Seasonal incidence of sucking insect pests and their association with predatory coccinellid beetles on bitter gourd

Abstract

The seasonal incidence of sucking insect pests (aphid, leafhopper, thrips and whitefly) on bitter gourd and their association with predatory coccinellid beetles was studied during kharif and rabi seasons, 2014-15. The mean population of aphid, leafhopper, thrips and whitefly varied from 0.40, 0.65, 0.30 and 0.60 in kharif, 3.86, 1.66, 1.50 and 0.11 in rabi, respectively. Similarly the numbers of predatory coccinellid beetles varied from 0.15 in kharif and 0.48 in rabi. The incidence of aphids, leafhopper and predatory coccinellids were positively correlated (r = 0.85, 0.62, 0.86) respectively, with maximum temperature. The association of sucking pests and predatory coccinellids revealed a positive correlation. A significant positive correlation existed between aphid and predatory coccinellid beetles (r = 0.69 and r = 0.94 per cent) during kharif and rabi season, respectively. These results showed that increase in the incidence of sucking insect pests led to increased population of predatory coccinellid beetles on bitter gourd. Numbers of predatory beetles and other natural enemies should maintain populations of sucking pests below economic injury level on bitter gourd.