Avoid fence to fence cropping | Helpful insects feed on other insects that damage crops
RIDGETOWN, Ont. — Farmers like to see an endless carpet of crop, but natural areas need to be part of the mix if they hope to tap into farm-friendly insects.
“In order to bolster the population of these insects, it’s important to have some floral diversity,” Ben Phillips, an extension worker at Michigan State University, said during the Diagnostics Day held at the University of Guelph’s Ridgetown Campus July 9-10.
“If there’s less than two percent natural area, there are not enough resources to sustain an adequate population, and if there’s more than 20 percent, it’s likely they will not bother coming into your field to help. The sweet spot is somewhere between two and 20 percent.”
Jim Chaput, Ontario’s minor use co-ordinator for pest control products, encouraged Ontario farmers to get back to integrated pest management. He said insects, including pollinators, can be part of the mix.
Interested farmers can encourage native, non-weed perennials around field edges to attract insect predators that attack crop pests, Phillips said. Ideally, something should be flowering from early spring until well into the fall.
Larger areas may be direct seeded, but many species will begin to flower in only three to five years.
For smaller areas, rooted seedlings sold in pots can be used with flowers appearing in one or two years.
Choose local seed sources and match species to soil type and other site characteristics. Site preparation is crucial to control weeds.
Favoured species vary depending on location.
Wild strawberry is an example of an early season choice for much of Ontario and Michigan.
Phillips also cited several examples of beneficial insects, including a variety of fly species that lays its eggs on insect pests. The pests succumb to the feeding activities of the larvae once they emerge.
Other insects attack their prey as adults.
“Lady beetles and ground beetles are voracious predators,” Phillips said.
“It’s like the Serengeti desert out there, but on a small scale. There are a lot of interactions happening.”
Friendly insect predators use a variety of techniques. Some eat pests the way humans chow down on a piece of steak. Those with sucking mouth parts often ambush their prey, while insects such as the alligator beetle inject their prey with poison.
Most beneficial insects are native to North America, but there are some notable exceptions.
The Asian multi-coloured ladybeetle was introduced to counter the soybean aphid, while three weevils were introduced to attach purple loosestrife.
Phillips said these “classical introductions” require much research beforehand. Sometimes the introduction can became a nuisance or a pest in itself.