ECOLOGICAL STUDIES ON CERTAIN HOMOPTEROUS INSECTS INFESTING BROCCOLI PLANTS AND THEIR ASSOCIATED PREDATORS INSECTS AT SHARKIA GOVERNORATE.

Field studies had been carried out in broccoli plants at Minia El – Kamh, district, Sharkia Governorate. Survey and seasonal abundance of certain Homopterous insects (aphids, Leafhoppers and whitefly) and their associated predatory insects during the two successive years 2006 / 2007 and 2007/2008. In addition, we evaluated the effect of temperature and relative humidity on the population densities of these insects under field conditions. Obtained results revealed that aphid species were Brevicoryne brassicae (Linnaeus), Myzus persicae (Sulz), leafhopper species were Empoasca decipiens (Poali) , Empoasca decedens (Poali) , and Balclutha hortensis (Linds.), the white fly was Bemisia tabaci (Genn.), also six predators were associated with these insects. These predators were Coccinella undecimpunctata , Cydonia vicina isis , Paederus alferii, Scymnus syriacus, Chrysoperla carnea and Metasyrphus corollae. The population density of immature stages of B.tabaci (Genn.) occurred with two peaks in end January and February in 2006/2007 season and mid January and February in 2007/2008 season. In the same time, there was one peak of adult stage in mid of February in 2006/2007 season while two peaks in end of January and February in second season. Two peaks for B.brassicae(L.) and M. persicae (Sulz.) in end December and February in 2006/2007 season also two peaks in mid of December and February in second season. Two peaks for E.decipiens (Paoli) were found in end November and February in 2006/2007 and 2007/2008 seasons, also two peaks for E.decedens (Paoli) were recorded during mid of December and February in both seasons. The occurrence of B.hortensis (Linds) occurred with only one peak in end November in first and second season. One peak for predator insects was found in the mid March in the 2006/2007 season, also one peak in the second season at end of February. The statistical analysis showed that temperature and relative humidity had significant with some insects and insignificant with the other.