Lethal effects of azadirachtin, spiromesifen and thiamethoxam insecticides on the greenhouse whitefly, Trialeurodes vaporariorum and it’s parasitoid Encarsia formosa

Pesticides application is the main approach to manage Trialeurodes vaporariorum Therefore, the effects of azadirachtin, spiromesifen and thiamtoxam on whitefly and its parasitoid Encarsia formosa were investigated. In evaluating the lethal concentration of the treatments on eggs and 3rd nymph of whitefly, the highest lethal effect (LC50) was on egg and 3rd nymphal stage by spiromesifen and thiamtoxam were 89.55 and 76.25 ppm, respectively. The results of analysis of variance of treatment mortality on E. formosa after seven days showed that azadirachtin had the least adverse effect with 60% emergence of parasitoides and thiamtoxam had the highest adverse effect with 12% emergence for E. formosa. In assessment of the oviposition preference of E. formosa, among pesticide treatments, despite highest oviposition in low concentration of thiamtoxam and spiromesifen, but the highest egg hatching was related to azadirachtin. Also, the effectiveness of insecticides against whitefly nymphs in greenhouse and laboratory conditions was compared. The percentage of effect of treatments three, seven and 14 days after spraying showed that the greatest effect on nymphal stage was related to thiamethoxam with 80% mortality in three days after spraying, but in seventh and fourteenth days after spraying, was related to azadirachtin with 96.47 and 95.77% mortality, respectively. According to the results of this study, spiromsifen and thiamtoxam were effective in high population of this insect, but in integrated management program simultaneous use of E. formosa with azadirachtin is recommended.