(Beyond Pesticides, April 29, 2010) Pest control officials in Wyoming are prepared to spray swaths of U.S. Bureau of Land Management (BLM) property with insecticide if the state experiences a grasshopper outbreak this summer as predicted by officials. Based on adult grasshopper surveys conducted by the U.S. Department of Agricultureâ€™s (USDA) Animal and Plant Health Inspection Service(APHIS) unit in fall 2009, APHIS is expecting that the 2010 summer season of grasshopper infestations will be significantly higher than past seasons. It is estimated that 6.7 percent or 1.2 million acres of the 18 million acres of lands in Wyoming administered by the BLM are currently threatened by a predicted infestation of grasshoppers. Pest control officials consider outbreak levels to be about 15 grasshoppers per square yard – enough to cause economic problems.
Such an infestation, according to BLM, would result in substantial loss of vegetation and ground cover that is vital to providing food and habitat to wildlife and livestock populations and maintaining properly functioning ecosystems. While the insects are native to Wyoming, outbreaks of certain pest species can be problematic because of their voracious appetites for grass.
In discussions with APHIS and local county weed and pest districts, the BLM believes that all BLM states, excluding Alaska and Eastern States, may require some treatments and those grasshopper suppression treatments will be essential to protect private rangelands and crops. Treatments also protect federal rangelands from massive defoliation, particularly the loss of forbs, essential for many wildlife species.
Grasshoppers, as well as other insects, are an important food source for chicks, and treatment as well as application timing could potentially disturb sageâ€“grouse, particularly during early brood rearing.
Earlier this year, scientists were looking into a fungus that eats Mormon crickets (which are more closely related to grasshoppers than crickets) alive by depositing spores inside them that multiply and eventually break through their exoskeletons. While the fungus is already providing an organic method of controlling crickets and grasshoppers in Australia, Africa and South America, exotic species laws prevents its importation into the U.S.
According to the National Sustainable Agriculture Information Service (ATTRA), a healthy and diverse farm environment usually discourages the build-up of a lasting infestation and improving biodiversity is the single most important step that can be taken. The best way to control grasshoppers is by preventing them in the first place by taking cultural measures, such as tillage, fall clean-up, trap cropping, early seeding and early harvest, in conjunction with biological controls, such as Nosema locustae, a naturally occurring protozoan that causes disease and death in crickets and grasshoppers.
Typically, the pesticides utilized by APHIS in the grasshopper program include carbaryl, diflubenzuron and malathion. APHIS applies these pesticides by ground equipment by distributing baits usually made of wheat bran or rolled oats and carbaryl or aerially by distributing ultraâ€“lowâ€“volume applications (any application of less than .5 gallons per acre).
Instead of using full coverage insecticide treatment, the BLM has selected the “Reduced Area and Agent Treatments” (RAATs) method, which will purportedly require less land area and uses insecticides at lower rates. The plan involves spraying alternating strips of land with the toxic pesticide diflubenzuron, which stops grasshoppers from growing.
While this is slightly better than the alternative of blanket spraying, the BLM decided against another alternative that would have required more restrictive buffers around certain bird and big game habitat. Under the other alternative–RAATs with Additional Buffers– additional seasonal or spatial buffers would have be employed to protect specific resources, as described below:
â€˘ To protect raptors during the breeding season, no aerial or ground treatments would occur within 0.5 mile of known active nests. This would extend the 1,000-foot buffer described above for bald and golden eagles to 0.5 mile and would extend this protection to all raptors. The primary concern for bird species is related to disturbance (from aircraft or vehicles used in the application of the pesticides) and the effects of decreases in insect populations from pesticide applications on insectivorous species rather than to the direct toxicity to birds.
â€˘ To protect the greater sage-grouse, an ESA candidate species, no aerial or ground treatments would occur within 3 miles of known leks or brood rearing areas until after June 30. The primary concern for sage-grouse is the effect the grasshopper suppression program would have on the forage base of young sage-grouse, which rely most heavily on insects during the first three weeks of life. Although RAATs methodology would leave a significant food base under both action alternatives, this measure would ensure that no additional disturbance occurs around leks and early brood rearing areas.
â€˘ No aerial or ground treatments would occur within 1 mile of known mountain plover nesting areas until after July 31. The mountain plover (Charadrius montanus) is an ESA candidate species that nests and feeds in shortgrass prairie habitat, especially in heavily grazed areas and within prairie dog colonies. The primary concern for the mountain plover is the effect the grasshopper suppression program would have on their insect food base and the potential for ground-based treatments to destroy their nondescript nests.
â€˘ No aerial or ground treatments would occur within one mile of known big game parturition areas until after the calving season is complete, typically by July 15. The primary concern for big game animals would be the disturbance caused by aircraft or vehicles used in the application of the pesticides.
â€˘ No ground treatments would occur within 1,000 feet of known pygmy rabbits burrows. Pygmy rabbit (Brachylagus idahoensis) populations have been declining throughout the west and they have been petitioned for ESA listing. Pygmy rabbits are typically found in areas of tall, dense sagebrush upon which they depend for both food and shelter. The primary concern for the pygmy rabbit is the potential for ground-based treatments to destroy their burrows.
The agency was taking feedback until April 26th on its environmental study, however based on an Environmental Assessment (EA) conducted by BLM, it concluded that implementing their preferred treatment- the RAATs method- not pose a threat and therefore an Environmental Impact Statement will not be prepared. Wyoming BLM Weed and Pest Coordinator Ken Henke said: “If public comments come in, if there’s something really significant we missed or some issue we just overlooked, that also could be addressed in the final (environmental assessment).â€ť
For more information on grasshopper control, please see ATTRAâ€™s Grasshopper Management Page.
The scoping notice, maps, and all other future documents related to this action including the EA can be found on the BLM Grasshopper & Mormon Cricket Control webpage.
Source: The Associated Press