A Brief Assessment of Drosophila suzukii (Diptera: Drosophilidae) Abundance in Forest and Non-Forested Habitats Across an Altitude Gradient on Mauna Loa, Hawai‘i

Abstract: Drosophila suzukii (Diptera: Drosophilidae) is a significant pest of wild and cultivated soft-skinned fruits. D. suzukii was first detected outside of its native range in 1983 on Mauna Ka‘ala in Wai‘anae, Hawai‘i, and has since spread throughout North America, South America, and Europe. While D. suzukii is not considered a crop pest in Hawai‘i, little data is available on the distribution of the species on a landscape scale on the archipelago. In this study, we document the distribution and abundance of D. suzukii and characterize its host use of ‘ōhelo (Vaccinium reticulatum) across an altitude gradient on the eastern slope of Mauna Loa, Hawai‘i. In total we collected 2,503 D. suzukii across 14 field sites over a four-month period in 2016. Endemic ‘ōhelo is a host for D. suzukii as we detected adult emergence across field sites with up to 1.88 flies per 1 mL of berries. Our preliminary population data shows that D. suzukii abundance is greater at higher altitudes and in forested habitats on Mauna Loa. Given the population abundance of D. suzukii and their ability to use at least one of the three endemic Vaccinium in Hawai‘i as a host, further research on host–use interactions with native and non-native insects is warranted.