Effect of Some Conventional Insecticides on the Egg Parasitoid, Trichogramma evanescens (West.) (Hymenoptera: Trichogrammatidae)

The study was carried out to evaluate the effect of three different insecticides on biological aspects of the egg parasitoid Trichogramma evanescens; parental adult mortality, percent of parasitism, developmental period, adult emergence percent, and sex ratio. The insecticides tested were chlorpyrifos 48% EC & profenophos 72% EC (organophosphate) and lambda-cyhalothrin5% EC (pyrethroid) at five different concentrations. Chlorpyrifos caused the lowest percent of parasitism followed by profenophos and lambda-cyhalothrin (averaged 7.00, 15.14 and 17.47%, respectively), compared to untreated (76.60%). The same effect was found on % adult emergence (11.63, 14.0 and 24.4%), compared to the untreated (77.06%). Applications of the three tested insecticides did not affect the developmental period and sex ratio significantly. Negative relationship between the insecticides concentrations and the % parasitism or % adult emergence was recorded. However, the LC50 values indicated that profenophos was the most toxic compound to T. evanescens adult wasps 24 and 48 hrs post treatment, followed by chlorpyrifos and lambda-cyhalothrin. The results pointed out that lambda-cyhalothrin was the most appropriate insecticide due to its less harmful effect on T. evanescens and could be recommended to apply in the IPM programmes.