Meeting Abstract
Organisms rely on exogenous cues to entrain their biological rhythms to daily and seasonal fluctuations of the environment. Circadian outputs are mediated by a zeitgeber, which resets molecular feedback loops referred to as clocks. Common zeitgebers found across organisms are the lengths of night and day. Temperature fluctuations can also entrain these feedback loops. The alfalfa leafcutting bee, Megachile rotundata is a pollinator used in commercial farming. It is commonly reared under artificial temperatures with no daily fluctuations. Despite the widespread use of these thermal treatments, little is known about how adult emergence is mediated by environmental cues. Adults emerge from a maternally-made brood cell within a cavity where conditions may vary from the external environment. We found that 20-40% of light penetrates the brood cell and internal brood cell temperatures can differ by 2-3°C from ambient conditions. We hypothesized that emergence from the brood cell is predominately controlled by temperature instead of photoperiod, due to their cavity-nesting life history. In contrast to our hypothesis, adult emergence patterns from the brood cell are affected by day length, with longer days entraining emergence more than shorter days. Furthermore, we found M. rotundata can quickly respond to a changing environment when exposed to constant conditions then exposed a zeitgeber, where temperature fluctuations greatly impacted emergence rhythms, depending on the amplitude of fluctuations. This knowledge is crucial for understanding the effect of a changing climate on clocks mediating emergence rhythms of pollinators.
