Modeling Rangeland Grasshopper (Orthoptera: Acrididae) Population Density Using a Landscape-Level Predictive Mapping
Erica Kistner-Thomas1, Sunil Kumar2, Larry Jech3
1United States Department of Agriculture (USDA) Midwest Climate Hub, Ames, IA, USA.
Journal of Economic Entomology
|June 27, 2021
Summary
Grasshopper outbreaks in Wyoming rangelands are influenced by environmental factors like precipitation and past grasshopper density. Incorporating these variables improves forecasting accuracy for pest management.
Area of Science:
- Ecology
- Entomology
- Agricultural Science
Background:
- Grasshoppers cause millions in damages to North American rangelands and croplands annually.
- Current forecasting by the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) relies only on previous year's density, neglecting environmental influences.
Purpose of the Study:
- To investigate the impact of climate and landscape heterogeneity on grasshopper populations.
- To develop a more accurate grasshopper density forecasting model for Wyoming rangelands.
Main Methods:
- Assessed grasshopper density data from 56 sites (2007-2017) against 72 geographic information system (GIS)-based environmental variables.
- Developed a regression model to predict grasshopper density, utilizing Akaike's Information Criterion (AICc) for model selection.
Main Results:
- The best predictive model explained 34.5% of the variation in grasshopper density (2012-2016).
- October precipitation and prior grasshopper density (2007-2011) were key predictors.
- Specific areas in Sheridan, Johnson, and Washakie Counties were identified as high-risk for outbreaks.
Conclusions:
- Both biotic and abiotic factors significantly influence grasshopper density.
- Future grasshopper forecasting models should integrate environmental variables for improved accuracy and targeted management strategies.
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