Oviposition Behavior and Egg Parasitoids of Sophonia rufofascia (Homoptera: Cicadellidae) in Hawaii Volcanoes National Park

Oviposition behavior of Sophonia rufofascia, a polyphagous leafhopper recently introduced to the Hawaiian Islands, was studied on 6 common plant hosts in Hawaii Volcanoes National Park. The average number of eggs per leaf was approximately 1 in ’a’ali’i (Dodonea viscosa) and firetree (Myrica faya), and closer to 2 in Hawaiian holly (Ilex anomala), ’ohi’a lehua (Metrosideros polymorpha), sandalwood (Santalum paniculatum) and ’ohelo (Vaccinium calycimum). Over all plant species there was a weak positive correlation between leaf size and the number of eggs. All oviposition scars were in the midvein of ’a’ali’i, firetree, ’ohi’a lehua, and ’ohelo, but in holly and sandalwood oviposition also occurred away from the midvein. In holly, the proportion of eggs laid away from the midvein was positively correlated with leaf thickness. Variation among host plants also existed for egg position relative to the basal, middle, and apical third of the leaf, but in all species the middle third of the leaf was the most common oviposition site. S. rufofascia eggs in the park are attacked principally by two endemic mymarids in the genus Polynema; this represents a host shift or host range expansion for these native wasps. Introduction The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh) (Homoptera: Cicadellidae) is a recent accidental introduction into the Hawaiian Islands. It was first discovered on the island of Oahu in 1987 (Kumashiro and Heu 1989) and has since spread to all the major islands in the archipelago. S. rufofascia has been recorded from 307 species of plants in 83 families, of which 66 are endemic or indigenous to the Hawaiian Islands and 15 are on the federal list of endangered species in the U.S. (Fukada 1996). On most hosts, feeding by S. rufofascia results in interveinal chlorosis or leaf distortion, but in a few hosts, plant death can occur. Damage can also occur when females deposit eggs in the leaf midvein, which blocks vascular tissue. Several plants in Hawaiian forests and watersheds are particularly susceptible to S. rufofascia feeding. For example, leafhopper feeding has been implicated in the dieback of large patches of the native false staghorn fern, Dicranopteris linearis, a dominant understory and gap species in Hawaiian forests and watersheds; dead uluhe patches often do not regenerate and become overrun by exotic weeds (Follett and Jones unpublished). In Hawaii Volcanoes National Park (HAVO) on the island of Hawaii, S. rufofascia is attacking several important tree species. Large areas of dieoff of Metrosideros polymorpha (’ohi’a lehua), the dominant tree in the native Hawaiian forest, have been linked to increased levels of leafhopper activity. Ironically, the other key species suffering from S.