Seasonal incidence of sucking insect pests on okra agro-ecosystem

Abstract

As many as 10 species of insect pests have been recorded in all stages of the okra. Among them, The blister beetle, Mylabris pustulata (Thunberg); grasshopper, Poecilocerus pictus (Fab.); grey weevil, Myllocerus viridanus (Fab.); flea beetle, Nisotra apicefulva (Bryant); aphid, Aphis gossypii (Koch.); leafhopper, Amrasca biguttula biguttula (Ishida); mites, Tetranychus urticae (Koch.); red cotton bug, Dysdercus koenigii (Fab.) were considered as serious defoliators and sucking pests. The fruit borers include Helicoverpa armigera (Hub.) Earias vittella (Fab.) and Earias insulana. The population of all insect pests was more abundant on the crop during August to November. A thorough knowledge of seasonal activity of different insect pests determines the predisposing climatic factors affecting their population dynamics. The study was carried out in the Zonal Agricultural and Horticultural Research Station Navile, Shivamogga. The observations on aphid, whitefly and leafhopper and natural enemy incidence was carried out simultaneously on 5 randomly selected plants per plot, from upper, middle and lower strata. Aphid population showed negative correlation with maximum and minimum temperature, rainfall and maximum and minimum relative humidity whereas, positive correlation with minimum temperature. Aphidophagous predators like coccinellids appeared more or less with aphid population. The coccinellids showed negative correlation with maximum, minimum and mean temperature, rainfall and maximum and minimum relative humidity. Leafhopper population showed negative correlation with maximum, minimum temperature and maximum and minimum relative humidity whereas positive correlation with rainfall.