Pests & Predators, Ep. 13: Weather effects — predicting pest populations


Mitigating pests will always be a top priority for many, but how much of a role can Mother Nature play in that process? In our season premiere of the Pests & Predators podcast, we’ll be talking about the relationship between unwanted pests and insects. This time we’re adding in a third element: weather.

Host Shaun Haney is joined by James Tansey of the Saskatchewan Ministry of Agriculture, and Meghan Vankosky of Agriculture and Agri-Food Canada (AAFC), based out of Saskatoon, Sask. Together they discuss the variable of weather and how that can affect your pest-control efforts.

The Prairies have been privy to some very hot and dry conditions throughout the summer months over the past few years, and Vankosky says these conditions have prompted several questions about insect populations.

“We thought it’d be very interesting to take this opportunity to talk about the complex relationships that insects have with temperature and with rainfall, and how the impacts on the pest might not actually line up well with the impacts on their natural enemies like entomopathogenic fungi, or the parasitoids that can play such an important role.”

With the summer months approaching, some of us will be looking forward to basking in the heat and others — well, not so much. Insects aren’t much different in the fact that some are heat lovers, and not all insects, of course, will respond the same way to specific weather influences.

One pest that many are well acquainted with, and who do enjoy the warmer side of the thermometer, are grasshoppers. Tansey explains how not all grasshoppers are actually pests, and in Saskatchewan, they are only on the lookout for four species that they classify as pests.

“They’re all ectotherms. So that is they all rely on the external temperature for their development and activity. In the case of the clearwing, they really like it warm, so maximum egg production about 30 to 37 degrees Celsius. So they like it quite warm. Migratory grasshopper upper temperature threshold for these ones 45 to 46,” he says.

“For two-striped — and you’ll see with a lot of these animals — they will actually bask to increase their internal temperatures, and they’ll maintain body temperatures between 32 and 38 Celsius throughout most of the day. So you can see how the potential for warm temperatures like we saw last year might have implications for these.”

Haney, Tansey and Vankosky also go into detail regarding how these specific weather patterns influence pests’ natural enemies, making sense of the complex nature that is nature.

Check out the full episode, below:


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