Additive multiple predator effects of two specialist paradiaptomid copepods towards larval mosquitoes

Abstract

Interactions between multiple predators can profoundly affect prey risk, with implications for prey population stability and ecosystem functioning. In austral temporary wetlands, arid-area adapted specialist copepods are key predators for much of the hydroperiod. Limited autoecological information relating to species interactions negates understandings of trophic dynamics in these systems. In the present study, we examined multiple predator effects of two key predatory paradiaptomid copepods which often coexist in austral temporary wetlands, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 and Paradiaptomus lamellatus Sars, 1985. Predation rates towards larval mosquito prey across different water depths were quantified. Using a comparative functional response approach, individual L. raynerae exhibited significantly higher feeding rates than P. lamellatus, characterised by higher attack rates, shorter handling times and higher maximum feeding rates. Increasing water depth tended to negatively affect prey consumption, particularly for L. raynerae. Interspecific multiple predator consumption combined additively, and thus prey risks were well-predicted from consumption rates by individual paradiaptomid copepod species, irrespective of water depth. Our results suggest that increasing copepod predator diversity in austral temporary wetland ecosystems additively heightens prey risk across different water volumes, and may help to regulate disease vector mosquito populations. Therefore, the numerical extent, phenology and diversity of predator hatching events during the hydroperiod may substantially mediate interaction strengths in these ecosystems.