Preference of whitefly, Bemisia tabaci, towards black gram genotypes: Role of morphological leaf characteristics

Considering that certain morphological leaf characteristics and foliar pubescence may affect insect feeding preference on plant genotypes, the present studies were undertaken to study the variation in leaf morphology and to further evaluate the influence of leaf characteristics in imparting resistance to black gram (Vigna mungo (L.) Hepper) genotypes against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Evaluation of nine black gram genotypes against B. tabaci in multiple-choice test revealed that moderately resistant genotypes KU 99-20 and NDU 5-7 recorded significantly lowest whitefly population (egg, nymph and adult) as compared to the susceptible genotypes IPU 02-043, KU 7-602, KU 7-605, KU 7-618 and Mash 1-1 and highly susceptible genotypes KU 7-504 and KU 7-505. Evidence for morphological leaf characteristics was gathered using data from leaf area meter, fluorescent, electron microscopy as well as direct visual observations. Correlations between morphological leaf characteristics of black gram genotypes and the whitefly population were examined. Leaf area, lamina thickness and trichome length were significantly and positively correlated with whitefly eggs, nymphs and adults whereas trichome density and angle were negatively correlated. Thus, black gram genotypes with narrow, thin and highly pubescent leaves having short, but erect trichomes should be selected for developing black gram varieties resistant to whitefly.