Collaborative Research: Host Race Formation Among Southern Hawthorn-Infesting Populations of Rhagoletis Pomonella

该研究项目的目标是了解苹果的主要害虫苹果蛆（Rhagoletis pomonella）如何在美国南部形成专门针对不同物种的本地山楂食用植物的种群。与蝗虫等昆虫不同的是，一个特定物种的所有个体都可以并且确实吃各种各样的食用植物，苹果蛆和类似的昆虫形成了只在一种或几种植物物种的果实中进食的当地种群（称为“宿主种族”）。为了了解它们是如何做到这一点的，将对美国南部攻击不同山楂物种的苍蝇种群进行测试，以确定：1）如果它们优先选择它们寄生的山楂果实的化学气味--这就是苍蝇在自然界中找到宿主植物交配并产卵的方式，2）如果苍蝇的生活周期的时间是适应不同的山楂树果实时的差异-一些南方山楂果实非常早的季节（5月）和一些晚（11月-11月），以及3）在何种程度上观察到的气味反应和生命周期的差异是基于遗传的。更广泛的影响的研究是多方面的，具有重要的应用和基本的好处。昆虫经常把食物转移到新的作物上。苹果蛆就是一个典型的例子，在过去的100年里，它从没有什么商业价值的本地山楂变成了具有巨大经济价值的引进苹果。关于这一过程如何发生的信息，将通过对南方山楂蝇的研究提供，是更好地管理害虫所需要的。例如，来自苹果的苹果小实蝇被红山楂的气味所排斥，反之亦然，这导致在各种南方山楂物种中可能发现甚至更好的天然驱避气味的可能性。该项目也具有基本的科学意义，因为对新植物的转移可能会触发许多宿主特异性昆虫的物种形成。最后，该项目将通过帮助整合地方、社区和大学层面的科学培训和教育，提供重要的额外社会效益

The goal of this research project is to understand how the apple maggot fly, Rhagoletis pomonella, a major pest of apples, can form populations that specialize on different species of its native hawthorn food plants in the southern United States. Unlike insects such as grasshoppers, where all individuals of a given species can and do eat a wide range of food plants, the apple maggot and similar insects form local populations (termed "host races") that feed within the fruits of only one or a few plant species. To understand how they do this, fly populations attacking different species of hawthorns in the southern United States will be tested to determine: 1) if they preferentially orient toward the chemical odor of the fruit of the hawthorn species they infest--this is how the flies find their host plants in nature to mate on and lay eggs into fruit, 2) if the timing of the life cycle of the flies is adapted to differences in when the various hawthorn trees fruit--some southern hawthorns fruit very early in the season (May) and some late (October-November), and 3) the degree to which any observed differences in odor response and life cycle are genetically based.The broader impacts of the research are multi-faceted, having both important applied and basic benefits. Insects frequently shift their feeding to new crops. The apple maggot fly is a classic example, having shifted in the last 100 years from native hawthorns of little commercial interest to introduced apples of great economic value. Information about how this process occurs, which will be provided by research on southern hawthorn flies, is needed for better management of pests. For example, Rhagoletis pomonella flies from apple are repelled by the odor of red hawthorn, and vice versa, leading to the possibility that even better natural repellent odors might be found among the various southern hawthorn species. The project is also of basic scientific interest because shifts onto novel plants may serve as a trigger for speciation for many host specific insects. Finally, the project will provide important additional societal benefits by helping integrate science training and education across the local, community, and university levels