Tracking twolined spittlebug, Prosapia bicincta, movement in upland pastures of Hawaiʻi

Abstract The twolined spittlebug, Prosapia bicincta (TLSB), is an invasive pasture pest on Hawaiʻi Island and causes extensive damage to rangelands. Despite a rapid spread, field-based estimates of adult TLSB movement remain limited. Here, we evaluate the feasibility of harmonic radar (HR) tracking to quantify short-term movement of adult TLSB in two upcountry pastures on Hawaiʻi Island. HR-tagged adults were released at two sites and tracked over ~ 24 h, achieving 95% recovery and observing a mean displacement of ~ 0.6 m (Experiment 1). Induced movements of tagged and untagged adults were recorded to assess potential tag effects; no statistical difference in movement distance was detected between treatments but the observed probability of movement behaviors (jump vs. jump-flight) differed (Experiment 2). However, testing and environmental variability suggest this result should be interpreted cautiously. While tag effects on survival and behavior are not fully characterized, our results provide evidence consistent with limited short-term impacts under field conditions. Males moved farther than females in both experiments. Correlated random walk simulations based on observed movement parameters estimated that 95% of lifetime movements occur within ~ 8 m of the origin under the conditions tested. These findings demonstrate the feasibility of HR tracking for TLSB and provide baseline data to inform future studies on dispersal and management.