A conceptual model to identify mechanisms that influence trap performance

Flight intercept traps are commonly used to survey and monitor forest insects. They function by presenting a physical barrier into which an insect flies and then falls into a collection vessel. These traps are primarily used to monitor bark and woodboring beetles. Despite their widespread use, little is known about the mechanisms by which their performance varies. This lack of understanding is problematic as it can result in a delay in the availability of effective survey tools. This delay can result in increased population levels, leading to increased difficulty and costs associated with pest management and a decreased likelihood of successful control. It also means that although the “best” available trap is used, it is unlikely to be an optimal design. The trapping literature is extensive and many factors contributing to semiochemical-baited intercept trap performance have been investigated. Unfortunately, we lack a mechanistic understanding of why the performance of different trap designs varies among taxa and habitats despite clear identification of several factors known to influence trap performance. This important knowledge gap means that the development and optimization of trapping protocol remains a trial-and-error reactionary process. In this talk I will present a conceptual model of trap performance and use longhorned beetles as a model system to illustrate the power of this approach to identify mechanisms that influence trap performance. Specifically, using this conceptual model we illustrate that: i) less than 50% of all beetles that approach to within 5 m of baited panel and multiple-funnel traps are captured; ii) the difference in the performance of the two trap designs seems to be due to differences in approach success in the near-field (< 1 m); and iii) both visual stimuli and impacts of trap design on plume structure could contribute to these near-field differences.