Additional host range testing of eucryptorrhynchus brandti (Coleoptera: Curculionidae) for the biological control of tree-of-heaven, ailanthus altissima (Simaroubaceae) in the U.S.A.

Authors: MCAVOY, THOMAS - Virginia Polytechnic Institution & State University; MAYS, RYAN - Virginia Polytechnic Institution & State University; GOLDSTEIN, SCOTT - Former ARS Employee; Dray, F Allen; YU, ZHOU - Yangzhou University; REARDON, RICHARD - Us Forest Service (FS); SALOM, SCOTT - Virginia Polytechnic Institution & State University

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2023
Publication Date: 12/21/2023
Citation: Mcavoy, T.J., Mays, R., Goldstein, S.L., Dray Jr, F.A., Yu, Z., Reardon, R., Salom, S.M. 2023. Additional host range testing of eucryptorrhynchus brandti (Coleoptera: Curculionidae) for the biological control of tree-of-heaven, ailanthus altissima (Simaroubaceae) in the U.S.A. Biocontrol Science and Technology. 1-26. https://doi.org/10.1080/09583157.2023.2294219.
DOI: https://doi.org/10.1080/09583157.2023.2294219

Interpretive Summary: Tree-of-heaven (from China) is invasive in North American plant communities and also supports the invasive spotted lantern fly. Host range studies showed development and feeding by the beetle Eucryptorrhynchus brandti, a proposed biological control agent, is largely restricted to tree-of-heaven. Small amounts of feeding was observed on native (to USA) corkwood trees, and a few larvae completed development on this species. However, feeding did not affect corkwood growth and the few females (n=3) that developed on corkwood failed to produce eggs or larvae. Consequently, the beetle was determined to pose no significant risk to native North American plant species while having the potential to be an effective management tool of tree-of-heaven and the spotted lanternfly, so the USDA APHIS Technical Advisory Group for Biological Control of Weeds has recommended approval of this beetle's release in the US.

Technical Abstract: Ailanthus altissima, native to China, is considered a highly invasive plant in North America, Europe, and other continents. This species displaces native plants by forming dense clonal thickets. Ailanthus altissima is shade intolerant, quickly invades fields, rights-of-way, urban areas, and disturbed areas in forests due to logging, fire, or pests. This species is also a primary host of the recent accidently introduced and economically damaging spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae). Eucryptorrhynchus brandti (Coleoptera: Curculionidae) is native to China and has been identified as a potential biological control agent of A. altissima. Eucryptorrhynchus brandti has been officially listed as a “National Forest Quarantine Pests” by the National Forestry Bureau in China and is actively controlled. Host feeding studies conducted on 11 non-target plant species demonstrated that E. brandti had some preference for the native Leitneria floridana and less preference for L. pilosa ozarkana, both closely related to A. altissima. All other species had adult feeding of less than 2% compared to A. altissima, with no oviposition or larval development occurring. Longevity of E. brandti in no-choice tests with L. floridana and L. pilosa ozarkana, were 60 and 68% shorter and the weevils consumed 86 and 98% less foliage compared to A. altissima, respectively. A total of 121 L. floridana replicates were used in the no-choice and two-choice tests in this study and a total of 332 E. brandti females were exposed throughout their life to L. floridana. Of the 121 L. floridana replicates used only 17% (n = 21) of the total trees tested had larval feeding and a total of 20 E. brandti adults emerged (8% of the total replicates, n = 10). None of the L. floridana trees died. Growth of L. floridana occurred below the lowest feeding point in all cases, even when feeding occurred just above the root. Although the number of the usable females that fed as larvae on L. floridana was low (n = 3), none of these females oviposited eggs. In containment, an F1 generation feeding only on L. floridana did not develop. No E. brandti (n = 76 E. brandti females) oviposition or larval development occurred using 19 potted L. pilosa ozarkana trees in a no-choice oviposition and larval development test. Eucryptorrhynchus brandti were found to pose no significant risk to native North American plant species while having the potential to be an effective management tool of A. altissima and the spotted lanternfly. On 4 June 2022, the Technical Advisory Group (TAG), an independent voluntary committee that recommends the release of biological control agents under the auspices of USDA Animal and Plant Health Inspection Agency, recommended that E. brandti be released in the field in the U.S.