Pestilence report of Helicoverpa armigera (Hübner) in apple fruit orchards in Northern Himalayan regions of India

Abstract

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) an extremely destructive pest, causes large economic losses in numerous crops under favourable conditions. In the past few years, it has been seen by researchers and orchardists, feeding on apple fruits grown under high density plantation system under Himachal Pradesh Horticulture Development Project in North Himalayan regions ranging in 320.22’-330.12’N and 750.47’-790.04E with an extent of damage upto 10–15 per cent at various sites. Therefore, in order to determine its biotic potential on apple as a potential host, we studied the demographics of H. armigera on three apple varieties viz., Jeromine, Gale Gala and Red Velox at three fruit growth stages i.e. pea, walnut and mature stage with chickpea and chickpea based diet as control. The test insect completed its life cycle on apple and the duration of different developmental stages was almost equivalent to control, signifying it as potential pest in coming time. H. armigera was unable to survive beyond fifth instar in mature fruits stages, thereby indicating its preference for immature fruits. The population growth parameters were nearly identical; however, the highest values of finite rate of increase (λ) and intrinsic rate of increase (r) with minimum generation time (T) was recorded on insects reared on Gale Gala fruits at walnut stage (1.17, 0.15 and 36.59 days, respectively) which was found to be the most suitable host, while Red Velox was found to be the least preferable host at both pea and walnut stage. Overall, investigations on the biology of H. armigera revealed that apple is a preferred prospective host. If favourable environmental conditions exist, the insect may cause significant harm to high density apple fruit crops, necessitating its management in the future.