Watch for a new invader

bradfordtimes.ca
April 18, 2014
By Miriam King

The Emerald Ash Borer is an invasive species that is decimating Ontario's ash trees, and changing the make-up of the forest canopy - but its economic impact is limited.

It will cost governments millions of dollars, to remove deadfalls and replant the urban landscape - but there's no economic sector that relies solely on ash trees.

Now imagine an invasive species that threatens crops in the way that Emerald Ash Borer threatens trees - an insect, also from Asia, that has few known enemies in North America, can hide in cargo, fly 2 to 50 km. in a day, and attacks crops.

The pest is the Brown Marmorated Stink Bug - a relatively big bug, as far as insects go, with adults measuring 12 to 19 mm in length. Shield-shaped, it is distinguished from other stink bugs by the white band on its long antennae, black and white banding around its shield, and bands on its legs as a "nymph." It is believed to have been imported in shipments of goods from Asia.

"It's a great hitchiker, " says Hannah Fraser, Entomology Program Lead with the Ontario Ministry of Agriculture and Food in Vineland, Ontario.

The Brown Marmorated Stink Bug was first identified in Pennsylvania in the early 1990s. In 1993, it was spotted in Canada, feeding on ornamental plants in urban gardens.

By 2010, the horticultural sector had recorded "huge losses, to multiple crops," Fraser said - especially to apples, and tender fruits - and researchers identified 170 "hosts" for the insect, from forest plants to cucumbers, summer squash, beans and soybeans, apples, peaches and cherries.

The bug is believed to have resulted in a loss of $37 million, in 2010, to apple crops in mid-Atlantic U.S.A. alone.

"It's starting to become an agricultural issue," Fraser said. "We are very worried about the distribution of the pests. "

The "hot spot" is still the eastern U.S., but the bug has been established in the Hamilton area since 2010, where breeding populations were identified in 2012.

Fraser was providing a "heads-up" to growers and others at the Muck Vegetable Growers Conference, held in Bradford on April 10 - talking about both the Brown Marmorated Stink Bug and the Leek Moth, another invader, this time from Europe.

The Leek Moth attacks onions, green onions, leeks and garlic - but at least there is a substantial amount of information on pest management available from Europe, and the pest has been successfully controlled using crop rotation, clean-up of plant debris, monitoring, pesticides and biological controls - some of them native predators.

Unfortunately, there is no such control as yet for the Brown Marmorated Stink Bug. Of 37 insecticides tested in the U.S., the most effective products were those that are broad-spectrum pesticides, harming the "good bugs" along with the bad.

Any strategy to control BMSB will need to involve not only pesticides, but repellents, trapping, physical barriers - and biological control. Native species of parasitic wasps are being studied, but "so far, the results are not terribly promising," Fraser says. The U.S. is looking to China for possible biological controls – but there are always concerns that an imported predator might attack other native stink bugs that are actually important predators of agricultural pests.