Acylsugars, the primary components of the exudate secreted by type IV trichomes of Lycopersicon pennellii (Carr.) D'Arcy LA716, mediate the resistance of this accession to silverleaf whitefly, Bemisia argentifolii Bellows & Perring, n. sp. Reduction in the settling of the adult silverleaf whiteflies correlates with the concomitant increase in applied acylsugars. Ovipositor of B. argentifolii is also affected by acylsugars, resulting: in a reduction in the number of eggs and nymphs found; however, acylsugars do not affect hatching of nymphs. The threshold amount of acylsugars required for deterring settling and oviposition is below the amount of acylsugars (50-70 µg/cm2) required for control of other insects.