BUG BUSINESS Environmental farming expert says identifying good and bad insects is the first step
Some insects are pests, but others are your allies and you want more of them on your farm.
Insects that perform valuable tasks such as pollination, recycling and microbial actions, are obviously good guys, but even some which feed on plants can be helpful, Ken Fry told attendees at the Alberta Farm Fresh Producers conference. A little bit of feeding by an insect can even make a plant stronger by inducing it to compensate and produce more, said the co-ordinator for the Environmental Horticulture program at Olds College.
“You actually get higher yields with a little bit of pruning,” said Fry.
He encouraged his audience to think holistically and consider how every action taken will affect the entire ecosystem on a farm. Fry specializes in organics and noted that type of farming uses a variety of methods to improve productivity — including chemicals.
“Chemicals can be one tool to fight pests in the organic tool box, but they need to be sourced from a natural source and used in a naturally compatible way,” he said. “They’re not a sledgehammer, more like a surgical cut with a scalpel.”
Fry said the key to organic growing is understanding natural mechanisms, and accepting a yield loss.
“You no longer have as much control as conventional growers do,” he said.
Growers should look at their property as a growing space for beneficial insects and should consider if there are alternate hosts and plant species which can house “beneficials.”
“You need to put everything in context and realize that the community of living things exists in an ecosystem of living and non-living things,” Fry said. “The non-living, such as the soil, is as much a partner in your enterprise as the living, so don’t ignore the abiotic (non-living) inputs in your ecosystem.”
The first line of defence in pest management is picking the right crop species and cultivars. Fry said producers need to consider what is palatable for the consumer, and what can grow in the region. He noted plants can attract or repel insects. In some cases, plants will produce a chemical resistance to prevent insects from feeding on them. Plants that have too much nitrogen actually become weaker and are less able to fight off insects. An abundance of nitrogen will attract pests to crops.
Biodiversity in the field can reduce the number of harmful insects as they have to work harder to find food sources.
“By putting things in a monoculture, you’re playing right into the strong suit of the insect,” Fry said.
Creating diverse growth habitats with different types and heights of crops can help bring beneficial insects to a yard. Changes in heights create wind resistance, block disease inoculum and change relative humidity.
“Where the most biodiversity occurs in terms of insects is when you change vertical scales,” he said. “You’ll see a lot more predators and parasitoids.”
Some will reduce the number of pest insects in a field, but will not eradicate them completely.
“Ideally you want equilibrium,” Fry said.
Some beneficial parasitoids that feed on other species may thrive on nearby weeds. Beneficial insects may also need some flowering species. Weed management is No. 1, but ornamental, shallow flowering plants will help cultivate desired insects. Hedgerows and beetle banks, shelterbelts and mulches are a good place for beneficial predators and parasitoids to live. Shelter banks and watering sources such as bird baths, sloughs or wetlands are also desired to bring the beneficials in. Fry noted some live in grasslands alongside fields or in ditches, and cutting this grass destroys some of their habitat.
“This land may be taken out of production, but you may give yourself a yield advantage by cutting down on pests,” said Fry. “You need to think about what constitutes a useful land use.”