Effect of pre-storage infestation levels of Callosobruchus analis (F.) on mungbean

The bruchids are major post-harvest pests of several legumes throughout the tropical and sub-tropical regions of the world. Bruchid infestation commences from mature pods and seeds in the field which persists and increases rapidly during storage causing nearly total loss of stored pulses depending on the duration of storage. A study was conducted to determine the population build-up and seed damage following 48 h exposure of mungbean to varied initial infestation levels, viz. one, two, three, four and five pairs of Callosobruchus analis (F.). A significant positive correlation was observed for infestation levels (r =0.98) and F1 population (r= 0.97) with seed damage. The regression studies indicated 99% variability in the seed damage due to initial infestation, egg density and population build up after F1 generation. Although the population build-up (F= 20.57, df= (4,15), P < 0.05) and associated seed damage (F= 22.56, df= (4,15), P < 0.05) were considerably higher when mungbean seeds carried initial infestation of five pairs of beetles. The egg-to-adult developmental period of Fj generation based on Howe's parameter was found to be 29 days in mungbean. The results indicated that a small initial infestation of C. Analis could multiply rapidly and cause considerable damage to mungbean during storage.