A Study of Anagrus Egg Parasitoids Important for Biological Control

During year one of research, collections of Anagrus egg parasitoids of western grape and variegated leafhoppers were made on winegrapes in Napa Valley, Sonoma Valley, Alexander Valley, Russian River Valley (Guerneville-Trenton-Healdsburg-Asti areas), El Dorado Co., Mendocino Co., San Luis Obispo Co. (Paso Robles), Merced Co., and during September-November 1995 in Riverside County (Temecula area). Additional material, at no cost to this project, was available for study from vineyards in Sacramento Valley, Santa Barbara, and San Luis Obispo Counties (California) as well as from Arizona, Colorado, New Mexico, New York (USA), and Mexico. Four or five different species of Anagrus wasps which are associated with cultivated grapes in North America have been recognized. Two of these species occur on winegrapes in California as follows: Anagrus erythroneurae S. Trjapitzin & Chiappini and Anagrus new species (A. Sp.), both parasitic on western grape and variegated leafhoppers eggs. In most locations in California winegrape-growing areas where A. sp. occurs, A. erythroneurae is also present. These localities are in Sonoma Valley and Alexander Valleys (Sonoma Co.), Oakville (Napa Co.), Mondavi and El Rio Vineyards at Lodi (San Joaquin Co.), and Davis (Yolo Co.). In these areas A. erythroneurae is a dominant species, comprising more than 50-70%of all collected parasitoids per sample. In most of the other winegrape-growing areas of California, such as El Dorado Co., Santa Barbara Co., and Temecula wine country (Riverside Co.), we found only one species, A. erythroneurae. The same species dominates in the San Joaquin Valley (California, USA), Mexicali Valley and other areas of Baja California, Mexico but is rare in collections from Colorado, New Mexico and New York (USA). In September 1995, S. Triapitsyn made collections in Centralia, Illinois, which is the type locality of Anagrus epos Girault, a species which was previously mistakenly considered to be a major biological control agent of grape-infesting leafhoppers in North America. Two specimens similar to A. epos were collected in Centralia and compared with the type specimens of this species. As a result, it was determined that A. epos is not known to occur in California and subsequently plays no role in the natural control of leafhoppers on grapes in this state.