One becomes two: second species of the Euwallacea fornicatus (Coleoptera: Curculionidae: Scolytinae) species complex is established on two Hawaiian Islands
Paul F. Rugman-Jones,
Michelle Au,
Valeh Ebrahimi,
Akif Eskalen,
Conrad P.D.T. Gillett,
David Honsberger,
Deena Husein,
Mark G. Wright,
Fazila Yousuf,
Richard Stouthamer
Affiliations
Paul F. Rugman-Jones
Department of Entomology, University of California, Riverside, Riverside, CA, United States of America
Michelle Au
Department of Plant & Environmental Protection Sciences, University of Hawaiʻi at Manoa, Honolulu, Hawaiʻi, United States of America
Valeh Ebrahimi
Department of Entomology, University of California, Riverside, Riverside, CA, United States of America
Akif Eskalen
Department of Plant Pathology, University of California, Davis, Davis, CA, United States of America
Conrad P.D.T. Gillett
Department of Plant & Environmental Protection Sciences, University of Hawaiʻi at Manoa, Honolulu, Hawaiʻi, United States of America
David Honsberger
Department of Plant & Environmental Protection Sciences, University of Hawaiʻi at Manoa, Honolulu, Hawaiʻi, United States of America
Deena Husein
Department of Entomology, University of California, Riverside, Riverside, CA, United States of America
Mark G. Wright
Department of Plant & Environmental Protection Sciences, University of Hawaiʻi at Manoa, Honolulu, Hawaiʻi, United States of America
Fazila Yousuf
Department of Plant & Environmental Protection Sciences, University of Hawaiʻi at Manoa, Honolulu, Hawaiʻi, United States of America
Richard Stouthamer
Department of Entomology, University of California, Riverside, Riverside, CA, United States of America
The cryptic species that make up the Euwallacea fornicatus species complex can be readily distinguished via their DNA sequences. Until recently, it was believed that the Hawaiian Islands had been invaded by only one of these cryptic species, E. perbrevis (tea shot hole borer; TSHB). However, following the 2016 deposition of a DNA sequence in the public repository GenBank, it became evident that another species, E. fornicatus (polyphagous shot hole borer; PSHB), had been detected in macadamia orchards on Hawaiʻi Island (the Big Island). We surveyed the two most-populous islands of Hawaiʻi, Big Island and Oʻahu, and herein confirm that populations of TSHB and PSHB are established on both. Beetles were collected using a variety of techniques in macadamia orchards and natural areas. Individual specimens were identified to species using a high-resolution melt assay, described herein and validated by subsequent sequencing of specimens. It remains unclear how long each species has been present in the state, and while neither is currently recognized as causing serious economic or ecological damage in Hawaiʻi, the similarity of the newly-confirmed PSHB population to other damaging invasive PSHB populations around the world is discussed. Although the invasive PSHB populations in Hawaiʻi and California likely have different geographic origins within the beetle’s native range, they share identical Fusarium and Graphium fungal symbionts, neither of which have been isolated from PSHB in that native range.
