Okanda F M, Dao A, Njiru B N, Arija J, Akelo H A, Touré Y, Odulaja A, Beier J C, Githure J I, Yan G, Gouagna L C, Knols B G J, Killeen G F
International Centre of Insect Physiology and Ecology, PO Box 30772, Nairobi, Kenya.
Malar J. 2002 Aug 14;1:10. doi: 10.1186/1475-2875-1-10.
Plasmodium-refractory mosquitoes are being rapidly developed for malaria control but will only succeed if they can successfully compete for mates when released into the wild. Pre-copulatory behavioural traits maintain genetic population structure in wild mosquito populations and mating barriers have foiled previous attempts to control malaria vectors through sterile male release.
Varying numbers of virgin male and female Anopheles gambiae Giles, from two strains of different innate sizes, were allowed to mate under standardized conditions in laboratory cages, following which, the insemination status, oviposition success and egg batch size of each female was assessed. The influence of male and female numbers, strain combination and female size were determined using logistic regression, correlation analysis and a simple mechanistic model of male competition for females.
Male An. gambiae select females on the basis of size because of much greater fecundity among large females. Even under conditions where large numbers of males must compete for a smaller number of females, the largest females are more likely to become inseminated, to successfully oviposit and to produce large egg batches.
Sexual selection, on the basis of size, could either promote or limit the spread of malaria-refractory genes into wild populations and needs to be considered in the continued development and eventual release of transgenic vectors. Fundamental studies of behavioural ecology in malaria vectors such as An. gambiae can have important implications for malaria control and should be prioritised for more extensive investigation in the future.
用于疟疾防控的疟原虫抗性蚊子正在迅速培育，但只有当它们被释放到野外后能够成功竞争配偶时才会取得成效。交配前的行为特征维持着野生蚊子种群的遗传种群结构，而交配障碍致使之前通过释放不育雄蚊来控制疟疾媒介的尝试受挫。
将来自两种先天体型不同品系的不同数量的冈比亚按蚊吉尔斯处女雄蚊和雌蚊，置于实验室笼子中的标准化条件下进行交配，之后评估每只雌蚊的受精状态、产卵成功率和卵块大小。使用逻辑回归、相关分析以及雄蚊争夺雌蚊的简单机制模型，确定雄蚊和雌蚊数量、品系组合以及雌蚊体型的影响。
冈比亚按蚊雄蚊会根据体型选择雌蚊，因为大体型雌蚊的繁殖力更强。即使在大量雄蚊必须争夺较少数量雌蚊的情况下，体型最大的雌蚊更有可能受精、成功产卵并产出大量卵块。
基于体型的性选择可能会促进或限制疟原虫抗性基因向野生种群的传播，在转基因媒介的持续研发和最终释放中需要加以考虑。对冈比亚按蚊等疟疾媒介行为生态学的基础研究可能对疟疾防控具有重要意义，未来应优先进行更广泛的调查。
