Vol. 9, Issue 9, Part A (2025)

Field experiments were conducted during Kharif 2024 at the Research Farm, R.A.K. College of Agriculture, Sehore (M.P.), to investigate the seasonal incidence of major defoliators and their natural enemies in soybean (Glycine max L.) variety NRC-152. The crop was sown in 40 cm spaced rows with seeds placed 4-5 cm deep using a hand liner. Three main defoliators i.e., green semilooper (Chrysodeixis acuta), tobacco caterpillar (Spodoptera litura) and gram pod borer (Helicoverpa armigera) were seen at different crop stages, along with spiders as a natural enemy. The green semilooper appeared at the vegetative stage, persisting from the 2^nd last week of July to the last week of September, with peak population (4.44 larvae/mrl) in the 3^rd week of September. Tobacco caterpillar and gram pod borer also emerged at the vegetative stage, with activity recorded between the 30^th and 38^th Standard Meteorological Weeks, both peak in the 34^th SMW with 2.89 and 3.78 larvae/mrl, respectively, coinciding with higher temperatures and lush vegetative growth. Spider populations were recorded from 28 days after sowing until crop maturity, ranging between 0.22 and 1.44 spiders/plant. Correlation analysis revealed that green semilooper and tobacco caterpillar populations had significant positive associations with relative humidity (r = 0.652 and r = 0.669, respectively; p<0.05), while spider populations showed a significant positive correlation with maximum temperature (r = 0.733, p<0.05).