The Absence of Antipredator Behaviour in the Larvae of Leucorrhinia dubia (Odonata) and the Consequences for Their Distribution

Abstract

Acidified bog ponds were the only previously reported habitat of larvae of the dragonfly Leucorrhinia dubia (Van der Lind.) (Odonata: Libellulidae). To study its present range of habitats, twenty lakes in southwestern Sweden were sampled. Ten of the lakes supported fish, the other ten lakes were fishless and acidified. L. dubia was found to occur in all ten fishless lakes but in none of the lakes which contained fish. To test the hypothesis that fish predation was the factor behind the distribution of L. dubia, a laboratory study was made where perch (Perca fluviatilis L.) was shown to discover and catch significantly more L. dubia than other dragonfly larvae from lakes with fish. When exposed to a simulated fish attack larvae of L. dubia tried to escape, whereas most larvae of two other genera from lakes with fish feigned death. This result, together with earlier studies on diel activity of L. dubia, supports my opinion that L. dubia is more susceptible to fish predation than are larvae of certain other genera from lakes with fish.