Cost-Benefit Analysis of Monitoring Insect Pests and Aerial Spraying of Insecticides: The Case of Protecting Pine Forests against Dendrolimus pini in Brandenburg (Germany)

Monitoring of insect pests and aerial spraying of insecticides have proven to be effective in protecting forests against needle-feeding insect pests. However, the literature on the economic viability of insect monitoring and aerial spraying of insecticides is scant. This research conducts a cost-benefit analysis of monitoring insect pests and use of insecticides for 5600 ha of managed pine forests. The case studied is the mass outbreak of the pine tree lappet moth (Dendrolimus pini L.) in Brandenburg (Germany) in 2014. Costs were estimated based on information from standardized questionnaires and semi-structured expert interviews. Benefits were analyzed by comparing the loss of revenue due to D. pini with the costs of insect monitoring and insecticide spraying in two scenarios of pine production (with protection vs. without protection). The results show that monitoring D. pini and aerial spraying of insecticides are economically beneficial to forest owners. The total net present value (NPV) of protection was about EUR 1965 ha(-1) at a discount rate of 0% and the benefit-cost ratio (BCR) was about 22.14. NPVs and BCRs per hectare were highest for protecting stands with high site index and stands in the age class of 20-39 years. Sensitivity analyses revealed that NPV results are more sensitive to changes in timber prices than to changes in protection costs. The authors conclude that monitoring insect pests and aerial spraying of insecticides are economically viable options to protect forests against needle-feeding insect pests.