Mortality of Nymphal Instars of Anthocoris nemoralis (Heteroptera: Anthocoridae) Exposed to different Insecticides under Laboratory Conditions

Abstract

Pesticides not only minimize the population of certain notorious insect pests of our important fruit, vegetables and crops, but they also contaminate our soil, water as well as the environment. Intensive and unconscious application of pesticides also cause economic damage to our important plants and such situation is called as phytotoxicity. Different species of parasitoids and predatory insects are naturally found in ecosystem to fight against the population of harmful insects of our agricultural products. But unfortunately, the population of natural enemies are being affected because of the usage of pesticides. Anthocoris nemoralis (F.) is one of the polyphagous predatory insects which helps to keep the population of certain harmful insect pests under economic injury level to our important plants. The main objective of this research work is to investigate the side effects of commonly used insecticides in the chemical control of insect pests of fruit orchards where this predatory bug is naturally found. According to the obtained results from this research study, the highest mortality rate (96.66%) was found in chlorpyrifos ethyl and spinetoram treated 3rd nymphal instars of the predatory bug, but the lowest mortality rate (76.66%) has been recorded in the individuals of same nymphal instars treated with diflubenzuron insecticide after 72 hours. In case of the 5th nymphal instars of the predatory bug, the mortality rate didn’t show a significant difference with relation to different insecticides application. It is concluded that the A. nemoralis has different level of susceptibility to different active ingredients during both nymphal stages. Thus, diflubenzuron and spinetoram are suggested to be used in the integrated pest management program of the insect pests of fruit orchards along with the presence of the 3rd and 5th nymphal instars of the predatory bug, respectively because these two active ingredients cause low mortality to this beneficial insect. Keywords: Anthocoris nemoralis, Biocontrol, Insecticide, Mortality, Nymphal instar, Predatory bug DOI: 10.7176/JSTR/6-09-10