|Rinehart, Joseph - Joe|
|Kemp, William - Bill|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2013
Publication Date: 6/1/2013
Publication URL: http://handle.nal.usda.gov/10113/56899
Citation: Bennett, M.M., Petersen, K., Yocum, G.D., Rinehart, J.P., Kemp, W.P., Greenlee, K.J. 2013. Effects of extended prepupal storage duration on adult flight physiology of the alfalfa leafcutting bee (Hymenoptera: Megachilidae). Journal of Economic Entomology. 106(3):1089-1097. Interpretive Summary: The alfalfa leafcutting bee, Megachile rotundata (F.), is a solitary, cavity-nesting bee and is the primary pollinator for alfalfa seed production. This is an intensively managed insect, and a significant portion of the management protocol includes storing an immature stage at refrigerator temperatures during the winter. Recently, our group found that by giving cold stored bees a daily one hour pulse at 68°F, the shelf-life of the bees could be dramatically extended. This expansion of bee shelf-life extended into the next growing season, thereby giving users of this alternative pollinator greater flexibility while protecting them from yearly fluctuations in bee prices. However, although the bees were still viable, their quality remained unclear. This study used flight metabolic rates and the percent of oxygen below which metabolism could no longer be sustained as quality control measures for cold stored bees. No differences were seen between bees stored for one season and those stored for two seasons, suggesting that the quality of the bees is unaffected by longterm storage. While additional studies are needed, these findings suggest that extended storage is a viable option for this alternative pollinator.
Technical Abstract: The alfalfa leafcutting bee, Megachile rotundata (F.), is a solitary, cavity-nesting bee and is the primary pollinator for alfalfa seed production. Bee management practices include cold storage during the prepupal stage. Fluctuating thermal regimes (FTR) during cold storage increases survival of cold storage and allows a doubling of the cold storage period with no decrease in survival. However, survival, characterized as successful adult emergence, is not qualitative. In this study, we determined whether extended storage affects adult bee respiration or flight physiology. We overwintered bees for a single winter (CMP) or for 12 months longer (ES). We used resting and tethered flight metabolic rates and resting critical PO2 (the oxygen partial pressure below which metabolism can no longer be sustained) as indices of adult bee quality. We found no significant differences in body mass, resting or flight metabolic rates or critical PO2 between the two groups. Together these data indicate that extended storage of M. rotundata produces bees of similar respiratory capacity and flight ability. These findings could increase the use of M. rotundata as an alternative pollinator, allowing for extended storage to time adult emergence with early-blooming crops.