Pheromones in the Field: Monitoring Bertha Armyworm Populations



Yeah, I am a bit of a nerd, but who wouldn’t be terribly excited to be a part of the Alberta Pest Monitoring Network (APMN)? Setting up the bertha armyworm pheromone traps last week required battling the mosquito cavalry, but the mozzies were no match for my baggy sweater and good help. The traps were on duty by noon on June 17th.

We decided to set the traps just off of a lease road, on the west side of a canola field. This will hopefully benefit their operation in a few ways:

  1. The road provides easy access to the family members I have assigned with moth-counting duties (because the best way to involve yourself in a project is to set it up, delegate and then leave…).
  2. The wind often blows in from the west, so will carry pheromone over the canola field and lure moths with higher accuracy. (Consider pheromone movement similar to standing down-wind from someone who has seemingly bathed in their perfume bottle…only to moths, it’s attractive).
  3. Trees will not impede air movement, as there are few in the area we selected (yes, Special Areas has trees, thank you very much).
  4. Moths will not be distracted by yard lights, as buildings are further from that side than any other (yes, Special Areas has human inhabitants, thank you very much).

Trap set-up was pretty easy, though doing a little research (like a good journalist) would have made it foolproof.  In fact, Scott Meers, entomologist with Alberta Agriculture and Rural Development, outlines exactly what needs to be considered in Alberta Agriculture’s how-to video.

But, back to my nerdy excitement.  Besides loving insects in general, I think what excites me about being a part of the APMN is that growers in our region may actually have some warning of the potential for bertha armyworm presence in their crops.  It seemed like we were all caught off-guard last year when high populations of berthas were very suddenly evident in our canola, leaving little time for research and decision-making, let alone spraying (where necessary).

The presence of monitoring traps does not replace the need for field scouting, but it will certainly give us a better idea of what we expect to find when we get out there.

We’ll be back to explain scouting for bertha armyworms, economic thresholds and pre-harvest intervals again later.  In the meantime, keep an eye on the APMN’s weekly updates on bertha armyworms.

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