Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2015
Publication Date: 6/23/2015
Citation: Neven, L.G. 2015. Reduction of optimal thermal range in aging western cherry fruit flies(Rhagoletis indifferens Curran). Journal of Insect Science. 15(1):77. Interpretive Summary: The western cherry fruit fly is an economically important pest of sweet cherries in the western U.S., and may have potential to spread to new areas. This potential to invade other geographic areas is probably limited by intolerance to extreme temperatures resulting in a shutdown of metabolic activity and development. This can be measured as its oxygen consumption and metabolic rate. Scientists at the USDA, ARS Yakima Agricultural Research Laboratory in Wapato, WA determined that the fly tolerance of temperature extremes is impacted by the age of the fly. Newly emerged flies showed the broadest tolerance to temperatures, maintaining metabolic activity from 6.6 to 42.2 degrees C (a range of 35.8 degrees), and fly tolerance to temperature variation was reduced with age; 28-day old flies showed the shortest range of temperatures suitable for metabolic activity from 10.5 to 37.8 degrees C. These results will be used to refine a model to predict the potential distributions of this pest on national and global bases, which in turn will be useful for refining trade quarantines against the western cherry fruit fly.
Technical Abstract: The western cherry fruit fly is an economically important pest of sweet cherries in the western United States. The potential of this pest to establish and spread in areas in which it is not currently present has been the focus of recent research. Most published information on the thermal tolerance and optimal thermal range of this pest has focused primarily on the diapausing pupae and predictive phenology models. Microrespirometry and differential calorimetry can be useful tools in describing the thermotolerance and optimal thermal range of insects. This methodology was employed to investigate the effects of western cherry fruit fly adult age on the optimal thermal range. Newly emerged flies exhibited the widest optimal thermal range spanning from 6.6 to 42.2°C for a total range of 35.8°C. This range diminished as the flies aged, with the shortest span observed with 28-d old flies ranging from 10.5 to 37.8°C, a span of 27.2°C. The loss of thermotolerance in adult flies can influence the species ability to establish and spread in climates where daily temperatures exceed the optimal thermal range of this species.