Research Note 2: Egg raft density and feeding preference of Culex species in Yola, north-eastern Nigeria

Abstract

The renewal of malaria and filarial parasite control efforts has led to re-invigoration in malaria and vector research involving laboratory rearing of mosquitoes, particularly Culex and Anopheles species. Too often, researchers spend valuable time
estimating the egg density in culicine rafts and despite dwindling research budgets, a lot of funds are committed to the feeding of mosquitoes in the laboratory with traditional feeds. A study was carried out to estimate the population parameters
of culicine egg rafts and the food preferences of immature feeding stages and adult Culex species kept in an outdoor-cage in Yola, Nigeria. The mean eggs per raft varied from 148 for Culex in captivity to 227.6 for those in the wild. The difference
between egg rafts in the wild and those laid in the laboratory are therefore not similar in density but can be estimated to be about 150 eggs. Larvae fed on yeast have twice as much chance for survival as those fed on crayfish. However there were no
observable differences in adult preference for table sugar and sucrose solutions. The adult female and male fed on the feed that was available and fed equally on both feeds when kept together. Investigators requiring the rearing of mosquitoes will
find the results from this study useful for estimating the number of eggs in a culicine egg raft, making a decision on larvae food preference and using the easily available table sugar instead of the more expensive sucrose in adult rearing.

Keywords:mosquito eggs, mosquito larvae, culicine mosquito, egg raft density.

Nigerian Journal of Parasitology Vol. 28 (2) 2007: pp.131-134