Succession of Major Insect Pests and their Natural Enemies on Soybean in Malwa Region of Madhya Pradesh, India

Abstract

The present study was conducted during Kharif- 2024 at the Experimental Research Farm, R.A.K. College of Agriculture, Sehore (M.P.). The primary objectives were to document the succession of major insect pests and their natural enemies in soybean and to assess the influence of meteorological parameters on pest dynamics. The key insect pests observed were stem fly (Melanagromyza sojae), girdle beetle (Obereopsis brevis), tobacco caterpillar (Spodoptera litura), semilooper (Chrysodeixis acuta), and gram pod borer (Helicoverpa armigera) along with natural enemies such as the ladybird beetle (Coccinella septempunctata) and spiders. Girdle beetle infestation initiated in the 31st Standard Meteorological Week, peaking at 40.20% plant infestation in the 39th SMW. The stem fly appeared in the 31st SMW, reaching a maximum infestation of 72% and 46.70% tunneling in the 40th SMW. The highest population of tobacco caterpillar (2.70 larvae/mrl) and green semilooper (4.90larvae/mrl) were recorded in the 35th SMW, while the gram pod borer peaked (4.10larvae/mrl) in the 36th SMW. The ladybird beetle and spider populations peaked in the35th and 38th SMWs, respectively, underscoring their role in natural pest control. Correlation analysis revealed a significant negative relationship between relative humidity and the populations of green semilooper and gram pod borer. Similarly, populations of tobacco caterpillar, lady bird beetle and spider showed significant negative correlations with both relative humidity and rainfall. These findings provide valuable insights into pest dynamics and can support the development of more effective, ecologically based pest management strategies for soybean cultivation.