Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso.
MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France.
Parasit Vectors. 2020 May 20;13(1):266. doi: 10.1186/s13071-020-04135-w.
The sterile insect technique (SIT) is a vector control strategy relying on the mass release of sterile males into wild vector populations. Current sex separation techniques are not fully efficient and could lead to the release of a small proportion of females. It is therefore important to evaluate the effect of irradiation on the ability of released females to transmit pathogens. This study aimed to assess the effect of irradiation on the survival and competence of Anopheles arabiensis females for Plasmodium falciparum in laboratory conditions.
Pupae were irradiated at 95 Gy of gamma-rays, and emerging females were challenged with one of 14 natural isolates of P. falciparum. Seven days post-blood meal (dpbm), irradiated and unirradiated-control females were dissected to assess the presence of oocysts, using 8 parasite isolates. On 14 dpbm, sporozoite dissemination in the head/thorax was also examined, using 10 parasites isolates including 4 in common with the 7 dpbm dissection (oocyst data). The survivorship of irradiated and unirradiated-control mosquitoes was monitored.
Overall, irradiation reduced the proportion of mosquitoes infected with the oocyst stages by 17% but this effect was highly inconsistent among parasite isolates. Secondly, there was no significant effect of irradiation on the number of developing oocysts. Thirdly, there was no significant difference in both the sporozoite infection rate and load between the irradiated and unirradiated-control mosquitoes. Fourthly, irradiation had varying effects on female survival with either a negative effect or no effect.
The effect of irradiation on mosquito competence strongly varied among parasite isolates. Because of such isolate variability and, the fact that different parasite isolates were used to collect oocyst and sporozoite data, the irradiation-mediated reduction of oocyst prevalence was not confirmed for the sporozoite stages. Our data indicate that irradiated female An. arabiensis could contribute to malaria transmission, and highlight the need for perfect sexing tools, which would prevent the release of females as part of SIT programmes.
无菌昆虫技术（SIT）是一种依赖于大量释放不育雄虫进入野生媒介种群的病媒控制策略。目前的性别分离技术并非完全有效，可能会导致少量雌虫的释放。因此，评估辐照对释放雌虫传播病原体能力的影响非常重要。本研究旨在评估辐照对实验室条件下感染疟原虫的阿拉伯按蚊雌蚊的生存和繁殖能力的影响。
将蛹用 95Gy 的伽马射线照射，然后用 14 株自然分离株中的一株感染新羽化的雌蚊。在血餐 7 天后（dpbm），解剖辐照和未辐照对照雌蚊，用 8 株寄生虫分离株评估卵囊的存在。在 14 dpbm 时，还使用 10 株寄生虫分离株（包括与 7 dpbm 剖检相同的 4 株）检查头部/胸部的孢子传播情况。监测辐照和未辐照对照蚊的存活率。
总体而言，辐照使感染卵囊阶段的蚊子比例降低了 17%，但这种效应在寄生虫分离株之间高度不一致。其次，辐照对卵囊的发育数量没有显著影响。第三，辐照和未辐照对照蚊的感染率和载量没有显著差异。第四，辐照对雌蚊的生存有不同的影响，要么有负面影响，要么没有影响。
辐照对蚊子繁殖力的影响在寄生虫分离株之间有很大的差异。由于这种分离株的变异性，以及使用不同的寄生虫分离株来收集卵囊和孢子数据，因此没有确认辐照对孢子阶段卵囊流行率的降低。我们的数据表明，辐照后的雌性阿拉伯按蚊可能会有助于疟疾传播，并强调需要完善的性别分离工具，以防止在 SIT 计划中释放雌性。
