Submitted to: Formosan Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2006
Publication Date: December 20, 2006
Citation: Siderhurst, M.S., Jang, E.B. 2006. Attraction of oriental fruit fly, bactrocera dorsalis to terminalia catappa fruit extracts in wind tunnel and olfactory tests. Formosan Entomologist. 26:45-55. Interpretive Summary: The absence of a good female lure for fruit fly species is a limiting factor on the control and monitoring of these pests. The development of such a lure would allow direct targeting of female flies, a more effective strategy than trapping males, and give a better understanding of fly biology in the field. In this study we evaluated the female biased/selective attraction of oriental fruit fly, Bactrocera dorsalis (Hendel), to extracts from the tropical almond fruit, Terminalia catappa L. Different solvents were used to extract potentially attractive chemicals from the fruit. These extracts were tested in three different arenas with attractive chemicals guiding flies into traps where they are caught and counted. Ethanol extracts of the fruit were highly attractive to females only in two of the arenas, and to both females and males in the other arena. The male activity is presumably due to the presence of methyl eugenol, a strong known attractant for males, which was identified in the fruit extracts by chemical analysis. The results of this study show that the tropical almond contains attractants for both sexes of the oriental fruit fly and that further study to characterize the female attractants present in the fruit seems warranted.
Technical Abstract: Extracts of the tropical almond, Terminalia catappa L., a preferred host of the oriental fruit fly, Bactrocera dorsalis (Hendel), were tested for attractancy with both male and female flies in three separate bioassay arenas. Multi-choice laboratory olfactometer tests showed female biased responses to an ethanol extract of T. catappa. These results were confirmed by laboratory wind-tunnel experiments with mature mated females responding significantly more to the ethanol extract than males, immature, or virgin females. Outside olfactometer tests with the ethanol extract showed strong attraction over the control but, in contrast to the laboratory bioassays, there were no differences between the numbers of males and females caught. The male activity is presumably due to the presence of methyl eugenol, which was identified in the T. catappa extracts by GC/MS analysis. Surprisingly, when methyl eugenol alone was tested in the outside olfactometer, a little over a quarter of the flies caught were female. These results suggest that while the compound(s) responsible for the attraction of B. dorsalis to T. catappa are largely unknown, methyl eugenol may play an important role in the interaction of fly and host. Female attraction to methyl eugenol and its presence in T. catappa are discussed in relation to the ‘ancestral host hypothesis’.