Nosema Locustae—Fight Grasshoppers
With a Microbe

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Nosema locustae is a naturally occurring microbe that infects and kills grasshoppers and Mormon crickets when these pests ingest bait that contains Nosema.

Based on appropriate testing, this active ingredient is safe for humans, wildlife, and the environment when used according to label directions.

The active ingredient consists of spores of a naturally occurring microbe.

For use in pesticide products, the spores are mixed with bait, which is then applied to soil as a solid or liquid.

When a target insect ingests the bait, the spores become active, the microbes grows and replicate in the insect's digestive system, and the insect soon dies.

The bait is most effective if used when the insects are still in their immature nymph stage, before they become adults.

Most live microbes that work as as pesticides are bacteria. Bacillus thuringiensis (Bt) is one of the better known examples.

Nosema, by contrast, belongs to a category of microbes called protozoans. Protozoans are one-celled animals, just as bacteria are one-celled plants. As of October 2000, Nosema was the only protozoan registered as the active ingredient in a pesticide.

Where It's Used

Nosema locustae is used on agricultural crops, rangeland and grasses, and ornamental plants.

Target Pests

Nosema's target pests are the grasshopper and the Mormon cricket.

Application Methods

The active ingredient is a powder. It's mixed with other materials, such as bran, to become part of a bait. The bait is then applied to infested areas as a solid or liquid using ground equipment.

Human Health Risks

No risks to humans are expected from using products containing Nosema locustae as the active ingredient. Toxicity tests in rats and mice showed no harmful effects. It does not infect mammals and birds, and cannot replicate in them.

Almost all the leftover bait will be on the soil surface rather than on the crop, thus minimizing exposure when people consume the crops.

Environmental Risks

Various toxicity tests showed that Nosema locustae does not harm mammals, birds, fish, aquatic invertebrates, or honeybees. No adverse effects to the environment are expected when Nosema is used in pesticide products.

Regulatory Information

Nosema locustae was initially registered (licensed for sale and distribution) in 1980 to control grasshoppers and crickets. The EPA prepared a reregistration document in 1992 to ensure that the registered products met updated safety standards. As of October 2000, there were three products containing Nosema locustae as the active ingredient.

For further information:

Biopesticides and Pollution Prevention Division (7511C)
Office of Pesticide Programs
Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460

Some of this information courtesy of the Environmental Protection Agency.

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