By Pat Dray
The Garden Spot
Pat Dray
I recently took an online course sponsored by the National Garden Clubs that briefly covered integrated pest management.
One of the key components of IPM is biological control – letting nature do more of the work for you. The core idea is simple: use living organisms – predators, parasites and pathogens – to keep pest populations in check, reducing the need for chemicals.
Since most insects are beneficial insects, biological control helps to restore the balance of nature in your garden. You want to encourage beneficial insects to reduce the need for chemicals.
Predators are the “good guy” insects you may already have in your garden. Some examples are lady beetles that devour aphids, predatory mites that feed on thrips and scale insects and spiders which help keep a wide range of pests in check. Predators actively hunt and consume pests, often eating dozens per day. Yum.
Parasites are mostly tiny wasps and flies that lay eggs in or on pest insects. An example is parasitic wasps, which can lay an egg inside an aphid. The developing larva then kills the aphid from within.
Many parasites specialize in specific pests, making them highly targeted and effective. They’re invisible garden heroes working quietly in the background. Don’t fear the insects.
Pathogens are microorganisms such as bacteria, fungi, nematodes, protozoa and viruses that cause disease in pests. Some are available commercially as bio-insecticides. Probably the best known is H. bacteriophora, a nematode (tiny worm) that attacks caterpillars and immature beetles, among other insects. It can also be used against white grubs in lawns. These are especially useful for soil-dwelling pests or large infestations.
Just like our pollinators, predators and parasites need a nectar source and a habitat. Some plants to consider for both include marigolds to attract lady beetles, white alyssum to attract parasitic wasps and dill, fennel, yarrow and cosmos to support a wide range of predators.
For habitat, consider mulch, perennials, a water source and an overwintering site such as leaf littler and hollow stems from plants.
Please avoid broad-spectrum insecticides that kill beneficial insects along with pests, disrupting the natural balance you’re trying to build.
In the next Garden Spot, I’ll cover another part of IPM: companion planting to reduce garden pests. In the meantime, enjoy the spring weather.
Pat Dray is a past president of the Garden Club of Orange and a master gardener.