Changes in predator diversity via extinction and invasion are increasingly widespread and can have important ecological and socio-economic consequences. Anticipating and managing these consequences requires understanding how predators shape ecological communities. Previous predator biodiversity research has focused on post-colonization processes. However, predators can also shape communities by altering patterns of prey habitat selection during colonization. The sensitivity of this non-consumptive top down mechanism to changes in predator diversity is largely unexamined. To address this gap, we examined patterns of dipteran oviposition habitat selection in experimental aquatic habitats in response to varied predator species richness while holding predator abundance constant. Caged predators were used in order to disentangle behavioural oviposition responses to predator cues from potential post-oviposition consumption of eggs and larvae. We hypothesized that because increases in predator richness often result in greater prey mortality than would be predicted from independent effects of predators, prey should avoid predator-rich habitats during colonization. Consistent with this hypothesis, predator-rich habitats received 48% fewer dipteran eggs than predicted, including 60% fewer mosquito eggs and 38% fewer midge eggs. Our findings highlight the potentially important links between predator biodiversity, prey habitat selection and the ecosystem service of pest regulation.

Dipteran oviposition response to varied predator species richnessThis dataset contains raw oviposition count data for species of Diptera in Charles City county, Virginia, USA. Insects colonized artificial aquatic mesocosms that contained predator communities of varying predator species richness. Zero predators, or no predators contained no predator organisms. One predator, or single species treatments contained three individuals of only one of the three predator types used in the experiment. The three predator, or high richness treatment mesocosms each contained three individuals, one of each predator type used in the experiment. The Culex raft and chironomid mass columns contain counts of egg clutches for Culex spp. mosquitoes and chironomid midges, respectively, only. The dipteran clutches column contains counts for Culex spp. mosquitoes, chironomid midges, and additional dipteran colonizers, all summed for the indivudual mesocosm. These data were collected in the field during summer, 2014.MASTER.DATASET.xlsx