EFFECTS OF PREDATION RISK AND FOOD AVAILABILITY ON THE ACTIVITY, HABITAT USE, FEEDING-BEHAVIOR AND MATING-BEHAVIOR OF A POND WATER STRIDER,GERRIS-MARGINATUS (HEMIPTERA)

By experimentally manipulating predation risk and food availability, w e explored the effects of these factors on refuge use, general activit y, feeding activity, and mating activity of adults of the pond water s trider Ge,ris marginatus. Predation risk (from adult backswimmers Noto necta undulata) profoundly influenced the behavior of G. marginatus, r educing mating activity, general activity in males and females, decrea sing feeding activity in females and increasing the use of refuge by b oth sexes. Surprisingly, variations in food availability failed to pro duce significant effect:; on any of these behavior patterns. Risk x fo od interactions were also not statistically significant for any gerrid behavior. The significant responses to predators all changed in direc tions that should decrease the risk of predation for G. marginatus.