Establishment and pest status of the twolined spittlebug, Prosapia bicincta, in Hawai'i

The twolined spittlebug, Prosapia bicincta, was detected for the first time in Hawaii in 2016. Scouting and field surveys carried out on Hawaii Island, Kona District, over 31 consecutive months between Hualalai and Keokea detected these insect pests from 548-1,585 m elevation, primarily on high quality kikuyugrass pastures used for livestock forage. Surveys were conducted monthly over a range of elevations (518-1,860 m elevation) to collect data on local abundance and seasonal occurrence of nymph and adults, and the association with plant species composition and grass cover. Since its initial detection, P. bicincta rapidly expanded its range across an estimated 176,124 acre area stretching from below Pu’u Anahulu to south of Keokea, and it continues to disperse to new locations. In areas of high infestation this pest can cause complete dieback of key pasture grasses for livestock, leading to the establishment of low-quality grasses and weeds such as Pamakani, fireweed, Hilo grass, and wild blackberry. Therefore, Prosapia bicincta has become a major economic threat to Hawaii’s pasture-based livestock industry.