Effect of some conventional insecticides on functional response parameters of Macrolophus pygmaeus (Hem.: Miridae) on Tuta absoluta (Lep.: Gelechiidae).

IPM programs based on using both predator Macrolophus pygmaeus and pesticides are widespread in the tomato greenhouses, these days. In the current study, side effects of abamectin, imidacloprid and chlorpyrifos as the widely used insecticides were investigated on functional response type and parameters of M. pygmaeus, fed on Tuta absoluta eggs. Sublethal concentration (LC 30 ) of insecticides was evaluated in 24 h, using dried residues. The results showed that chlorpyrifos was the most toxic insecticide against M. pygmaeus adults. Functional response study (using different densities including 1, 2, 3, 4, 5, 8, 10, 15, 20 and 30 prey eggs) showed that predatory bug showed type II functional response before and after treatment with LC 30 of insecticides. Two insecticides (imidacloprid and chlorpyrifos) decreased attack rate and increased handling time of the predator whilst abamectin did not change its handling time, significantly. Thus, it is concluded that abamectin had the lowest adverse effects on the predator at laboratory condition. [ABSTRACT FROM AUTHOR]

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