The energetic costs of diving in Aedes aegypti and Aedes albopictus pupae

Undisturbed mosquito pupae rest at the water surface and respond to passing shadows or vibrations by diving. Pupae do not feed and rely solely on ener gy stored from the larval stage. The ability of a newly emerged adult mosqu ito to survive, and therefore to transmit disease, depends on these energy reserves. Earlier studies of diving behavior in Aedes aegypti, Ae. albopict us, and Ae. triseriatus pupae provided evidence that pupae sense their stat e of buoyancy and modify their diving behavior accordingly. With strong sti mulation pupae tend to dive to a depth where they become neutrally or negat ively buoyant and commonly rest on the bottom. This behavior, as well as th e tendency to rest when not disturbed, may logically be viewed as energy-co nserving. The results of these studies also generated the hypothesis that t he diving behavior displayed by these container-breeding mosquitoes helps t hem avoid being washed from their container by overflowing water during rai nfall. Rainfall Stimulates diving and logically, prolonged, heavy rainfall stimulates excessive diving, a likely drain on energy reserves. Our objecti ves were to determine, in Ae. aegypti and Ae. albopictus, the energetic cos ts associated with resting behavior, with frequent diving, and with buoyanc y reduction. Using survival rate, mean survival after adult emergence, and measurement of total calories, we found a clear energetic cost associated w ith frequent diving. In contrast, relative to diving, essentially no energy cost was associated with buoyancy reduction, that is, pupae behave in resp onse to variations in buoyancy in a way that does not impact significantly on energy reserves.