Population dynamics of major pests of okra

Abstract

Seasonal incidence of major insect pests of okra was studied during kharif 2017 on the basis of standard meteorological weeks (SMW) at the College of Agriculture Jabalpur, on variety GAO5. The jassid Amrasca biguttula biguttula and aphid Aphis gossypii were observed to be active from August to October with their peak during 40th SMW (2.3 jassid and 1.5 aphid/leaf). The whitefly Bemisia tabaci occurred between second week of August and third week of October with peak in 38 SMW (7.4 whitefly/plant). Red spider mite Tetranychus urticae was observed from 6th to 30th October with peak at 42 SMW (690.7 nymph+ adult mites/leaf). The shoot and fruit borer Earias vitella was observed from second week of September (37 SMW) up to fourth week of August (43 SMW) with three peaks in 38, 41 and 43 SMW (5.61, 6.38 and 4.67% fruit infestation). Correlation and regression analysis of incidence with weather factors revealed that population of jassid (nymph+ adult/leaf) had a significant positive relation with maximum temperature (r=0.68); and aphid (nymph+ adult/leaf) had a significant positive correlation with number of rainy days and morning vapour pressure (r=0.64 and 0.62).