Has Resistance Taken Root in U.S. Corn Fields? Demand for Insect Control
利用2005和2010年田间数据，分析美国玉米种植者对种子和土壤杀虫剂的选择，评估根虫抗性发展情况，发现抗性尚未广泛蔓延但可能增加杀虫剂使用。
Abstract Corn farmers reported unexpectedly severe damage on fields planted with genetically‐engineered rootworm‐resistant (Bt‐CRW) corn seeds during the 2009 growing season. Entomologists later determined that rootworms on these fields had developed resistance to the insecticidal proteins produced by Bt‐CRW corn. This article explores what corn farmers' seed and soil insecticide choices imply about rootworm resistance in the United States. First, a soil insecticide demand function is derived using a damage‐abatement model. Next, this demand function is estimated using field‐level data from 2005 and 2010. We find that rootworms ( Diabrotica spp.) cost farmers approximately $1.3 billion in 2005 and $2 billion in 2010. When used, Bt‐CRW seeds were very effective, reducing average yield losses by approximately five bushels per acre and providing over twice as much control (on average) as soil insecticides. We found no evidence that soil insecticide use was higher on fields where resistance was most likely to develop. However, we did find that demand for soil insecticides was elastic. These results suggest that rootworm resistance was not widespread in 2010, but that it could substantively increase soil insecticide use if it evolved and spread.