PHYSIOLOGY, BIOCHEMISTRY, AND TOXICOLOGY Development and Emergence of the Alfalfa Pollinator Megachile rotundata (Hymenoptera: Megachilidae)

Megachile rotundata (F.), a gregarious, cavity-nesting, leaf-cutting bee, is used throughoutNorthAmerica for the pollination of alfalfa,Medicago sativaL., seed crops.We examined the inßuence of various temperature regimes on development, survival, emergence, and longevity in both nondiapausing and diapausing forms of this species. In general, development rates increased with increasing constant temperatures used in this study (18, 22, 26, and 298C), but the 26 and 298C treatments were clearly superior as rearing temperatures for immatures. In diapausing individuals, a variable temperature treatment 14:278C (8:16 h daily cycle, mean 228C) reduced the length of prepupal and pupal development stages following incubation in the early summer when compared with individuals reared under the constant 228C treatment. We discuss the importance of differing temperature regimes on M. rotundata development, survival, and longevity over the entire life cycle. We also discuss the importance of making a connection between immature development and sufÞcient wintering conditions to postdiapause development, a topic that has received much more attention in the literature.