BIOLOGICAL PEST CONTROL IN EURASIA
This broad region has traditionally experienced pest organisms of native origin which are managed in a variety of ways that do not usually include classical biological control. With the exception of certain Mediterranean areas, classical biological control is not practiced. There is considerable emphasis on the deployment of pathogenic organisms, and on augmentation with parasitoids, especially in glasshouse culture. The preservation of naturally occurring predators and parasitoids is also emphasized. Nevertheless, there are real possibilities for the incorporation of classical biological control tactics, especially against invaded pests such as the Colorado potato beetle, synanthropic flies and cockroaches, as well as exotic weeds.
Development and application of biological control in Europe was reviewed by Franz (1961a,b), Franz & Krieg (1972), Greathead (1976), Hagen & Franz (1973), Hussey & Scopes (1986), van Lenteren (1986) and van Lenteren & Woets (1988).
According to these authors, an initial practical demonstration of biological control in Europe was in France in 1840. M. Boisgiraud released the carabid Calosoma sycophanta (L.) against the gypsy moth, Lymantria dispar (L.) on poplars. At the same time in Germany, J. R. C. Ratzeburg moved heavily parasitized Dendrolimus pini (L.) into an outbreak area and recommended the use of ants, Formica rufa group, against forest defoliators. The method of artificial colonization of forest ants has been studied extensively in the 20th century (Greathead 1976). Also efforts to increase insectivorous bires by providing nesting facilities were common in Europe, and the ant and bird work are specific elements in the European pattern of biological control (Franz 1961b). G. L. Hartig had suggested conservation of natural enemies in Europe as early as 1827. Many attempts to augment existing natural enemy populations were made thereafter, often an a local scale. Most are inadequately documented and, therefore, are not treated in any detail here.
The earliest, and unsuccessful, attempt to colonize a natural enemy in Europe was the importation of the acarid predator Rhizoglyphus phylloxerae (Riley * Planchon) in 1873 for control of the grape phylloxera, Viteus vitifolii Fitch. The first successful use of exotic organisms was in 1897 when Rodolia cardinalis (Mulsant) was imported to Portugal for control of cottony cushion scale, Icerya purchasi Maskell, following its first appearance in Europe in the previous year. This ladybird beetle was later introduced to other European countries and the success strongly stimulated interest in "classical" biological control. Several other coccinellids were introduced against a variety of pests, but these programs were less successful.
The first introduction of a parasitoid dates to 1906 when Berlese imported Prospaltella berlesi (Howard) against mulberry scale Pseudaulacaspis pentagona (Targ.) (Berlese & Paoli 1916). The failure of the 1926-1944 campaign to control the Colorado potato beetle, Leptinotarsa decemlineata (Say), tempered enthusiasm for biological control in Europe. Apart from Rodolia, classical biological control in Europe has not been very successful. The main reason is that Europe has few imported pests. Simmonds & Greathead (1977) estimated that more than 60% of the 200 insect pest species in the United States were imported, whereas very few arthropod pests were imported to Europe. The rationale that biological control will be most successful in situations where natural enemies are imported from abroad, against pests which were also imported, is obviously hampering further attempts. Van Lenteren et al. (1987) have shown that all combinations of exotic and native natural enemies and pests are worth considering.
One notable exception to a number of failures to deploy exotic natural enemies against exotic pests was Speyer's success with the parasitoid Encarsia formosa for control of Trialeurodes vaporariorum in glasshouses (Speyer 1927). This parasitoid is still commercially used on a large scale, and forms the focal point of integrated pest management for glasshouses (van Lenteren & Woets 1988). The use of native natural enemies for biological control during the first part of the 20th century was summarized by Sachtleben (1941) and Greathead (1976). Since Greathead's (1976) review a number of native natural enemies have been evaluated and selected for biological control and are used commercially (van Lenteren et al. 1987).
Interest in biological control in Eurasia diminished with the appearance of synthetic pesticides after 1940, but the development of resistance and the recognition of unwanted side-effects during the 1950's revived biological control somewhat, leading to the formation of the International Organization for Biological Control (IOBC) in 1956 (now called the Western Palearctic Regional Section of the IOBC). This European section of the IOBC has been the driving force behind a change of thinking in crop protection since, and coordinated many cooperative biological control projects.
Inundative releases of natural enemies were first undertaken in Russia in 1913 with the mass rearing and periodic releases of Trichogramma. However, inundation has not been used on as large a scale in western and southern Europe. Such releases have figured prominently in the attempt to control olive fly, Dacus oleae (Gmel.), using Opius concolor Szépl. (Liotta & Mineo 1968). In Italy O. concolor was successfully deployed during the 1960's but its status is presently (1992) unknown. Another major program with inundation involved Trichogramma. Schieferdekker (1970) reviewed this work. The first experiments date from the 1920's (Voelkel 1925), but most work was discontinued and rated unsuccessful (Greathead 1976). In 1992 there is one project where Trichogramma evanescens seems commercially successful in the control of Ostrinia nubilalis. The most important development in augmentative releases in western Europe have been in glasshouses. However, recent work by Sherif Hassan at the Bundesanstalt für Biologische Schädlingsbekämpfung in Darmstadt, Germany shows great promise for field vegetable crops (see references).
Eurasia has served as an important geographic area for export of natural enemies principally to the United States and Canada for more than a century (Clausen 1978, Greathead 1976). Collection and exploration of natural enemies has been the area of activity of the Commonwealth Agricultural Bureau's International Institute of Biological Control (CIBC), the European Parasite Laboratory of the U. S. Department of Agriculture, and the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia.