Effect of abiotic factors on Incidence of sucking insect pests and their major natural enemies of Okra

The present research was aimed to study the seasonal incidence of major sucking pests and their natural enemies on okra, Abelmoschus esculentus (L.) Moench under field conditions at Department of Entomology, S.K.N. College of Agriculture, Jobner, Rajasthan during kharif, 2014. The crop revealed that two sucking pests viz., jassid, Amrasca biguttula biguttula (Ishida) and whitefly, Bemisia tabaci (Genn.) appeared as major sucking pests. The incidence of jassid and whitefly was first commenced in the second week of August and reached to peak (16.50 jassids and 18.80 whiteflies per three leaves) in the third week of September, at 34.5 0C maximum temperature, 22.1 0C minimum temperature, 71.0 per cent relative humidity, thereafter, the insect population started declining. The correlation studies revealed that the infestation of jassid and whitefly on okra crop showed non-significant correlation with maximum temperature (r = -0.02 and -0.03), minimum temperature (r = 0.30 and 0.33) and rainfall (r = 0.45 and 0.48), while positive significant correlation with relative humidity (r = 0.65 and 0.64) and predatory lady bird beetle (r = 0.98 and 0.97). The predatory lady bird beetle, Menochilus sexmaculatus Fab. was also recorded during the crop season. The population of lady bird beetle was first recorded in the third week of August which gradually increased and reached to peak (4.70 beetles/ five plants) in the third week of September, thereafter, their population started to decline. The correlation studies showed a non-significant correlation with maximum temperature, minimum temperatures and rainfall, while, significant correlation with relative humidity. Lady bird beetles showed a significant effect on the pest species.