The effect of resource limitation on the temperature dependence of mosquito population fitness

Abstract

Laboratory-derived temperature dependencies of life history traits are increasingly being used to make mechanistic predictions for how climatic warming will affect vector-borne disease dynamics, partially by affecting abundance dynamics of the vector population. These temperature-trait relationships are typically estimated from juvenile populations reared on optimal resource supply, even though natural populations of vectors are expected to experience variation in resource supply, including intermittent resource limitation. Using laboratory experiments on the mosquito Aedes aegypti, a principal arbovirus vector, combined with stage-structured population modelling, we show that low-resource supply in the juvenile life stages significantly depresses the vector's maximal population growth rate across the entire temperature range (22-32°C) and causes it to peak at a lower temperature than at high-resource supply. This effect is primarily driven by an increase in juvenile mortality and development time, combined with a decrease in adult size with temperature at low-resource supply. Our study suggests that most projections of temperature-dependent vector abundance and disease transmission are likely to be biased because they are based on traits measured under optimal resource supply. Our results provide compelling evidence for future studies to consider resource supply when predicting the effects of climate and habitat change on vector-borne disease transmission, disease vectors and other arthropods.

The effect of resource depletion on the thermal response of mosquito population fitness

“…The negative effect of low-resource concentration on these traits delayed the onset of reproduction and population-level reproductive output, respectively. This finding--that juvenile traits contribute more to rm than adult traits--is consistent with general studies of fitness in organisms with complex lifecycles (Caswell 1978;Kammenga et al 1996;Huey & Berrigan 2001;Cator et al 2020), including mosquitoes (Juliano 1998;Huxley et al 2020).…”

“…While recent studies have shown that resource availability can affect the rm TPC in aquatic ectotherms (Orcutt & Porter 1984;Koussoroplis & Wacker 2016;Thomas et al 2017), very studies have examined how the rm TPC in terrestrial arthropods may be shaped by variation in resource availability (but see Huxley et al 2020). Therefore, the question of whether and how temperature and resource depletion interact to modulate disease transmission together through effects on underlying vector traits remains open.…”