Pathogenicity of indigenous Beauveria bassiana (BKN 20) against tea mosquito and its compatibility with a few insecticides

Abstract

A local indigenous strain of entomopathogenic fungus, Beauveria bassiana (BKN-20) was isolated from the tea ecosystem of Dooars in West Bengal with the help of the multiple tube dilution technique (MTDT) which was later characterized taxonomically and deposited at ITCC, IARI, New Delhi (accession no. 9242.13). The invitro pathogenicity of the same was evaluated against tea mosquito, Helopeltis theivora. The results revealed that the strain is pathogenic to this pest resulting in 80 per cent mortality. The mycelial growth appeared on the dead insect’s body within a week’s time, from which, the same fungus was re-isolated, confirming the pathogenicity and the cause of mortality of tea mosquito. In addition, the compatibility study was also carried out using the recommended  insecticides such asquinalphos, thiamethoxam bifenthrin and  deltamethrin.The results indicated that quinalphos has showed the maximum effect on this entomopathogen, which has resulted in the growth inhibition to the tune of 70.69 per cent followed by bifenthrin (28.81%), deltamethrin (19.74%) whereas thiamethoxam showed the lowest inhibition of growth (9.7%).