As the public grows more concerned about chemical use, many growers struggle with how to keep their product salable while using fewer pesticides.
Some growers are turning to a new kind of ‘undercover operative’ to deal with crop pests.
“Biological controls or biocontrol agents attack and ‘neutralize’ or reduce pests in a cropping system and can be used to manage insects as well as weeds and diseases,” said Dustin Morton, a provincial commercial horticulture specialist.
“These increasingly popular agents are just one aspect of a good Integrated Pest Management program.”
Beneficial control agents (BCAs) or “natural enemies” include beneficial bacteria, fungi, nematodes and insects that feed on harmful organisms. BCAs are often introduced into an area like a greenhouse or field, or can be native natural enemies that are encouraged to proliferate or colonize, as in many field situations.
“Most growers are familiar with predation as a control method,” said Morton. “Predation can mean one insect feeding on another, such as ladybugs on aphids, but can also include mites and flatworms feeding on nematodes or soil-dwelling animals dining on fungi. BCAs that control through predation might be specific (they only control a certain life stage or certain species) or they may be more generalist like a true ‘00 agent’ and eat a number of different species.”
More specialized than predation, parasitism involves an agent living in or feeding on a pest. “Parasites, however, should not be confused with parasitoids which tend to be more common in biocontrol,” said Morton. “This differentiation is important as parasitoids will actually control the pest by eventually killing it, as opposed to parasites which may just slow it down. Common examples of these agents are parasitic wasps or fungal pathogens.”
With herbivory, “assassin” insects or diseases are imported from a problematic weed’s native range to deal with a weed problem. While these agents are not as common in Canada, there are successes, as with the black dot spurge beetle controlling leafy spurge or the root-crown weevil on knapweed.
Given the options available, growers need to consider these important, not-so-secret agents as part of their IPM program, added Morton.
“By incorporating these into their cropping systems, growers can reap the benefits of a diversified pest management plan and truly give these agents a licence to kill.”