01 Oca 2026 Perşembe
Biology, feeding behaviour and seasonal incidence of Herpetogramma bipunctatus (Lepidoptera: Crambidae) on brinjal at Dharmadam, Kannur, Kerala, India
Abstract : Herpetogramma bipunctatus (Fabricius) (Lepidoptera: Crambidae) has recently been recognised as a major defoliator of brinjal (Solanum melongena L.) in Kerala, causing extensive foliar damage and consequent reduction in plant vigour and yield. The present study was undertaken at Dharamadam, Thalassery, Kerala, during 2024–2025 to investigate the biology, feeding behaviour, and seasonal incidence of H. bipunctatus under both laboratory and field conditions. Eggs were deposited in small groups on stems, measuring 1.0 ± 0.08 mm in length and 0.74 ± 0.05 mm in breadth. The mean incubation, larval, pupal and adult periods were 8 ± 2, 14.29 ± 1.1, 7.4 ± 0.48 and 10 ± 3 days, respectively, with a total life cycle of 39 ± 4 days. Larvae exhibited characteristic leaf-folding and webbing behaviour, forming four types of nests—single folded leaf pockets, double-leaf webbings, multi-leaf nests, and inter-branch silk connections. Feeding occurred mainly on the mesophyll tissue, leaving only veins intact and causing typical leaf skeletonization. Mature larvae descended to the soil for pupation, where silken cocoon was formed. Seasonal monitoring revealed a distinct population peak during the post-monsoon period (September–November), coinciding with high humidity and moderate temperature, whereas population density declined during the summer and early monsoon months. The study provides detailed information on the developmental biology, feeding ecology, and population dynamics of H. bipunctatus on brinjal, which will be useful for forecasting pest outbreaks and developing ecologically sound integrated pest management (IPM) strategies in Kerala.