The dangerous insect pest known as rice leaf folder Cnaphalocrocis exigua (Butler), which reduces rice output globally, twists and feeds on the young rice plant's leaves. Protein elicitors are hypothesized to be biological components that promote rice in becoming herbivore resistant. The evolving elicitor protein PeBL2, obtained from Brevibacillus laterosporus A60, was tested for biocontrol against C. exigua. Four distinct PeBL2 doses (74.23, 45.53, 22.26, and 11.13 μg mL-1) were assigned to evaluate the impact of PeBL2 on immature growth, survivability, and lifespan. Adult reproductive efficiency and the interaction between the pest and the disease were assessed against C. exigua. Further, the assessment of active compounds in PeBL2 with multi-acting entomopathogenic effects investigated the direct correlations of PeBL2 with temperature and climatic change in plants of rice (Oryza sativa L.). When compared to controls, PeBL2 treatments reduced the growing population of second- and third-generation C. exigua. Cnaphalocrocis exigua colonized control plants faster than PeBL2-treated O. sativa plants in a host selection test. PeBL2 doses delayed the development of the larval stage of C. exigua. PeBL2-treated seedlings generated less offspring than control seedlings, identical to fecundity. Trichomes and wax formation on PeBL2-treated leaves generated an adverse environment for C. exigua. PeBL2 altered the surface topography of the leaves, preventing colonization and reducing C. exigua reproduction. PeBL2-treated O. sativa seedlings exhibited somewhat increased amounts of jasmonic acid (JA), salicylic acid (SA), and ethylene (ET). Systemic defensive processes also included the activation of pathways (JA, SA, and ET). Following these results versus C. exigua, the use of PeBL2 in an agroecosystem with integrated pest management and biocontrol appears to be reasonable. These findings shed new light on a cutting-edge biocontrol technique based on B. laterosporus A60.
Keywords: Cnaphalocrocis exigua; ET; JA; PeBL2; SA; defense-related gene expressions; fecundity; nymphal instars; plant resistance; protein elicitor; signaling pathway.