A system of markers (based on relative body thickness and eye development) that characterizes the development of fourth instar/pharate-adult B. argentifolii was used to track development on pubescent vs. glabrous-leafed plants. When reared on the pubescent leaves of green beans and tomatoes, the period of whitefly development prior to becoming pharate adults could be divided into five stages, with depth (thickness) reaching a maximum of 0.25 to 0.3 mm during stages 4-5. In contrast, when reared on the glabrous leaves of cotton, collard or sweet potato, whitefly body thickness rarely surpassed 0.17 mm, a thickness equivalent to Stage 2. However, whitefly nymphs on glabrous plants were significantly longer and wider than those developing on pubescent leaves. Ecdysteroid titers were significantly higher in stage-2 whiteflies reared on glabrous leaves than in stage-2 whiteflies reared on pubescent leaves; but, in all whitefly plant associations, regardless of leaf pubescence, ecdysteroid titers always peaked in early Stage 6 nymphs, either just prior to or at the onset of pharate adult development. Thus, it is apparent that the changes in nymph thickness enabling us to characterize developmental stages 3-5 in nymphs that develop on pubescent leaves, take place within morphological Stage 2 of nymphs that grow on glabrous leaves.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA