Management of Potato Leafhopper, Empoasca fabae (Homoptera: Cicadellidae), on Alfalfa with the Aid of Systems Analysis

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Abstract
Efficient management of the potato leafhopper (Homoptera: Cicadellidae) on alfalfa requires a procedure for dealing with the complexities of the ecological and economic system. We developed a mathematical model to represent this agroecosystem and demonstrated how systems analysis can help to make management more efficient and less risky. Our management policies were based on two criteria: annual income calculated from the nutrient yields of three harvests, and level of carbohydrate reserve in the taproots at the end of the season, We determined the dynamic economic thresholds for controlling the leafhoppers as immigrants on each of the cuttings of alfalfa. During development of the thresholds we tested a variety of control tactics, including timing of harvests, We found that, for adult immigrants on the second crop, the economic thresholds increase exponentially as stem height increases, Tactics associated with these thresholds included insecticide treatments and early cutting of the second harvest. The results indicated that temperature pattern has an important effect on the economic thresholds and risk. Evaluation of the model and its results through sensitivity analysis, validation, and a comparison with current recommendations showed that the model can be a useful tool in research and management.