| dc.description.abstract | Environments can vary across seasons. One characteristic of spring in temperate regions is fluctuations in temperature. Sudden bouts of low temperature can have lasting effects on ectotherms that rely on ambient temperature. For developing insects, being unable to avoid or manage these low temperatures puts them further at risk. For example, Megachile rotundata undergo active development in the spring. Exposure to low temperatures as pupae for short periods does not decrease survival but does affect adult morphology. Pollination services may also be affected if temperatures are too low to promote flight in adults. The overall question is what are the short- and long-term physiological effects of temperature in pupae and adults? The first objective of this dissertation is to investigate the long-term effects of low temperature stress by measuring flight performance, reproductive output, and offspring characteristics. After receiving a constant low temperature for a week, females were less likely to nest and changed their offspring investment. Additionally, offspring of bees exposed to fluctuating low temperature stress were more likely to enter diapause despite being early in the season. The second objective was to test if oxygen consumption across temperatures generated a thermal performance curve as a short-term effect in M. rotundata pupae. Results indicate that oxygen consumption scales non-linearly like a thermal performance curve; however, the negative slope at high temperatures was not observed. The third objective was to determine how microclimate conditions affect flight initiation in M. rotundata adults. Two different activity boxes were designed to measure environmental variables and to manipulate cavity temperature. The first activity box measured several environmental variables and showed that even at very close proximities, M. rotundata experience different temperature conditions. In the other activity box design, internal cavity temperature was manipulated to increase early in the morning. Results show that increasing the cavity temperature promoted earlier flight and at lower ambient temperatures. This dissertation shows that the life stage an insect experiences a thermal stress can affect short- and long-term effects on physiology and life history in M. rotundata. | en_US |
