Comparison of torula yeast and various grape juice products as attractants for Mexican fruit fly (Diptera: Tephritidae)

Authors: Mangan, Robert; Thomas, Donald

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2013
Publication Date: 4/1/2014
Citation: Mangan, R.L., Thomas, D.B. 2014. Comparison of torula yeast and various grape juice products as attractants for Mexican fruit fly (Diptera: Tephritidae). Journal of Economic Entomology. 107(2):591-600.

Interpretive Summary: A series of trapping experiments compared activity of grape products including grape juice, grape concentrate and powdered grape drink mix to hydrolyzed torula yeast pellets that have been the standard bait for tropical fruit flies. Experiments were carried out in a relatively small orchard ( HA) at a location in Nuevo Leon in the foothills of the Sierra Madre mountains, is surrounded by alternate hosts, is minimally managed, and has historically been heavily infested by Mexican fruit fly. A second orchard was much larger (HA) located on the coastal plain of San Luis Potosi was better managed was surrounded by other managed citrus orchards or livestock pastures and had much lower Mexican fruit fly populations. Trapping results for both orchards carried out from 2004-2011 showed that grape juice caught the most total flies and had the fewest traps that caught no flies. Each of the 3 grape products caught the most total flies in at least 1 experiment. Dissection of trapped females in 2011 at both sites found no preference differences between immature and gravid (mature) females. We conclude that grape products, which are less expensive and more available, are a viable option compared to the hydrolyzed yeast pellets for monitoring Mexican fruit fly populations.

Technical Abstract: Early research during the 1930’s focused on attractants for the Mexican fruit fly indicated that fermentation products were effective attractants for Mexican fruit flies and other tropical Tephritidae, but that attraction to fruit components was only of academic interest. Tests reported here were carried out on populations of Mexican fruit flies from 2004-2011 after reports and cooperative research by the authors and scientists in Brazil showed that grape juice was an effective attractant to Anastrepha fraterculus (Wiedemann), the South American fruit fly. Trapping experiments carried out at sites in the states Nuevo Leon and San Luis Potosi compared grape juice, reconstituted grape concentrate and powdered grape mixes, and torula yeast extract in orchards at each site. The Nuevo Leon orchard was mixed with alternate rows of pears and surrounded by alternate hosts. The San Luis Potosi site was surrounded by other orange orchards or non-hosts. Each test was run for at least 10 months and included highest and lowest trapping periods. Results showed that grape juice captured the most total flies and had the fewest samples with zero flies. However, in the series of experiments, each product had the most captures in at least one experiment. Hydrolyzed torula was superior in one of the six experiments. In five of the tests, polyethylene glycol was tested as an additive to the grape products but never improved capture rate compared to the product without the additive. The results of these tests indicate that grape juice is a superior attractant to concentrate or powdered products and that this fruit product is at least equal to torula yeast hydrolysate in tests with pest populations of Mexican fruit flies in commercial orchards.