The stinging nettle caterpillar, Darna pallivitta (Moore) (Lepidoptera: Limacodidae) in Hawaii : its current host range, biology and population dynamics

Thesis (M.S.)--University of Hawaii at Manoa, 2006.Includes bibliographical references.ix, 91 leaves, bound ill. (some col.) 29 cmDarna pallivitta was first described by Moore in 1877 and is a native of China, Taiwan, Thailand, Malaysia, Java, and Borneo (Cock, et al. 1987). Darna pallivitta was first found in Japan on the island of Okinawa in 1996 (Yoshimoto, 1997). Cock, et al. (1987) list palms (Areca sp., coconut, and oil palm), Adenostemma sp., Breynia sp. Ficus sp., grasses and Zea mays as food plants and Tominaga (1999) recorded larvae feeding on the grasses Panicum repens and Paspalum urvillei in Okinawa. Darna pallivitta is listed as a minor pest by Cock, et al. (1987). Yoshimoto (1997) predicted that D. pallivitta's status as a harmful insect in Japan would remain low due to a slow range expansion. Darna pallivitta was first discovered in Hawaii in September 2001 (Conant, et al. 2002). The first observations were at a nursery in the Panaewa area of Hilo, Hawaii. It is likely that D. pallivitta likely arrived as pupae on a shipment of rhapis palms that originated in Taiwan (L. Nakahara, personal communication). Darna pallivitta escaped eradication efforts and has established itself on the Big Island with occasional outbreaks occurring (Fig. 1.3). Nagamine (unpublished data) has found that each developmental stage of D. pallivitta in Hawaii is longer in duration than that listed in Cock, et al. (1987). It was also found that some larvae in Hawaii take on a pink to reddish hue prior to reaching maturity (C. Kishimoto, personal observation) (Fig. 1.4). This coloration has not been noted elsewhere in D. pallivitta though Cock, et al. (1987) state that this trait does occur in other Limacodid species. In Hawaii, larvae of D. pallivitta have been observed feeding on at least 45 different plant species in 22 families (Conant, et al. 2005 and California Plant Pest and Disease Report, 2005), thus becoming a quarantine pest to the export foliage and cut flower industries in Hawaii which are worth approximately US $35 million annually (Hawaii Agricultural Statistics Service, 2003). Darna pallivitta also poses a health concern to local residents as it possesses stinging spines which induce an immediate burning sensation as soon as it contacts the skin (Chun, et al. 2005) Since its arrival to the state of Hawaii, D. pallivitta, as of May 2006 has not expanded its range from the island of Hawaii (Chun, et al. 2005) and the known expansion of its range has been approximately 16.1 kin (10 miles) from the initial site of infestation. The Hawaii Department of Agriculture intercepted larvae and pupae on the island of Maui in 2004 but subsequent surveys have found no establishment (D. Oishi, personal communication). However as with other invasive insect species, it is probable that D. palliivitta will eventually spread to the other Hawaiian Islands (State of Hawaii Department of Agriculture, 2000). Five interceptions of D. pallivitta have also been made in California (California Plant Pest and Disease Report, 2005). Interceptions in California have occurred on fishtail palms (Caryota mitis) and on a lei and flowers of ilima (Sida fallax) (Epstein and Kinnee, 2003) Recent studies by the United States Department of Agriculture (USDA) Pacific Basin Research Center in Hawaii has isolated a pheromone (7.9-decadeinoates) from D. pallivitta females in an effort to discover a successful method for detection of D. pallivitta on the other islands in the State of Hawaii (M. Siderhurst, personal communication). Initial results have shown some promise in this research. 1.4. Thesis Structure: An understanding of Darna pallivitta's ecology in Hawaii is the central aim of this thesis. D. pallivitta's food-plant range in Hawaii is investigated and descriptions on field biology are reported. The effect of abiotic factors on D. pallivitta populations will be determined and natural enemies of D. pallivitta that currently reside in Hawaii will be documented. Host Range in Hawaii. The family Limacodidae is highly polyphagous in nature and the host range of Darna pallivitta has not been studied in Hawaii. Investigation of a wide range of plants is necessary to determine risks to economically important species, indigenous species, and other refugia species that are potential sources of infestation (e.g. weeds). Both commercially important and weed species of plants will be tested and field observations carried out to further determine food plants of D. pallivitta. Field Biology of D. pallivitta. Currently, the basic biology of D. pallivitta is known from laboratory observations while little is known about its behavior under field conditions. Spatial determination of larval feeding sites and temporal periods of adult activity will be studied