INCORPORATION OF RASPBERRY KETONE IN THE RECTAL GLANDS OF MALES OF THE QUEENSLAND FRUIT-FLY, BACTROCERA-TRYONI FROGGATT (DIPTERA, TEPHRITIDAE)

Most males of dacine fruit fly species respond either to methyl eugenol or cue-lure/raspberry ketone (DREW, 1974; FLETCHER, 1987). Methyl eugenol was shown to be a precursor of the male sex pheromone which also acts as an allomone against vertebrate predators in the Oriental fruit fly complex, Bactrocera dorsalis HENDEL and B. papayae DREW and HANCOCK (NISHIDA et al., 1988; TAN and NISHIDA, 1994). On the other hand, males of the melon fly, B. cucurbitae COQUILLETT, feed on and sequester raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) for storage in their rectal glands (NISHIDA et al., 1993). The ketone was suggested to play a pheromonal role in the courtship sequence, although the actual function has not been clarified (NISHIDA et al., 1990, 1993). These findings suggest the biological importance of male rectal substances, particularly in association with male attractants, in the life history of dacine fruit flies, since those attractant chemicals are frequently found in nature as essential oil components from various plants. Males of the Queensland fruit fly, B. tryoni FROGGATT, are strongly attracted to both cue-lure and raspberry ketone. A series of several endogenous aliphatic amidcs have been identified from the rectal glands of B. tryoni (BELLAS and FLETCHER, 1979). This paper demonstrates the selective accumulation of raspberry ketone in the rectal glands and discusses its possible role in the behavior of the Queensland fruit fly.