Sy Faty Amadou, Faye Ousmane, Diallo Mawlouth, Dia Ibrahima
Unité d'Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Sénégal.
Laboratoire d'Ecologie Vectorielle et Parasitaire, Departement de Biologie Animale, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal.
J Vector Borne Dis. 2019 Jul-Sep;56(3):207-211. doi: 10.4103/0972-9062.289401.
BACKGROUND & OBJECTIVES: The emergence and spread of insecticide resistance in African malaria vectors raise concerns over the control of malaria disease. Therefore, the implementation of better control strategies need a thorough understanding of the effects and mechanisms of resistance on vector adaptation capacities. We studied the effects of insecticide resistance on the reproductive potential of two laboratory sub-strains of the malaria vector Anopheles coluzzii characterised by phenotypic resistance/susceptibility to DDT.
The two sub-strains were selected from a laboratory strain of An. coluzzii using WHO test tubes. For each sub-strain, the number of produced and hatched eggs, developmental time, mosquito stages mortality, sex ratio and insemination rates after dissection of spermathecae were compared as measures of reproductive potential.
Overall, the susceptible sub-strain produced higher but not significant mean numbers of eggs. However, the mean numbers of hatched eggs, larvae, pupae and adults were significantly lower than those of the resistant substrain. The mean time from egg-hatching to adult-emergence, egg-flooding to hatching, I instar to pupae and pupae to adult were similar between the two sub-strains. The mortality rates at the pupal stage were significantly different between the two sub-strains. Of the dissected spermathecae, 85.1% of the females from the resistant sub-strain were fertilized compared to 66.1% of the females from the susceptible sub-strain (p <0.0001). The resistant sub-strain produced more females in comparison to the susceptible sub-strain (respective mean sex ratio 1.37 vs 1.03, p = 0.01).
INTERPRETATION & CONCLUSION: The results show differential life history traits between the two sub-strains of the malaria vector An. coluzzii, particularly fertility, insemination rate and sex ratio. They may have varied implications for insecticide resistance spread, monitoring and management; and hence underscore the need of further investigations before any generalization.
非洲疟疾媒介中杀虫剂抗性的出现与传播引发了对疟疾控制的担忧。因此，实施更好的控制策略需要深入了解抗性对媒介适应能力的影响及机制。我们研究了杀虫剂抗性对疟疾媒介科氏疟蚊两个实验室亚株繁殖潜力的影响，这两个亚株对滴滴涕具有表型抗性/敏感性。
使用世界卫生组织的试管从科氏疟蚊的一个实验室品系中选取这两个亚株。对于每个亚株，比较所产卵的数量、孵化的卵数量、发育时间、蚊虫各阶段死亡率、性别比以及解剖受精囊后的受精率，以此作为繁殖潜力的衡量指标。
总体而言，敏感亚株产出的卵平均数量更高，但差异不显著。然而，孵化出的卵、幼虫、蛹和成虫的平均数量显著低于抗性亚株。从卵孵化到成虫羽化、从卵浸没到孵化、从一龄幼虫到蛹以及从蛹到成虫的平均时间在两个亚株之间相似。两个亚株在蛹期的死亡率存在显著差异。在解剖的受精囊中，抗性亚株85.1%的雌性已受精，而敏感亚株为66.1%（p<0.0001）。与敏感亚株相比，抗性亚株产生的雌性更多（平均性别比分别为1.37对1.03，p = 0.01）。
结果显示疟疾媒介科氏疟蚊两个亚株之间存在不同的生活史特征，尤其是繁殖力、受精率和性别比。它们可能对杀虫剂抗性的传播、监测和管理具有不同的影响；因此强调在进行任何概括之前需要进一步研究。
