Developmental biology and pestilence of <i>Helicoverpa armigera</i> (Lepidoptera: Noctuidae) in apple orchards of North Himalayan India: an assessment based on age-stage 2-sex life table

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), commonly known as the American Bollworm, was observed by researchers and orchardists, feeding on apple fruits grown in high-density plantations with an extent of damage up to 10-15% at various sites. We tested its biotic potential as a potential host for 3 apple varieties namely, Jeromine, Gale Gala and Red Velox at the pea, walnut and mature fruit stages with chickpea- and chickpea-based diet used as control. The experiment was conducted in the North Himalayan region spanning between 33.120625, 75.571136 to 32.223586, 77.801360. The test-insect completed its life cycle on immature apple fruits but didn't survive beyond fifth instar for the mature fruits stage, indicating its preference for immature fruits. The biological and population growth parameters were observed with highest values of finite rate of increase (λ) and intrinsic rate of increase (r) and minimum generation time (T) for insects reared on fruits of Gale Gala at the walnut stage (1.17, 0.15, and 36.59 d, respectively). Among all the varieties, Gale Gala was found to be the most suitable host at the walnut stage, while Red Velox was the least preferable host at both pea and walnut stage. Overall, investigations on the biology of H. armigera revealed apple as a preferred prospective host. If favourable environmental conditions like warm temperatures and high humidity exist, the insect may cause significant harm to high-density apple fruit crops, necessitating its management in the future.