Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 1999
Publication Date: N/A
Technical Abstract: Whitefly species are responsible for crop damage totaling hundreds of millions of dollars per year. Biological control of whiteflies using hymenopteran parasitoids may become practical if cost-effective artificial diets are developed for the whitefly host or for the parasitoid itself. Compared with other economically important pests, very little research has been done in whitefly physiology. There is a critical need for such research if artificial rearing of whiteflies or their natural enemies is to succeed. We have developed a system of markers to characterize the development of 4th instar T. vaporariorum, based on body thickness and adult eye development. Measurement of body depth combined with size and color of the developing adult whitefly eye were used to divide the instar into ten stages. Maximum body thickness is attained by stage 5 and adult eye development commences at stage 6; the adult eye is fully developed by stage 8. Histological studies suggests that apolysis probably occurs after the whitefly body has grown to maximum thickness and just prior to the beginning of eye development, i.e., in stage-5 4th instars. In stage-6 4th instars, the wing buds have undergone considerable development. By stage 7, spines were observed on the new cuticle, indicating that adult cuticle was well-formed by this stage. Results for Bemisia argentifolii 4th instars were similar. Typically, in preparations of stage 6 or older 4th instars, the larval cuticle was either separated from the epidermis or had become detached during processing. Thus, apolysis, had probably occurred prior to this stage. We are attempting to measure ecdysteroid titres in 4th instar whiteflies in order to precisely determine the onset of adult development.