Nosema locustae is a biological control agent used to manage populations of grasshoppers and certain locust species. This microsporidian parasite is a single-celled pathogen that specifically targets these insects. It offers an alternative to chemical insecticides, as it is considered safe for humans, pets, livestock, and beneficial insects. The spores are applied in a bait formulation, providing a natural method for long-term grasshopper suppression.
How Nosema Locustae Works
Control begins when a grasshopper ingests the bait containing Nosema locustae spores. Once inside the host, the spores germinate and infect the cells of the digestive system, primarily targeting the fat bodies. This infection hinders the insect’s ability to metabolize energy and grow.
Infection leads to debilitating effects, including lethargy and a significant reduction in food consumption. It is a slow-acting control agent, with noticeable effects appearing within 7 to 10 days, which is key to its long-term strategy. The disease spreads when healthy grasshoppers consume the carcasses or feces of infected individuals, a behavior known as cannibalism. Survivors experience reduced development and a substantial decrease in reproductive capacity, often reducing egg production by 60% to 80%.
Applying the Biological Control Agent
For maximum effectiveness, the timing of application is crucial and should occur early in the season, targeting young grasshoppers, specifically the first or second instar nymphs. These younger insects are significantly more susceptible to the infection than older adults. Applying the agent before maturity limits the total damage they can inflict on vegetation.
The product is commercially available as spores mixed with a consumable bait carrier, most commonly large flake wheat bran. This bait is broadcasted over the infested area and surrounding habitat, such as drying grasses and rangelands. Proper dispersal ensures grasshoppers encounter and consume the treated bran.
Apply the bait during warm, sunny days when grasshoppers are actively feeding. Avoid application when rain is expected within a few hours, as moisture compromises effectiveness and washes spores away. For heavy infestations, a second application four to six weeks after the first may be necessary to target newly hatched nymphs.
Sourcing and Storage Requirements
The most common product format is spore-coated wheat bran bait, sold under various trade names. Consumers can find this product through online specialty retailers focused on biological pest control or organic gardening supplies. Agricultural supply stores and regional garden centers, especially those serving rural communities, may also stock it during the spring application season.
Product packaging provides coverage rates to help determine the necessary purchase amount. A typical application rate for grasshopper control is 1 to 2 pounds of the spore-bran mixture per acre, though higher rates may be recommended for severe infestations. The bait is considered ready-to-use and requires no mixing or dilution.
Maintaining spore viability requires careful temperature control, making storage a significant consideration. The bait has a limited shelf life at room temperature, often only a few weeks. To preserve viability, the product must be stored in a cool, dry place. Refrigeration or freezing extends the shelf life significantly, sometimes for months or even a year. Incorrect storage degrades the effectiveness of the biological agent.