Population dynamics of sucking pests and their natural enemies in okra as influenced by weeds

Abstract

Field experiments were conducted to study the seasonal incidence of major sucking insect pests of okra viz., leafhopper, Amrasca biguttula biguttula Ishida, whitefly, Bemisia tabaci Gennadius, and aphids, Aphis gossypii Glover and their natural enemies viz., coccinellids and spiders of okra at the Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai during rabi and summer seasons of 2015–16. Summer sown okra crop was more susceptible to sucking insect pests with more population of natural enemies than rabi okra crop. In rabi crop, the incidence of leafhopper commenced from third week of November 2015, aphid from third week of December 2015 and there was no whitefly incidence. In summer crop, leafhopper and aphid reached maximum in third week of April 2016, while whitefly during first week of April 2016 itself. Results revealed that leafhopper and whitefly had significant positive relationship with maximum and minimum temperature while sucking pests were negatively correlated with relative humidity and rainfall. Okra crop with partial weeding harboured more sucking insects like leafhopper, whitefly and aphids than the weed free okra plot. In addition, maximum population of natural enemies viz., coccinellids and spiders was found in partially weeded plot.