Collaborative Research: Detection, Perception and Utilization of Floral CO2 by Manduca sexta

许多昆虫对环境中的二氧化碳（CO2）很敏感，众所周知，这对于吸引吸血物种到它们的宿主那里是很重要的，但是二氧化碳对以花蜜为食的昆虫的行为意义在很大程度上是不清楚的。初步的研究结果表明，螳螂（鳞翅目：蛛科）可能利用新开的花朵释放的二氧化碳来帮助它在觅食过程中找到未开发的花蜜来源。本研究的主要目的是通过研究曼都卡植物对二氧化碳的感觉检测的生态学、行为学和神经生理学方面的研究，确认和建立花中的二氧化碳在蛾的觅食行为和花的授粉中的作用。具体而言，该项目旨在发现：(1)在飞蛾来访前后，一朵花的花蜜含量与花前二氧化碳浓度之间的关系；(2) Manduca在觅食过程中是否以及如何利用花的CO2；(3)关于二氧化碳的感官信息是如何在蛾的大脑中与花香信息进行加工和整合的。在单独的实验中，对目标(2)中的觅食行为的调查表明，蛾子是否会评估有利可图的单株花或植物斑块，以及觅食的蛾子是否利用关于花的二氧化碳的感官信息来增加花蜜的摄入量。我们还将测试飞蛾是单独使用花香二氧化碳还是与花香结合使用。为了达到这些目标，我们将采用多种实验方法。我们将测量单个飞蛾的行为反应，无论是在实验室（在隧道和气候控制的飞行场所对飞蛾进行实验）还是在野外（在室外飞行围栏中），对花蜜、二氧化碳和花香的数量不同的人造和天然花朵。我们将使用感觉神经生理学技术来记录飞蛾大脑嗅觉中枢神经细胞的反应，当飞蛾分别或同时受到二氧化碳和花香化合物的刺激时。这种方法将有助于了解觅食飞蛾对植物刺激的适应性反应及其潜在的神经生物学机制。在其更广泛的影响中，这项研究预计将对农业社区有用，因为许多飞蛾和其他植物相关昆虫是有益的传粉者和/或经济上重要的害虫。通过二氧化碳线索操纵昆虫的行为已经被用于控制吸血昆虫，如蚊子，并且在这项研究的基础上，可能会开发出类似的方法来帮助控制农业环境中的飞蛾。这项工作也有助于评估如果环境二氧化碳水平继续增加，如对全球气候变化的预测，对生态相互作用（食物网、互惠关系）的后果。此外，重要的是，该项目的参与者将受益于其多学科方法，并获得一系列方法和技术挑战的经验。计划有两名本科生参与。这两个合作实验室都有支持和培训少数民族学生的记录，并将继续这样做。南卡罗来纳州实验室的本科生将从全州范围内的SC少数民族参与研究联盟（SCAMP）中选出，每年将访问图森，与项目参与者会面并参加外展活动。研究结果将以书面和口头形式在科学会议上以及通过面向公众的机构，例如亚利桑那-索诺拉沙漠博物馆传播。

COLLABORATIVE RESEARCH: DETECTION, PERCEPTION AND USE OF FLORAL CO2 IN NECTAR FEEDING BY MANDUCA SEXTAJohn G. Hildebrand and Robert A. RagusoUniversity of Arizona and University of South CarolinaMany insects are sensitive to environmental carbon dioxide (CO2), and it is known to be important for attraction of blood-feeding species to their hosts, but the behavioral significance of CO2 for insects that feed on floral nectar is largely unclear. Preliminary studies yielded findings suggesting that the hawkmoth Manduca sexta (Lepidoptera: Sphingidae) may use elevated CO2, emitted by newly opened flowers, to help it find unexploited nectar sources during foraging. The principal goal of the proposed research is to confirm and establish the roles of floral CO2 in moths' foraging behavior, and hence pollination of flowers, by investigating ecological, behavioral, and neurophysiological aspects of the sensory detection of CO2 in Manduca. In particular, the project aims to discover: (1) the relationship between a flower's nectar content and CO2 concentration in front of the flower, both before and after a moth's visit; (2) whether and how Manduca uses floral CO2 during foraging; and (3) how sensory information about CO2 is processed and integrated with information about floral scent in the moth's brain. The investigation of foraging behavior in aim (2) addresses, in separate experiments, whether moths evaluate profitable individual flowers or plant patches, and whether foraging moths use sensory information about floral CO2 to increase their nectar intake. We also will test whether moths use floral CO2 alone or in conjunction with floral odor. To achieve these aims, we will use a combination of experimental approaches. We will measure behavioral responses of individual moths, both in the laboratory (for experiments on flying moths in a tunnel and in a climate-controlled flight arena) and in the field (in outdoor flight enclosures), to artificial and natural flowers that vary in the amounts of nectar, CO2, and floral scent that they emit. We will use the techniques of sensory neurophysiology to record responses of nerve cells in the olfactory center of the moth's brain, when the moths are stimulated with CO2 and floral-scent compounds, both separately and together. This approach should yield insights about the adaptive responses of foraging moths to floral stimuli and their underlying neurobiological mechanisms. Among its broader impacts, this research is expected to be useful to the agricultural community, as many moths and other plant-associated insects are beneficial pollinators and/or economically important pests. Manipulation of insect performance via CO2 cues is already used to control blood-feeding insects such as mosquitoes and, on the basis of this research, may be developed similarly to help control moths in an agricultural context. This work may also help to assess the consequences for ecological interactions (food webs, mutualisms) if ambient levels of CO2 continue to increase, as is predicted for global climate change. Importantly, moreover, participants in the project will profit from its multidisciplinary approach and gain experience with a range of methods and technical challenges. Involvement of two undergraduate students is planned. Both collaborating laboratories have records of supporting and training minority students and will continue to do so. The undergraduate student in the South Carolina laboratory will be chosen from the state-wide SC Alliance for Minority Participation in Research (SCAMP) and will visit Tucson each year to meet with project participants and participate in outreach activities. Research findings will be disseminated in written and oral form at scientific conferences and through institutions targeting the public, e.g. the Arizona-Sonora Desert Museum.