Temperature is known to affect survival and development time of larval mosquitoes, as well as survival, size, and longevity of adult mosquitoes. As vectors of disease, temperature has been shown to alter competence (ability to maintain and transmit a pathogen) of some mosquito species, as well as pathogen incubation period. Understanding how temperature interacts with larval mosquito community dynamics is vital for modeling how vector communities and vectorial capacity may be altered by climate change. We aimed to answer the following question: can vector community composition alter the thermal niche of mosquito species through interspecific larval competition? We performed laboratory microcosm experiments to explore the effects of interspecific larval competition on the thermal niche of three vector mosquito species (Culex quinquefasciatus, Aedes albopictus, and Aedes aegypti). Using measurements of survival, development time, and body size, we estimated population growth rates for each species in mono-, bi-, and tri-specific treatments. We then fit curves to these data to estimate the thermal niche (i.e., the temperature range in which population growth rate is non-negative) of each species under each competition scenario.
The estimated intraspecific thermal niche of Cx. quinquefasciatus ranged from 11.26 (± 2.08) °C to 40.46 (± 2.11) °C, with a thermal optimum at 29.27 (± 0.007) °C. Competition with Ae. aegypti significantly decreased the thermal maximum and thermal optimum, as well as increased the thermal minimum, of Cx. quinquefasciatus’ thermal niche relative to intraspecific competition. The estimated intraspecific thermal niche of Ae. albopictus ranged from 12.75 (± 1.298) °C to 40.00 (± 0.913) °C, with a thermal optimum at 29.41 (± 0.003) °C. Competition with Cx. quinquefasciatus significantly increased the thermal optimum of Ae. albopictus’ thermal niche. Competition with Ae. aegypti significantly increase the thermal minimum and decreased the thermal maximum of Ae. albopictus’ thermal niche relative to intraspecific competition. The estimated intraspecific thermal niche of Ae. aegypti ranged from 10.53 (± 1.440) °C to 43.47 (± 1.270) °C, with a thermal optimum of 31.12 (± 0.005) °C. Competition with Ae. albopictus, as well as multi-species competition, significantly lower the thermal optimum of Ae. aegypti’s thermal niche.