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‘Throwing up’ new tools in pest management

One of the oft-cited, but probably unjustified, grower objections to trying biological control for the first time is “cost.”

One of the oft-cited, but probably unjustified, grower objections to trying biological control for the first time is “cost.” In a session at the Lower Mainland Horticultural Improvement Association (LMHIA) Growers Short Course at the Pacific Agriculture Show, four panelists were invited to offer their hints and tips to make the most of the beneficials that you buy.

Kristine Schlamp, pest management instructor at Kwantlen University, offered her version of “Biologicals 101.” She
reminded growers that there are three basic types of biocontrol systems

• Introduction – bringing new beneficial control agents into a crop situation.
• Augmentation – increasing the number of existing beneficials in an ecosystem.
• Conservation – the maintenance of existing, naturally balanced systems.^₁

She suggested that whichever system you chose, there are some things you can do that will swing the balance of insects in favour of good bugs not bad bugs, and so increase your chances of success.

Obviously, it’s essential to know which insects you are dealing with – both the good ones and the bad ones. You should also be cognizant of providing habitat, food and water supplies for beneficials: suitable plants, flowers (to provide pollen and nectar) and open water such as ponds and creeks.

HELPING PUSH THE BALANCE OF POWER IN FAVOUR OF NATURAL PEST MANAGEMENT
This takes me back several decades to when the U.K. Ministry of Agriculture paid grants to arable farmers who took field margins out of production and installed hedgerows that acted as natural habitat for wildlife and beneficial insects. Seen at the time somewhat cynically by non-farmers as a cash grab for (already) wealthy landowners, it was clearly a great (and cost-effective) way to push the balance in favour of natural pest management. Sounds like the Environmental Farm Plans of today.

As mentioned in a previous “Inside View,” Dr. Bill Snyder from Washington State University has been researching ways to increase biodiversity in agricultural habitats to promote beneficial organisms using Colorado beetle in potato crops as the model.²

One of the interesting findings of his work was that when attacked by predators, Colorado beetles will literally throw up on themselves. This is presumably not out of fear! At first, this might seem a rather strange thing to do – the invertebrate
version of “fight or flight” perhaps. But as Bill pointed out, think for a moment about the main ingredient of the Colorado beetle diet – yes, potato leaves. And we’re all taught as kids not to eat the seed pods of potatoes (or green potatoes) for the simple reason that they’re considered to be poisonous. Oh, what better way to protect yourself from being eaten than to cover yourself in half-digested poison! So how is that relevant here? Well…

Other panel members were from three local insectories at the Pacific Ag Show. Each session offered a number of other hints and tips, including the need to consider “attracting” beneficials rather than “repelling” pests. There has been discussion of the “push-pull strategy” for biological control for some years, and here it is again.

While not wanting to reinforce any kind of “chemical
mentality” approach to pest management, might it be worth considering natural sprays that could be applied to crops that act as the equivalent of Colorado beetle puke toward pest species on the one hand or as “bacon-(or coffee)-smell-in-the-morning-at-the-campsite” for beneficial species on the other?

I can sense you’re salivating already!

There must be many equivalents to the Colorado beetle
strategy that beneficial insects apply to stay alive. Similarly, there are probably natural chemical repellants (e.g., garlic sprays) that might dissuade pest species from taking up residence in our greenhouse crops, or otherwise attract beneficials to make our tomato plants their home.

What is it, for instance, that makes marigolds and alyssum attractive to pests and beneficials? Can we use those smells that work as attractants and repellants to our benefit by artificially making those same chemical compounds? Or what about visual cues that these plants use? Can we mimic these to our benefit?

Let’s face it, as intelligent as we are, we can still learn much from watching the natural world…even from beetle puke.

¹Summarized from Payne, Ronda “Being nice to beneficials will benefit your crops,” in Country Life, July 2014.
²See “Inside View,” Greenhouse Canada, March 2014.

Gary Jones is co-chair of Horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at gary.jones@kpu.ca.