Complementary impacts of heterospecific predators facilitate improved biological control of mosquito larvae

Natural enemies can play a critical role in regulating pests, with simplified ecosystems often favoring pest proliferation via reduced predation pressure. As predator-predator interactions and size refuge effects directly influence prey risk, an understanding of multiple predator effects across prey ontogeny could be useful for quantifying natural enemy impacts on target populations. In the present study, we used functional responses (FRs) to quantify the combined predatory impacts of a copepod, Lovenula falcifera (Copepoda: Diaptomidae), and a notonectid, Anisops sardea (Hemiptera: Notonectidae), on Culex pipiens larvae over the course of their development. The impacts of copepods and notonectids differed across larval mosquito ontogeny. Copepods were most efficient consumers of early instar mosquitoes, but were unable to handle larger late instars, whereas notonectids were most effective against later instars. Both predators exhibited Type II FRs and typically contributed additively to prey risk, with synergistic impacts evident on prey of intermediate sizes. Thus, community diversity can potentially facilitate improved predatory impacts on larval mosquitoes across their ontogeny. The additive feeding rates of this copepod-notonectid combination suggests a lack of interference among these predators. Therefore, the promotion and conservation of such complementary predator assemblages in temporary wetlands can be recommended to suppress populations of mosquitoes which vector pathogens and parasites.