Buoyancy and diving behavior in mosquito pupae
Romoser, W.S.; Lucas, E.A.
Journal of the American Mosquito Control Association 15(2): 194-199
1999
ISSN/ISBN: 8756-971X PMID: 10412114 Document Number: 502697
Mosquito pupal diving behaviour has been studied mostly in Aedes aegypti, and in this species pupal buoyancy varies relative to several factors. The research reported herein addresses the 2 following questions. Does diving behaviour vary among different mosquito genera and species? How is diving behaviour influenced by variation in buoyancy? Depth and duration of dive, and dive pattern, were compared among A. aegypti, Culex pipiens, Anopheles stephensi, Aedes albopictus and A. triseriatus. In response to the stimulation associated with transferring pupae between containers, diving behaviour varied dramatically among the different genera studied. C. pipiens and Anopheles stephensi make short-duration, shallow dives and remain positively buoyant. The 3 aedine species studied make longer-duration dives, typically to a depth at which they become neutrally or negatively buoyant. Buoyancy reduction effects were studied in the 3 aedine species. Normally buoyant pupae tend to dive to greater depths and for longer periods of time than reduced-buoyancy pupae. Aedine pupal diving behaviour clearly is closely regulated relative to buoyancy variation. To the earlier hypotheses that pupal behaviour may help avoid predation and be energy-conserving, the authors add the suggestion that the diving behaviour displayed by the container-breeding aedine pupae studied represents an adaptation that helps keep them from being washed from their container habitat by overflowing water during rainfall. They also suggest that the diving behaviour of all the species studied may help pupae survive heavy pelting rainfall, by enabling them to avoid the mechanical shock of a direct hit by a raindrop, which could cause disruption of the gas in the ventral air space, thereby causing the loss of hydrostatic balance and drowning.