Resin tapping shifts beetle (Coleoptera) community composition in a maritime pine forest in northwest Spain

Pines produce resin, a complex mixture of terpenes, as a defence mechanism against external attacks. When exposed to the air, resin releases volatile organic compounds (VOCs) that can attract or repel insects. Resin is also a bioproduct of interest in many industrial sectors and is extracted from living trees by successive wounding along the stem. Despite its economic and ecological relevance, it remains unclear how resin-tapping affects nearby insect communities. To investigate this interaction, 69 insect flight interception traps were installed following a spatially explicit design in different directions and at various distances around three central tapped areas in a Pinus pinaster Ait. forest in northwest Spain. Between 2023 and 2024, a total of 9233 beetles belonging to 227 species were collected, some of which have life cycles closely linked to pine wood. Analyses of the total number of beetles collected and of the number of individuals collected within each trophic group revealed that the insect community was significantly impacted by resin-tapping. Both species richness and the number of individuals trapped, especially those of wood-associated trophic groups such as phloeophagous and mid-stage saproxylic beetles, as well as predators, increased in resin-tapped areas. These effects decreased with increasing distance from the tapped zone. Due to the dispersal of VOCs emitted from central tapped pines, dominant winds played a key role in the observed patterns concentrating insects leeward of the tapped area. Our results highlight that resin tapping can alter beetle community composition and distribution. These findings suggest that resin tapping may influence forest ecological processes and pest dynamics by modifying host tree and habitat conditions, resource availability, and chemical cues associated with resin-tapped trees.