MARK-RELEASE-RECAPTURE EXPERIMENTS WITH ANOPHELES-GAMBIAE SL IN BANAMBANI VILLAGE, MALI, TO DETERMINE POPULATION-SIZE AND STRUCTURE

Mark-release-recapture experiments with Anopheles gambiae s,l, were pe rformed during the wet seasons of 1993 and 1993 in Banambani, Mali. Al l recaptured mosquitoes were identified to species by PCR analysis and , when possible, by chromosomal analysis to chromosomal form. Two spec ies of the An. gambiae complex were present: An. gambiae s.s. and An. ambiensis; their ratio differed greatly from one year to the next. Thr ee chromosomal farms of An. gambiae s.s. were found Bamako, Savanna an d Mopti. The drier 1993 was characterized by a high frequency of An. a rabiensis and of the Mopti chromosomal forms of Art. gambiae s.s. Thes e trends were consistent with large-scale geographical patterns of abu ndance along a precipitation gradient. We observed no difference in di spersal between the two species, nor among the chromosomal forms of An . gambiae s.s. Therefore, in this situation at least, it is reasonable to group such data on the An. gambiae complex as a whole for analysis . Population size of An. gambiae s.l. females in the village was estim ated to be 9000-11 000 in 1993 and 28 000 in 1994. The corresponding n umbers were somewhat higher when independently-derived values of daily survival were used. These were consistent with estimates of effective population size obtained from patterns of gene frequency change.