Effects of mating, nutritional condition, and mouthpart separation on ingestion and destination of sugar and water by the mosquito Culiseta inornata

Abstract

ABSTRACT. ‘Hungry’ tethered female Culiseta inornata (Williston) (Diptera: Culicidae) with their mouthparts separated, respond in the sugar‐feeding mode when the fascicle is immersed in 1 M sucrose, and in the drinking mode when the fascicle is immersed in water. Similarly treated animals that are ‘not hungry’ respond in the drinking mode to water on the fascicle, but when given 1 M sucrose on the fascicle take less than a normal amount and tend to put it in the midgut instead of the crop. ‘Starving’ animals respond in the sugar‐feeding mode to sucrose on the fascicle, but when given water on the fascicle take slightly more than a normal amount, and about 50% put it in the crop. These results occurred whether the labellum was immersed in water, 1 M sucrose, or nothing. Differences in responses by tethered animals with separated mouthparts and non‐tethered intact animals can be attributed to mouthpart deployment. These results do not agree with those of other workers who report that similarly treated female C. inornata require stimulation of both the fascicle and labellar chemoreceptors before they will ingest. These differing results raise interesting questions concerning the range of feeding behaviours available to different demes of this mosquito, and indicate how these behaviours are modified by differences in pre‐test nutritional condition and mouthpart deployment.