Identification of Grape Juice Aroma Volatiles and Attractiveness to the Mexican Fruit Fly (Diptera: Tephritidae)

Abstract

Volatiles from a Concord grape juice produced in Mexico were identified, tested for attractiveness, and mixed into an attractive blend. Volatiles were sampled with solid phase microextraction (SPME). Chemicals were analyzed by gas chromatography and identified by mass spectrometry (GC-MS). Identified chemicals were ethanol, ethyl propionate, ethyl butyrate, ethyl 2-methylbutyrate, ethyl decanoate, ethyl dodecanoate, D-limonene, sorbic acid, benzoic acid, methyl anthranilate, and dimethyl anthranilate. Chemicals were tested at 2 concentrations, 1 µg and 100 ng, for attractiveness to Mexican fruit flies (Anastrepha ludens) in laboratory cage-top bioassays. All test chemicals except sorbic acid were attractive to either sugar-fed or sugar-starved flies over both concentrations tested. A nine-component synthetic grape essence mixture was developed that matched the headspace volatiles profile of the grape juice. Attractiveness of the mixture was equal to that of the grape juice in laboratory bioassays. The mixture was 70% as attractive as the juice in traps in field tests. Results demonstrate that most of the attractive principals of the juice were identified.

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