An invasive population of Roseau Cane Scale established in the Mississippi River Delta, USA originated from northeastern China

Authors: Schneider, Scott; BROADLY, HANNAH - Animal And Plant Health Inspection Service (APHIS); ANDERSON, JEREMY - Department Of Environment And Conservation; ELKINTON, JOSEPH - Department Of Environment And Conservation; HWANG, SHAW-YHI - Chung Hsing University; LIU, CHENXI - Institute Of Plant Protection - China; NORIYUKI, SUZUKI - Kochi University; PARK, JONG-SEOK - Chungbuk National University College Of Medicine; HANG, THI - Plant Protection Research Institute - Vietnam; Lewis, Matthew; GOULD, JULI - Animal And Plant Health Inspection Service (APHIS); Hoelmer, Kim; DIAZ, RODRIGO - Louisiana State University

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2021
Publication Date: 5/9/2022
Citation: Schneider, S.A., Broadly, H.J., Anderson, J.C., Elkinton, J.S., Hwang, S., Liu, C., Noriyuki, S., Park, J., Hang, T., Lewis, M.L., Gould, J.R., Hoelmer, K.A., Diaz, R. 2022. An invasive population of Roseau Cane Scale established in the Mississippi River Delta, USA originated from northeastern China. Biological Invasions. https://doi.org/10.1007/s10530-022-02809-3 .
DOI: https://doi.org/10.1007/s10530-022-02809-3

Interpretive Summary: The Roseau Cane Scale, a newly invasive scale insect from Asia, has contributed to massive die-off of reed stands along the Louisiana coast and the Mississippi River Delta. The death of these reeds has the potential to erode major shipping channels, destroy vital estuary breeding habitat, and even harm the oil industry because these marshes protect extensive oil infrastructure. This article summarizes the results of genetic and ecological analyses used to identify the source of the invasive insect, which is now known to have originated from northeastern China. It provides crucial guidance to identify natural enemies that will ultimately be used to suppress populations of Roseau Cane Scale in the United States below damaging levels. These efforts will contribute toward the restoration of this critical natural resource and gateway to a major shipping hub in the United States. Furthermore, this research offers new insights into the biology of a rarely studied group of insects and has identified new cryptic species among this group. This work is the product of a multinational collaboration among scientists from seven nations and territories. The results of this study are important to restoration managers, biocontrol experts, ecologists, federal and local authorities (domestic and foreign), and to the scale insect research community

Technical Abstract: The recent decline of Phragmites australis stands in the Mississippi River Delta is due, in part, to damage from herbivory by the non-native roseau cane scale, Nipponaclerda biwakoensis. In Louisiana, P. australis communities, known locally as roseau cane, protect the marsh ecosystem from erosion and storm-related impacts, stabilize shipping channels, and shield oil and inland infrastructure. Intense infestations by N. biwakoensis have contributed to widespread dieback of reeds in this region since 2016. Identifying suitable biological control agents from the source population is key to managing the invasive population of N. biwakoensis and protecting the delicate marsh ecosystem. Therefore, we used mitochondrial COI sequence data, drawn from collections of N. biwakoensis spanning the native and invasive range, to identify the origin of the established population in Louisiana and Texas. Network analysis using TCS 1.21 revealed a rich diversity of 57 unique COI haplotypes distributed across the native range in East Asia. One haplotype from the native range, restricted to northeastern China, is identical to the dominant USA haplotype, and indicates that N. biwakoensis was introduced from northeastern China to the United States. In contrast, ecological niche modeling of habitat suitability based on host plant records from across East Asia, using MaxEnt 3.4.4, identified southeastern China as the best location to search for potential natural enemies to match the climatic conditions in the Mississippi River Delta. These two pieces of evidence provide critical guidance to focus future biological control efforts, and we discuss the importance of examining both genetic and environmental data when searching for potential biological control agents. Additionally, we identified two cryptic species of Nipponaclerda on Phragmites, one in Japan and another in Viet Nam. This research offers new depths of perspective on population structure for a rarely studied group of scale insects, the flat grass scales (Aclerdidae). Together the evaluation of scale insect genetics and ecological niche modeling will optimize foreign exploration efforts for biological control agents.