(SitNews) - Insects are essential, so farmers and gardeners benefit by studying them, according to University of Alaska Fairbanks Professor Pat Holloway.

While Holloway has focused her research on peonies during the past 10 years, she has kept an eye on the insects that visit the Georgeson Botanical Garden flower gardens and berry patches for the past 30 years. “We always have honey bees; I just had to figure out what else is out there,” she said.

Graduate student Rehanon Pampel discovered 19 kinds of bumblebees, with 14 being in large supply, and informally surveyed other insect visitors. The heath bumblebee (Bombus jonellus) appears to be the most prolific in interior Alaska.

A bumblebee visits a trollius at the Georgeson Botanical Garden.

The honey bees tend to be fickle, meaning they will jump from one type of flower to another, depositing pollen randomly as they forage. Bumblebees tend to be faithful; they work a single plant, thus increasing the chances for cross pollination from the same plant.

Bumblebees particularly love squash. “Plant a big field of squash to keep bumblebees busy,” Holloway said. “This is participatory farming; try identifying the insects in your own areas, because every farm and garden is different.”

Insects provide an ecosystem service to plant producers. “If you want good fruit production, you have to identify the pollinator and understand that it usually takes more than one pollen grain to make a fruit. You need lots of visits from many insects to get good fruit set,” Holloway said.

Farmers can take a shotgun or targeted approach.

The shotgun, she said, is when farmers don’t know what specific insects are around; they just know they need them. “They can grow great pollen and nectar sources, add a source of water, nesting and over-wintering sites and attract insects; there’s nothing wrong with that.”

Targeting what to grow to attract pollinators allows growers to increase their yield. “I prefer this one,” Holloway said. “It gets you into the biology of the insect and the plant.”

To attract pollinators, Holloway advises growing a diversity of native and non-native flowering plants, trees and shrubs. The Georgeson Botanical Garden website, www.georgesonbg.org (under native plant research), has a guide to plants and the types of insects they attract. A few shining stars include flowering onions, coriander, sweet alyssum, mustard, delphiniums, false spiraea, honeyberries, willows, fireweed and all kinds of cherries.

“Everybody loves the hummingbird moth,” she said. Lilacs, dianthus and wild bedstraw attract it. The caterpillar stage of this butterfly is disgustingly ugly, and it feeds mostly on members of the fireweed family. Most people want to kill it because they think it’s the tomato hornworm they knew in gardens farther south.

“Not so! If you want the hummingbird moth, you also need to feed the caterpillar,” Holloway said.

Growers need to be aware of competition between blooming times. “Last year, because of our very late spring, our pin cherries and wild blueberries bloomed together. The insects loved the cherries. We didn’t get as much fruit from the blueberries.”

Organic farms have greater diversity of insects. “If you use insecticide, read the label; don’t apply when the insects are flying.”

Holloway is a professor of horticulture in UAF’s School of Natural Resources and Extension. She can be reached at psholloway@alaska.edu.

This column is provided as a service by the UAF School of Natural Resources and Extension and the Agricultural and Forestry Experiment Station.
Nancy Tarnai is the school and station’s public information officer. She can be reached at ntarnai@alaska.edu.

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