Fight Fungus Gnat with Biological Controls

Fungus gnats are common greenhouse pests that favor moist growing media. Apart from the nuisance and decreased aesthetic value associated with adults, fungus gnat larvae can damage plant roots, stunting growth. Root feeding also makes plants vulnerable to diseases such as Pythium, Fusarium, and Phytophthora. TerraLink offers three predators that target fungus gnat larvae, as well as sticky traps that can be used as physical control for the adults.

Many growers are already using the nematode Steinernema feltiae against fungus gnats and other pests. Nematodes are microscopic roundworms applied in solution at planting or during the growing season. It is important to create a moist environment prior to application and for 1-2 weeks following, since they need a water film to move through the media. The nematodes will then seek the host needed to complete their life cycle, a process which kills the host. Thousands of new nematodes emerge from each host, giving sustained control if conditions are favourable. TerraLink offers nematodes in a clay-based carrier that is OMRI Listed and dissolves easily.

The second popular control option is the soil-dwelling mite Stratiolaelaps scimitus (formerly Hypoaspis). Both the larval and adult mites are voracious predators that live, eat, and reproduce in both soil and soilless media. These mites can feed on a variety of soil pests, including fungus gnat larvae, shore fly larvae, and thrips pupae. They do not require a water film to be maintained and can easily spread throughout the crop.

The final beneficial insect is less well-known but should be considered as a strong biocontrol option. Dalotia coriaria (formerly Atheta), is also known as the rove beetle. This fast moving predator feeds aggressively and spends most time in the substrate but can also fly. Rove beetles are generalists with an impressive range of prey and can quickly colonize a new environment. They are omnivores and can feed on algae, so they are excellent for preventative programs. They are available in two formats: loose application, and an extended release “breeder bucket”. The latter comes with rove beetles that will emerge over several months. Regardless of the application method, these beetles flourish under a wide range of conditions, target a diverse array of prey, and have excellent longevity in the production area.

Contact TerraLink to order your beneficial insects today!