D3118: Does nest cavity temperature determine the timing of daily first flights in alfalfa leafcutting bees?

The alfalfa leafcutting bee is a solitary, cavity nesting species critical for pollination relating to alfalfa seed production. When managed for pollination, their domiciles are usually faced to the southeast to improve morning warming and increase early activity. However, a definitive link between nest temperature and the timing of the daily first flight has not been established. Toward this end we conducted two studies that investigated microenvironmental conditions at the time of first flight in the morning. In the first study, we recorded various microenvironmental conditions, including temperature within the nest and at the face of the nesting block, at the time each insect began its first flight. In the second study, we built a custom-designed nesting block that could be heated prior to sunrise each morning and compared when bees nesting in these nestling blocks started to fly with the flights of bees in unheated control nests. Our data provides interesting insight into the microenvironmental factors affecting the timing of daily first flights for this important pollinator.