Oral effects of thiamethoxam on biological parameters of predator, Orius albidipennis (Hem.: Anthocoridae) feeding on Aphis gossypii (Hem.: Aphididae)

Compatibility between the widely used insecticides and biological control agents is a basic principle in integrated pest management (IPM) programs. In this study, sideeffects of neonicotinoid insecticide, thiamethoxam on predator bug, O. albidipennis, as an important biological control agent, were investigated by feeding on insecticidetreated-Aphis gossypii as prey. Bioassays were done by 1st instar nymph of cotton aphids dipping in three concentrations of thiamethoxam including Factory recommended dose (FRD), ½ and ¼ of it and sterile distilled water containing 0.05% tween 80 as a control. Treated aphids were offered to one 1st instar nymph of predator in Petri dish on cucumber leaves on agar bed (100 replications). Pre-adults survival rate, fecundity, and adult longevity were recorded daily until all individuals died. Data were analyzed according to the age-stage, two-sex life table. Obtained results showed all predator individuals died before they became adult in FRD and half of it. Also, all population parameters including the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), mean generation time (T) and Gross reproductive rate (GRR) significantly decreased through the application of quarter of FRD. The values of r were 0.1151±0.003, 0.022±0.019 (d-1) for control and 0.25-FRD respectively and R0 values were 43.85±4.11 (control), 1.85±0.89 (0.25- FRD) offspring/individual. According to results of life table study (an important instrument for investigation of insecticide efficiency), thiamethoxam is very toxic for this predator even by 0.25-FRD. Therefore, foliar application of thiamethoxam shouldn’t be recommended in cotton aphid s IPM programs.

کلیدواژه ها:

predator ، thiamethoxam ، insect-dip ، recommended dose ، life table