Sustainable Controls for Vine Mealybug: Biological Control
As part of an ongoing foreign exploration and importation initiative for vine mealybug (VMB), Planococcus ficus Signoret, parasitoids have been collected in the Mediterranean regions of Europe, northern Africa, and South Africa. Natural enemies were either sent first to the USDA-ARS laboratory in France, and then to the UC Berkeley Quarantine Facility (collections by Sforza) or sent directly to UC Berkeley Quarantine (collections by Daane). Our goals were to screen the imported natural enemies for their potential to lower VMB populations in California, and for their possible non target impacts. In 2007, new material was collected in Portugal, but has not yet been screened in Quarantine. From previous collections, we identified populations of the parasitoids Anagyrus pseudococci from northern Italy and Coccidoxenoides perminutus from South Africa. These populations have been approved for release in California. C. perminutus was studied in the laboratory to help determine its potential. It has high lifetime fecundity (149 ± 21 adult offspring per female) and will attack all VMB life stages. The high reproductive rates of C. perminutus observed in the laboratory may not be duplicated in the field. However, C. perminutus may be expected to perform better than A. pseudococci in vineyards with high densities of Argentine ants.
In 2007, releases of A. pseudococci and C. perminutus were made in vineyards the in San Joaquin Valley (SJV), the Northern Interior Winegrape Region (Solano and Sacramento Counties), the North Coast (Sonoma and Napa Counties), and Central Coast (San Luis Obispo County) regions. There were nearly 75,000 female A. pseudococci produced and released. A. seudococci ?northern Italy? was produced in the UC Berkeley Insectary (11,750 females released) as well as the commercial ?Sterling Insectary? (58,500 females released). A small colony of A. pseudococci Sicily was maintained at the UC Berkeley insectary and field production of this strain was directed by CDFA Insectary. The more easily reared C. perminutus, of which approximately 143,000 were released, were produced at the UC Berkeley Insectary.
To date, we have recovered A. pseudococci at all sites, however, we have not yet completed the molecular work on samples to determine if the recovered material was from our release (northern Italy) or the A. pseudococci strain resident in California (Israel). We have recovered C. perminutus at some Central Coast, North Coast, Sacramento, and Central Valley release sites. We also recovered Leptomastidea abnormis in Fresno County (from 2005 releases), where we now consider this species to be established, and Sacramento County. Leptomastix dactylopii was recovered in Sacramento County. VMB parasitism levels range from 0 ? 80%of the collected mealybugs per sample date ? lower in the early summer, higher in the fall and on the exposed vs. protected VMB. As mentioned previously, VMB density and percent parasitism will be presented in the report on mating disruption.
