Do migrant moth species have adaptations that reduce the cost of long distance flight on future reproduction?

对几种表现出翅膀多态性（同时具有翅膀和无翅形态）的昆虫物种的研究表明，无翅成虫的繁殖能力高于从日益恶化的栖息地迁徙出来的有翅昆虫。这些结果被解释为支持“飞行是以繁殖为代价”的观点。然而，对于所有成虫都有翅膀并且需要飞行来寻找食物、交配和产卵地点的物种，这一点尚未得到仔细研究。此外，据推测，迁徙物种已经进化出一些特征，以降低后续繁殖输出中维护飞行装置的成本。在我的研究小组中，我们一直使用真正的粘虫 P. unipuncta（所有成虫都具有功能性翅膀）作为模型系统来研究信息素介导的交配，并表明迁徙（北美）和非迁徙（亚速尔群岛）种群之间存在显着的行为和生理差异。我们将使用北美 (NA) 迁徙种群以及来自亚速尔群岛 (AZ) 和夏威夷 (HA) 的非迁徙种群来研究单态物种的繁殖飞行成本，并检验迁徙者进化出降低迁徙成本的性状的假设。我们将比较夏季（非迁徙）和秋季（迁徙）期间在实验室不同控制条件下和自然田间条件（昆虫）下人工饲料和天然寄主植物饲养的 NA 个体。我们将测试形态（翅膀大小、胸部质量）的差异，以确定飞行机械（肌肉/翅膀）是否存在差异分配，并检查不同持续时间的飞行对飞行前后喂养不同糖制度的非迁徙者和迁徙者的繁殖力的影响。这些实验将使我们能够确定是否存在与迁徙相关的繁殖成本，以及迁徙后的进食和交配是否可以减轻这些成本。我们还将检查胸肌，以确定居民和移民（来自自然种群和野外饲养）之间是否存在结构和/或生理差异，以确定移民是否进行了减少繁殖飞行成本的修改。这些实验将在来自 AZ 和 HA 的非移民个体中重复进行，因为 AZ 成虫体型较小，性成熟年龄更小，但终生生殖输出却显着高于 NA 的成虫。 我们最近的工作表明，在三个不相关的物种中，与信息素介导的交配相关的行为会随着大气压力（AP）的短期变化而发生变化。我们现在将测试以下假设：成年粘虫蛾的飞行倾向不仅受到季节变化相关线索的影响，而且还响应 AP 的每日波动，AP 提供可靠的飞行条件指标。

Studies on several insect species exhibiting wing polymorphism (having both winged and wingless morphs) have shown that the reproductive output of wingless adults is higher than their winged counterparts that migrate out of deteriorating habitats. These results have been interpreted as supporting the idea that flight comes at a cost to reproduction. However, this has not been examined carefully in species where all adults are winged and require flight for the location of food, mates and oviposition sites. Furthermore, it has been hypothesized that migrant species have evolved traits to reduce the cost of maintaining flight apparatus on subsequent reproductive output. In my research group we have been using the true armyworm, P. unipuncta, where all adults have functional wings, as a model system to study pheromone mediated mating and have shown there are marked behavioural and physiological differences between migratory (North America) and non-migratory (Azores) populations. We will use the North American (NA) migrant population, and non migrant populations from the Azores (AZ) and Hawaii (HA), to examine the cost of flight on reproduction in a monomorphic species and to test the hypothesis that migrants have evolved traits to reduce the costs of migration. We will compare NA individuals reared under different controlled conditions in the laboratory and under natural field conditions (insectary) on both artificial diet and natural host plants during the summer (non-migrants) and fall (migrants). We will test for differences in morphology (wing size, thoracic mass) to determine if there is differential allocation to flight machinery (muscle/wings) and examine the effect of flight of different durations on the fecundity of non-migrants and migrants fed different sugar regimes before and after flight. These experiments will allow us to determine if there are reproductive costs associated with migration and whether post-migratory feeding and mating might mitigate them. We will also examine thoracic muscle to determine if there are structural and/or physiology differences between residents and migrants (from natural populations and field rearings) to determine if migrants have modifications that reduce the costs of flight on reproduction. These experiments will be repeated with non migrant individuals from AZ and HA, as AZ adults are smaller and become sexually mature at a younger age, yet have a significantly higher life time reproductive output than those from NA. Our recent work has shown that the behaviours associated with pheromone mediated mating in three unrelated species changed in response to short term changes in atmospheric pressure (AP). We will now test the hypotheses that flight propensity of adult armyworm moths will be not only be affected by cues associated with seasonal change, but also in response to daily fluctuations in AP that provide reliable indicators of flight conditions.