|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1996 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Males of tephritid fruit fly species show strong affinity to specific chemicals produced by plants. The oriental fruit fly, Bactrocera dorsalis(and several within its complex species), are strongly attracted to methyl eugenol and some related phenylpropanoids often found as flower fragrances or plant constituents. Males that fed on the attractants selectively converted the compounds into female-attracting pheromone and stored them in the rectal glands. Males scented with the phenylpropanoids were more successful in mating than unscented males, indicating the advantage of acquiring the compound (s) in mating success. Pharmacophagous acquisition of phenylpropanoids by B.dorsalis seems to have evolved within the context of sexual selection, particularly female preference for males "scented" with chemicals derived from plants.
On the other hand, alpha-Copaene, a potent attractant for males of Mediterranean fruit fly, Ceratitis capitata, is found as a minor component in the essential oils of various plant species including its major hosts such as orange, guava and mango. Despite such specific attraction, the male flies never feed on the intact compound and hence the biological significance of alpha-copaene remains unknown. In laboratory tests, lek-like behavior of C.capitata was induced artificially using a plastic leaf model treated with(+)-alpha-copaene. It was also found that alpha-copaene affected virgin females provoking 'pseudomale'courtship behavior in the short-range bioassay. Mating occurred exclusively on the artificial leaves treated with alpha-copaene, suggesting the compound serves potentially as one of the chemical cues to facilitate orientation of the flies to the rendezvous site in their host habitat.