NATIVE HAWAIIAN INSECTS ATTRACTED TO THE SEMIOCHEMICAL METHYL EUGENOL, USED FOR MALE ANNIHILATION OF THE ORIENTAL FRUIT-FLY (DIPTERA, TEPHRITIDAE)

This study addressed the potential susceptibility of native Hawaiian i nsects to the semiochemical methyl eugenol used for male annihilation of the oriental fruit fly, Bactrocera dorsalis (Hendel). The effects o f trap type (methyl eugenol, methyl eugenol + toxin, toxin only, and c ontrol) and trap height (0, 1, 2, or 4 m above ground) were studied in native forest on the island of Kauai. A malaise trap was used to dete rmine the relative abundance of insects in the immediate vicinity of t he methyl eugenol traps. Seven species of native Hawaiian Drosophilida e, two species of Muscidae, and one species of Phoridae were found to be attracted to methyl eugenol. For four other taxa, including species of Miridae, Anobiidae, and Proctotrupidae, attraction to methyl eugen ol is suggested but equivocal. For all species except Drosophila villo sipedis (Drosophilidae) and Brachyserphus hawaiiensis (Proctotrupidae) both males and females were attracted to methyl eugenol. For Drosophi la perissopoda, Drosophila basimacula, Scaptomyza varipicta, and Scapt omyza rostrata, ground level traps caught significantly more individua ls than traps above ground, and for all drosophilids, 4-m high traps c aught the fewest individuals. Among non-Drosophilidae, trap height was not a significant factor in captures for only the Anobiidae and Saron a species (Miridae). Megaselia sp. (Phoridae) was similar to Scaptomyz a tantalia (Drosophilidae) in that almost all individuals were capture d in ground level traps. Orthotylus sp. (Miridae) was the only species in which 4-m high traps caught the greatest number of individuals. Fo r Lispocephala species (Muscidae) and B. hawaiiensis, 1-2-m high traps tended to catch more individuals than the ground-level or 4-m high tr aps. Malaise trap data suggest that methyl eugenol traps either attrac ted these species roughly in proportion to their local abundance (D. v illosipedis, D. basimacula) or they captured only a portion of the loc al pool of individuals (S. varipicta, D. perissopoda, D. kokeensis, Li spocephala spp.). Because of the low level of attraction displayed by the native insects and the potential to mitigate the impact by placeme nt of baits in the forest canopy, it is suggested that an environmenta lly acceptable application of methyl eugenol can be devised for use in the Hawaiian Islands.