The Relative Susceptibility of Certain Okra Varieties Against the Spiny Bollworm Earias Insulana (Boisd.) (Lepidoptera: Noctuidae)

Abstract

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.