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Two detection methods for the little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), both employing the pheromone attractant 2,5-dimethyl-3-(2-methylbutyl)pyrazine (2-MeBu-diMePy), were compared with peanut butter based detection, in order to evaluate differences in species specificity and detection reliability. Trapping was conducted using a transect through a macadamia orchard on the island of Hawaii. The transect consisted of a series of three-tree plots, each plot contained a peanut butter coated stick (the most common detection method used for W. auropunctata in Hawaii), a one—way trap treated with 2-MeBu-diMePy, and a piece of double-sided tape treated with 2-MeBu-diMePy. While there were no differences in the number of W. auropunctata counted with each detection method, and no differences in detection reliability (detecting the known presence of W. auropunctata in a plot), the pheromone—incorporating methods showed greater species specificity, retaining W. auropunctata almost exclusively. These results demonstrate the potential of pheromone—detection methods to selectively capture target ant species even when other ants are present and abundant. Combined data from all three detection methods and a previous visual survey along the transect showed a marked difference in the frequency of cohabitation among ant species. Of the 10 ant species collected, W. auropunctata was found as the sole ant species on a given tree at a significantly higher frequency than all other ant species except Pheidole fervens. 94% percent of the trees with W. auropunctata had only W. auropunctata, supporting previous observations that this species tends to displace other ant species. In addition, W. auropunctata microhabitat preferences were investigated using one—way traps containing 2-MeBu-diMePy, which were placed in three arboreal and three non—arboreal locations. While the number of ants captured did not differ by trap placement, when grouped, captures were significantly higher in arboreal than non-arboreal microhabitats.

The nettle caterpillar, Darna pallivitta (Moore) (Lepidoptera: Limacodidae), is an invasive pest with established populations on three Hawai'ian islands. Indigenous to Southeast Asia, D. pallivitta caterpillars cause defoliation of ornamental nursery stock and pose a human health hazard due to their urticating hairs that can cause painful skin reactions. Identification of the pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOnBu) from D. pallivitta has made it possible to investigate the phenology and population dynamics using baited traps. Male captures in Jackson traps baited with E7,9-10:COOnBu showed a vegetation preference for tall-grass fields and forest/grass interfaces over forest areas. Microlocation preferences were also found for trap height, with over 65% of males being caught in traps suspended at 1 m, compared with the traps at 3 and 5 m. Captures of male moths in traps baited with live females, and direct observations of female calling behavior, showed peak activities 6-7 h after the onset of scotophase. This is a much later communication period than for D. bradleyi and D. trima and may provide a mechanism by which D. pallivitta maintains reproductive isolation in areas where all three species are present. Coastal and inland transects established in eastern Hawai'i measured aspects of population fluctuations and radiation into new areas with relation to elevation and microclimate. Population expansion was measured by comparing moth population means and 80% population boundaries over time. Both population measures showed a higher expansion for the coastal transect. Differences in population expansion may be attributed in part to temperature and elevation, while precipitation does not seem to have a strong effect. Both the behavioral and ecological data collected can be used to optimize deployment of detection/control strategies and to predict population expansion/risk assessment for establishing quarantine protocols for the nettle caterpillar.

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