The melon fly, Bactrocera cucurbitae (Coquillett), is a serious crop pest throughout the Asia Pacific sub-continent and Southeast Asia, causing damage to tree fruits, cucurbits, and related crops. Attractants for female melon flies are of particular interest as they could be used in control tactics to reduce pest levels. Previous work has shown that freshly sliced cucumbers are attractive to female melon flies, but the compounds responsible for this attraction were not identified. The objective of the present study was to create a synthetic lure for female B. cucurbitae based on its close association with Cucurbitaceae. Coupled gas chromatography-electroantennogram detection (GC-EAD) analysis of fresh and aged puréed cucumbers identified 31 compounds that were detected by females. Compounds that elicited EAD responses initially were screened as single components in glass McPhail traps in outdoor rotating olfactometer experiments. Four criteria were used to select compounds for testing in blends: a) strength of EAD response elicited; b) amount of compound present; c) relative attractiveness of a single compound; and d) compound novelty to Cucurbitaceae. Several synthetic blends attracted significant numbers of females in outdoor rotating olfactometer experiments; a nine-component blend (lure #7) was the most attractive. Field captures of female B. cucurbitae in traps baited with lure #7 were twice those in traps baited with Solulys protein bait. Besides having a female-biased attraction, this lure may have several advantages over protein baits: it can be used with a dry trap, is long lasting, and it captured low numbers of non-target species. Possible applications of this lure include trapping (for detection and/or monitoring/delimitation) and control/eradication (e.g., mass trapping, attract-and-kill, or as an attractant for existing protein insecticide bait sprays such as GF-120).

Coupled gas chromatography-electroantennogram detection (GC-EAD) analysis of volatiles from tropical almond fruit, Terminalia catappa L., revealed 22 compounds that were detected by antennae of oriental fruit fly females, Bactrocera dorsalis (Hendel). Both solid-phase microextraction (SPME) and Porapak Q were used for sampling odors in fruit headspace, with SPME collections producing larger EAD responses from a greater number of compounds. Geranyl acetate and methyl eugenol elicited the largest EAD responses. A synthetic blend containing SPME collected, EAD stimulatory compounds showed female-biased attraction in laboratory wind tunnel bioassays, but heavily male-biased trap captures in a larger olfactometer arena. A nine-component subset of compounds eliciting relatively small EAD responses (EAD minor) and consisting of equal parts ethanol, ethyl acetate, ethyl hexanoate, hexyl acetate, linalyl acetate, ethyl nonanate, nonyl acetate, ethyl cinnamate, and (E)-beta-farnesene, attracted mainly females. This EAD minor blend was as attractive to females and much less attractive to males when compared to torula yeast in field cage experiments using glass McPhail traps. Similar results were obtained with outdoor rotating olfactometer tests in which the EAD minor blend was almost completely inactive for males.

Gray kernel is an important disease of macadamia (Macadamia integrifolia) that affects the quality of kernels, causing gray discoloration and a permeating, foul odor. Gray kernel symptoms were produced in raw, in-shell kernels of three cultivars of macadamia that were inoculated with strains of Enterobacter cloacae. Koch's postulates were fulfilled for three strains, demonstrating that E. cloacae is a causal agent of gray kernel. An inoculation protocol was developed to consistently reproduce gray kernel symptoms. Among the E. cloacae strains studied, macadamia strain LK 0802-3 and ginger strain B193-3 produced the highest incidences of disease (65 and 40%, respectively). The other macadamia strain, KN 04-2, produced gray kernel in 21.7% of inoculated nuts. Control treatments had 1.7% gray kernel symptoms. Some abiotic and biotic factors that affected incidence of gray kernel in inoculated kernels were identified. Volatiles of gray and nongray kernel samples also were analyzed. Ethanol and acetic acid were present in nongray and gray kernel samples, whereas volatiles from gray kernel samples included the additional compounds, 3-hydroxy-2-butanone (acetoin), 2,3-butanediol, phenol, and 2-methoxyphenol (guaiacol). This is believed to be the first report of the identification of volatile compounds associated with gray kernel.

Measuring and modeling the attractiveness of semiochemical-baited traps is of significant importance to detection, delimitation, and control of invasive pests. Here, we describe the results of field mark-release-recapture experiments with Ceratitis capitata (Wiedemann) and Bactrocera dorsalis (Hendel) to estimate the relationship between distance from a trap baited with trimedlure and methyl eugenol, respectively, and probability of capture for a receptive male insect. Experiments were conducted using a grid of traps with a central release point at two sites on Hawaii Island, a Macadamia orchard on the East side of the island and a lava field on the West side. We found that for B. dorsalis and methyl eugenol there is a 65% probability of capture at ∼36 m from a single trap, regardless of habitat. For C. capitata, we found a 65% probability of capture at a distance of ∼14 m from a single trap in the orchard and 7 m in the lava field. We also present results on the spatial and temporal pattern of recaptures. The attraction data are analyzed via a hyperbolic secant-based capture probability model.