New insights toward the design of an effective trapping method for <i>Coraebus undatus</i> F. (Coleoptera: Buprestidae)

Abstract Coraebus undatus has emerged as a significant threat to the health and productivity of Quercus suber in the Mediterranean region, as its attacks result in a depreciation of commercialized cork planks, leading to severe economic losses. The development of an effective monitoring methodology is essential for the optimal implementation of management strategies as the level of C. undatus infestation can only be assessed after cork debarking. Hence, we conducted a series of studies to assess the efficacy of trap type, color, and size, as well as lure type, for trapping C. undatus. Field trials were conducted in 2020 and 2023 in various infested cork oak stands in Sardinia (Italy). The results demonstrated that the four trapping systems tested (i.e. cross-vane interception traps, prism traps, panel traps, and plastic films) were effective in intercepting C. undatus females. The number of females found in purple cross-vane traps in 2020 was consistently higher than that of other colored traps (i.e. black, green) regardless of the lure tested (cork oak green leaf volatiles or a mixture of three longhorn beetle pheromones). However, data from 2023 field trials showed that the attractiveness of unbaited purple prism traps was higher than that of traps releasing host volatiles. Our observations also revealed that the trapping surface had a significant effect on the number of insects intercepted when testing panel traps. Among the trapping methods we tested, unbaited sticky purple films attached to the cork oak trunk yielded the highest number of catches. Overall, this work contributes to the body of knowledge on the features influencing the efficiency of trapping C. undatus. Our results serve as a baseline for the development of an effective monitoring tool, which may be further improved for use in a mass trapping program.