Meeting Abstract
66.7 Monday, Jan. 6 09:30 Low temperature stress during development and its effects on adult performance in alfalfa leafcutting bees BENNETT, MM*; COOK, K; OWINGS, AA; YOCUM, G; RINEHART, J; GREENLEE, KJ; North Dakota State Univ.; Stevenson Univ.; North Dakota State Univ.; USDA, NDSU; USDA, NDSU; North Dakota State Univ. meghan.bennett@my.ndsu.edu
Megachile rotundata develop in brood cells constructed in cavities by adult females. Pre-pupal bees diapause over winter and resume development as temperatures (Ta) increase in spring. While many insects are tolerant of suboptimal Ta in their overwintering stages, insects that initiate active development early in the spring due to an increase in the diurnal Ta range may be vulnerable to sudden cold spells, and global climate change is predicted to increase Ta variability, including the risk of spring frost. We tested the hypothesis that pupal bees may be less resistant to low Ta stress and that this stress may result in altered adult phenotypes. Developing pupae were given one of three treatments: 1) normal Ta at 29°C, 2) interrupted with a low Ta stress (6 °C for 1 week; STR), or 3) interrupted with low Ta stress plus fluctuating Ta (daily, 1h pulse of 20°C for 1 week; FTR). As an index of adult phenotype, we assessed flight performance and measured flight metabolic rate (MR). Male STR-treated bees had lower flight MR, and 50% of all bees were unable to fly. To determine if the lower MR was due to decreased energy availability, we assessed feeding behavior. STR-treated animals had the lowest feeding activity. To determine if the flight defects were due to structural defects, we measured wing length. STR-treated animals had 3-6% shorter wings, which could impact wing loading. While it is clear that low Ta stress during pupal development negatively affects adult flight performance, resulting in structural and behavioral changes, the underlying mechanism remains unknown. Effects of Ta stress during development may have serious consequences for pollinators that rely on flight for reproduction and feeding.
