Epsilon Archive for Student Projects

Abstract

Road infrastructure is an integral part of human-dominated landscapes worldwide and is partially responsible for the global decline in insects through vehicle collisions and acts as a barrier for dispersal. Road verges, however, are gaining attention as potential insect conservation sites due to their potential similarity to semi-natural grasslands. However, most research exploring this conservation dilemma has focused on diurnal insects, particularly butterflies. Since 60 % of all invertebrates and 96 % of Lepidoptera are nocturnal, insects like moths, and their mortality in road traffic are a topic worthy of exploring. Thus, this study explores the effects of traffic intensity and road verge characteristics on moth abundance and mortality along 20 roads in Sweden. Mowing management emerged as the strongest driver of moth abundance, with unmown verges supporting on average 2.56 times more moths than mown verges. Moth abundance also increased significantly across the summer season from June to August. Unlike butterflies, moth abundance was not significantly influenced by flowering plant species diversity, potentially reflecting differing ecological traits between diurnal and nocturnal Lepidoptera. While higher road verge abundance was associated with increased mortality, traffic intensity was negatively associated with moth road mortality. This may be explained by a depletion mechanism whereby highly trafficked roads support fewer moths in adjacent verges. These findings raise the question of whether well-managed road verges could act as ecological traps for moths by attracting individuals into a zone of high collision risk. Even though research on butterflies and bumblebees suggests that high-quality road verges reduce the mortality risk of insects, further research dedicated to moths is necessary. Therefore, I suggest focusing conservation measures such as suspended mowing on road verges adjacent to low-traffic roads.