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ARS Home » Office of International Research Engagement and Cooperation » OBCL Research Highlights » Determining the Distribution, Source Population, and Natural Enemy Complex of the Roseau Cane Scale in China

Determining the Distribution, Source Population, and Natural Enemy Complex of the Roseau Cane Scale in China

Field survey Guangdong Province China
Yi Guo, Dunsong Li, Chenxi Liu, and Jun Yang conduct field survey in Guangdong province in China. Photo taken on July 11, 2019. (Photo courtesy of the Sino-American Biological Control Laboratory)

Roseau cane or common reed (Phragmites spp.) is the dominant plant species and a critical component of the Mississippi River Delta in Louisiana. The community of Phragmites in the Mississippi River Delta is made up of different varieties, which together protect the marsh ecosystem from erosion and storm-related impacts, maintaining shipping channels and oil infrastructure. Widespread dieback and thinning of roseau cane stands in the Delta were found in fall 2016. These diebacks coincide with observations of heavy infestation by roseau cane scale, a non-native insect originating from Asia.

Management options of the scale in the Delta are limited. Due to the large oil infrastructure, controlled burns to reduce scale infestations are not possible. In addition, the estuary environment is the breeding habitat of several organisms. Therefore, pesticides cannot be used. Pesticides are also a challenge to use because the scale establishes under the leaf sheaths and are protected from applications. To provide a safe, cost-effective, and long-term approach for the management of this invasive scale, classical biological methods are being considered. Prior research shows that natural enemies play an important role in suppressing populations of roseau cane scale in their native range and at least four different species of parasitic wasps have been documented in China.

Sino-American Biological Control Laboratory (Sino-ABCL) researchers conducted two years of study in 2019 and 2020 in China. Substantial progress was made from the research. Sino-ABCL researchers recruited local cooperators in Shandong, Shanghai, Guangxi, Guangdong, Hebei and Yunnan during field survey and sampling. With the cooperator’s help, Sino-ABCL researchers were able to complete field sampling and analysis on host plant health, scale density, and the associated parasitoid community seasonally and at a variety of sites.

Four species of parasitoids have been identified in the survey sites in China including Astymachus japonicus, Boucekiella depressa, Aprostocetus sp. and Platencyrtus parkeri. Studies will continue to survey the parasitoid community across the native range of roseau cane and evaluate their role on the population dynamics of the scale. In addition, laboratory colonies of the scale and candidate parasitoids will be established to commence host range testing. Together this project aims to contribute biological control methods as a critical component to the multifaceted effort toward preserving roseau cane and the vital role it serves in the Mississippi River Delta.

Collection of parasitoids 
Images of some of the collections from China showing (a) large wasp larvae in an unsclerotized female scale, (b) very small wasp larvae in a female scale, (c) a parasitized adult female, and (d) a crawler. 

 Contact: Chenxi Liu,

The Sino-American Biological Control Laboratory (Sino-ABCL) was established in 1988 through an agreement between USDA ARS and the Chinese Academy of Agricultural Sciences (CAAS) and is based in the Institute of Plant Protection in Beijing. The objective of the Sino-ABCL is to search for, identify, and evaluate the potential of natural enemies of pest insects, weeds, and plant diseases that affect Chinese and U.S. agriculture, develop biological control agents, and evaluate biodiversity of insects based on DNA barcoding. Sino-ABCL established a collaborative working group with local collaborators, most of whom are from local agricultural research units, academies, and universities from 30 provinces in China. These collaborators help Sino-ABCL researchers conduct field surveys for biocontrol agents across China. Sino-ABCL has more than 30 years’ experience in classical biological control and other areas of pest management targeting species that include Asian Longhorn Beetle, salt cedar, soybean aphid, wheat stem sawfly, leafy spurge, emerald ash borer, brown marmorated stink bug, spotted wing drosophila and roseau cane scale. As a fundamental part of its research program, Sino-ABCL conducts studies in insect physiology, insect taxonomy, and insect biochemistry and molecular biology.