Aedes aegypti disregard humidity-related conditions with adequate nutrition.

Weather variations have clear associations with the epidemiology of dengue fever and populations of Aedes aegypti mosquitoes. Data on humidity associations, however, lags with respect to its effect on host-biting, nectar-seeking and survival. This experimental study on Ae. aegypti, sourced from the arid tropics, investigated the effect of low and high relative humidity and diet in relation to host-biting, temporal variations in feeding frequency, and mosquito mortality. In each environmental setting, 10 replicates, containing one male and five female mosquitoes, were challenged with different nutritional sources every six hours over 12 days. Results showed that host-biting did not diminish in low humidity and was six times higher than expected. Sucrose feeding was observed to significantly moderate host-biting and water alone was inadequate for survival. The high host-biting rates help to explain the intensity of dengue epidemics, while the ability of the mosquito to disregard adverse humidity-related conditions helps to explain how dengue epidemics in arid tropical regions can be just as devastating as those in the wet tropics.

Aedes aegypti disregard humidity-related conditions with adequate nutrition

Weather variations have clear associations with the epidemiology of dengue fever and populations of Aedes aegypti mosquitoes. Data on humidity associations, however, lags with respect to its effect on host-biting, nectar-seeking and survival. This experimental study on Ae. aegypti, sourced from the arid tropics, investigated the effect of low and high relative humidity and diet in relation to host-biting, temporal variations in feeding frequency, and mosquito mortality. In each environmental setting, 10 replicates, containing one male and five female mosquitoes, were challenged with different nutritional sources every six hours over 12 days. Results showed that host-biting did not diminish in low humidity and was six times higher than expected. Sucrose feeding was observed to significantly moderate hostbiting and water alone was inadequate for survival. The high host-biting rates help to explain the intensity of dengue epidemics, while the ability of the mosquito to disregard adverse humidity-related conditions helps to explain how dengue epidemics in arid tropical regions can be just as devastating as those in the wet tropics.

Adaptation of Aedes aegypti (Diptera: Culicidae) oviposition behavior in response to humidity and diet.

Effects of humidity and sugar concentration on the fecundity, temporal oviposition patterns and survival of a tropical strain of Aedes aegypti (L.) were investigated. Fecundity was significantly reduced by low humidity, but was not affected by sugar concentration. Low humidity caused a significant decrease in percentage survival after 19 days as compared to high humidity. Oviposition was inhibited by host availability for eight successive days. When access to a host was no longer provided, oviposition continued for 10 days in three to four distinct cycles without additional bloodmeals. Humidity stress and high sugar concentration caused oviposition to be delayed for one to four days, which is the typical duration of extreme low humidity periods in nature. These responses are hypothesized to protect the eggs of ovipositing females against the environmental hardships of periodic humidity stress and lack of hosts, thus enabling the perpetuation of the vector and the diseases it transmits in hot and dry seasons.