December 2017

Good for what "Ails" you? A gift from Heaven?
Agrilus smaragdifrons

For more information contact Jil Swearingen, Invasive Species Consultant, Cheverly, Maryland: jilswearingen@gmail.com

Agrilus smaragdifrons. Photo by Antonio Liberta, 2014; used with permission.

ANNAPOLIS, MD (December 1, 2017) - Tree of heaven (Ailanthus altissima) is a highly invasive plant species native to China and East Asia, that impacts natural areas, agricultural areas, and urban areas. It was first introduced into the U.S. around 1784 by William Hamilton at his Philadelphia, Pennsylvania estate and is now found in over 40 U.S. states. The highest densities of Ailanthus are found in the Northeast. It is difficult, but not impossible, to control with herbicides. However, it would appear that Mother Nature wants to help rid the U.S. of this plant. The newly discovered Asian metallic wood-boring beetle (Agrilus smaragdifrons), may provide the additional help we need to turn the table on this nasty invader. Agrilus smaragdifrons joins a fungal pathogen (Verticillium albo-atrum) and insects, including the recently introduced spotted lanternfly (Lycorma delicatula), the Ailanthus webworm moth (Atteva aurea), and an herbivorous weevil (Eucryptorrhynchus brandti) from China, that is under evaluation as a biological control agent. Just in time for the holidays and bearing good news for control of tree of heaven, the Maryland Invasive Species Council has chosen Agrilus smaragdifrons Ganglbauer, a green and red Christmas-colored beetle, as the December Invader of the Month.

Agrilus smaragdifrons (A-gri-lus sma-rag-di-frons) is a metallic wood-boring beetle in the family Buprestidae and is native to East Asia (China: Beijing, Gansu, Shaanxi, Sichuan, Tianjin). The species name comes from the Latin nouns 'smaragdus' (emerald or green precious stone) and 'frons' (forehead or front). Agrilus smaragdifrons is related to the invasive emerald ash borer (Agrilus planipennis, "EAB") and could be confused with it. While both species are slender and green, A. smaragdifrons is notably smaller than EAB, ranging from 1/5-1/3 in. (6-8 mm.) long, in contrast to EAB at 1/3-1/2 in. (8-13 mm.). The elytra (outer wings) of A. smaragdifrons are greenish, bluish, or blackish; its head and pronotum ("neck") are golden-red or golden-green, and it has a distinctly flattened, and brilliant emerald green frons or "face." Because Agrilus is a huge genus with nearly 3,000 known species worldwide, these species could be confused with other members of the genus. Accurate identification is crucial and is made especially challenging by the lack of adequate, complete published keys to Agrilus species occurring in North America.

Agrilus smaragdifrons. Photos by Antonio Liberta, 2014; used with permission.

Agrilus planipennis. Photos by David Cappaert, 2006 and Stephen Cresswell, 2012; used with permission.

The first record of A. smaragdifrons is from an image posted to BugGuide.net taken in Hudson County, New Jersey, in June 2011. Additional reports include photos taken in New York City in 2014 and, more recently, specimens collected in New Jersey and Connecticut in 2015 as trap by-catch from surveys for EAB, and in Pennsylvania in 2016 in EAB and spotted lanternfly survey traps. It's likely this new buprestid occurs elsewhere in the Northeast and mid-Atlantic. Additional surveys should reveal a more accurate distribution. How it was introduced is not yet understood.

From all indications, A. smaragdifrons is a specialist on tree of heaven and is not expected to have ill effects on U.S. native plants. In China, tree of heaven is the only known host plant for A. smaragdifrons. However, continued long-term monitoring in the U.S. will be needed to follow its spread, to evaluate its impact and specificity to tree of heaven, and to understand its life history in the U.S. The biology of A. smaragdifrons is similar to that of EAB. Larvae feed and tunnel under the bark, creating sinuous galleries and causing damage to vascular tissues. Feeding damage can result in branch dieback and tree death. Adults emerging from the trunk create D-shaped exit holes in the bark.

Discovery of A. smaragdifrons points out the importance of pest surveys and, especially, the unexpected "by-catch" of survey trapping efforts. These can lead to discoveries of new potential biological control agents as well as new pest species, and suggests that, whenever possible, trap collections should be preserved and inspected for both target and non-target species.

For more information about other Invasive Species of Concern in Maryland, visit the Maryland Invasive Species Council or call the Maryland Department of Agriculture at 410-841-5920.

For further information:

BugGuide images for Agrilus smaragdifrons
https://bugguide.net/node/view/1428755

E. Richard Hoebeke, Eduard Jendek, James E. Zablotny, Ryan Rieder, Rosa Yoo, Vasily V. Grebennikov and Lily Ren. 2017. First North American Records of the East Asian Metallic Wood-Boring Beetle Agrilus smaragdifrons Ganglbauer (Coleoptera:Buprestidae:Agrilinae), a Specialist on Tree of Heaven (Ailanthus altissima, Simaroubaceae). Proceedings of the Entomological Society of Washington July 2017: Vol. 119, Issue 3 (Jul 2017), pg(s) 408-422.
http://www.bioone.org/doi/abs/10.4289/0013-8797.119.3.408

Herrick NJ1, McAvoy TJ, Snyder AL, Salom SM, Kok LT. 2012. Host-range testing of Eucryptorrhynchus brandti (Coleoptera: Curculionidae), a candidate for biological control of tree-of-heaven, Ailanthus altissima. Environ. Entomol. 2012 Feb;41(1):118-24. doi: 10.1603/EN11153.
https://www.ncbi.nlm.nih.gov/pubmed/22525066

Matthew T. Kasson, Matthew D. Davis, and Donald D. Davis. 2013. The Invasive Ailanthus altissima in Pennsylvania: A Case Study Elucidating Species Introduction, Migration, Invasion, and Growth Patterns in the Northeastern US. Northeastern Naturalist, May 2013: Vol. 20, Monograph 10: pg(s) 1- 60.
http://www.bioone.org/doi/abs/10.1656/045.020.m101

Invasive Plant Atlas of the United States - Distribution of Tree of Heaven (Ailanthus altissima)
https://www.invasiveplantatlas.org/subject.html?sub=3003

Jae-Cheon Sohn, Chun-Sheng Wu. 2013. A Taxonomic Review of Attevidae (Lepidoptera: Yponomeutoidea) from China with Descriptions of Two New Species and a Revised Identity of the Ailanthus Webworm Moth, Atteva fabriciella, from the Asian Tropics. Journal of Insect Science June 2013: Paper 66, pg(s) 1-16.
http://www.bioone.org/doi/abs/10.1673/031.013.6601

Lawrence E. Barringer, Leo R. Donovall, Sven-Erik Spichiger, Daniel Lynch, and David Henry. 2015. The First New World Record of Lycorma delicatula (Insecta: Hemiptera: Fulgoridae) . Entomological News June 2015: Vol. 125, Issue 1, pg(s) 20-23.
http://www.bioone.org/doi/abs/10.3157/021.125.0105

Mauro, T.R. Native and Non-native Forest Pests of Concern. USDA-APHIS-PPQ 350 Corporate Blvd, Robbinsville NJ 08691 609-259-5249; Tiffany.R.Mauro@APHIS.USDA.GOV.
https://njforests.org/wp-content/uploads/2016/09/SAF-Native-and-Non-native-Pests-of-Concern-to-Foresters-Final.pdf