THERMOREGULATION OF AN UNUSUAL GRASSHOPPER IN A DESERT ENVIRONMENT - THE IMPORTANCE OF FOOD SOURCE AND BODY-SIZE

1. The black cone-headed grasshopper, Poekiloceros bufonius, lives in hot, arid environments. Its diurnal behavior exposes it to direct sunl ight. 2. P. bufonius is able to withstand the poisonous sap of its foo d plants and thus may have an abundant water supply available to it. T he sexual dimorphism of the species suggests the 5 x larger females ma y have an advantage in water storage over the males. 3. Both genders w ere able to depress their internal temperatures below the higher tempe ratures of their environment by evaporative cooling. 4. The males lost proportionately more water by evaporation, produced drier feces and m ay be more constrained by water availability. The females appear to be more profligate with their water reserves which supports the idea tha t large body mass may be an advantage to an insect in the desert.