Evidence for diet-driven habitat partitioning of Melanoplinae and Gomphocerinae (Orthoptera: Acrididae) along a vegetation gradient in a western Oklahoma grassland.

Grasshoppers (Orthoptera: Acrididae) are important arthropods in the grassland ecosystem as sources of herbivory, nutrient recycling through frass production, and as prey items for other insects, mammals, and birds. It has been observed in previous research that common Acrididae subfamilies have dietary preferences: many species of Gomphocerinae are specialists on grass plants, many Melanoplinae species are polyphagous forb eaters. We characterized the community of Acrididae along a vegetation gradient in the Beaver River Wildlife Management Area, Beaver County, OK, and tested the hypothesis that these subfamilies would be in greater abundance in areas dominated by their preferred food resource. Vegetation types were characterized into four different functional groups: grass, forb, litter, and bare ground. The proportion of cover of functional groups was found to be correlated with relative abundance of Gomphocerinae and Melanoplinae grasshoppers. Gomphocerinae were in greater abundance in vegetation types consisting of a larger proportion of grass. Melanoplinae were in greater abundance in vegetation types consisting of larger proportions of forb cover. A factor analysis indicated that forb cover and grass cover contributed more than litter and bare ground cover to the relative abundance of these grasshopper subfamilies and it is our conclusion that this is evidence for dietary-based habitat partitioning as observed through subfamilial relative abundance.