Vol. 12, Issue 6 (2023)

Author(s):
Abhilasa Kousik Borthakur, Preetipuja Kashyap, Gunjan Gogoi, Manoranjan Neog and PK Pathak

Abstract:
Helicoverpa armigera (Hubner) is a cosmopolitan pest and its polyphagous nature has resulted in loss of production of economically important crops including Tomato, King Chilli, Maize and blackgram in Dhemaji district of Upper Brahmaputra Valley Zone of Assam, India. On February 8, 2023, larvae of Helicoverpa armigera feeding voraciously on the pods of Rapeseed (Brassica napus var. napus) were reported for the first time in a village near Lechia river of Dhemaji where rapeseed is cultivated over 1000 hectares of contiguous area. The larvae were found to be feeding on the green pods as well as on the mature pods leaving behind its distinctive circular hole on the pods. The mean larval population was 14.8 /m². The infestation resulted in a yield reduction of 38% in the area. High relative humidity during the outbreak of the pest might have led to a high population buildup of the larvae. However further research is needed to unravel the exact cause behind the sudden outbreak of the pest.