The potential of semiochemical blends to monitor saproxylic beetle communities

Abstract The biodiversity of forests is threatened by intensive forestry. Due to a drastic decrease in the supply of dead wood, saproxylic insects constitute a great part of this threatened biodiversity. Their cryptic lifestyles make them hard to find, and we currently lack an effective method for surveying saproxylic insect communities. In this study, we aimed to assess if baited traps can be used to survey saproxylic beetle communities, with a focus on jewel beetles (Buprestidae), longhorn beetles (Cerambycidae), and weevils and bark beetles (Curculionidae). We also asked how sampling efficiency is affected by spatial and temporal factors, and if several blends outperform single-blend surveys. To answer these questions, we used traps baited with three different semiochemical blends aimed at sampling species associated with coniferous wood across three ports and six years. The baited traps managed to capture between 80 and 99% of the previously known saproxylic beetle communities associated with coniferous wood at each port across all years. The efficiency of the baited traps differed between sites, suggesting there are site-specific factors to consider. Sampling across consecutive seasons provided a more comprehensive overview of the total community than single-season surveys. Having multiple blends also increased the proportion of the community sampled, compared to any single blend. To our knowledge, this is the first study evaluating the possibility of using semiochemical blends to sample broad saproxylic beetle communities. We argue that semiochemical blends are an effective addition to conventional sampling schemes when surveying saproxylic beetle communities.