Popillia cyanea Hope, 1831 (Coleoptera: Scarabaeidae): A New and Emerging Pest of Cowpea (Vigna unguiculata L.) in Garhwal Range of Uttarakhand, India

Abstract

Background: Cowpea (Vigna unguiculata L.)  is a vital legume crop in tropical regions, valued for its nutritional and agricultural benefits. However, insect pests like the scarab beetle Popillia cyanea cause significant yield losses, and their adaptability to new hosts poses a threat to cowpea production. Aim: The study aims to document the first occurrence of Popillia cyanea Hope, 1831 (Coleoptera: Scarabaeidae) feeding on cowpea (Vigna unguiculata L.) in Uttarakhand, India, and to describe its feeding behaviour and associated damage symptoms. Study Design: A field-based observational study was carried out on cowpea during the Rabi season of 2025. Methodology: Systematic field observations were carried out in cowpea fields to record the incidence, feeding behaviour, and damage symptoms caused by adult beetles. Observations focused on the time of activity, aggregation behaviour, plant parts affected, and the nature of foliage damage. Species identification was based on characteristic morphological features, including metallic-green colouration and typical scarab beetle morphology. Results: Adult beetle P. cyanea caused severe defoliation on flowers, young leaves, and tender shoots of cowpea. Feeding occurred mainly during early morning and late evening, with beetles aggregating in small groups on the canopy. Leaf skeletonisation and reduced photosynthetic area resulted in noticeable growth retardation and yield loss, indicating P. cyanea as an emerging pest of cowpea in the region. Conclusion: The study documents P. cyanea as an emerging pest of cowpea in Uttarakhand, India, highlighting the need for monitoring and eco-friendly management strategies to mitigate its impact on cowpea production.