Lesser Grain Borer

📖 Description

Lesser Grain Borer (Rhyzopertha dominica) is one of the most destructive storage pests of wheat, rice, maize and other cereals across the Indian subcontinent, responsible for post-harvest losses of 20-50% in untreated stored grain. The pest is unusual among storage beetles in that both adults and larvae feed on grain — adults bore into grain kernels and feed internally, while larvae feed on grain dust and damaged kernels. The pest is particularly damaging because (a) adults are strong fliers and can disperse between storage structures, (b) the cylindrical body allows them to bore deep into grain masses where they are protected from contact insecticides, (c) they produce characteristic powdery grain dust that signals heavy infestation, and (d) they cause heating and moisture buildup that favours mould growth and mycotoxin contamination. The pest is most severe in warm dry grain storage (28-35°C, 50-70% humidity) and is particularly problematic in wheat storage (where it can cause 30-50% loss in untreated conditions). IPM with thorough sun-drying before storage, hermetic storage using PICS bags (most effective preventive measure), activated clay or neem oil treatments, and biological control with parasitic wasps (Anisopteromalus) provides effective and sustainable control. The pest has developed resistance to phosphine (the most common fumigant) in many regions, making resistance management critical — rotate fumigants and use hermetic storage wherever possible. The pest is most severe in storage structures with poor sanitation and in areas with continuous grain storage.