Page 16 - Free State Summer 2023

IT'S TIME FOR SHARING (Continued)

It also spread into Western Asia and Northern Africa. In
August 2018, it was detected in Toronto, Canada and in
2021 in Niagara County, New York. Between August 2020
and April 2021, possibly infected boxwood was trucked
from a nursery in Ontario into seven states. They are:
Connecticut, Massachusetts, Michigan, New York, Ohio,
South Carolina and Tennessee. While the ultimate US
distribution of the box tree moth is unknown, it is likely to
adversely affect many large regions.

This rapid, long-distance movement is due primarily to
two reasons. The moth is strong and capable of flying up
to six miles. It has been suggested that sustained flights
of over 20 miles, are possible by gliding in prevailing wind
currents. Because there are 1 to 5 generations each year
(depending on its location and weather), the annual
rate of spread in Europe peaked at 96 miles. Then,
the commercial transportation industry, including the
boxwood industry, have accelerated this rapid spread.

Boxwood Damage

Because B. sempervirens has not co-evolved with Cydalima,
this European Buxus species and its cultivars are more
susceptible the feeding damage of the box tree moth.
Cydalima introduced into western Europe, had a new,
virtually unlimited food supply. As a bonus, the BTM
had no natural predators at the new invasive range. It is
believed, after a few years of exposure indigenous birds, Korea, Russian Far East) has Cydalima predators. In East
wasps, and other predators may learn to feed on this new Asia, Chelonus tabonus causes parasitism of up to 50%.
pest.
This hypothesis of natural boxwood susceptibility, or
Because Asian boxwood co-evolved with Cydalima, these resistance, to BTM is dramatically illustrated (top pge
species and cultivars are less likely to be eaten. The humid 16). Taken on August 1, 2022, in the second generation,
subtropical regions of East Asia (India, China, Japan, near the end of its feeding stage (larval), in Youngtown,

16 SUMMER 2023 • Free State News