Blood-feeding drive inhibition of Aedes sierrensis (Diptera: Culicidae) induced by the parasite Lambornella clarki (Ciliophora: Tetrahymenidae).

Female Aedes sierrensis (Ludlow) infected with the parasitic ciliate Lambornella clarki Corliss and Coats were significantly less responsive toward a human host than uninfected females. The proportion of infected females that were inhibited in host-seeking and blood-feeding remained high in all daily exposures to the host. Those that did respond took approximately twice as long to land on the host and 25% longer to complete probing as did uninfected females. In contrast, nearly all uninfected females more than 5 d old rapidly responded to and blood fed on the host. Uninseminated females were more similar in their behavior to infected females than to uninfected inseminated females. For females allowed to ingest blood, the time from completion of probing to engorgement was not significantly different for infected versus uninfected females. Some blood-fed, uninfected females took one additional small blood meal 1-3 d after the first blood meal, but most (56%) were inhibited in blood feeding until after ovipositing. Overall feeding time and most sequential behaviors associated with blood feeding were similar to those reported for other mosquito species. Parasite-induced inhibition of the blood-feeding drive may explain low capture rates of L. clarki-infected mosquitoes at human bait.