Abstract
The possible attraction of endemic and beneficial nontarget insects to synthetic lures used to monitor and mass-trap pestiferous fruit flies (Diptera: Tephritidae) was evaluated on Hawai`i and Maui islands. Traps baited with the male lures cue-lure and methyl eugenol and the food lure BioLure, and traps artificially baited with decaying fruit flies, mimicking the accumulation of dead trapped target flies, were maintained in endemic forest, nonnative forest and agroecosystems. While cue-lure did not attract nontargets, methyl eugenol attracted low numbers of five species of flower-associated insects, including honeybee, and two endemic species of Sciaridae and Miridae. Saprophagous nontarget flies were abundant and diverse in traps with decaying flies and in BioLure traps. Previously published records of attraction to male lures are demonstrated to actually be secondary attraction to decaying fruit flies drawn to the lures. Numerous endemic Drosophilidae and Calliphoridae were attracted to BioLure and decaying flies in endemic forests, but mostly introduced species were collected in nonnative habitats. Flower insect captures were reduced when methyl eugenol traps were used on nonflowering support trees or past the flowering stage. Comparing attraction to the separated ingredients of BioLure revealed that ammonium acetate and, to a lesser extent, putrescine are most attractive to nontargets, and omitting putrescine did not drastically decrease Ceratitis capitata captures, but reduced nontarget captures by 20%. BioLure was also more attractive to nontargets than the protein-based solulys or torula yeast attractants, and torula yeast dissolved in water was more attractive to Bactrocera fruit flies than BioLure. The distribution and abundance of endemic Drosophilidae are also reported. Of the 291 species expected in the sampled areas, 121 were collected, and 91% of the specimens belonged to 24 common species. Endemic species were abundant in native forest, present in lower numbers in the strawberry guava, tropical ash, pine and Eucalyptus plantation forests adjacent to from native forest, and small numbers were still collected in fruit and coffee orchards, even 10 Km distant from endemic habitats. An annotated list of the 32 immigrant species of Drosophilidae established in Hawai`i is also provided.