Effect of temperature on rate of water loss in some water boatmen (Hemiptera: Corixidae)

Abstract

Evaporative water loss was compared in Cenocorixa bifida, Cenocorixa expleta, Cenocorixa blaisdelli, and Callicorixa vulnerata and examined in relation to environmental temperature change. In Ce. bifida, evaporative water loss was also studied with respect to rearing temperature and temperature of adult acclimation. Cenocorixa bifida (reared at 20 °C and acclimated to 20 °C) had the lowest rate of water loss at 20 °C of all species, while Ce. expleta had the highest. This pattern also occurred when the activation energy for water loss among species was compared: Ce. expleta had the lowest and Ce. bifida, the highest. High rearing temperatures and high acclimation temperature both reduced water loss at 20 °C in Ce. bifida. This pattern was also reflected in the activation energy for water loss in the different groups of insects exposed to the various temperatures of emergence or acclimation. These data suggest that cuticle lipids vary among these water boatman species and that changes in the proportions of unsaturated lipids may occur in relation to prior long-term exposure to high temperature. Despite differences in rates of water loss and activation energy for water loss, it appears that temperature does not restrict the distribution of any of these insects.