Ngowo Halfan S, Hape Emmanuel E, Matthiopoulos Jason, Ferguson Heather M, Okumu Fredros O
Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania.
Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12, 8QQ, UK.
Malar J. 2021 Mar 12;20(1):148. doi: 10.1186/s12936-021-03677-3.
The malaria vector Anopheles funestus is increasingly recognized as a dominant vector of residual transmission in many African settings. Efforts to better understand its biology and control are significantly impeded by the difficulties of colonizing it under laboratory conditions. To identify key bottlenecks in colonization, this study compared the development and fitness characteristics of wild An. funestus from Tanzania (FUTAZ) and their F offspring during colonization attempts. The demography and reproductive success of wild FUTAZ offspring were compared to that of individuals from one of the only An. funestus strains that has been successfully colonized (FUMOZ, from Mozambique) under similar laboratory conditions.
Wild An. funestus (FUTAZ) were collected from three Tanzanian villages and maintained inside an insectary at 70-85% RH, 25-27 °C and 12 h:12 h photoperiod. Eggs from these females were used to establish three replicate F laboratory generations. Larval development, survival, fecundity, mating success, percentage pupation and wing length were measured in the F -FUTAZ offspring and compared with wild FUTAZ and FUMOZ mosquitoes.
Wild FUTAZ laid fewer eggs (64.1; 95% CI [63.2, 65.0]) than FUMOZ females (76.1; 95% CI [73.3, 79.1]). Survival of F-FUTAZ larvae under laboratory conditions was low, with an egg-to-pupae conversion rate of only 5.9% compared to 27.4% in FUMOZ. The median lifespan of F-FUTAZ females (32 days) and males (33 days) was lower than FUMOZ (52 and 49 for females and males respectively). The proportion of female F-FUTAZ inseminated under laboratory conditions (9%) was considerably lower than either FUMOZ (72%) or wild-caught FUTAZ females (92%). This resulted in nearly zero viable F-FUTAZ eggs produced. Wild FUTAZ wings appear to be larger compared to the lab reared F-FUTAZ and FUMOZ.
This study indicates that poor larval survival, mating success, low fecundity and shorter survival under laboratory conditions all contribute to difficulties in colonizing of An. funestus. Future studies should focus on enhancing these aspects of An. funestus fitness in the laboratory, with the biggest barrier likely to be poor mating.
在许多非洲地区，疟疾媒介冈比亚按蚊越来越被认为是残余传播的主要媒介。在实验室条件下对其进行饲养的困难严重阻碍了更好地了解其生物学特性和进行控制的努力。为了确定饲养过程中的关键瓶颈，本研究比较了来自坦桑尼亚的野生冈比亚按蚊（FUTAZ）及其F代后代在饲养尝试过程中的发育和适应性特征。将野生FUTAZ后代的种群统计学和繁殖成功率与在类似实验室条件下已成功饲养的唯一冈比亚按蚊品系之一（来自莫桑比克的FUMOZ）的个体进行了比较。
从坦桑尼亚的三个村庄收集野生冈比亚按蚊（FUTAZ），并将其饲养在昆虫饲养室中，相对湿度为70 - 85%，温度为25 - 27°C，光周期为12小时:12小时。这些雌蚊所产的卵用于建立三个重复的F实验室世代。对F - FUTAZ后代的幼虫发育、存活率、繁殖力、交配成功率、化蛹率和翅长进行了测量，并与野生FUTAZ和FUMOZ蚊子进行了比较。
野生FUTAZ雌蚊产卵数（64.1；95%置信区间[63.2, 65.0]）少于FUMOZ雌蚊（76.1；95%置信区间[73.3, 79.1]）。F - FUTAZ幼虫在实验室条件下的存活率较低，从卵到蛹的转化率仅为5.9%，而FUMOZ为27.4%。F - FUTAZ雌蚊（32天）和雄蚊（33天）的平均寿命低于FUMOZ（雌蚊和雄蚊分别为52天和49天）。在实验室条件下受精的F - FUTAZ雌蚊比例（9%）远低于FUMOZ（72%）或野外捕获的FUTAZ雌蚊（92%）。这导致产生的可存活F - FUTAZ卵几乎为零。与实验室饲养的F - FUTAZ和FUMOZ相比，野生FUTAZ的翅膀似乎更大。
本研究表明，幼虫存活率低、交配成功率低、繁殖力低以及在实验室条件下存活时间短，这些都导致了冈比亚按蚊饲养困难。未来的研究应专注于提高冈比亚按蚊在实验室中的这些适应性方面，其中最大的障碍可能是交配不佳。
