Beneficial Nematodes

General Information: Beneficial nematodes (Steinernema feltiae) are microscopic roundworms which prey on soil and wood-boring pests, such as flea larvae, white grubs, cutworms, strawberry weevils, cabbage root maggots, and fungus gnat larvae. They act by penetrating pest hosts and in conjunction with bacteria they carry, kill most hosts within several days. Steinernema complete their lifecycle in the host’s body, which culminates in the emergence of juvenile nematodes. The entire cycle takes between 7 to 14 days. This particular species of nematode is not harmful to humans, gophers, domestic animals, earthworms, ladybugs, lacewings, or praying manti.

Release: Beneficial nematodes (BN) may be released any time of the year when the soil temperatures are 60° F or above. In the Bay Area, release from March to November is safe. BN thrive in moist soil conditions, but will not withstand soggy soils. They also cannot withstand direct sunlight, so must be applied after sundown or in shaded areas. Populations remain effective for up to 2 years, but annual application is recommended for maximum efficacy.

Coverage: Each package contains 7 million BN and covers up to 2500 square feet. Faster results occur with higher concentrations.

Directions: Water the areas to be treated, thoroughly, the day before spreading the BN. BN sold as Nema Globe nematodes appear as a very fine light brown powder packaged in a Ziploc bag. This package contains about 7 million BN and covers up to 2500 square feet. Fill a one quart jar 3/4 full with warm water. Pour the BN powder into the jar of water, and rinse the Ziploc package and any remaining powder into the jar of water. Vigorously shake the jar with its BN powder and let stand for a ½ hour or until the contents have dissolved. Break apart any large clumps to help them dissolve. After the powder has dissolved vigorously shake the solution again and pour the contents into a 1 ½ to 2 gallon watering can half filled with lukewarm water. Add enough water to fill the watering can, using the added water to rinse the one quart jar. Stir the BN solution in the watering can frequently to keep the BN suspended. Distribute the BN solution directly from the watering can or pour the solution into a tank sprayer and spray the solution over the affected area. Use a slightly coarse spray and a strong pressure. Agitate the container frequently to keep the BN suspended. Keep the lawn moist for the next 3 days (or a week in dry weather) to ensure nematodes are flushed down into the root zone where feeding grubs are present.

BIOLOGY: Specifically the BN enter the host through its mouth, anus or spiracles. Inside the host, they develop into adult males and females, they mate and lay eggs. The eggs hatch and the nematodes continue reproducing inside the host until crowding forces them to leave the dead host and seek a new host. The nematodes have a mutually beneficial relationship with a bacterium which lives in its gut. The bacteria are released from the anus of the nematodes and multiply rapidly in the host’s bloodstream. The host dies within 24 hours from blood poisoning caused by the bacteria. The nematodes continue to use the bacteria as a food source inside the host’s body until they leave to find a new host.

11/19/14