Department of Experimental Medicine, University of Perugia, Perugia, Italy.
Present address: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
Parasit Vectors. 2019 Feb 6;12(1):70. doi: 10.1186/s13071-019-3289-y.
Novel transgenic mosquito control methods require progressively more realistic evaluation. The goal of this study was to determine the effect of a transgene that causes a male-bias sex ratio on Anopheles gambiae target populations in large insectary cages.
Life history characteristics of Anopheles gambiae wild type and Ag(PMB)1 (aka 124L-2) transgenic mosquitoes, whose progeny are 95% male, were measured in order to parameterize predictive population models. Ag(PMB)1 males were then introduced at two ratios into large insectary cages containing target wild type populations with stable age distributions and densities. The predicted proportion of females and those observed in the large cages were compared. A related model was then used to predict effects of male releases on wild mosquitoes in a west African village.
The frequency of transgenic mosquitoes in target populations reached an average of 0.44 ± 0.02 and 0.56 ± 0.02 after 6 weeks in the 1:1 and in the 3:1 release ratio treatments (transgenic male:wild male) respectively. Transgenic males caused sex-ratio distortion of 73% and 80% males in the 1:1 and 3:1 treatments, respectively. The number of eggs laid in the transgenic treatments declined as the experiment progressed, with a steeper decline in the 3:1 than in the 1:1 releases. The results of the experiment are partially consistent with predictions of the model; effect size and variability did not conform to the model in two out of three trials, effect size was over-estimated by the model and variability was greater than anticipated, possibly because of sampling effects in restocking. The model estimating the effects of hypothetical releases on the mosquito population of a West African village demonstrated that releases could significantly reduce the number of females in the wild population. The interval of releases is not expected to have a strong effect.
The biological data produced to parameterize the model, the model itself, and the results of the experiments are components of a system to evaluate and predict the performance of transgenic mosquitoes. Together these suggest that the Ag(PMB)1 strain has the potential to be useful for reversible population suppression while this novel field develops.
新型转基因蚊控制方法需要越来越现实的评估。本研究的目的是确定导致雄性偏性性别比的转基因对大型昆虫笼中目标冈比亚按蚊种群的影响。
为了对预测种群模型进行参数化，测量了野生型和 Ag(PMB)1（又名 124L-2）转基因蚊子的生活史特征，其后代 95%为雄性。然后，以两种比例将 Ag(PMB)1 雄蚊引入含有稳定年龄分布和密度的目标野生型种群的大型昆虫笼中。比较了大笼中预测的雌性比例和观察到的雌性比例。然后，使用一个相关模型来预测在西非村庄释放雄性对野生蚊子的影响。
在 1:1 和 3:1 释放比例处理（转基因雄蚊：野生雄蚊）中，转基因蚊子在目标种群中的频率在 6 周后分别平均达到 0.44 ± 0.02 和 0.56 ± 0.02。转基因雄蚊分别导致 1:1 和 3:1 处理中的性别比扭曲为 73%和 80%的雄性。随着实验的进行，转基因处理中产卵数量下降，3:1 处理的下降速度快于 1:1 处理。实验结果部分符合模型预测；在三次试验中有两次，效应大小和变异性与模型不一致，模型高估了效应大小，变异性大于预期，可能是由于重新放养时的抽样效应。估计假设在西非村庄释放对蚊子种群影响的模型表明，释放可以显著减少野生种群中的雌性数量。释放间隔预计不会产生强烈影响。
用于对模型进行参数化的生物数据、模型本身以及实验结果是评估和预测转基因蚊子性能的系统的组成部分。这些一起表明，在这一新型领域发展的同时，Ag(PMB)1 株具有成为可逆种群抑制的潜在用途。
