Spotted Pod Borer, Maruca vitrata Geyer in Legumes: Ecology and Management

摘要

Spotted pod borer is one of the key insect pests of tropical food legumes damaging tender leaf axils, flower buds, flowers and pods by webbing and boring clusters of flowers or pods during cooler parts of the year on about 39 hosts. Short duration, determinate pigeon peas and cowpeas with compact clusters are more susceptible. In cowpea the damage was about 25-40% and in pigeonpea, it was 9-84 % across the globe. Female moths laid about 200 flat scaly eggs on floral buds, flowers, leaves, leaf axils,terminal shoots and tender pods. Larvae are photonegative and larval period lasted from 8 to 21 days on different hosts.Pupal period lasted from 6 to 14 days. Longevity of female moths was more (7-10 days) than males (5-6 days). Peak incidence started from 40th (October) to 47th standard week (November). Temperature preferenda ranged from 20 to 28°C for growth and development. For screening pigeon pea genotypes for resistance, a comprehensive methodology (Plant Susceptibility Index) involving webbingdamage, larval density and flower damage was attempted. In cowpea and pigeonpea, higher phenol, lower sugar, amino acid and crude fibre contents might contribute for resistance. Qualitative traits such as red petals, pink pod streaks may also supplementfor low resistance. A total of 27 parasitoids, 20 predators, two protozoans and two bacteria were reported on egg, larva and pupa. Cultural practices such as removing leguminous weeds, trap cropping with Crotalaria spp., intercropping monocots like sorghum, maize, pearl millet or finger millet, mung and urd beans reduced pod damage in main crop. Biocides like Neem Seed kernel extract (NSKE), Neem Oil (NO) and Bacillus thuringiensis (Bt) showed varied levels of potency either alone or in combination withinsecticides. Due to concealed larval habitat, insecticides showed varied levels of effectiveness. However, Controlled Droplet Application (CDA), strip application and sequential spraying of selected insecticides were effective in reducing pod damage.