Effect of Leaf Age and Silverleaf Symptoms on Oviposition Site Selection and Development of <I>Bemisia argentifolii</I> (Homoptera: Aleyrodidae) on Zucchini

Abstract

The development of whitefly control tactics that provide a safer alternative to using pesticides requires a thorough understanding of the interaction between these insects and their host plants. In this study, we investigated the effect of leaf age of zucchini, Cucurbita pepo L., on the oviposition site selection and on the development and survival of immature Bemisia argentifolii Bellows & Perring. Also, we evaluated the effect of squash silverleaf symptoms on adult alighting and oviposition site selection, and on the development of immatures. Whiteflies oviposited significantly more on younger, hairier leaves than on older leaves when tested in a dual-choice petri dish clip cage. Time to 50% emergence was longer on younger versus older leaves, yet survival of immatures did not differ statistically between the leaves tested. In free-flight choice experiments, whiteflies (male and female) alighted significantly less frequently on silverleaf-affected plants than on healthy green plants. However, in dual-choice oviposition experiments, whiteflies did not discriminate between silvered and healthy green leaves. Further experiments revealed no differences in the development of immature B. argentifolii on healthy and silvered leaves. This indicates that the chemical and physiological changes in silverleaf-affected leaves do not have a detrimental effect on the survival or development of whitefly nymphs.