Effects of insecticide and metarhizium anisopliae combinations against Leptocorisa acuta

This study evaluated the effects of combining the entomopathogen green muscardine fungus Metarhizium anisopliae (Metchnikoff)with three compatible chemical insecticides (imidacloprid, thiamethoxam, and pymetrozine) against the rice gundhi bug Leptocorisa acuta (Thunberg) in rice under field conditions. The results revealed that among the various treatments, imidacloprid exhibited the most promising results, leading to a bioefficacy of 71.13% followed by imidacloprid (half-dose) + M. anisopliae combination, which achieved a bioefficacy of 63.95% in the field over two consecutive seasons. The highest reduction in L. acuta population over control was observed in the imidacloprid (69.73%) followed by M. anisopliae + pymetrozine (half-dose) (65.79%). In terms of rice grain yield, imidacloprid again outperformed other treatments with a yield of 41.98 q ha^-1 with a benefit-cost ratio of 2.57 followed by the imidacloprid (halfdose) + M. anisopliae combination, which yielded 41.61 q ha^-1 with B:C ratio of 2.42.