Submitted to: Chemoecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2008
Publication Date: 3/10/2009
Citation: Jang, E.B., Siderhurst, M., Conant, P., Siderhurst, L. 2009. Phenology and Population Radiation of the Nettle Caterpillar, Darna pallivitta (Moore) in Hawai'i. Chemoecology. 19:7-12 2009 Interpretive Summary: The nettle caterpillar is a pest of ornamental plants and a new invasive species to Hawaii. We have recently identified the sex pheromone of this species and are now using this chemical to detect and delimit the population of this new pest in Hawaii. Several aspects of the biology of this pest are discussed in this paper. Further use of the pheromone for areawide suppression of populations are planned.
Technical Abstract: 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 poses a human health hazard due to their urticating hairs that can cause painful stings. Identification of the pheromone component n-butyl (E)-7,9-decadienoate from D. pallivitta has made it possible to investigate the phenology or population dynamics using this attractive lure. Male captures in Jackson traps baited with the synthetic lure showed a vegetation preference for tall-grass fields and forest/grass interfaces over forest. 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. Mountain and coastal transects established in eastern Hawai’i measured aspects of population fluctuations and radiation into new areas with relation to elevation and microclimate. Comparing the 80 and 90 % population boundaries of the moth populations along these transects showed significant differences in population expansion. The coastal transect population radiated at least twice a fast as the mountain population. 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.