Status of American bollworm, Helicoverpa armigera (Hubner) on cotton in Haryana

摘要

Fortnightly surveys of cotton crop for the incidence of Helicoverpa armigera (Hubner) ( Lepidoptera : Noctuidae) carried out in the cotton growing belt of Haryana during July-October for six years (1993-1998) indicated that the pest was present on thecrop in low numbers (about one larva/100 plants) as early as in the middle of July. However, the population continued to multiply further reaching its peak in second fortnight of September to early October. During this period as high as 79-91 per cent fields were found infested with the larvae and the population in 7-35 per cent fields was above 50 larvae/100 plants. The pest's incidence was relatively more in years having higher and frequent rains. Based on pest's incidence certain endemic pockets indifferent districts of the state were identified. Factors affecting the pest's incidence on the crop are discussed.