Research Paper

Beyond pests: intermittent rivers as habitats for Thysanoptera and Scolytinae

¹ Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10 000 Zagreb, Croatia
² Croatian Agency for Agriculture and Food, Centre for Plant Protection, Department for diagnostics and analytics, Gorice 68b, 10 000 Zagreb, Croatia
³ Faculty of Teacher Education, University of Zagreb, Trg Matice hrvatske 12, 44 250 Petrinja, Croatia
⁴ Faculty of Forestry and Wood Technology, University of Zagreb, Svetošimunska cesta 23, 10 000 Zagreb, Croatia
⁵ Zuzana Redžović and Lea Ružanović are co-first authors with equal contribution and importance

^* Corresponding author: andreja.brigic@biol.pmf.hr

Received: 30 July 2025
Accepted: 26 September 2025

Abstract

Intermittent rivers are dynamic ecosystems increasingly affected by climate change which extends their dry phase and alters connectivity. Drying events create temporal dispersal corridors for terrestrial animals including pest taxa with potential agricultural and forestry impacts. We aimed to investigate dispersal of thrips (Thysanoptera) and bark (and ambrosia) beetles (Scolytinae) in the Mediterranean karst intermittent river Krčić, Croatia, during its dry phase by assessing spatiotemporal distribution across habitats, reaches and times of day as well as the wind effect on their activity density. Insects were sampled using cross-vane window traps in riparian and dry riverbed habitats at upper and lower reaches. Traps were emptied every 12 h over seven days in July 2021, with wind continuously monitored. Thysanoptera activity density was significantly higher in the upper reaches and during the day; light wind enhancing their dispersal, but they showed no clear habitat preference. Scolytinae preferred riparian habitat relative to the dry riverbed, likely due to differences in environmental conditions, such as temperature, light intensity and humidity. While these taxa are commonly studied in relation to their host plants, this study highlights their ecology, contributing to a better understanding of how prolonged dry periods in intermittent rivers affect biological communities.