Population Dynamics of Major Insect Pests of Little Millet (Panicum sumatrense L.) in Relation to Weather Parameters in Eastern India

Abstract

Little millet (Panicum sumatrense L.) is an important climate-resilient and nutritionally rich crop cultivated predominantly under rainfed conditions of eastern India. Despite its adaptability to marginal environments, its productivity is significantly constrained by insect pests, particularly the shoot fly, grasshopper, and earhead bug. The present investigation entitled “Population Dynamics of Insect Pests on Little Millet” was conducted during Kharif 2022 and 2023 at the Agricultural Research Farm, Birsa Agricultural University (BAU), Kanke, Ranchi, Jharkhand, India. The experiment was laid out in a Randomized Block Design with three replications under natural field conditions without insecticidal protection to allow natural pest buildup. Seasonal incidence revealed that pest populations initiated around Standard Meteorological Week (SMW) 28 and reached peak levels during SMW 33–34 in both years. During Kharif 2022, shoot fly population peaked at 3.8 larvae/10 plants, while grasshopper and earhead bug reached 3.2 and 1.4 insects/10 plants, respectively. A similar trend was observed in Kharif 2023, with maximum shoot fly (3.6/10 plants) and grasshopper (3.4/10 plants) populations recorded during SMW 34. Correlation analysis demonstrated that rainfall was the most influential abiotic factor, exhibiting highly significant positive associations with pest incidence, particularly shoot fly and earhead bug. Afternoon relative humidity also positively influenced pest buildup, whereas maximum temperature showed significant negative correlations, indicating suppression of pest activity under higher temperature regimes. The findings confirm that moderate temperature coupled with high rainfall and humidity during monsoon creates a congenial microclimate for rapid pest multiplication in little millet ecosystems. Pest populations declined after SMW 34 due to crop maturation and changing weather conditions. The study highlights the climate-driven and predictable nature of pest outbreaks and underscores the importance of weather-based forecasting and timely Integrated Pest Management (IPM) interventions to minimize yield losses and enhance sustainable productivity of little millet under eastern plateau agro-climatic conditions.