Acridids (grasshoppers and locusts) can range from being rare curiosities to abundant menaces. Some are threatened with extinction and become subjects of intensive conservation efforts, while others are devastating pests and become the objects of massive control programmes. Even within a species, there are times when the animal is so abundant that its crushed masses cause the wheels of trains to skid (the Rocky Mountain grasshopper, Melanoplus spretus Walsh in western North America in the 1860s and I 870s), while at other times the animal is alarmingly scarce (the Rocky Mountain grasshopper went extinct in the early 1900s). Why are there these extremes in one insect family, and even in a single species? The NATO workshop examined this paradox and its implications for Environmental Security, which must address both the elements of land use (agricultural production and pest management) and conservation of biodiversity. The reconciliation of these objectives clearly demands a critical assessment of current knowledge and policies, identification of future research, and close working relationships among scientists. Insects can present two clear faces, as well as the intervening gradation. These extremes require us to respond in two ways: conservation of scarce species and suppression of abundant (harmful) species. But perhaps most important, these opposite poles also provide the opportunity for an exchange of information and insight.

Zusammenfassung
Proceedings of the NATO Advanced Research Workshop on Acridogenic and Anthropogenic Hazards to the Grassland Biome: Managing Grasshopper Outbreaks without Risking Environmental Disaster, Estes Park, Colorado, U.S.A., September 11-18, 1999

Inhalt
A Novel Approach to Solving Complex Ecological Problems: An International Polylogue on the Art and Science of Applied Acridology.- 1. Grasshoppers as Integral Elements of Grasslands.- 1. Do Grasshoppers Diminish Grassland Productivity? A New Perspective for Control Based on Conservation.- 2. What are the Consequences of Ecosystem Disruption on Acridid Diversity and Abundance?.- 3. What is the Role of Grassland Vegetation in Grasshopper Population Dynamics?.- 2. Grasshopper Population Ecology and Management.- 4. How do Spatial Population Structures Affect Acridid Management?.- 5. Can Micropopulation Management Protect Rare Grasshoppers?.- 6. What Factors Govern Orthopteran Community Structure and Species Prevalence?.- 3. Grasshopper and Locust Control Strategies and Tools.- 7. How Can Acridid Population Ecology Be Used to Refine Pest Management Strategies?.- 8. What are the Consequences of Non-Linear Ecological Interactions for Grasshopper Control Strategies?.- 9. What Tools Have Potential for Grasshopper Pest Management? A North American Perspective.- 4. Grasshopper Control and Grassland Health.- 10. How Can Acridid Outbreaks Be Managed in Dryland Agricultural Landscapes?.- 11. Can Locust Control Be Compatible with Conserving Biodiversity?.- 12. How Does Insecticidal Control of Grasshoppers Affect Non-Target Arthropods?.- The Risks of Grasshoppers and Pest Management to Grassland Agroecosystems: An International Perspective on Human Well-Being and Environmental Health.- List of Contributors.- List of Participants.