Effective biopesticides for sustainable management of Plutella xylostella L. (Lepidoptera: Plutellidae) in cauliflower: A comprehensive study on isolation, characterization and virulence assessment of highly virulent entomopathogenic fungi

Abstract

Cauliflower faces a significant threat from the notorious pest Plutella xylostella L., which has become challenging to manage using conventional insecticides due to the development of resistance. Seeking an environmentally sustainable solution, this study was conducted to explore the potential entomopathogenic fungi (EPF) for the management of P. xylostella. In the present study, soil samples were collected from the cauliflower growing regions of Tamil Nadu for the isolation of EPF, resulting in the isolation of 61 EPF isolates. Morphological and molecular characterization revealed that among the 61 isolates isolated, 42 were Beauveria bassiana and 19 were Metarhizium anisopliae. Preliminary bioassay was conducted for the virulent isolates, and the results revealed the remarkable virulence of M. anisopliae A11 (OR536962) and B. bassiana A10 (OR533688) isolates causing 87.50 ± 0.25 and 85.00 ± 0.40 percent mortality of P. xylostella, respectively at the conidial load of 1 × 108 conidia/ml. Dose and time mortality response revealed that the M. anisopliae A11 (OR536962) isolate has LC50 and LT50 values of 2.70 ×106 conidia/ml and 107.15 h, respectively. On the other hand, the most virulent B. bassiana A10 (OR533688) isolate has LC50 and LT50 values of 4.12 ×106 conidia/ml and 113.48 h, respectively against P. xylostella. The study concludes that these isolates demonstrate high virulence against P. xylostella, offering promising prospects for effective management of this pest in field conditions.