| Grasshoppers (Orthoptera: Acrididae) are pests of rangeland and crops in temperate Eurasia (Siberia) where landscapes are dominated by short-grass vegetation and have many common features with the prairies of the Great Plains of North America. The zone of economic importance of grasshoppers in Siberia is localized in its southern part between 50° and 55°N and 68° and 132°E. In particular, grasshopper infestations are concentrated in close proximity to Lake Baikal, the world's deepest lake, holding one-fifth of the Earth's total fresh water supply. From a biodiversity perspective, Lake Baikal is unparalleled because >80% of its 1,085 plant and 1,550 animal species are endemic. Broad-scale pesticide applications in the zone close to the Baikal ecosystem can seriously aggravate the hazards of environmental pollution, with potentially catastrophic consequences on a vast scale.; Specific composition and density of grasshopper communities were studied over a variety of habitats. Of about 50 local grasshopper species, two gomphocerines, Aeropus sibiricus and Chorthippus albomarginatus, dominated grasshopper communities in dry and mesic habitats, respectively. These species accounted for the most of the crop damage during recent outbreaks in the 1990s requiring large-scale insecticidal control. Annual fluctuations of grasshopper infestations appeared to track changes in air temperature and summer precipitation, but only a synthetic “Aridity index” was statistically significant.; Spatial distribution of historic grasshopper infestations was studied using GIS (ERDAS IMAGINE®) and remote sensing (Landsat TM satellite imagery) and was found to be significantly clumped. The highest grasshopper densities were associated with dry grasslands in transitional zones between foothills and valleys characterized by a particular elevation (600–650 m), soil type (sod-forest, or pararendzina), amount of April–October precipitation (250 mm) and degree of grazing (moderate). Identification of such zones allows for the efficient concentration of management resources and optimization of spatial structuring of grasshopper survey. Development of GIS and remote sensing techniques in applied acridology will contribute to progress towards more rational, economically sound and environmentally viable methods of grasshopper pest management. |
