Pests and pesticides, risk and risk aversion

Theoretical and applied literature on risk in decision making for agricultural pest control is reviewed. Risk can affect pesticide decision making either because of risk aversion or because of its influence on expected profit. It is concluded that risk does not necessarily lead to increased pesticide use by individual farmers. Uncertainty about some variables, such as pest density and pest mortality, does lead to higher optimal pesticide use under risk aversion. However, uncertainty about other important variables, such as output price and yield, leads to lower optimal levels of pesticide use. Neglect of these variables in most studies has led to the false assumption that pesticides are always risk-reducing inputs. Furthermore, there is evidence that, in general, the pesticide dosage which maximises expected profit is lower under risk than under certainty. Depending on the balance of forces to increase and decrease pesticide use under risk, in many circumstances the net effect of risk on optimal decision making for pest control may be minimal. The effect on risk of information about pest density and other variables (as in integrated pest management programmes) is discussed. Evidence on this issue is mixed. A range of analytical techniques for analysing risk in pest control is reviewed. Throughout the paper, gaps in the existing literature are identified