Natural enemy mediated population regulation of Chilo partellus on wheat

Abstract

Chilo partellus (Swinhoe) and Mythimna separata (Walker) are economically important lepidopteran pests of cereal crops, but information on their natural population regulation in wheat is limited. A field life-table study was conducted during the rabi season of 2020–21 under pesticide-free conditions at the Post Graduate Experimental Farm, Department of Entomology, College of Agriculture, Latur, Maharashtra, India, to quantify stage-specific mortality and identify the major mortality factors affecting both species. Both pests completed only one generation during the crop season and failed to establish subsequent generations. In C. partellus, mortality was confined to the early larval stage, where Cotesiaflavipes and Callibracon sp. caused 33.31 and 49.95% mortality, respectively, resulting in a generation survival of 0.33 and a total generation mortality (K) of 0.777. In M. separata, Cotesia sp. caused 24.98% mortality in early instars and 33.30% in late instars, with a generation survival of 0.50 and a total generation mortality (K) of 0.602. The trend index was zero for both species, indicating the absence of population carryover beyond the first generation. The study indicates that larval parasitoids were the predominant mortality factors regulating both pest populations under field conditions and emphasizes the value of conserving indigenous natural enemies in wheat-based production systems.