Adverse effects of soil applied insecticides on the predatory coccinellid Hippodamia undecimnotata (Coleoptera: Coccinellidae)

We studied, under laboratory conditions, the possible effects of sublethal doses of two soil applied insecticides (carbofuran and imidacloprid) on development, survival and fecundity of the predator Hippodamiaundecimnotata. For studies, predator fed upon Aphis fabae that was reared on Vicia faba plants treated with the systemic carbofuran and imidacloprid. Survival of immature stages in insecticides treatments (67.6% and 52.2%, for carbofuran and imidacloprid, respectively) was lower than control (77.4%). Both insecticides did not affect significantly total immature developmental time, while carbofuran caused a significant reduction of adult weight. Adult average longevity was significantly higher for the control than the insecticides treatments. Moreover, females oviposited fewer eggs in both insecticide treatments than the control (33% and 55% reduction in average fecundity for imidacloprid and carbofuran, respectively). Population increase parameters were also adversely affected by insecticides application. The importance of the adverse effect of sublethal doses of systemic insecticides on designing and management of insects’ pests are discussed.