avril 29, 2021

Mini wasps against the emerald ash borer

Par Guillaume Castagné

The emerald ash borer drill has caused great fear in the Atlantic since it first appeared last spring. Thousands of ash trees killed in North America.

An army of tiny wasps has come to MidWest to fight the emerald ash borer, the insect that has killed millions of trees in North America. It was first discovered in the Atlantic at Edmundston in2002. It arrived from China by wood importations.

A natural predator of the emerald ash borer, this variety of Asian wasps is tiny (less than 4 mm) and harmless to humans because it does not sting. However, it is very effective in fighting the drill.

The wasps lay their eggs directly on the larvae of the emerald ash borer, which is found on the surface of the bark of ash trees. When wasp eggs hatch, the young wasps feed on their host’s eggs or larvae, says the American Food Inspection Agency.

Between 500 and 1000 of these mini wasps have been released in the Edmundston (Canada) area last summer, as a test. The same project  will be done in North West US next year.

It will be four years before we know if the wasps have successfully established themselves in the region’s forests.

Promising results in Michigan

American wood institutes believe they could prevent the emerald ash borer from spreading to the Atlantic. Their use in US is relatively new, explain-t-il, more in Michigan, where they are used since the middle of 2010’s. We have seen a decrease in the population of emerald ash borer and many trees were saved.

The wasps were then introduced to Michigan, Wisconsin, Vermont and Maine from 2013.

Tests were conducted prior to release into the forests to ensure that native species similar to the emerald ash drill would not attack.

An impressive insect against emerald ash borer

Like predatory wasps, the emerald green ash borer comes from Asia. It lays its eggs under the bark of ash trees and when they hatch, its larvae feed on the phloem, through which the sap circulates, which eventually kills the tree.

An emerald green ashworm larva extracted from the bark of a tree with a knife.

eremarl ash borer nymph

An emerald ash worm larva is removed from an infected tree in Saugerties, New York.

It was also discovered in the Atlantic in Edmundston (Canada) and last fall in a park in the Halifax area.

It’s also very worrying in Fredericton, which has thousands of ash trees mostly in Odell City Park but also along residential streets.

The emerald ash drill can move 400 to 700 meters per year, but its progress is sometimes accelerated by moving firewood from one province to another. For this reason, the Canadian Food Inspection Agency is restricting the movement of wood into areas where the insect has been discovered.

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