Location: Fruit and Vegetable Insect Research
Title: Efficacy of brown sugar flotation and hot water methods for detecting Rhagoletis indifferens (Dipt., Tephritidae) larvae Author
Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 16, 2011
Publication Date: December 22, 2011
Citation: Yee, W.L. 2011. Efficacy of brown sugar flotation and hot water methods for detecting Rhagoletis indifferens (Dipt., Tephritidae) larvae. Journal of Applied Entomology. DOI:10.1111/J.1439-0418.2011.01672.x pp. 1-12. Interpretive Summary: The western cherry fruit fly damages sweet cherry fruit and must be strictly controlled to avoid export quarantines in the western U.S. Personnel at the USDA-ARS Yakima Agricultural Research Laboratory in Wapato, WA examined the efficacy of several methods for detecting larvae in cherries used to show that fruit are not infested before being exported to other countries. It was found that a brown sugar flotation method detected up to 95% of all larvae, more than a hot water method. Results suggest the brown sugar flotation method could be used as part of a multi-strategy approach to show the absence of larvae in cherries, reducing or eliminating the need to fumigate cherries with methyl bromide.
Technical Abstract: The brown sugar flotation and hot water methods are accepted procedures for detecting larval western cherry fruit fly, Rhagoletis indifferens Curran, in sweet cherry [Prunus avium (L.) L.] and could be included in a systems approach for showing the absence of larvae in fruit. The methods require crushing cherries and then submerging them in brown sugar solution or hot water to extract the larvae. Larvae are visually detected when they float to the surface of the brown sugar solution or sink in the hot water. The objective here was to test the efficacy of these two methods. Both methods detected at least one larva in all 288 moderately to heavily infested cherry samples. The brown sugar flotation and hot water methods detected 89.6–94.7% and 83.0–85.9% of total larvae, respectively, from cherry samples on each of three dates. Significantly higher percentages of 1st instars were detected using the brown sugar than hot water method on two dates, of 3rd instars on one date, and of total larvae on two dates. Percent detection of 3rd instars was higher than of 1st instars using both methods. For both methods, greater percentages of split whole cherries with seeds and non-split cherries had larvae than split whole cherries with no seeds and halved cherries. The brown sugar method may be more efficacious than the hot water method and could be integrated into a systems approach for R. indifferens, although more thorough crushing of cherries may result in even higher detection rates.