The effect of Imidacloprid on Trialeurodes vaporariorum and parasitoid wasp (Encarsia formosa)

The effect of imidacloprid on the greenhouse whitefly and parasitoid wasp studied in greenhouse conditions, on Lantana camara L., in a completely randomized block design with five treatments of 0.02, 0.04, 0.08, and 0.16 g/liter of insecticide and control (water) for two periods of short and long term (seven and 125 days after treatment). In short term the difference of mean of the adults’ mortality, rate of oviposition, hatching of eggs, percentage of nymphal instars mortality, and percentage of adults’ exclusion of T. vaporariorum with controls was significant (P<0.01). The dosages of 0.02, and 0.04 g/liter of insecticide caused significant difference in last aleyrodid population density, but the dosages of 0.08 and 0.16 controlled it perfectly. The effect of insecticide in long term on aleyrodid was significant and the results were similar to short term period. Longevity of emerged adults in different dosages was significantly shorter than controls (P<0.05). Therefore, the effect of insecticid lasts in the plant tissues, at least for 125 days after treatment. The effect of insecticide studied on the mean percentage of mortality the parasitoid, percentage of parasitism, percentage of adult’s exclusion and longevity of emerged parasitoids. There was positive correlation between the increasing of insecticide concentration and its effect on different life stages of the parasitoid. It is concluded that the 0.02 g/liter dosage affected all the life stages of the aleyrodid and had no adverse effect and would be the recommended dosage.