In animals, successful reproduction involves the identification and location of a suitable partner, an essential activity that is most commonly modulated by sensory inputs such as vision, smell and sound. This proposal addresses the question of how the sense of smell influences behavioral decisions to take flight and subsequent flight performance in insects, specifically moths. Physiological measurements will be made to determine the temperature at which males initiate flight in response to varying odor inputs. Subsequent behavioral studies performed in a wind tunnel will examine the consequences of these decisions in terms of male ability to fly upwind and locate an odor source. From these studies, researchers will gain novel insights into the weighting of different factors (external signals, physiological state) in the "decision-making" process used by male moths to engage in flight behavior and follow odor plumes released by calling females. In terms of broader impacts, this research uses a significant agricultural pest and insights gained from the proposed experiments may lead to novel or improved methods for the control of these insects. In addition, new classroom exercises for K-12 students as well as undergraduate students at the University of Utah are already being developed. Select undergraduate students will also be directly involved in conducting the proposed experiments, thereby exposing them to scientific research.

Project Report

Muscles located in the thorax provide power to the wings for insect flight. In order to generate sufficient lift, the flight muscles have to deliver appropriate power. Power production is dependent upon temperature and, as such, insects must warm up their flight muscles in order to overcome the physiological limitations that would be imposed by trying to fly at ambient temperatures. Moths, like many derived insects (bees, wasps, flies), engage in shivering in order to raise the temperature of their thoracic flight muscles above ambient temperatures before taking flight. In this project, we demonstrated that male moths exposed to a complete female odor blend (pheromone) warmed-up at a faster rate and took flight more quickly when compared to males that were exposed to incomplete odor blends. These results were the first to demonstrate that pre-flight heating rates and takeoff temperatures are not constant as had previously been assumed but instead are dependent upon sensory stimulus. In a follow-up experiment, the mechanism underlying this variability in heating rate was demonstrated to be the result of increased activation of flight muscles during shivering. Finally, we showed that taking flight with a lower muscle temperature (and, hence, below optimal power production) had consequences for male moths. In a wind tunnel study, male moths that took flight with lower thoracic temperatures were less successful in locating the odor source. These results indicate that males make trade-offs in competition for females. In summary, these studies provide important insights into the behavioral and physiological bases of the behavior of insects with implications for many economically and medically important groups. Moreover, these studies also provide some foundation for future investigations into how environmental disturbances might affect important insect activities ranging from crop pollination to disease transmission. Elements of the project have been included in efforts to disseminate information to a broader audience. These efforts have included development of an insect thermoregulation lab for an undergraduate course as well as participation in graduate level courses (entomology and mechanical engineering). In addition, outreach activities have involved the provision of insect diet and materials to 2nd and 3rd grade school children as part of their curricular requirements to study life cycle and habitat. A talk to the general public as part of the College of Science "Science Night Live" series was presented. In addition, we have prepared a series of articles on the subject of how temperature affects sports performance in humans (in collaboration with University of Utah Athletics and the Center for Science & Math Education). Links to these articles are provided below:

National Science Foundation (NSF)
Division of Integrative Organismal Systems (IOS)
Standard Grant (Standard)
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Program Officer
Michelle M. Elekonich
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University of Utah
Salt Lake City
United States
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