Driving sex conversion for the genetic control of agricultural pests

许多种类的昆虫以农作物为食并对其造成损害。例如，一些苍蝇在成熟的水果中产卵，然后通过喂食幼虫来分解。这会减少农业生产，并可能给农民造成空腹和经济损失。世界气候正在变化，使得昆虫入侵新的地区，繁殖速度更快。不断增长的人口给世界农业系统带来了越来越大的压力，同时昆虫对杀虫剂的抗药性也越来越强。这些挑战迫使我们设想可持续控制昆虫的新方法。昆虫遗传控制是一种特定物种的生物控制形式，通过释放转基因昆虫来减少或消除野生昆虫种群造成危害的可能性。例如，几十年来，大量释放绝育雄性一直被用来减少许多害虫的种群数量。一种遗传控制策略是使用被称为基因驱动的遗传元素。这些元素由几种经过改造的昆虫引入种群中，可以繁殖并影响整个害虫种群的基因构成，例如降低雌性昆虫的生育力。另一种方法是影响人口的性别比例，并将其转向男性。由于雌虫的数量对害虫种群的数量很重要，而且作物损害完全是通过雌虫的活动发生的，这种干扰雌性生育和雌性发育的方法是非常有希望的。在这个研究项目中，我们正在开发一种新的控制策略，试图将这两种方法结合起来，以实现更强大的干预。我们将在一种经过充分研究的害虫物种--头状蜡虫、能够危害许多果树的地中海果蝇(地中海果蝇)和一种相关害虫种类的模式昆虫--中率先采用这项技术。在麦德蝇中，真性变即雌性转变为完全可育的雄性是可能的，当受到基因驱动的影响时，也降低了雌性的生育力，预计将导致害虫种群的迅速消除。我们将设计和测试用于基因驱动和性别转换的分子构件，并将它们结合在一起，以证明这种害虫物种的笼子种群可以在实验室中消除。

Many insect species feed on and damage crop plants. Some flies for example lay their eggs in ripening fruit which are then decomposed by feeding larvae. This reduces agricultural production and can cause both empty stomachs and economic losses for farmers. The world's climate is changing allowing insects to invade new regions and reproduce faster. A growing human population puts a rising strain on the worlds agricultural systems while at the same time insects are becoming increasingly resistant to pesticide chemicals. These challenges are forcing us to envision novel ways in which we can sustainably control insects.Genetic control of insects is a species-specific form of biological control where the release of modified insects reduces or eliminates the potential of wild insect populations to do harm. For example, the mass-release of sterilized males has been used to reduce the population size of many insect pests for many decades. One genetic control strategy is the use of genetic elements called gene drives. These elements, introduced by a few modified insects into a population, can propagate and affect the genetic makeup of the entire pest population, for example reducing the fertility of females. Another approach is affecting the population's sex ratio and shifting it towards males. Since the number of females is important for the size of an insect pest population and since crop damage occurs solely through the activities of females, such approaches that interfere with female fertility and female development are very promising.In this research project we are developing a novel control strategy that seeks to combine these two approaches for an even more powerful intervention. We will pioneer this technology in a well studied insect pest species Ceratitis capitata, the Mediterranean fruit fly (medfly) capable of damaging many fruit crops and a model insect for a whole range of related pest species. In the medfly true-sex conversion i.e. the transformation of females into fully fertile males is possible and, when effected by a gene drive that also reduces female fertility, is predicted to lead to the rapid elimination of pest populations. We will design and test the molecular building blocks for both gene drive and sex conversion in the medfly and combine them to demonstrate that caged populations of this pest species can be eliminated in the lab.