Novel synthetic lure for fruit flies (Diptera: Tephritidae) based on the aroma of concord grapes

A food product (Savor Uva) made from concentrated Concord grape juice (Fruitibases S. A. de C.V., Monterrey, Neuvo Leon, MX) was chemically analyzed. The aroma of Savor Uva revealed 12 major components and 12 minor components. Chemicals identified and chosen for testing were: ethanol; ethyl propionate; ethyl butyrate; ethyl 2-methylpropionate; ethyl 3-methyl butyrate; ethyl 2-methylbutyrate; ethyl decanoate; ethyl dodecanoate; butyl butyrate; pentyl butyrate; 3-methylbutyl propionate; D-limonene; acetic acid; benzoic acid; sorbic acid; methyl anthranilate; dimethyl anthranilate; and propylene glycol. After testing each chemical for attractiveness, a synthetic mixture of 15 chemicals that simulated the aroma volatiles of Savor Uva was developed in aqueous solution and tested against Savor Uva in wind-tunnel bioassays with Mexican fruit flies (Anastrepha ludens). The synthetic mixture was equal to the Sabor Uva in attractiveness. Through a series of deletion experiments, the mixture was pared down to a 5-chemical blend that is more attractive than the original 15-chemical mixture. The 5-chemical blend components are: propylene glycol; acetic acid; methyl anthranilate; ethyl 2-methyl propionate; and 3-methylbutyl propionate. Mixtures containing fewer than these 5 chemicals by deleting either of the branched-chain esters were less attractive than the 5-chemical mix but were still effective. Propylene glycol is not a component of Concord grape aroma, however it was probably added as a preservative and adjuvant by Fruitibases. Propylene glycol is critical to the mixture’s attractiveness, as well as important in dissolving most of the organic components in the water solution. Water is critical for maximum attractiveness of the mixture.