Control of Coraebus florentinus by multi-year pruning activities: a pilot study in Sardinian cork oak forests

Abstract: Coraebus florentinus (Herbst) (Coleoptera: Buprestidae) is a xylophagous beetle that causes drying and death of branches of several oak species. The use of insecticides is not
feasible to control this pest in forest environments and the only control method currently
available is to prune and remove infested branches. Infested branches are easy to recognize
because of the typical symptoms (i. e., yellowish leaves and/or desiccation), and removing them before adult emergence reduces the buprestid population successively. Because C. florentinus completes its development in 2-3 years and the symptoms of damage in the branch mainly occur when the insect has reached the pupa stage, a substantial decrease in pest population density can be obtained only after at least two years of consecutive pruning. The current work aimed to evaluate the technical and economic sustainability of selective pruning to control C. florentinus infestations at a large spatial scale. Trials were conducted in a cork oak forest area of 150 hectares in Sardinia (Italy) in 2021 and 2022. Pruning activities were performed in April/May in both years by three teams of three workers each, with a total of 14230 and 7335 branches being cut and burned in 2021 and 2022, respectively. During the two years of selective pruning, the cost of working activity (504 labor days) was approximately 58000 euros, and the cost to operate the cutting equipment (i. e., gasoline and oil for the telescopic pruners) was 4000 euros. Overall, the average cost for C. florentinus control by pruning was 413 euros per hectare. However, for a proper cost-benefit analysis, the monitoring of C. florentinus infestation density in the area subjected to selective pruning is needed in the next years as the average cost for control the pest should be weighed against the duration of its effectiveness.