Resistance Assessment of Different Cultivars of Okra ( Abelmoschus esculentus ) Against Whitefly ( Bemisia tabaci )

Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a substantial pest of Okra crop, Abelmoschus esculentus, that caused substantial losses through sucking cell sap. On the basis of susceptibility, a field experiment was carried out to assess the different genotypes of A. esculentus during growing season (July–August) against B. tabaci . Plant genotype resistance and vigor were also evaluated in this study. Meanwhile, morphological parameters were also recorded as well as whitefly-infested and healthy leaves were collected for biochemical analysis. The obtained results revealed that the Okra varieties A. esculentus OK-1304 and Pen Beauty were less infested (mean populations 4.10, 4.97 adults/leaf, respectively) while OK-1307 was highly susceptible to B. tabaci (10.22 adults/leaf). Meanwhile, comparative analysis revealed that B. tabaci population was negatively correlated to relative humidity and positively correlated with low and high temperature. The low concentrations (0.5%) of salicylic acid and citric acid effectively reduced the infestation to 4.63 adults/leaf and 4.87 adult/leaf, respectively, as compared to control (10.17 adult/leaf). The biochemical analysis represented that the catalase concentration decreased in infested leaves and the concentrations of peroxidase, phenolics and superoxide dismutase that act as resistant compound against insect feeding increased.