Ips sexdentatus Mass-Trapping: Mitigation of Its Negative Effects on Saproxylic Beetles Larger Than the Target

Research Highlights: We investigated the negative effects of bark beetle mass trapping, especially non-target catches among target’s natural enemies. Slot traps modified with mesh screen and escape windows were tested to improve their selectiveness. Background Objectives: Two main enemies beetles, Thanasimus formicarius (L.) Temnoscheila caerulea (Olivier), are frequently trapped in high numbers Ips sexdentatus (Böerner) pheromone traps, along other saproxylic insects; this may lead much larger pest populations successive 4–20 generations. From 2016–2019, during I. mass-trapping a pine forest Tuscany (Italy), tallied. Trap modifications evaluated mitigate catches, those concerning beetles’ Materials Methods: A total 25 bark-beetle slot placed about 75 m apart stand infested by sexdentatus. Traps baited aggregation pheromone, whose components ipsenol, ipsdienol, 2-methyl-3-buten-2-ol. Catches collected every 10 days from March December. In 2019, 13 applying 6-mm on top collection container providing three 60 mm × 8 immediately above screen. These “modified traps” captures considered separately 12 remaining “standard traps.” All species recorded, as well all > mm. Results: Overall, target amounted for <10% catches. The most-collected was Orthotomicus erosus Wollaston. modification allowed species, resulting reduction average size caught specimens. Even though predators still high, proportion major (T. T. caerulea) beetles showed statistically significant predator an encouraging outcome. Conclusions: problem reducing than target. However, key is schedule trapping only seasons when adults more active adults, thus limiting and, consequently, management biodiversity.