Stacey, C. L. | bioRxiv Science

bioRxiv2024

Multiple bouts of blood feeding in mosquitoes allow prolonged survival and are predicted to increase viral transmission during drought

Survival through periods of drought is critical for mosquitoes to reside in semi-arid regions with humans. Dry conditions increase blood feeding propensity in mosquitoes, but it is unknown if dehydration-induced bloodmeals increase feeding beyond what is necessary for reproduction. Following a bloodmeal, prolonged exposure to dry conditions increased secondary blood feeding in mosquitoes by nearly two-fold, and chronic blood feeding allowed mosquitoes to survive up to twenty days without access to water sources. This refeeding did not alter the number of eggs generated, suggesting this refeeding is for hydration and nutrient replenishment. Exposure to desiccating conditions following a bloodmeal resulted in increased activity, decreased sleep levels, and prompted a return of CO2 sensing before egg deposition. Increased blood feeding during the vitellogenic stage and higher survival during dry periods are predicted to increase pathogen transmission, allowing for a rapid rebound in mosquito populations when more favorable conditions return. This explains the elevated levels of specific arbovirus cases in association with periodic dry conditions and warrants further consideration as climate change progresses. Overall, these results solidify our understanding of the role of dry periods on mosquito blood feeding and how mosquito dehydration contributes to vectorial capacity and disease transmission dynamics Significance statementBouts of dehydration yield substantial changes to insects physiology and behavior. Mosquitoes are exceptionally prone to dehydration due to high water loss rates, but few integrative studies have examined the comprehensive impact of drought conditions on mosquitoes. Here, we demonstrate that dry conditions lead to multiple blood feeding events, allowing mosquitoes to survive dry periods. This repeated blood feeding is associated with higher activity and an early return of attraction to vertebrate hosts. Increased dry season survival and more frequent blood feeding are predicted to yield higher transmission of mosquito-borne viruses. This suggests that a higher prevalence of drought associated with climate change will have varying impacts on mosquito-borne diseases.

physiology↗

bioRxiv2024

Developmental stage and level of submersion in water impact the viability of lone star and winter tick eggs during flooding

Female ticks deposit large egg clusters that range in size from hundreds to thousands eggs each. These clusters are immobile and restricted to a deposition site, usually under leaf litter and other debris. These sites can be exposed to periodic flooding, where the cluster of tick eggs can float to the surface or remain underneath organic debris entirely submerged underwater. Here, we examined the viability of egg clusters from winter ticks, Dermacentor albipictus, and lone star ticks, Amblyomma americanum, when partially or fully submerged in water and in relation to the developmental stages of the eggs. In general, egg clusters that were older and partially submerged had a higher viability than fully submerged, younger eggs. A. americanum was more resistant to water exposure between the two species. These studies highlight that egg clusters for certain tick species can remain viable when exposed to water for at least two weeks. These studies also suggest that distribution by flooding of egg clusters could occur for some species and flooding will differentially impact tick egg survival based on the specific developmental stage of exposure and species.

ecology↗