Multicoloured Asian lady beetle larvae (right) sometimes eat more aphids than when they are adults (left).

These heroes may not wear capes, but some of them have wings.

The Western Grains Research Foundation (WGRF) launched an online and print campaign called ‘Field Heroes’ this summer to raise awareness and educate the industry about beneficial insects – specifically the natural predators and parasites to potentially harmful, yield-reducing pests.

Beneficial insects can positively contribute to a producer’s bottom line by reducing the need for spraying, lowering production costs, saving time in the field and protecting the environment. But according to John Gavloski, an entomologist with Manitoba Agriculture who was very involved in launching Field Heroes, some people in the industry don’t factor beneficials into their crop production decisions.

“Some people either aren’t looking for them or don’t know how to recognize them,” says Gavloski. “Through Field Heroes, we want to help people recognize beneficials and provide information on just how valuable they can be.”

Some of the common beneficial insects include damsel bugs, ground beetles, hover flies, lady beetles (commonly known as lady bugs) and parasitic wasps.

“Natural enemies can provide free pest control,” says Gavloski. “If you build up healthy populations of beneficials, not only are you reducing levels of crop-feeding insects in an environmentally-friendly manner, but it’s also more cost-effective in the long run.”

Assessing the Economic Risks

In order for agronomists and growers to use beneficials, Amber Knaggs, a sales agronomist with Munro Farm Supplies based in MacGregor, Man., says they need to accept a certain level of pest population, but that doesn’t necessarily mean they will cause economic damage to the crop.

“There does have to be a population of pests to sustain the beneficials,” she says. “But just because you have pests in the field, that doesn’t mean they’re at a level where they’re going to cause economic damage.”

If you’re not considering beneficials, you’re not looking at the entire picture and you may be spending money you don’t need to spend. 
Amber Knaggs

Knaggs encourages agronomists and producers to analyze their economic thresholds before making the decision to spray a field. If the pest population is below the economic threshold, final yield and profit won’t be affected.

“When I’m working with my customers, we consider very closely whether or not there is a reason to spray. Are we at economic levels? Are there beneficials in the field or any other reason why we shouldn’t spray?” she says. “Insecticide is a hard trigger for me to pull; we have to make sure we’re at the economic threshold.”

Knaggs says she uses beneficials with all of her customers as part of their integrated pest management strategies. If any of her customers are reluctant to use them, she says she does everything she can to help change their mind.

“If you’re not considering beneficials, you’re not looking at the entire picture and you may be spending money you don’t need to spend,” she says. “People who aren’t aware of beneficials may not realize that not every insect is bad. They just need a bit of education to help identify which beneficials are in their fields and what they’re doing.”

Discovering A Hero’s Secret Identity

Gavloski says this is where retailers can come in. By using resources like Field Heroes, retailers can ensure their agronomists are well-versed in beneficials and can encourage their producer customers to learn more.

“Field Heroes is a great resource for agronomists to use with their customers,” says Knaggs. “Even experienced agronomists should have a refresher and a reminder. It’s great to have a resource you can review with your customer and refer back to throughout the season.”

When agronomists are doing initial crop scouting with their customers, they can keep an eye out for beneficials and identify any that may be in the field. However, according to Gavloski, correctly identifying beneficials is sometimes easier said than done.

Gavloski says many people can identify the adult beneficials, but few people can identify the larvae. He stresses that recognizing larvae is an important part of utilizing beneficials, as some species are most effective in the larvae stage. “When lady beetles reach their later larvae stages, sometimes they’re actually eating more aphids than they will as an adult,” he says.

John Gavloski sweeps a wheat field for beneficial insects.

Holding Out for a Hero

Once you know you have beneficials in the field, you can monitor how well they’re controlling the pest populations. Even if pest populations look like they’re rising, Gavloski says agronomists should wait before they spray.

“We’re really trying to encourage people to hold off on spraying an insecticide until you absolutely know you have levels that are going to create economic issues,” he says.

Knaggs says she reached this point when soybean aphids created problems for some of her customers this past year.

“There were a few fields that I was watching, and I knew the beneficials were there, but the aphid numbers were rising,” she says. “Eventually we just had to spray an insecticide on one field. We held off for about a week or so, hoping the lady beetles would get the aphids under control, but that just didn’t happen.”

When you have no choice but to spray a field, Gavloski recommends choosing your insecticide carefully.

“Insecticides are often broad spectrum. Where it’s practical, you can consider more selective insecticides,” he says. “If you can use a selective product that will only kill one type of insect, you’re saving natural enemies for future years.”

According to Gavloski, wiping out beneficials in one season can leave the field more vulnerable the next year, increasing the risk of yield loss and economic damage.

“Taking away too many natural enemies will actually assist the pests,” he says. “Especially when it comes to something like aphids, which can multiply extremely quickly. If you take away nature’s controls, the pests can spread very rapidly.”

By preserving yields, reducing spraying costs and protecting the environment, beneficial insects have earned their title as Field Heroes.

“Beneficials are valuable – that’s why they’re called beneficials,” says Knaggs. “They’re part of the bigger picture you need to consider whenever there’s an issue with pests. They can save producers money, and that’s reason enough to be aware of them.”

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