Tree-killing Invasive Bugs Make Jump to New Tree Species

By Joshua Rapp Learn

Ash borer This image shows an emerald ash borer (Agrilus planipennis) on a leaf.
Image Credit: David Cappaert, Michigan State University, Bugwood.org

A tiny invasive insect from Asia that has laid waste to North American ash trees is expanding its attack to white fringetrees, according to new research.

Don Cipollini, Professor of biological sciences at Wright State University and an author of a paper that came out today in the Journal of Economic Entomology, was looking at trees in Yellow Springs, Ohio this past summer when he noticed signs of emerald ash borer (Agrilus planipennis) infestation in a white fringetree (Chionanthus virginicus). “Their damage was thought to be restricted to ash trees so far,” Cipollini said.

But Cipollini was looking at trees in Yellow Springs, Ohio this past summer when he noticed signs of ash borer infestation in a white fringetree (Chionanthus virginicus).“Lo and behold on the fourth tree I walked up to, there was an exit hole staring me in the face,” he said of the holes the bugs make after their larvae have matured. He took a closer look, peeling bark from the tree and found actively feeding larvae. “I thought immediately that I had a tiger by the tail,” Cipollini said.

He expanded his research on white fringetrees and found that four of the 20 he examined had ash borer infestations. While the case was closed for him, his findings weren’t confirmed until he sent a sample of an adult male he found dead in a sample section he took from a tree back to an independent lab researcher.

Emerald ash borer

This image shows emerald ash borer larva recovered from white fringetree. (A) Dorsal habitus. (B) Ventral habitus. (C) Dorsal view of head. (D) Ventral view of head.
Image Credit: Entomological Society of America

The finding is significant because white fringetrees are threatened or endangered in parts of its range, which includes tktktk. “The white fringe tree is a regulated tree. In a state like Ohio it’s considered as threatened or potentially threatened because of its rarity.”

He said that while they make up less of the forest biomass than ash trees, white fringetrees produce flowers with nectar important for pollinators. Other wildlife also depends on the olive-like fruits they produce.

If the emerald ash borer continues to expand its North American range, Cipollini also worries that it may eventually reach parts of central Florida that play host to the pygmy fringe-tree (Chionanthus pygmaeus) — a similar species that’s listed as federally endangered under the Endangered Species Act.

Cipollini said it isn’t clear why the ash borer was able to make this jump to the fringetrees, but that related Chinese fringetrees are more resistant to attacks from the insect. “It presumably has a history with the emerald ash borer,” he said.