Title: Flight metabolic rate as an expression of quality in temperature stressed alfalfa leafcutting bees, Megachile rotundata Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 7, 2012
Publication Date: January 3, 2013
Citation: Bennett, M., Owings, A., Yocum, G.D., Rinehart, J.P., Greenlee, K. 2013. Flight metabolic rate as an expression of quality in temperature stressed alfalfa leafcutting bees, Megachile rotundata [abstract]. The Society for Integrative Comparative Biology Annual Meeting. January 3-7, 2013. San Francisco, CA.Abstract Book page 24. Interpretive Summary: With the significant decrease in recent years of the number of honey bee colonies due to disease and other factors, producers of crops requiring bee pollination are facing amounting crisis. Therefore, there is acute need for other pollinators that can be used to supplement the honey bee in pollination services. The alfalfa leafcutting bee, Megachile rotundata is a solitary bee species that can be used to pollinate a number of specialty crops such as melons, blueberry and in the production of seeds for alfalfa and onions. Currently, there are a number of key issues in M. rotundata husbandry that need to be addressed to insure the quantity and quality of bees to meet the demand for pollination services. One of these needs is the development of quality control biomarkers. In a series of experiments, we investigated the response of the M. rotundata respiratory system to various management manipulations. Results show that how the bees are managed during development affects adult respiratory physiology. Therefore, respiratory physiology can serve as a sensitive quality control biomarker for the development of optimized management practices for this key alternative pollinator.
Technical Abstract: The alfalfa leafcutting bee,Megachile rotundata F.(Hymenoptera: Megachilidae)is a solitary species that develops inside a maternally constructed brood cell. Pre-pupal M. rotundata diapause over winter and resume development as ambient temperatures increase. Environmental cues are known to initiate biological processes in many insects, allowing better survival of anticipated stressors, such as temperature fluctuations. However, insects are limited in their ability to deal with extreme temperature fluctuations when not in a diapausing state. To better understand how temperature fluctuations during juvenile development affect adult physiology, we exposed pupal M. rotundata to one of three temperature treatments and assessed changes in adult flight physiology. Pre-pupae were reared normally at 29°C for 14 days. At that point, some insect development was interrupted for 1 week by placement in either constant 6°C or 6°C with a 1h daily pulse of 20°C (FTR). Pupae were returned to 29°C and allowed to develop to adulthood. Because insect flight is metabolically expensive and is essential for success for the next generation, flight metabolism was used to indicate quality. Flight metabolic rates were measured using flow through respirometry. When compared to uninterrupted or FTR development, females from constant 6°C had higher metabolic rates, while males from constant 6°C had lower metabolic rates. Surprisingly, 53% of bees from the 6°C group were unable to fly and had morphological defects. These data suggest that interrupting bee development with placement in a constant 6°C, a common rearing method, negatively affects adult bee physiology.