Monitoring arthropods under the scope of LIFE-BEETLES project – Baseline Data

Abstract

The presented database is part of the LIFE BEETLES project which aims to conserve three species of endemic beetles that are not protected by the Habitats Directive: Tarphius floresensis Borges & Serrano, 2017, Pseudanchomenus aptinoides (Tarnier, 1860), and Trechus terrabravensis Borges, Serrano & Amorim, 2004. These species are single island endemics respectively from Flores, Pico, and Terceira. They are threatened by environmental degradation, facing the dual challenge of restricted distribution and habitat degradation. The study established a comprehensive database derived from a long-term arthropod monitoring survey that used SLAM (Sea, Land, Air, Malaise) traps and pitfall traps. Our findings present a proxy for assessing the overall habitat quality for endemic invertebrates, using arthropods as principal indicators. From September 2020 to June 2023, a total of 31 SLAM traps were monitored. The traps were set up as follows: seven in Flores (three in mixed forest and four in native forest), 10 in Pico Island (four in mixed forest and six in native forest), and 14 in Terceira (three in mixed forest and 11 in native forest). Traps installed in a mixed forest dominated by exotic species were monitored every six months, while traps installed within native forest fragments were monitored every three months. In addition, we employed 19 transects consisting of 15 non-attractive pitfall traps. The transects were set up during two weeks at the end of August every year between 2020 and 2023. Eight transects were established in Flores, consisting of one in pasture, four in mixed forest, and three in native forest. Six transects were established on Pico, consisting of two in pastures and four in native forest. Five transects were established in Terceira, consisting of two in mixed forest and three in native forest. A total of 243 arthropod taxa were recorded, with 207 identified at the species or subspecies level. These taxa belonged to four classes, 24 orders, and 101 families. Out of the 207 identified taxa, 46 were endemic, 60 were native non-endemic, 80 were introduced, and 21 were indeterminate. Habitat information is also provided, including general habitat and dominant species composition. This publication contributes to the conservation of highly threatened endemic beetles by assessing habitat quality based on arthropod communities and habitat description (e.g. native or exotic vegetation). Additionally, it provides an updated inventory of arthropods from Pico, Terceira, and Flores islands.