The potential contribution of larval Agabus (Coleoptera: Dytiscidae) for mosquito suppression in constructed wetlands

Wetland insect predators have the potential to structure aquatic prey communities via selective predation and may be important for suppression of pest populations. Dytiscid beetles in particular are effective predators in temporary waters and are known predators of mosquito larvae. We conducted laboratory microcosm experiments to determine the potential contribution of two species of early-season, larval dytiscid beetles (Agabus punctatus, Agabus disintegratus; Coleoptera: Dytiscidae) in structuring the prey community via selective predation, and in suppression of mosquito populations in constructed wetlands. Both species consumed copepods, ostracods, and mosquito larvae in no-choice tests. When offered a choice, 76% of all prey consumed were mosquito larvae, indicating selective predation. With follow-up experiments, we determined this preference was due to ease of capture and energetic profitability of mosquito larvae over alternative prey. Cannibalism and intraguild predation were also common within and between species of Agabus, which may affect the overall impact of selective predation. Studies of the ecological interactions between native wetland predators, such as Agabus, and mosquito larvae may lead to a better understanding of how to suppress mosquito populations. Specifically, our experiments demonstrated the ability of Agabus to consume microcrustaceans as alternate prey if preferred mosquito larvae prey were not present. Agabus larvae are therefore good candidates for conservation biological control of mosquitoes in constructed wetlands.