Resistance of Tomato Subsamples to Bemisia tabaci Biotype B (Genn.) (Hemiptera: Aleyrodidae)

Whitefly (Bemisia tabaci) causes damage to tomato (Solanum lycopersicum L.) and is controlled by insecticides harmful to man and the environment. Development of resistant cultivars is ideal for whitefly management, with alternate genetic sources being indispensable. Germplasm banks are potentially good sources of resistant cultivars. Agronomic characteristics of the tomato subsamples from the Horticultural Germplasm Bank (HGB) at Universidade Federal de Vicosa (UFV) have been typified but little is known about their insect resistance. Thus, the objective of this study was to assess the resistance of 103 HGB-UFV tomato subsamples to B. tabaci as well evaluate the resistance mechanism. The characteristics of the subsamples evaluated were the number of nymphs and eggs per plant and the resistance index compared with the susceptible cultivar Santa Clara, arbitrarily chosen as the susceptible standard. The trichome number per 0.04 cm(2) of the leaf blades and 15 leaf hydrocarbon concentrations were also determined. Resistant subsamples were submitted to antibiosis test and the mortality (%) and life cycle of the B. tabaci were evaluated. The difference in the number of eggs per plant, nymphs per plant, and nymph/egg ratio in the tomato subsamples was evaluated. A positive correlation was observed between the hydrocarbons undecane and tridecane with B. tabaci nymphs. Significant and positive differences in the trichome per 0.04-cm(2) density were found between the trichome density and the number of eggs per plant. The subsamples HGB-225, -327, -630, -813, -985, -2029, -2030, -2055, -2057, -2060, -2062, and -2068 were resistant to B. tabaci biotype B through antixenosis and antibiosis resistance mechanisms.