Several methods have been employed for evaluating plant resistance to whiteflies. Although, a few researches have been conducted aiming to determine the whitefly nymphal dispersion on crops. The objective of this work was to evaluate the oviposition of B. tabaci biotype B and nymphal dispersion in leaflets with and without exudates on tomato genotypes. Seven genotypes were used: LA716, LA1739, PI134417, LA462, LA1584, 'Santa Clara' and P25 (susceptible control). The oviposition of B. tabaci biotype B was evaluated by using ten couples of the insect in clip cages (2.8 cm²) attached to the abaxial surface of the leaflets. For evaluating the nymphal dispersion, it was considered the insect movement beyond the limits of the occupied area by the clip cages. The evaluated variables were adult mortality 24 hours after the liberation, egg numbers, egg viability, incubation period, nymph numbers and nymphal dispersal. Under leaflets with glandular exudate, LA716, LA1739 and PI134417 caused the highest mortality values. Dead adults found in leaflets of those genotypes were trapped to the glandular exudates, causing reduced oviposition by the insect. For nymphal dispersal, in leaflets with glandular exudate, the highest values occurred in LA716, LA462 and P25. In leaflets without glandular exudate, LA716 promoted the lowest value for nymphal dispersal. The exudate influences negatively on the insect survivorship and oviposition. The nymphal dispersal is also affected by the glandular exudate, but other factors can make an important role on insect movement.
Insecta; Aleyrodidae; silverleaf whitefly; Lycopersicon spp.
