Biology and damage of Asian walnut moth, Garella musculana (Lepidoptera: Nolidae), a major insect pest of Juglans regia in Kashmir Himalaya

Over past two decades, Garella musculana (Erschoff, 1874) (Lepidoptera: Nolidae) has surged as a prominent pest in Eurasia infesting Juglans regia. Its caterpillar causes an extensive damage to young fruits and shoots of natural and cultivated varieties of J. regia. The larval instars were seen feeding on nuts from May to August. In August, they start leaving nuts for pupation to continue life cycle next year. The pupation took place inside the loose bark or crevices of walnut trees in white cocoons. In this study life cycle and extent of damage was studied. The larva goes through five growth stages (instars) and lasts for about 67.1±2.26 days. It overwinters in the pupal stage in a white dense cocoon and then emerges in spring as adult when environment becomes favourable. The mean generation time was 297.5±4.45 days. It is univoltine in nature and its larva consumes young walnut pericarp resulting in deformed nuts and there early fall leading to substantial yield loses. The deposition of excrement by larva of G. musculana on the outer green thick layer (husk) degrades its quality and thereby reduces the economic value of the walnut. Knowledge of life-history is crucial for the design of management strategies. The management possibilities of this pest are limited as the feeding destructive larvae are present within the shell or nut. Understanding the life cycle is important to spray timing and effective control. The emergence of the pest and egg laying are important attributes in controlling this pest. Besides natural enemies as eco-friendly approaches acting as bio control agents are encouraged as the most viable alternative for management of this insect pest in this particular area. It is also important to promote the development of new walnut cultivars in newly planted walnut orchards with high potential output and higher shelling percentages.