaware and Maryland.  Maximum parasitism in autumn was 51%.  Spotted alfalfa aphid in southern California was found susceptible to infection by five species of Entomophthora, two of which also occur in the Old World.  Epizootics in high populations were widespread in the autumn of 1955 (hall & Dunn 1957). 

 

Please see the following for additional detail on biological control effort and biologies of host and natural enemies (Harpaz 1955, van den Bosch 1957, Hall & Dunn 1958, Schlinger & Hall 1959, Hall et al. 1962, Force & Messenger 1964a,b, 1965, 1968; Mackauer & Finlayson 1967, Messenger 1968).

 

 

REFERENCES:            [Additional references may be found at:   MELVYL Library ]

 

 

Angalet, G. W.  1970.  Population, parasites, and damage of the spotted alfalfa aphid in New Jersey, Delaware and the eastern shore of Maryland.  J. Econ. Ent. 63:  313-15.

 

Barnes, O. L.  1960.  Establishment of imported parasites of the spotted alfalfa aphid in Arizona.  J. Econ. Ent. 53:  1094-96.

 

Dickson, R. C., E. F. Laird, Jr. & G. R. Pesho.  1955.  The spotted alfalfa aphid (yellow clover aphid on alfalfa).  Hilgardia 24:  93-118.

 

Force, D. C. & P. S. Messenger.  1964a.  Duration of development, generation time, and longevity of three hymenopterous parasites of Therioaphis maculata, reared at various constant temperatures.  Ann. Ent. Soc. Amer. 57:  405-13.

 

Force, D. C. & P. S. Messenger.  1964b.  Fecundity, reproductive rates, and innate capacity for increase of three parasites of Therioaphis maculata (Buckton).  Ecology 45:  706-15.

 

Force, D. C. & P. S. Messenger.  1965.  Laboratory studies on competition among three parasites of the spotted alfalfa aphid, Therioaphis maculata (Buckton).  Ecology 46:  953-59.

 

Force, D. C. & P. S. Messenger.  1968.  The use of laboratory studies of three hymenopterous parasites to evaluate their field potential.  J. Econ. Ent. 61:  1374-78.

 

Hagen, K. S.  1962.  Biology and ecology of predaceous Coccinellidae.  Ann. Rev. Ent. 7:  289-326.

 

Hagen, K. S. & R. van den Bosch.  1968.  Impact of pathogens, parasites, and predators on aphids.  Ann. Rev. Ent. 13:  325-84.

 

Hagen, K. S., R. van den Bosch & D. L. Dahlsten.  1969.  The importance of naturally-occurring biological control in the western United States.  In:  C. B. Huffaker (ed.), Biological Control.  Plenum / Rosetta Press, New York.  511 p.

 

Hall, I. M. & P. H. Dunn.  1957.  Entomophthorous fungi parasitic on the spotted alfalfa aphid.  Hilgardia 27:  159-81.

 

Hall, I. M. & P. H. Dunn.  1958.  Artificial dissemination of entomophthorous fungi pathogenic to the spotted alfalfa aphid in California.  J. Econ. Ent. 51:  341-44.

 

Hall, J. C., E. I. Schlinger & R. van den Bosch.  1962.  Evidence for the separation of the "sibling species" Trioxys utilis and Trioxys pallidus (Hymenoptera: Braconidae, Aphidiinae).  Ann. Ent. Soc. Amer. 55:  566-68.

 

Harpaz, I.  1955.  Bionomics of Therioaphis maculata (Buckton) in Israel.  J. Econ. Ent. 48:  668-71.

 

Mackauer, M. J. P. & T. Finlayson.  1967.  The hymenopterous parasites (Hymenoptera: Aphidiidae et Aphelinidae) of the pea aphid in eastern North America.  Canad. Ent. 99:  1051-82.

 

Mackauer, M. & P. Starư.  1967.  "Hym. Ichneumonoidea: World Aphidiidae.  Index of Entomophagous Insects.  LeFrancois, Paris. p. 195.

 

Manglitz, G. R. & L. M. Russell.  1974.  Cross matings between Therioaphis maculata (Buckton) and T. trifolii (Monell) (Hemiptera: Homoptera: Aphididae) and their implications in regard to the taxonomic status of the insects.  Proc. Ent. Soc. Wash. 76:  290-96.

 

Messenger, P. S.  1968.  Bioclimatic studies of the aphid parasite Praon exsoletum: I.  Effects of temperature on the functional response of females to varying host densities.  Ann. Ent. Soc. Amer. 100:  728-41.

 

Messenger, P. S.  1972.  Climatic limitations to biological controls.  Proc. Tall Timbers Conf. Ecol. Anim. Contr. Habitat Management 3:  97-114.

 

Schlinger, E. I. & J. C. Hall.  1959.  A synopsis of the biologies of three imported parasites of the spotted alfalfa aphid.  J. Econ. Ent. 52:  154-57.

 

Simpson, R. G., C. C. Burkhardt, F. G. Maxwell & E. E. Ortman.  1959.  A chalcid parasitizing spotted alfalfa aphids and green bugs in Kansas.  J. Econ. Ent. 52:  537-38.

 

Smith, R. F.  1959.  The spread of the spotted alfalfa aphid Therioaphis maculata (Buckton) in California.  Hilgardia 26:  647-85.

 

Smith, R. F. & K. S. Hagen.  1959.  The integration of chemical and biological control of spotted alfalfa aphid.  Impact of commercial insecticide treatments.  Hilgardia 29:  131-54.

 

Smith, R. F. & K. S. Hagen.  1965.  Modification of the natural regulation of aphids by local climates in California.  Proc. XII Intern. Congr. Ent., London (1964):  372-74.

 

Smith, R. F. & K. S. Hagen.  1966.  Natural regulation of alfalfa aphids in California, p. 297-315.  In:  I. Hodek (ed.), Ecology of Aphidophagous Insects.  W. Junk Publ., The Hague, Netherlands.  360 p.

 

Stern, V. M. & R. van den Bosch.  1959.  The integration of chemical and biological control of the spotted alfalfa aphid.  Field experiments on the effects of insecticides.  Hilgardia 29:  103-30.

 

Stern, V. M., R. F. Smith, R. van den Bosch & K. S. Hagen.  1959.  The integration of chemical and biological control of the spotted alfalfa aphid.  The integrated control concept.  Hilgardia 29:  81-101.

 

van den Bosch, R.  1957.  The spotted alfalfa aphid and its parasites in the Mediterranean region, Middle East and East Africa.  J. Econ. Ent. 50:  352-56.

 

van den Bosch, R., E. I. Schlinger, E. J. Dietrick & J. C. Hall.  1959.  The role of imported parasites in the biological control of the spotted alfalfa aphid in southern California.  J. Econ. Ent. 52:  142-54.

 

van den Bosch, R., E. I. Schlinger, E. J. Dietrick, J. C. Hall & B. Puttler.  1964.  Studies on succession, distribution, and phenology of imported parasites of Therioaphis trifolii (Monell) in southern California.  Ecology 45:  601-21.