Trehalulose and Multiple Day Flight in the Physiology and Ecology of Bemisia tabaci (Gennadius)

Abstract

Physiological factors that might influence ecological dynamics were investigated to better explain the biology of Bemisia tabaci in the desert southwest. Trehalulose, a unique disaccharide only found in unusually large quantities in B. tabaci honeydew, was shown not to be different from sucrose in promoting longevity in honeydew-consuming parasitoids, indicating this insect-modified sugar does not affect the nutritional quality of aleyrodid excreta. Trehalulose is not believed to function as a feeding deterrent to natural enemies. Experiments were designed to examine the effect of temperature on sorbitol and trehalulose production by the whitefly. High performance liquid chromatography analysis of honeydew and whole body extractions revealed a negative relationship between amounts of trehalulose in the honeydew and sorbitol accumulation in the whitefly body, linking these two molecules as important to the nutritional ecology of whiteflies. In another experiment to better understand the dispersal of whiteflies across the landscape, studies of flight over multiple days were conducted to describe the role of prior flight experience on dispersal and migratory flight. Flight performance traits were measured over multiple days of flight to compare two groups of B. tabaci, those trapped moving outside of planted fields with those collected within fields. Trap-caught individuals exhibited flights of significantly shorter duration in a vertical flight chamber. Flights determined to have characteristics of migratory behaviors were initially of longer duration for trap-captured whiteflies than their field-collected counterparts. Over the context of multiple days, however, their longer flights were followed by much shorter flights on subsequent days. Although many insects from both groups were capable of movement on multiple days, almost all of these flights were of a foraging nature. Foraging flights of short duration would likely not add to dispersal distances, thereby limiting whiteflies to their originating patch.