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.