CHEMICAL SIGNALS FOR MANAGING INSECTS
Title: Ring-fluorinated analog of methyl eugenol: Attractiveness to and metabolism in the oriental fruit fly, Bactrocera dorsalis (Hendel)
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2008
Publication Date: February 8, 2009
Citation: Khrimian, A., Siderhurst, M. S., McQuate, G. T., Liquido, N. J., Nagata, J., Carvalho, L., Guzman F., Jang, E. B. 2009. Ring-fluorinated analog of methyl eugenol: attractiveness to and metabolism in the oriental fruit fly, bactrocera dorsalis. Journal of Chemical Ecolology 35:209-218. Available www.springerlink.com/content/3600q55011315ptm/?.
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 methyl eugenol (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 its carcinogenicity. In an attempt to develop safer alternatives to ME, we report on the synthesis of its new chemical analog. This chemical appeared moderately attractive to males of the oriental fruit fly in field trials. Upon feeding on this analog, the flies metabolized it faster than ME. Further research is needed to reveal whether the synthesized analog has a potential to replace ME. 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.
Oriental fruit fly, Bactrocera dorsalis (Hendel), males are highly attractive to the natural phenylpropanoid methyl eugenol (ME). They compulsively feed on ME and metabolize it to ring and side-chain hydroxylated compounds which have both pheromonal and allomonal functions. Side-chain metabolic activation of ME leading to (E)-coniferyl alcohol has long been recognized as a primary reason for hepatocarcinogenicity of this compound in rodents. Earlier, we demonstrated that introduction of a fluorine atom at the terminal carbon atom of the ME side chain significantly depressed the metabolism and specifically reduced formation of coniferyl alcohol, but had little effect on field attractiveness to B. dorsalis. In the current paper, we demonstrate that fluorination of ME at the 4 position of the aromatic ring blocks metabolic ring-hydroxylation but overall enhances side-chain metabolism by increasing production of fluorinated (E)-coniferyl alcohol. In a laboratory experiment, oriental fruit fly males were attracted to and readily consumed 1,2-dimethoxy-4-fluoro-5-(2-propenyl)benzene (I) at rates similar to ME. Flies that consumed the fluorine analog were as healthy post feeding as ones fed on methyl eugenol. In field trials, the fluorine analog I was ~ 50% less attractive to male B. dorsalis than ME.