Editorial on “Biological control of pests and pathogens in forests: Current status and future trends in the years to come”

In the last decades, insect and disease outbreaks occur at an alarmingly increasing rate in forests globally, something that can be directly associated with international trade and climate change (Roques, 2010). Although endemic insects and diseases constitute integral parts of forest ecosystems, non-native species pose a threat that is much harder to contain given the lack of natural enemies and the unsuitability of conventional approaches that are often used in agricultural practices (e.g. use of insecticides). For that, conservation, augmentation or classical biological control programs often constitute the only feasible approach to control pests and diseases in forests (Kenis et al., 2017). Back in 2022, when launching the Special Issue entitled “Biological control of pests and pathogens in forests: current status and future trends in the years to come”, we aimed to cover a vast and rich in variety area of knowledge that is located on a cutting-edge of entomological research. Nevertheless, the manuscripts submitted and finally published in this Special Issue exceeded by far these expectations. It was thus more than exciting to capture and comprehend how native European ant species interact with the invasive ambrosia beetle Xylosandrus compactus, reducing the reproductive success of this invading species (Giannetti et al., 2022) while on the same time, the study on Anaphes nitens demonstrated vividly how the detrimental impact of genetic bottlenecks that is frequently observed in classical biological control agents, can be overcome (Barten et al., 2023). Similarly, searching for the most suitable biological control agent against the Japanese giant silkworm Zang et al. (2023) evaluated and compared three different Anastatus species, and f inally provided robust evidence on the fact that A. japonica is by far the most appropriate one on the basis of both biological traits and net killing rate. In an innovative approach to control the spread of Heterobasidion annosum in an established stump infection, Piri et al. (2023) employed a biocontrol fungus (Phlebiopsis gigantea) with striking results that were further strengthened by the simultaneous occurrence of HetOV13-an1 virus, providing an alternative approach to slow down the spread of H. annosum in Europe. Finally, using the case study of the hemlock wooly adeligid Adelges tsugae, Mayfield et al (2023) provided a detailed review on the biological control program against this forest pest, highlighting on the same time essential issues and intrinsic details that should be carefully considered when implementing similar biological control programs in the future. In summary, what has really become obvious from the papers included in the current Special Issue, is that despite the progress that has been made, there are still many things to be explored and investigated ☆ regarding the biological control of forest insects…for that, we hope that this Special Issue will serve as the ground for many more studies to thrive in the future.