Bugging Out in the Greenhouse

Pests are among the most common and destructive issues in greenhouses and other controlled environments. Left unchecked, pests can overrun a crop and destroy it. Insect pests have natural enemies, also known as biological control agents, that help reduce pest populations by keeping them below damaging thresholds rather than eliminating them.

Biocontrol allies are categorized into:

Predators: agents that eat the pest
Parasitoids: agents that deposit eggs and develop in or on the pest, killing the pest in the process; includes nematodes and insects
Biopesticides: agents that reduce pest populations by repelling, excluding, killing, or disrupting pest growth or reproduction; includes plant extracts and microbes (fungi, viruses, bacteria)

Biocontrol agents are released into the crop to help prevent the pest populations from establishing and to control active infestations. Biological control is a crucial component of Nourse Farms' Integrated Pest Management (IPM) strategy because it supports long-term pest suppression while protecting plant health and beneficial species.

Common greenhouse pests include spider mites, broad mites, cyclamen mites, aphids, thrips, and fungus gnats, all of which can wipe out a crop quickly. In our greenhouses, we use a multitude of different beneficial insects to help prevent pest populations from establishing and to control active infestations. For example:

Phytoseiulus persimilis: This speedy mite controls spider mites; use year-round
Amblyseius cucumeris: This mite controls other mites, broad spider, cyclamen mites, and thrips in egg and larval stages; thrives in cooler temperatures, and optimal use is in the early and late season
Neoseiulus: This mite controls other mites, broad spider, cyclamen mites, and thrips in egg and larval stages; thrives in warmer temperatures, and optimal use is during summer months

For soil-borne pests and pests with a life stage in the soil, we use a mix of Stratiolaelaps scimitis and the beneficial nematodes Steinernema feltiae and Steinernema carpocapsae. The scimitis and feltiae target primarily the larval stages of fungus gnats; however, they also control most other soil-borne life stages of common greenhouse pests, such as shore flies, root aphids, and root knot nematodes. Carpocapsae targets larger soft-bodied insects, such as the grubs of various beetles and caterpillars.

Nourse Farms Grower Christian adds, “Beneficial insects are cheap, effective, and nontoxic. This practical pest solution should be the basis of preventive measures to stop pests from establishing in the crop.” Utilizing beneficial insects and other biocontrol agents helps us to minimize pest outbreaks, improve crop productivity, and decrease pesticide use and exposure.

Tip: The key to an effective pest control program lies in regular monitoring, accurate identification, and proper timing of control, including the introduction of biological agents early, before pest populations reach damaging levels.

Did you know?: The U.S. Department of Agriculture reports that less than 1% of insect species are considered harmful.