Ecology, Environment and Conservation Paper

LABORATORY EVALUATION OF CONCENTRATION AND TIME MORTALITY RESPONSE OF ONION THRIPS, THRIPS TABACII (LINDEMAN) TO DIFFERENT ENTOMOPATHOGENIC FUNGI

S. Sangamithra, S. Jeyarani and K. Ramaraju

Abstract

Onion thrips, Thrips tabaci Lindeman is major pest worldwide in onion and causes severe yield reduction. The present study is aimed to investigate the potential of nine different isolates of entomopathogenic fungi as effective alternative to synthetic pesticides against onion thrips, Thrips tabaci Lindeman. The results showed that all the fungi were pathogenic to thrips with clear concentration and time mortality response. The concentration mortality response (LC 50) of thrips to isolates ranged from 1.01 – 1.97 x 106 spores mL-1. The time mortality response (LT50) was found to be in the range of 94.43 – 112.24 hrs. Among the nineisolates tested, Beauveria bassiana (Bb101) was found to cause the fifty percent mortality at low concentration of 1.01 x 106 spores mL-1 and also within in a short time (94.43 h) than other test fungi.