Aphis gossypii Glover (Hemiptera: Aphididae) poses a major threat to okra cultivation, causing significant yield losses worldwide. This study evaluated the efficacy of the entomopathogenic fungus Lecanicillium fusisporum strain NBAIR-Vl8 against A. gossypii in both laboratory and field environments, along with Metarhizium anisopliae NBAIR-Ma4 and Beauveria bassiana NBAIR-Bb5a. L. fusisporum NBAIR-Vl8 exhibited high virulence, with an LC₅₀ of 4.22 × 10⁴ spores/mL and LT₅₀ and LT₉₀ values of 60.45 h and 86.97 h, respectively. Over 2 years of field trials, there were significant reductions in aphid (73.65%) and leafhopper, Amrasca biguttula biguttula (67.93%) populations and increased yield (6.64 q ha- 1) compared to untreated plots (3.98 q ha- 1). LC-MS/MS and GC-MS analyses of NBAIR-Vl8 identified important bioactive metabolites, including penitrem D, zwittermicin A, β-sitosterol, curcumin, and (1 R,2S)-naphthalene 1,2-oxide. To explore potential molecular targets, homology models of A. gossypii nicotinic acetylcholine receptor (nAChR) and chemosensory protein CSP8, as well as A. biguttula biguttula ribosomal protein L13 and tubulin beta chain, were developed and validated. Molecular docking using AutoDock Vina revealed that penitrem D had the highest binding affinities (-8.9 kcal/mol for nAChR), surpassing the commercial insecticide thiamethoxam (-5.4 kcal/mol for nAChR). β-sitosterol and curcumin also demonstrated strong interactions with CSP8 and structural proteins. These targets are essential for neurotransmission, olfaction, protein synthesis, and cytoskeletal integrity, indicating a multitarget mechanism of action of the drug. NBAIR-Vl8 shows significant biocontrol potential, supported by in vitro, field, and in silico evidence, highlighting its potential as a broad-spectrum microbial pesticide for integrated pest management.
Aravindaram et al. (Thu,) studied this question.