Risk-taking Farmers Are More Likely to Apply Pest Prevention

Pest prevention plays an important role in reducing pesticide use. Nevertheless, the use of such measures is below the social optimum. A generally cautious attitude towards risk and adoption of other risk management measures hinder farmers’ prevention efforts.

Pest prevention can play a key role in reducing pest pressure and pesticide use while maintaining food production, and therefore facilitate reaching policy goals to reduce pesticide use in agriculture. However, the uptake of these preventive non-chemical strategies is below the social optimum, and could lead to an overuse of pesticides.

Preventive measures and insecticides for the control of Drosophila suzukii

Invasive species are an increasing threat to Swiss agriculture. Spotted wing drosophila (Drosophila suzukii) is one major invasive pest of soft fruits including wine grapes across Europe. Common pest control strategies in viticulture include preventative measures and synthetic insecticides. Viticulture accounts for a significant share of pesticides used in Swiss agriculture.

Which factors are related to the optimum effort for pest control?

Our study investigates farmers’ pest prevention decisions. We first develop a theoretical model to analyze which conditions, as well as farm and farmers’ characteristics, favor or hinder the uptake of preventive measures. Our results show that higher risk aversion hinders farmers’ prevention efforts. While this result may seem counterintuitive at first sight, one rationalization is that a more risk averse farmer tends to use less prevention measures due to the higher uncertainty in the benefits of prevention measures compared to pesticides. The investment in prevention measures would only payoff in hindsight if infestation eventually occurs, while pesticides are often only applied after the occurrence of an infestation.  Furthermore, so-called both state-dependent (e.g. uncertainty on pest related losses) risk in the case of infestation and general background risk (e.g. other production or price risk) would increase a farmer’s optimal level of pest prevention. In addition, prevention effort increases with perceived pest pressure based on prior experience, and decreases with the cost of prevention relative to farmers’ wealth.

Case Study on the control of Drosophila suzukii in Swiss Viticulture

We test the theoretical results using an empirical application of Swiss grapevine producers’ decisions to use preventive measures in response to spotted wing drosophila. Our analysis uses data from an online survey sent to Swiss grapevine producers over 2016, 2017, and 2018, and focuses on non-organic producers. The survey contains variety-specific information on measures taken to prevent or control spotted wing drosophila, as well as farmers’ perceived infestation due to the pest in the corresponding year. Prevention measures include installation of insect nets (lateral insect nets, netting of specific rows with insect nets, or netting of multiple rows with insect nets), sanitation measures (e.g. removal of harvest residue, mowing/mulching, and clean harvest of every fruit), and early harvest. In the case that infestation occurs, farmers can also choose to apply insecticides to control infestation, though insecticides are considered as the last resort for pest control for Swiss grapevine growers.

We find empirical evidence consistent with the theoretical findings. For example, controlling for other factors, higher risk aversion is associated with significantly lower prevention efforts. Furthermore, farmers with crop insurance (proxy for lower background risk) are less likely to adopt prevention measures by 19 to 23 percentage points compared to farmers without crop insurance.