Seasonal Abundance of Insect Pest and Varietal Performance of Country Bean in Sylhet Sadar, Bangladesh

The study was conducted in Entomology field in SAU to know the incidence of insect pests at different growth stages, intensity of infestation, relative abundance, effect of yield due to different insect during winter and summer season under natural condition. In both season, 4 insect pests found in country bean. The pod infestation by pod borer and aphids in experiment field. Only the field cricket attacked in seedling in summer season. In shoot borer and epilachna beetle infested in leaf and shoot of country bean. Aphid and pod borer were major pests of country bean field. Aphid infested in all stages of country bean but pod borer mainly infested during flowering and fruiting stages of country bean stages. The experiment was laid out in Randomized Complete Design (RCBD) with three replications. The research field was divided into three blocks and each block represented one replication. The accumulated population density was the highest observed aphid (408.74) and the lowest was recorded in shoot borer (20.66) in winter season. Similarly, the accumulated population density was the highest recorded aphid (205.89) and the lowest was observed field cricket (3) summer season. Total number of arthropods was recorded 734 and 346 in winter and summer season; respectively. The highest number of aphids was observed and relative abundance was recorded 55.58% in winter and in summer the highest number of aphids was noted and relative abundance was observed 59.24%. In winter bean flowering stage was recorded the highest number of aphids (150) and the lowest number was recorded in vegetative stage (120); in epilachna beetle was recorded flowering stage was recorded the highest (31) number and the lowest number was recorded in vegetative stage (24); followed by the shoot borer mainly infested in vegetative stage and lowest the others two stages and pod borer infested the highest (235) number in reproductive stage and nil in vegetative stage and moderate number in flowering stage.