Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2014
Publication Date: 6/1/2014
Citation: Yee, W.L. 2014. Comparison of brown sugar, hot water, and salt methods for detecting western cherry fruit fly (Diptera: Tephritidae) larvae in sweet cherry. Florida Entomologist. 97:422-430.
Interpretive Summary: The cherry fruit fly is a major quarantine pest of sweet cherries in the Pacific Northwest of the U.S. Export markets require that cherries be free of fly larvae before fruit are shipped, but methods for detecting larvae in fruit have not been well studied. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA determined the efficacy of brown sugar flotation, hot water, and salt flotation methods for detecting fly larvae in crushed sweet cherries. Based on recovery of larvae, the brown sugar flotation method was better than the hot water method, whereas the brown sugar and salt flotation methods were equally good, with recoveries of over 90%. Results are important because they provide experimental support showing that both methods are good for confirming the absence of larval infestations in cherries before they are exported.
Technical Abstract: Brown sugar or hot water methods have been developed to detect larvae of tephritid fruit flies in post-harvest fruit in order to maintain quarantine security. It would be useful to determine if variations of these methods can yield better results and if less expensive alternatives exist. This study reports detection rates of Rhagoletis indifferens Curran (Dipt., Tephritidae) larvae from crushed sweet cherries (Prunus avium [L.] L.) using brown sugar flotation versus hot water and sodium chloride (salt) flotation methods. The brown sugar flotation method detected more total larvae than the hot water method when using a clear dish or black pan after cherries were shredded through a 2-mm gap in a cherry crusher, resulting in 95, 85, and 85% detections, respectively. Brown sugar and salt flotation methods resulted in similar detection rates of 85–99% after cherries were shredded through a 2- or 5-mm gap, even though the 2-mm gap resulted in greater shredding. In brown sugar, hot water, and salt solutions, 26–88% of 1st instars (when there were at least eight individuals) were detected versus 77–100% of 2nd and 3rd instars. Results provide further experimental support for the high efficacy of the brown sugar flotation method for detecting larval R. indifferens. They also demonstrate that salt and brown sugar solutions are equally efficacious for detecting larvae of this species from crushed cherries. Salt solution is advantageous over brown sugar solution because it is less expensive.