Careful choice of insecticides in Integrated Pest Management strategies in maize conserves Orius spp. population in the field

A field experiment was set up in April 2011 at Legnaro, Italy, within the European Project PURE, to evaluate two IPM strategies against a conventional one in four-year maize-based cropping systems that will involve different crops in the rotations in subsequent years. Three different foliar insecticide treatments were applied to the first-year maize against the second generation larvae of Ostrinia nubilalis (Hübner) according to the strategy followed. Lambda-cyhalothrin was applied as the conventional strategy, while chlorantraniliprole, an insecticide selective to beneficial arthropods and a biological insecticide containing Bacillus thuringiensis var. kurstaki were applied as the two IPMbased strategies. The minute pirate bug (Orius spp.) was the most abundant among the beneficial organisms and was considered as the indicator species in this study. Statistical analysis showed no significance difference between strategies in Orius spp. density before the insecticide treatments, whereas after treatments Orius spp. was significantly lower in the conventional strategy compared to the IPM-based strategies. Ostrinia nubilalis damage was slightly higher when treated with the biological insecticide compared to the other two strategies. Treatment with chlorantraniliprole did not affect Orius spp. population confirming its selectivity to this species. The primary results of this study reveal that the careful choice of insecticides that exhibit selectivity to beneficial organisms and the inclusion of biological insecticides into IPM strategies in maize can promote conservative biological control.