Regulation of blood meal size in the mosquito.

In order to determine the r61e played by the central nervous system in regulating blood meal size, the ventral nerve cord was cut at various sites along its length in the female mosquito, Aedes aegypti. When the cord was cut anterior to the second abdominal ganglion, massive hyperphagia resulted, many females ruptured, and blood intake was more than four times that of the untreated controls. As the site of the operation was moved stepwise posteriorly leaving more ganglia connected to the brain via the ventral nerve cord, the degree of hyperphagia and quantity of ingested blood was reduced. On the basis of these observations it was concluded that the termination of feeding was initiated by segmental abdominal stretch receptors which act in concert and signal the presence of optimal blood meal volume to the brain. Five additional mosquito species were tested for hyperphagia and all ingested three to four times the normal blood meal volume when the ventral nerve cord was cut. Females with the nerve cord severed showed normal ovarian development and egg formation, but oviposition was inhibited.