Rice yields, production variability, and the war against pests: An empirical investigation of pesticides, host-plant resistance, and varietal diversity in Eastern China.

摘要

Rice pests reduce yields and increase yield variability, creating dual problems for rice farmers in Eastern China. The standard pest control strategy in Eastern China is to apply chemical pesticides, but negative consequences have increased interest in pesticide alternatives, including host-plant resistance and varietal diversity. The study presents the first production function framework measuring the impact of pesticides, host-plant resistance, and varietal resistance in rice production, and evaluating whether these factors increase yields and decrease yield variability.;Host-plant resistance in many Chinese rice varieties provides protection from pests. However, no systematic reduction in pesticide use occurs when farmers grow varieties with host-plant resistance, despite evidence that pesticides are less effective in the presence of host-plant resistance. Furthermore, pesticides may reduce the productivity of host-plant resistance, which is deteriorating in Eastern China.;Pesticides and host-plant resistance were incorporated into production models to measure productivity and substitutability. Estimating frameworks include Cobb-Douglas, Cobb-Douglas and translog with endogenous pesticides, and a new bio-economic model based on damage abatement models. Results indicate that pesticide productivity is low and may be negative when host-plant resistance is present. Pesticide use is allocatively inefficient. Host-plant resistance increases yields, and results suggest that yield increases from improved host-plant resistance exceed the cost of developing resistant varieties. Elasticities of substitution show that host-plant resistance can substitute for pesticides, and improvements in host-plant resistance can facilitate reduced pesticide use with no loss in yield.;Determinants of yield variability in rice include not only pesticides and host-plant resistance, but varietal diversity. Measures of varietal diversity were constructed and evaluated for Eastern China. Econometric estimation of a stochastic production function revealed that pesticides increase yield variability, whereas host-plant resistance and varietal diversity decrease yield variability.;The study's main contribution is use of innovative methods to show that common levels of pesticide use are inefficient and can be reduced in the presence of host-plant resistance, and reducing pesticide use while increasing adoption of diverse and pest-resistant rice varieties results in higher and more stable yields.