Nanochitosan–Lecanicillium saksenae Spore Composite for the Management of Rice Bug (Leptocorisa sp.)
J. Aswathy
Department of Entomology, College of Agriculture Vellayani, Kerala Agricultural University, Thiruvananthapuram, Pin: 695522, Keralam, India.
O. P. Reji Rani
*
Department of Entomology, College of Agriculture Vellayani, Kerala Agricultural University, Thiruvananthapuram, Pin: 695522, Keralam, India.
*Author to whom correspondence should be addressed.
Abstract
Aims: The present study aimed to synthesize nanochitosan and develop a nanochitosan–Lecanicillium saksenae (NC–LS) spore composite using an indigenous entomopathogenic fungal isolate obtained from soils of Vellayani, Keralam, India, and to evaluate its bioefficacy against the rice bug, Leptocorisa sp.
Study Design: Completely Randomised Design (CRD)
Place and Duration of Study: Biocontrol Laboratory for Crop Pest Management, Department of Entomology, College of Agriculture, Vellayani, Thiruvananthapuram during 2023-2026.
Methodology: Nanochitosan and the NC–LS spore composite was synthesized using the ionic gelation method, characterized for their physicochemical properties and checked their bioefficacy against rice bugs.
Results: The NC–LS spore composite exhibited a quasi-spherical morphology with increased surface roughness, as revealed by FESEM and AFM analyses. XRD analysis showed an amorphous nature with a broader diffraction peak at 2θ = 21.56° and a shoulder peak in the 15°–17° region, indicating the incorporation of fungal components into the nanochitosan matrix. Bioassay against rice bug nymphs revealed that complete mortality was achieved within 2 days at 2000 ppm. NC–LS spore composite at 2000 ppm exhibited an LC₅₀ of 107.59 ppm and an LT₅₀ value of 11.26 h against rice bug nymphs, indicating accelerated mortality.
Conclusion: The findings demonstrate the potential of the NC–LS spore composite as an eco-friendly strategy for the sustainable management of major sucking pests of rice, rice bug.
Keywords: Nanochitosan, Lecanicillium saksenae, entomopathogenic fungus, spore composite, ionic gelation, physicochemical characterization, bioefficacy, rice bug, Leptocorisa sp