Indirect Interactions Limit the Efficiency of Odonata as Natural Control Agents for Mosquito Larvae

Odonate nymphs are voracious predators and may be useful natural control agents. However, odonates are normally found in complex guilds with a high degree of conspecific and inter specific predation that may reduce their overall predation efficiency. The present study investigates whether indirect interactions, mediated via chemical predation signals, inhibit the consumption of mosquito larvae by two common odonates: Crocothemis erythraea and Ischnura evansi. Our results show that the predation rate of C. erythraea is reduced by chemical cues from Anax imperator, but the response of I. evansi to C. erythraea was statistically non-significant. This study shows that intra-guild interactions may limit the effectiveness of odonates as predators of mosquitoes.