Mosquito hydration status as a mechanism that alters pre-feeding host interactions and post-feeding physiology

Project summary
Insects are extremely prone to dehydration, where individuals may succumb after exposure to only a few hours
of dry conditions. Mosquitoes are highly susceptible to desiccation due to high water loss rates, especially
when temperatures are high, relative humidity is low, and drinking water is lacking. Importantly, if dehydrated
mosquitoes move to more humid areas, dehydration-induced phenotypes can last for many hours. Recent
studies have examined mosquito development and other specific topic areas under dry season conditions, but
no integrative studies have examined the role of dehydration bouts on mosquito behavior, physiology, and
potential for disease transmission. For most insects, exposure to xeric periods prompts their retreat into
favorable microhabitats until conditions improve, which could take hours or weeks. Our preliminary studies
indicate that activity and blood feeding in mosquitoes increase by three- to four-fold following sub-lethal
dehydration, but the potential mechanisms and impact of this phenotype are unknown. The focus of this
proposal will be examining the effect that dehydration has on mosquito biology, specifically how desiccation
stress alters general mosquito biology, host choice, host-pathogen interactions, and disease transmission. The
primary study organism will be the northern house mosquito, Culex pipiens, a vector for West Nile virus, with
comparative studies to mosquito species to Aedes aegypti. These studies are supported by 1) experimental
designs that can discern the effects between only exposure to dry conditions and direct mosquito dehydration
(= organismal water loss), 2) preliminary studies on CRISPR-Cas9 lines of chemosensory proteins which show
altered water attraction, 3) shifts in blood feeding and diversion of blood to the crop, 4) increased retention of
the bloodmeal in dehydrated mosquitoes when compared to hydrated counterparts, 5) differential expression of
immune genes following a bloodmeal if mosquitoes are dehydrated before host feeding, and 6) field-based
mesocosm experiments that indicate dehydrated mosquitoes are more prone to blood feeding.
This study has four specific aims: Specific Aim 1. Influence of dehydration on basic biological parameters
before and after blood feeding. Specific Aim 2. Examine aspects underlying behavioral modifications of
mosquitoes following dehydration stress. Specific Aim 3. Impact of dehydration on viral retention and
transmission. Specific Aim 4. Field-based observations and mathematical modeling of disease transmission
changes due to dehydration exposure. Overall goal accomplished by the completion of these proposed
studies: These proposed studies will be transformative by providing the first integrative experiments that
examine the effects of dehydration bouts on the dynamics between mosquito physiology, behavior, and
pathogen transmission.

Grant Number: 5R01AI148551-05
NIH Institute/Center: NIH
Principal Investigator: Josh Benoit