Influences of blood digestion on the development of Plasmodium gallinaceum (Brumpt) in the midgut of Aedes aegypti (L.).

Blood digestion of Aedes aegypti and development of Plasmodium gallinaceum were shifted against each other by giving the mosquitoes two consecutive blood meals. In this way the parasites were exposed to an environment where blood digestion was more advanced than in single blood meals. This procedure had an inhibiting effect on oocyst production when the two blood meals overlapped; an enhancing effect when they were well separated. The results are explained by the action of trypsin-like proteases on the parasites and indicate that plasmodia 0-10 h after blood meal are more sensitive to the enzymes than later stages of the parasites.