Implications of increasing temperature stress for predatory biocontrol of vector mosquitoes

BACKGROUND: Predators play a critical role in regulating larval mosquito prey populations in aquatic habitats. Understanding predator-prey responses to climate change-induced environmental perturbations may foster optimal efficacy in vector reduction. However, organisms may differentially respond to heterogeneous thermal environments, potentially destabilizing predator-prey trophic systems. METHODS: Here, we explored the critical thermal limits of activity (CTLs; critical thermal-maxima [CTₘₐₓ] and minima [CTₘᵢₙ]) of key predator-prey species. We concurrently examined CTL asynchrony of two notonectid predators (Anisops sardea and Enithares chinai) and one copepod predator (Lovenula falcifera) as well as larvae of three vector mosquito species, Aedes aegypti, Anopheles quadriannulatus and Culex pipiens, across instar stages (early, 1st; intermediate, 2nd/3rd; late, 4th). RESULTS: Overall, predators and prey differed significantly in CTₘₐₓ and CTₘᵢₙ. Predators generally had lower CTLs than mosquito prey, dependent on prey instar stage and species, with first instars having the lowest CTₘₐₓ (lowest warm tolerance), but also the lowest CTₘᵢₙ (highest cold tolerance). For predators, L. falcifera exhibited the narrowest CTLs overall, with E. chinai having the widest and A. sardea intermediate CTLs, respectively. Among prey species, the global invader Ae. aegypti consistently exhibited the highest CTₘₐₓ, whilst differences among CTₘᵢₙ were inconsistent among prey species according to instar stage. CONCLUSION: These results point to significant predator-prey mismatches under environmental change, potentially adversely affecting natural mosquito biocontrol given projected shifts in temperature fluctuations in the study region. The overall narrower thermal breadth of native predators relative to larval mosquito prey may reduce natural biotic resistance to pests and harmful mosquito species, with implications for population success and potentially vector capacity under global change.