COMPARATIVE FECUNDITY AND ASSOCIATED FACTORS FOR 2 SIBLING SPECIES OFTHE ANOPHELES-GAMBIAE COMPLEX OCCURRING SYMPATRICALLY IN THE GAMBIA

For two sibling species of mosquitoes belonging to the Anopheles gambi ae complex of malaria vectors, the effects of body size (wing length) and bloodmeal size (haematin excretion) on fecundity of wild females w ere investigated in The Gambia, West Africa. Freshly blood-fed individ uals from sympatric populations of An.arabiensis and An.gambiae sensu stricto were sampled by collection at 07.00-09.00 hours from within be dnets during July/August 1993, at the beginning of the rainy season. T he possible confounding effect of infection with Plasmodium parasites was removed by eliminating infected mosquitoes from the study samples. An.arabiensis females comprised 75% of the An.gambiae sensu late popu lation and were significantly larger (greater mean wing length) than t hose of An.gambiae s.s. mosquitoes. Mean egg production per female (fo r the subsequent gonotrophic cycle, excluding pre-gravids) for the two species was not significantly different, though the relationship betw een wing length and egg production showed An.gambiae s.s. to be more f ecund than the An.arabiensis of the same size. Pregravid An.gambiae s. s. had consumed significantly smaller bloodmeals than gravid females b ut the mean wing length of these two gonotrophic categories was not si gnificantly different. In contrast, An.arabiensis pre-gravids were sma ller and had consumed smaller bloodmeals than the gravids.