Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2006
Publication Date: 7/1/2006
Citation: Khrimian, A., Jang, E.B., Nagata, J., Carvalho, L. 2006. Consumption and metabolism of 1,2-dimethoxy-4-(3-fluoro-2-propenyl)benzene, a fluorine analog of methyl eugenol, in the oriental fruit fly, bactrocera dorsalis (hendel). Journal of Chemical Ecology. 32(7):1513-1526. Interpretive Summary: The oriental fruit fly is a destructive pest of a broad range of plants and agricultural crops. Males of the fruit fly are strongly attracted to and feed upon a commonly occurring plant constituent, named ME. ME has been successfully used in traps designed to detect, control and eradicate oriental fruit fly populations, worldwide. A potential problem to the continued use of ME in pest management programs are reports indicating that ME byproducts may be toxic to other animals. In an attempt to develop safer alternatives to ME, we synthesized a chemical analog that was attractive to males of the fruit fly and did not appear to produce high levels of unfavorable byproduct. These results are of interest to other chemists involved in the study of potential pest control compounds, and to scientists involved in monitoring and controlling the oriental fruit fly.
Technical Abstract: Methyl eugenol (ME) is a natural phenylpropanoid highly attractive to oriental fruit fly, Bactrocera dorsalis (Hendel) males. The flies eagerly feed on ME and produce hydroxylated metabolites with both pheromonal and allomonal functions. Side-chain metabolic activation of ME has long been recognized as a primary reason for hepatocarcinogenicity of this compound on rodents. In an attempt to develop a safer alternative to ME for fruit fly management, we developed a fluorine analog, 1,2-dimethoxy-4-(3-fluoro-2-propenyl)benzene (I), which in earlier field tests was as active to the oriental fruit fly as ME. Now we report that not only B. dorsalis males are attracted to, but also eagerly consume (up to ~ 1 mg/insect) compound I thus recognizing this fluorinated benzene as a close kin of the natural ME. The flies metabolized the fluorine analog I in a similar fashion producing mostly two hydroxylated products, 2-(3-fluoro-2-propenyl)-4,5-dimethoxyphenol (II) and (E)-coniferyl alcohol (III), which they stored in rectal glands. However, the introduction of the fluorine atom at the terminal carbon atom of the double bond favors the ring hydroxylation over a side-chain metabolic oxidation pathway, by which coniferyl alcohol is produced. It also appears that fluorination overall impedes the metabolism: ten flies offered 10 'l of test compounds consumed in total more fluorine analog I than ME but were unable to metabolize it as efficiently.