Evaluation of entomopathogenic fungi against diamondback moth larvae in cabbage

Abstract:

Globally, diamondback moth (Plutella xylostella L.) accounts for an estimated US $4-5 billion in annual losses to cruciferous crop production. This research assessed the pathogenicity of four entomopathogenic fungi against P. xylostella larvae on cabbage under laboratory and field settings at Narendra Deva University of Agriculture and Technology, Kumarganj, during rabi 2022 and 2023. Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii, and Isaria fumosorosea were evaluated at three spore concentrations in a completely randomized design for bioassays and a randomized block design for field trials. Under laboratory conditions, B. bassiana at 1×10⁸ conidia/ml caused 87.4% larval mortality at 72 hours. In field trials, B. bassiana reduced the larval population by 78.9% at seven days after treatment and produced 28.6 t/ha marketable yield, statistically comparable to spinosad 45 SC (30.2 t/ha). The LC₅₀ of B. bassiana was 2.8 × 10⁵ conidia/ml and its LT₅₀ was 38.6 hours. These results suggest B. bassiana and M. anisopliae are practical biocontrol candidates for diamondback moth management.