School Malaise findings 1 - pests

As announced on Friday I will use some posts this week to showcase the results from the School Malaise Trap Program. We have provided the schools with a list of the top 10 most interesting discoveries which I will share with the blog readers. Today we will start with the ones that represent potential threats to agriculture and forest.

Onion fly (Delia antiqua)

The Onion Fly was the most abundant species collected in the School Malaise Trap Program (6%) in fact, it was found in 79 of the 81 traps! Furthermore, it was found earlier in spring than previously recorded. This fly is found in the temperate regions of North America, Europe, and Asia.

Onion flies are grey and look much like house flies, except their legs are longer and their abdomen is narrower. Adults lay their eggs in the soil near onion bulbs of any member of the genus Allium which contains Onions, Garlic, Leek, Chives. The larvae are 8-10 mm long, white, and feed almost exclusively upon those plants. Damage due to the larvae feeding on young seedlings often results in plant death. Onion flies have three generations per year in Ontario so there is great potential for widespread damage to Allium crops. So far it was assumed that the first generation peeks early to mid June. According to the results at all the schools we are looking rather at early May. Given the fact that the flies need just a little over a week to hatch, mate and lay eggs any week earlier than expected might make a big difference for commercial farming.

Pear thrips (Taeniothrips inconsequens)

Pear thrips are an invasive species from Europe. They arrived in California the early 1900’s and are now be found throughout most of the USA and increasingly often in Canada. They are tiny, measuring only 1.2 to 1.7 mm long, with brown - black colouration, two pairs of wings, and rasping mouthparts. They use these mouthparts to cut open leaves and buds of hardwood trees so they can feed on plant fluids. The collection of pear thrips by the School Malaise Trap Program marks the first time they have been DNA barcoded from a Canadian location. They were found in 53 out 81 traps.

This is a very interesting discovery, and could signal a threat to Canadian forests especially because these animals are not restricted to pear trees as the name might suggest. Actually they are known to feed on a variety of maple species as well. In the late 1980’s pear thrips were responsible for damage to 1.3 million acres of Pennsylvanian forest. In North America, only female pear thrips have been found; they reproduce by parthenogenesis, producing eggs that do not require fertilization by a male.