Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 6, 1999
Publication Date: N/A
Interpretive Summary: A study was conducted to determine the impact of foliar insecticides on the parasites of the silverleaf whitefly in crops of cantaloupe, collard, cucumber, and tomato. Half of each crop was treated with chlorpyrifos (Lorsban) in 1994 and imidacloprid (Provado)in 1995 and 1996. Yellow sticky traps were used to trap and to monitor whiteflies and parasites. Their abundance varied among field locations and over each year. Parasite were found in all field locations and in all crops whether the vegetables were treated or not. They were captured in all plots throughout the study. About 60 to 70% of the captured parasites were from plots without insecticide. Five species of parasites were captured. Three species (Encarsia nigricephala, Encarsia pergandiella, and Eretmocerus sp.) made up about 95% of the captured parasites. The parasites were able to survive the insecticide treatments although their abundance was reduced. This information will be useful in developing biocontrol systems to manage silverleaf whitefly.
Technical Abstract: The abundance of parasitoids of Bemisia argentifolii was studied in fields of cantaloupe, collard, cucumber, and tomato. Evaluations were made using foliar applied chlorpyrifos (Lorsban) in 1994 and imidacloprid (Provado) in 1995 and 1996. Half of each crop within each field was treated weekly (1994) or bi-weekly (1995 and 1996) over 10 weeks. Yellow sticky cards were used to trap and to monitor whiteflies and parasitoids. Abundance of B. argentifolii and parasitoids varied among fields and across years. Five species of parasitoids were captured: Eretmocerus sp., Encarsia nigricephala Encarsia pergandiella, Encarsia quaintancei, and Encarsia strenua. Parasitoids persisted in all field locations and crops whether the vegetables were treated or not. They were captured in the treated plots throughout the study, although in fewer numbers than in the untreated plots. Overall, about 60 to 70% of parasitoids captured were from plots without insecticide.