EFFICACY OF CHITIN SYNTHESIS INHIBITORS IN ARRESTING GROWTH AND DEVELOPMENT OF OKRA JASSID, AMRASCA BIGUTTULA BIGUTTULA (ISHIDA)

Abstract

Chitin synthesis inhibitors (CSIs) are potential inhibitory chemical compound that disrupt molting process by interfering chitin synthesis and kill insects before attaining maturity. In this study, some chitin synthesis inhibitors (CSIs) viz. Tacoma 40SC (Buprofezin), Heron 5EC (Lufenuron), Pyrifen 10.8EC (Pyriproxifen) and Chitosan 75WP were tested against okra jassid, Amrasca biguttula biguttula (Ishida) to elucidate their potential effects in arresting body growth and development. The nymphs of jassids were exposed to selected CSIs through different application methods like topical, leaf-dip and the combination of both topical and leaf-dip. Weight data was collected at 7 days after treatment (DAT) application. Results showed that all of the CSIs except Chitosan had significant effect on the body weight reduction of okra jassid. Growth reduction was clearly concentrations and application method dependent. It has shown that higher concentrations were found to be more effective than lower concentrations. Bioassay study has showed that all the selected CSIs became able to enter in the insect body through contact as well as stomach action to disrupt molting process by inhibiting chitin synthesis that confirmed the contact and systemic actions of the selected CSIs. This study recommends that Tacoma 40SC @ 1.0 ml/L, Heron 5EC @ 1.5 ml/L and Pyrifen 10.8 EC @ 1.5 ml/L may be the potential alternatives of conventional neurotoxic insecticides in controlling jassids as they reduced 50-60% weight compared to untreated control. Moreover, protocols developed in this study for jassids collection and their safe transferring inside the petri dishes would be a useful and convenient approach for the researchers.