Using nature to control nature

Weeds, fungi, bacteria, viruses, insects and other animals, are all pests that cause devastating damage to crops and forests. One tool Washington producers use for managing these pests is biological control, or biocontrol. Biocontrol relies on a good understanding of the biology of the pest and its natural enemies.

Taking advantage of predator vs prey relationships

Birds, bats and spiders are all important predators of insects in fruit orchards. Farmers understand this and manage their farms to encourage these animals to be present. Spiders are great friends to have in an orchard, being gluttonous consumers of many pests such as larvae and moths. Flying insects are trapped by web-building spiders to be eaten later.

This crab spider is an example of a hunting spider. It’s coloring allows it to remain camouflaged, stalking its prey, which it will capture with its legs and mouth parts. Powerful crab spiders are commonplace in orchards, feeding on aphids, leafhoppers, stink bugs and mites.

Insect vs insect

Many beetles, such as lady bugs, feed on other insects like aphids. The best targets for biological controls in orchards, are insects that feed on the leaves and bark of the fruit trees. A thorough understanding of the biology of these helpful insects is necessary for planning the safe timing of other pest management tools such as the use of sprays.

Watch these predators in action

Microscopic organisms defeat pests

Many crops are attacked by creatures living in the soil that feed on roots. Producers use beneficial microrganisms to fight back. Fungus and bacteria are two examples of biocontrols used to kill nematodes that damage potatoes and onions.

Ag biochemists cultivate beneficial microbes to inoculate the root zone in the soil with billions of helpful organisms that can overwhelm the nematodes and protect the crop.

Washington uses biocontrol to fight the gypsy moth

Bird vs bird

Insects aren’t the only animals that threaten crops. Birds can cause a huge amount of damage by attacking ripe fruit during harvest.This can be an expensive loss to farmers.

One method some Washington growers use to protect their fruit is to hire a professional falconer to chase the birds away while the crop is being harvested. The falcons hunt, but do not kill the birds, causing the flock to become discouraged and forage elsewhere. This falcon named Hoko, in the photo above, is one of a number of raptors trained to protect valuable crops like sweet cherries and wine grapes.

Insects for weed control

Photo by Lynn Ketchum, Oregon State Extension

Insects can be an ally in the fight to eradicate invasive weeds. Tansy ragwort, shown in the picture above, can cause fatal liver failure in livestock and deer. It first showed up near Portland in 1922 and quickly spread throughout the northwest. The cinnabar moth caterpillar feeds on the weed and has been an effective tool in helping to decrease the presence of this toxic plant. Biocontrols like this can take many years to become effective, but are an important tool for controlling noxious weeds.

This moth can cause terrible damage to forests and orchards in our state

A success story using biocontrol is the effective use of a naturally-occurring soil bacterium in fighting the devastating gypsy moth. This year, Washington’s orchards, landscapes and forests are threatened with destruction by this pest. The bacteria known as BtK (Bacillus thuringiensis kurstaki (Btk) targets the caterpillar of the gypsy moth. Caterpillars feeding voraciously on the green growth of trees and shrubs can quickly strip a forest or orchard of leaves.  BtK bacteria, sprayed on trees, wreaks havoc with the digestive system of the caterpillars, but has been shown to be harmless to other life forms.

Please click here to learn how Washington Department of Agriculture keeps the gypsy moth from spreading across the state.

Click on the moth to watch gypsy moth videos.