Automated flight interception traps for interval sampling of insects

Abstract

Recent debates on insect decline require sound assessments on the relative drivers that may negatively impact insect populations. Often, baseline data rely on insect monitorings that integrates catches over long time periods. If, however, effects of time-critical environmental factors (e.g., light pollution) are of interest, higher temporal resolution of insect observations during specific time intervals are required (e.g., between dusk and dawn). Conventional time-critical insect trapping is labour-intensive (manual activation/deactivation) and temporally inaccurate as not all traps can be serviced synchronically at different sites. Also, temporal shifts of environmental conditions (e.g., sunset/sunrise) are not accounted for. We provide a battery-driven automated insect flight-interception trap which samples insects during seven user-defined time intervals. A commercially available flight-interception trap is fitted to a rotating platform containing seven flasks and a passage hole. The passage hole avoids unwanted sampling during time-intervals not of interest. Comparisons between two manual and two automated traps during 71 nights in 2018 showed no difference in caught insects. An experiment using 20 automated traps during 104 nights in 2019 proved that the automated flight interception traps is reliable. The automated trap opens new research possibilities as any insect-sampling interval can be defined. It is efficient and saves manpower and associated costs as activation/deactivation is required only every seven sampling intervals. Also, the traps are accurate because all traps sample exactly the same intervals. The trap is low maintenance and robust due to straightforward technical design. It can be controlled manually or via Bluetooth and smartphone.