THE MAIN SUCKING INSECT PESTS AND THEIR ASSOCIATED PREDATORS ON OKRA PLANTS

The present study was conducted to survey and evaluate the population densities of the major sucking insect pests infesting okra plants and their common associated predators and its relation with the prevailing temperature and relative humidity at Diarb-Nigm district, Sharkia Governorate, Egypt during the two summer growing seasons of 2015 and 2016. Bemisia tabaci (Gennadius), Oxycarenus hyalinipennis Costa, Aphis gossypii Glover, Empoassca lybica (Bergevin) and Thrips tabaci Linde were the main sucking insect pests on okra plants. The most dominant predaceous insect species were Metasyrphus corollae (Fabricius), Chrysoperla carnea (Stephens), Coccinella undecimpunctata Linnaeus and Coccinella septempunctata Linnaeus. B. tabaci showed four peaks in the first and the fourth weeks of July and in the fourth week of August and September in the first season. In the second season, it peaked in the first week of August and September. Two peaks of activity for A. gossypii occurred in the fourth week of July and August during the first season and in the second one it peaked in the fourth week of July and third week of August. T. tabaci peaked in the fourth week of August and the second week of September during the first season. In the second season, it peaked in the fifth week of August. E. lybica peaked in the third week of July, the fourth week of August and the second week of September during 2015 growing season, while in the season of 2016 it peaked in the second week of August and the first week of September. O. hyalinipennis peaked once in the third week of October in both seasons of the study. M. corollae recorded one peak in both seasons, in the first season it was observed in the fifth week of August, while in the second one it was in the second week of August. C. carnea recorded its maximum number in the third and the fourth weeks of July during the first and second seasons of the study, respectively. C. undecimpunctata showed three peaks of activity in the fourth week of June, the second week of July and the second week of August in the first season, while in the second one it peaked in the fourth week of July. C. septempunctata recorded two peaks in the second week of July and August during the first season of the study. In the second season, it peaked in the second week of July. Temperature and relative humidity influenced the populations of B. tabaci, O. hyalinipennis, A. gossypii, E. lybica, T. tabaci, M. corollae, C. carnea, C. undecimpunctata and C. septempunctata by 18.76, 3.19, 18.21, 10.79, 6.23, 15.20, 2.45, 11.75 and 1.45% in the first season of the study and by 41.48, 54.31, 41.47, 53.70, 54.31. 24.86, 7.61, 11.22 and 12.95% in the second one, respectively. Also, the predator-prey ratios were estimated.