To evaluate the impact of drought stress on the incidence of certain arthropod pests and their associated predators which inhabit cowpea plantations, field tests were conducted in two different levels of irrigation (10-and 20-day intervals) by using five newly produced cowpea cultivars. Results indicated that the main piercing and sucking pests Bemisia tabaci (Genn.) and Tetranychus urticae Koch. were represented in high numbers in stressed plantations when compared to non-stressed ones. On the other hand, the common predators associated with these pests had not been affected by these irrigation differences. Regarding to the damage percentage caused by the pod borer pest Etiella zinckenella Treitschke, an obvious increase was recorded on stressed plantations than on the normal irrigated ones in most of the tested cultivars. At harvest, the obtained results indicated an obvious decrease in the net yield income of all the tested cultivars in the stressed irrigated area than in normal irrigated one. Therefore, it must be recommended to irrigate cowpea plantations by at least 10-day intervals to avoid the high infestation by both of the sucking pests and pod borers, and also, to obtain high and good yield income.
Fourteen okra varieties were tested in Assiut governorate to estimate their fruit infestation degrees caused by the spiny bollworm Earias insulana (Boisd.) and to determine their susceptibility degrees against this insect pest. Irany, Red base and Balady 4 okra varieties recorded the highest infestation values with an average of 11.92% > 10.40% > 9.13%, respectively. However, Oraby, Balady 5 and Balady 6 okra varieties recorded the lowest values with an average of 6.93% > 6.79% > 6.75%, respectively, as an average of the two successive seasons of 2009 and 2010. The highest infestation was recorded during the last three weeks of August. Dependent on the mean numbers of (Bores + larvae), the tested varieties revealed different susceptibility degrees to the pest. Balady 5 and Balady 6 varieties harboured the lowest numbers and appeared as highly resistant (HR) varieties. The remaining varieties revealed different susceptibility degrees to the pest. Negative correlation was recorded between the numbers of hairs presented on fruit surface of both Balady 5 and Balady 6 varieties and the pest infestation. Therefore, okra varieties that showed some sort of resistance can be included among advanced breeding programs to select new varieties resistance to E. insulana.
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