We investigated how temperature and precipitation regime encountered over the life cycle of Aedes albopictus (Skuse) affects populations. Caged popul

Both density‐mediated and trait‐mediated indirect biotic interactions may be important in structuring communities. Indirect interactions in many study systems remain unexplored; in part, because they are often difficult to detect, and in many instances, have been identified empirically only when unexpected results arise. Indirect effects induced by competition may be particularly important among organisms with complex life cycles, wherein competitive effects experienced in one life stage influence species interactions in one or more subsequent stages. We determined whether species‐specific effects of larval competition in the mosquitoes Aedes albopictus and Aedes aegypti have indirect effects at the adult stage, specifically testing for effects on arboviral infection with Sindbis virus (SINV). For A. albopictus, but not for A. aegypti, competition resulted in greater infection, body titer, and dissemination rates compared to low‐competition conditions. Whole body titers of virus increased with adult size irrespective of competition. However, between competitive treatments, mosquitoes from low‐competition conditions had greater mean size, with lower infection rates and lower whole body titers than the smaller mosquitoes from high‐competition conditions. These results suggest that larval competition, common in natural mosquito populations, has important indirect effects on adults by altering mosquito– virus interactions. Such indirect effects may change transmission parameters of pathogens.

Zika, dengue, and chikungunya are three mosquito-borne viruses having overlapping transmission vectors. They cause diseases having similar symptoms in human patients, but requiring different immediate management steps. Therefore, rapid (< one hour) discrimination of these three viruses in patient samples and trapped mosquitoes is needed. The need for speed precludes any assay that requires complex up-front sample preparation, such as extraction of nucleic acids from the sample. Also precluded in robust point-of-sampling assays is downstream release of the amplicon mixture, as this risks contamination of future samples that will give false positives. Procedures are reported that directly test urine and plasma (for patient diagnostics) or crushed mosquito carcasses (for environmental surveillance). Carcasses are captured on paper samples carrying quaternary ammonium groups (Q-paper), which may be directly introduced into the assay. To avoid the time and instrumentation requirements of PCR, the procedure uses loop-mediated isothermal amplification (LAMP). Downstream detection is done in sealed tubes, with dTTP-dUTP mixtures in the LAMP with a thermolabile uracil DNA glycosylase (UDG); this offers a second mechanism to prevent forward contamination. Reverse transcription LAMP (RT-LAMP) reagents are distributed dry without requiring a continuous chain of refrigeration. The tests detect viral RNA in unprocessed urine and other biological samples, distinguishing Zika, chikungunya, and dengue in urine and in mosquitoes infected with live Zika and chikungunya viruses. The limits of detection (LODs) are ~0.71 pfu equivalent viral RNAs for Zika, ~1.22 pfu equivalent viral RNAs for dengue, and ~38 copies of chikungunya viral RNA. A handheld, battery-powered device with an orange filter was constructed to visualize the output. Preliminary data showed that this architecture, working with pre-prepared tubes holding lyophilized reagent/enzyme mixtures and shipped without a chain of refrigeration, also worked with human plasma samples to detect chikungunya and dengue in Pune, India. A kit, complete with a visualization device, is now available for point-of-sampling detection of Zika, chikungunya, and dengue. The assay output is read in ca. 30 min by visualizing (human eye) three-color coded fluorescence signals. Assay in dried format allows it to be run in low-resource environments.

Ornithophilic Culex species are considered the primary amplification vectors of West Nile virus (WNV) in bird hosts as well as vectors responsible for epidemic transmission. Culex coronator was first collected from Okaloosa, Santa Rosa, Walton, and Washington Counties in Florida in 2005 and has since spread throughout the state. The vector competence of Cx. coronator for WNV, known to be infected in nature, has not been assessed. Without this knowledge, we are unable to assess this species' potential as an enzootic and epidemic vector of WNV in Florida. In the current study, we investigate the reproductive biology and susceptibility to WNV infection, dissemination, and transmission by Cx. coronator . We show that Cx. coronator is capable of delaying oviposition for several weeks after blood feeding and that the number of eggs laid is greater for avian than mammalian hosts. Cx. coronator were highly susceptible to infection (∼80–100%) and dissemination (∼65–85% by 18 days since exposure) with lower rates of transmission (0–17% at 25°C and 28–67% at 28°C), suggesting that it is a competent vector of WNV under some conditions. The proportion of mosquitoes with disseminated infections related to the time since exposure and was higher at 28°C than at 25°C. The rapid and statewide distribution of Cx. coronator throughout Florida poses as a potential public health risk. This baseline knowledge is essential information for mosquito control and public health agencies to assess current and future disease risk to Southeastern United States.

Between 2014 and 2016 more than 3,800 imported human cases of chikungunya fever in Florida highlight the high risk for local transmission. To examine the potential for sustained local transmission of chikungunya virus (CHIKV) in Florida we tested whether local populations of Aedes aegypti and Aedes albopictus show differences in susceptibility to infection and transmission to two emergent lineages of CHIKV, Indian Ocean (IOC) and Asian genotypes (AC) in laboratory experiments. All examined populations of Ae. aegypti and Ae. albopictus mosquitoes displayed susceptibility to infection, rapid viral dissemination into the hemocoel, and transmission for both emergent lineages of CHIKV. Aedes albopictus had higher disseminated infection and transmission of IOC sooner after ingesting CHIKV infected blood than Ae. aegypti. Aedes aegypti had higher disseminated infection and transmission later during infection with AC than Ae. albopictus. Viral dissemination and transmission of AC declined during the extrinsic incubation period, suggesting that transmission risk declines with length of infection. Interestingly, the reduction in transmission of AC was less in Ae. aegypti than Ae. albopictus, suggesting that older Ae. aegypti females are relatively more competent vectors than similar aged Ae. albopictus females. Aedes aegypti originating from the Dominican Republic had viral dissemination and transmission rates for IOC and AC strains that were lower than for Florida vectors. We identified small-scale geographic variation in vector competence among Ae. aegypti and Ae. albopictus that may contribute to regional differences in risk of CHIKV transmission in Florida. The emergence of mosquito-borne chikungunya virus in the Americas starting in 2013 has been associated with geographically widespread outbreaks of human illness. Transmission of chikungunya virus in the U.S. is a major public health risk, especially in Florida where the environmental conditions are favorable for the two main mosquitoes involved in transmission. We measured susceptibility to infection and transmission for Florida Aedes aegypti and Aedes albopictus mosquitoes for two emergent strains of chikungunya virus (Indian Ocean and Asian strains). Both mosquito species showed high susceptibility to infection and rapid spread of the virus throughout the body of the mosquito, including the saliva for both emergent strains of chikungunya virus. Aedes albopictus had higher body infection and transmission of the Indian Ocean strain sooner after feeding on chikungunya virus infected blood than Ae. aegypti. Aedes aegypti had higher body infection and saliva infection later during infection with the Asian strain of chikungunya virus than Ae. albopictus. We also observed declines in body infection and transmission over time, suggesting that transmission risk declines with length of infection. The information here will be useful as parameters in models of risk of chikungunya virus transmission.