Comparison of behavior and vector efficiency of Anopheles gambiae and An. arabiensis (Diptera : Culicidae) in Barkedji, a Sahelian area of Senegal

The ecology, population dynamics, and malaria vector efficiency of #Anopheles gambiae$ and #An. arabiensis$ were studied for 2 yr in a Sahelian village of Senegal. Anophelines were captured at human bait and resting indoors by pyrethrum spray. Mosquitoes belonging to the #An. gambiae$ complex were identified by polymerase chain reaction. Of 26,973 females, #An. arabiensis$ represented 79% of the mosquitoes captured and remained in the study area longer than #An. gambiae$ after the rains terminated. There were no differences in nocturnal biting cycles or endophagous rates between #An. gambiae$ and #An. arabiensis$. Based on an enzyme-linked immunosorbent assay test of bloodmeals, the anthropophilic rate of these 2 vectors were both approximately 60%, when comparisons were made during the same period. Overall, 18% of the resting females had patent mixed bloodmeals, mainly human-bovine. The parity rates of #An. gambiae$ and #An. arabiensis$ varied temporally. Despite similar behavior, the #Plasmodium falciparum$ circumsporozoite protein (CSP) rates were different between #An. gambiae$ (4.1%) and #An. arabiensis$ (1.3%). #P. malariae$ and #P. ovale$ only represented 4% of the total #Plasmodium$ identified in mosquitoes. Transmission was seasonal, occurring mainly during 4 mo. The CSP entomological inoculation rates were 128 bites per human per year for the 1st yr and 100 for the 2nd yr. Because of the combination of a high human biting rate and a low CSP rate, #An. arabiensis$ accounted for 63% of transmission. Possible origin of differences in CSP rate between #An. gambiae$ and #An. arabiensis$ is discussed in relation to the parity rate, blood feeding frequency, and the hypothesis of genetic factors. (Résumé d'auteur