Diurnal Temperature Range and Chikungunya Virus Infection in Invasive Mosquito Vectors

Abstract

Climate strongly influences the geographic distribution and timing of mosquito-borne disease outbreaks. Environmental temperature affects phenotypic traits of mosquitoes including vector competence for arboviruses mediated by changes in infection, extrinsic incubation period and in rates of transmission. Most experiments, however, are done at constant temperatures. In nature, mosquitoes are more likely to experience daily fluctuations in temperature. Here we compare disseminated infection (leg infection) and saliva infection of Aedes aegypti (L.) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) from Florida following oral exposure to an Asian genotype of chikungunya virus emergent in the Americas. We evaluated experimentally the effect of variable temperature regimens on disseminated infection and saliva infection of these Aedes species. Each of three temperature regimes had approximately the same average temperature (27-28°C), but differed in the magnitude of the diurnal temperature range (DTR). The large DTR was 8.0°C (range 23-31°C) and the small DTR was 4.0°C (range 26-30°C) which approximate ranges in different locations of Florida during July-October when risk of transmission is highest. The constant temperature was set at 27°C. Testing three geographic populations of each mosquito species, significant effects on disseminated infection were detected for an interaction between temperature regime and geographic population for both Ae. aegypti and Ae. albopictus. There were no significant treatment effects of temperature, geographic population, or temperature by geographic population interaction on saliva infection for either mosquito species. Constant temperature resulted in a higher viral load in the saliva of Ae. albopictus, but not Ae. aegypti, compared to conditions where the temperature fluctuated.

The tortoise strategy as an arbovirus fitness phenotype within the mosquito as revealed by a novel formulation of age-structured vectorial capacity

“…Prediction of vector-borne disease spread remains difficult, as transmission of vector-borne disease is a dynamic, multifaceted system. This includes life traits of the mosquito, environmental factors, and vector-virus interactions [4,11,[39][40][41]. Here we demonstrate that mosquito age at the time of pathogen acquisition is a powerful driver of transmission potential due, in large part, to the age-dependence of daily mortality and biting habits.…”

“…Many things affect vector competence including vector species, discrete populations within species, and environmental factors [1, 14,19,20,28,40,42,43]. Several recent studies have focused on environmental factors such as temperature, and found that temperature not only affects vector competence of many arboviruses, especially in Aedes aegypti, but also several life traits of the mosquito [27,39,41]. This means that transmission is ultimately affected by the interactions of all of these temporally dependent processes, and while mathematical frameworks for assessing temperature and other extrinsic factors have been developed, they do not often explicitly consider age, another important temporal component to the transmission cycle of vector-borne diseases.…”

Arbovirus Vectors of Epidemiological Concern in the Americas: A Scoping Review of Entomological Studies on Zika, Dengue and Chikungunya Virus Vectors

“…aegypti [126,127,144,161–164,164–166], Ae. albopictus [127,144,162,164–167], Aedes terrens [168], and Haemagogus leucocelaenus [168] are all experimentally competent to transmit chikungunya virus. Chikungunya virus transmission in Ae.…”

“…Four studies measured the effect of temperature on vector competence [145,161,162,171]. Adelman et al [161] found that under silenced RNAi conditions, Ae.…”

“…aegypti were more predisposed to chikungunya infection at lower temperatures. Alto et al [162] found that larger fluctuations in diurnal temperature range led to higher rates of chikungunya infection, and Xiao et al [145] found that maximum dengue infection rates occurred at 31 °C. Mordecai et al [171] modelled Ae.…”