GrainsWest Spring 2021

Spring 2021 grainswest.com 25 farmers to be judicious with pesticide use.” While Catton does not object to insecticide use when it is necessary, she is using science to show the hidden costs of unnecessary application. The factor that determines when spraying should occur is the economic threshold. It is critical to understand this and utilize it properly in a given field. A farmer who may spray for aphids will be able to adequately control the population but may unintentionally end up killing beneficials that control other pests such as cutworms. “There’s a whole cascade of effects, which is why economic thresholds are important,” she said. Her catalogue will also include a calendar detailing which beneficials are active at what time of year. About 80 ground beetle species alone inhabit the average Prairie field. Each has its own lifecycle and it’s important to understand when certain beetles thrive. The giant beneficial insects research road map is her ultimate goal to help direct efforts on specific insect-related work in the future. A major motivation for Catton, as well, has been the work of the Western Grain Research Foundation’s promotional campaign, Field Heroes. She said the program, which began in 2018, has helped reignite positive conversation around the overall benefits of beneficials. Aside from identifying and better understanding beneficials, Catton aims to eventually ascribe dollar amounts to their worth, something very difficult to manage with accuracy. She said some days the work makes her feel like a horse racing bookie. “No one can predict the exact future. I can’t guarantee the winner, but I feel like my role as a scientist is to help farmers make an informed decision, in other words determine the odds of a situation working out in their favour,” she said. “The goal is to be able to say to farmers: ‘this many beneficials are worth this much money.’ Then the farmers can decide how to bet given those odds. In terms of influencing management, the more accurate the odds, the better the bets farmers can make. To apply insecticide or not is their final decision to make. It is their money on the line, and they need the best information possible to make those kinds of decisions.” But the value certainly is difficult to quantify. A 2017 study by Michigan State University determined the simple presence of certain beneficials such as spiders and lady beetles can cause pests to consume less. Despite a lack of robust beneficial data, limited studies have successfully quantified the information with hard data. A 2009 economic impact study by Owen Olfert calculated that the use of $248 million worth of insecticide was made unnecessary by the work of Macroglenes penetrans , the beneficial insect that kills orange blossom wheat midge. Another more recent finding is the brutal efficiency of the almost invisible predator wasp Tetrastichus julis , which kills cereal leaf beetle by laying eggs inside of the destructive insect. T. julis provides certain Prairie fields between 50 and 90 per cent control. “We think that T. julis is the reason why cereal leaf beetle did not explode on the Prairies,” she said. “People rarely have to spray for cereal leaf beetle here.” Catton’s national colleague on the project, Tyler Wist, is also an AAFC entomologist based in Saskatoon, SK. He also knows the value of beneficials and wants to share this knowledge with the world. The primary focus of his beneficial insect research involves identifying the predators of aphids in cereal and pulse crops to determine if they affect control of aphid populations. He also studies the parasitoids of the wheat midge and is looking into possible predators of flea beetles in canola through a multi-researcher, multi-province project. Wist said it is not a simple task to calculate the economic value of beneficials, but this does not mean it’s impossible. “You have to know at what point the insects damage the crop and when you need to take action,” he said. However, Wist cautions that farmers should be certain they are going to suffer an economic loss before spraying because of the potential untold damage that could occur to beneficial insects that roam farm fields. For instance, a number of insecticidal sprays are broad spectrum and will certainly work to kill the pest at hand, but will also kill beneficials. Certain sprays make the ground toxic to ground beetles for up to seven days post-application. The toxicity destroys the brain receptors that control a beetle’s basic motor functions. AAFC entomologist Haley Catton is at work on the creation of an ambitious catalogue of all Prairie insects that consume pests and weed seeds. Photo:CourtesyofHaleyCatton