The Asian longhorned beetle (Anoplophora glabripennis), a federally regulated invasive woodboring pest, was recently discovered in South Carolina—hundreds of miles from the nearest known infestation. Federal and state officials are working hard to try to eradicate this pest, and there are many research questions and opportunities associated with this infestation. (Photo by Melody Keena, USDA Forest Service, Bugwood.org)

By David Coyle, Ph.D.

David Coyle, Ph.D.

I still remember the exact moment I got the call from our state invasive species regulatory official. It was a Friday, May 29, 2020, to be exact, at about 2:30 in the afternoon. When I saw the name pop up on my phone, I remember thinking, “This is an odd time for him to be calling.” I mean, it was in the midst of the pandemic, schools were closed, and most people I knew who had kids at home usually checked out long before mid-afternoon on a Friday (myself included). But then, the news: there’s a new invasive forest pest in South Carolina, and this will go public early next week.

Equal parts excitement (This is what I’ve trained to do my whole career!) and dread (This is gonna suck!) immediately filled my head. I spent all weekend writing and updating extension materials, and by Monday, my professional life was 100 percent consumed by a big black beetle with white spots that’s killing hardwood trees all around Hollywood, South Carolina.

The Asian longhorned beetle (Anoplophora glabripennis) is an invasive forest pest from China, and it was first discovered in North America in 1996. Previous infestations have occurred in more northern latitudes compared to South Carolina, with the closest infestation being in southern Ohio. Our new paper published last week in the open-access Journal of Integrated Pest Management documents damage and host preferences, and outlines some of the regulatory challenges and research questions we’re currently dealing with in this South Carolina infestation.

Asian longhorned beetle (Anoplophora glabripennis) adults (A) have a black body with white spots and can be up to 4 centimeters long, with black and white banding on the antennae, which can be twice the length of the body for males and about 1.2 times the length of the body for females. Signs of the beetle’s presence include oviposition sites chewed into bark and round emergence holes made by adults when they exit the tree (B). Oviposition sites often have a jagged edge created by the adult mandibles chewing the wood (C). Larval feeding can cause “weeping” from oviposition sites (D). Frass and/or wood shavings may also appear below larval feeding sites (E). All trees pictured are red maple. (Photos A, B, D, and E by Dave Coyle, Ph.D. Photo C by Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org)

Biologically, this population of A. glabripennis seems to be exhibiting similar behavior as has been seen in other infestations, though there are still many questions about beetle developmental rates in this subtropical climate. For instance, this is the first time this pest has been found in a place where there isn’t a true winter, so will we see adult emergence earlier than expected? Do larvae have any sort of winter diapause? How many generations are there in a year? How quickly do populations grow and spread? There are a lot of basic biological questions for which we don’t yet have answers.

There are fewer questions from a regulatory perspective. We know how to eradicate this pest—cut down the trees and destroy the material. However, the environment in which this A. glabripennis infestation is established in South Carolina presents unique challenges, most notably the many swampy or perpetually wet areas in which red maples (the preferred host) grow. We will be evaluating new methods for beetle control starting this spring, so stay tuned for those results!

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service manages the national program to monitor for and control the invasive Asian longhorned beetle (Anoplophora glabripennis). This map shows known infestations of the beetle in the United States, as of December 20, 2020. As of August 2020, four states had areas regulated for ALB with active infestations. (Image originally published in Coyle et al 2021, Journal of Integrated Pest Management)

As exciting as this infestation is from a research perspective, it still means that either infested wood material was moved from within the U.S., or that contaminated solid wood packaging material arrived at one of the local ports (Charleston, South Carolina, or Savannah, Georgia). As much effort as goes into local and national educational programs such as the Don’t Move Firewood program, the movement of contaminated material is still an issue. Personally, I strongly suspect that this infestation came from infested firewood brought down from the Ohio population. We’ll likely never be able to definitively prove this, but all the signs (in my opinion) point to this as the source. So please, don’t move firewood, folks, because careful stewardship of our natural lands is essential in preventing the next invasive species outbreak.

David Coyle, Ph.D., is an assistant professor in the Department of Forestry and Environmental Conservation at Clemson University. Twitter: @drdavecoyle. Email: dcoyle@clemson.edu.