Moths and other insects are attracted by artificial light sources. This flight-to-light behaviour disrupts their general activity focused on finding essential habitat resources, such as mating partners, and increases predation risk. It thus has substantial fitness costs. In illuminated urban areas, spindle ermine moths Yponomeuta cagnagella were reported to have evolved a reduced flight-to-light response. Yet, the specific mechanism remained unknown, and was hypothesized to involve either changes in visual perception or general flight ability or overall mobility traits. Here, we test whether spindle ermine moths from urban and rural populations—with known differences in flight-to-light response—differ in flight-related morphological traits. Urban individuals were found to have on average smaller wings than rural moths, which in turn correlated with a lower probability of being attracted to an artificial light source. Our finding supports the reduced mobility hypothesis, which states that reduced mobility in urban areas is associated with specific morphological changes in the flight apparatus.

Human activities have an overwhelming impact on the natural environment, leading to a deep biodiversity crisis whose effects range from genes to ecosystems. We here analysed the effect of such anthropogenic impacts on bdelloid rotifers (Rotifera: Bdelloidea), for whom these effects are poorly understood. We targeted bdelloid rotifers living in lichen patches across urbanisation gradients in Flanders and Brussels (Belgium). Urbanisation was measured as the percentage of built-up area across different spatial scales, at circles from 50 m to 3,200 m of radius around the lichen. Urbanisation effects on biodiversity were assessed on abundance, species richness, and community-weighted mean body size of bdelloid rotifers, as well as on genetic diversity of one of the most common and widespread bdelloid species, Adineta vaga. Overall, no negative effect of urbanisation was found at any diversity level and at any spatial scale. Counterintuitively, built-up area quantified at the largest spatial scale had a positive effect on abundance. These results leave open the question of whether negative effects of urbanisation are present for bdelloid rotifers, or if such effects are only visible at even larger spatial scales.

Dramatic insect declines, and their consequences for ecosystems globally, have received considerable attention recently. Yet, it is still poorly known if ecological and life-history traits can explain declines and whether insect decline occurs also at high latitudes. Insects’ diversity and abundance are dramatically lower at high latitudes compared to the tropics, and insects might benefit from climate warming in high-latitude environments.  We adopted a trait- and biomass-based approach to estimate temporal change between 1993 and 2019 in Finnish macro-moth communities by using data from 85 long-running light traps. We analysed spatio-temporal variation in biomass of moth functional groups with Joint Dynamic Species Distribution Models while accounting for environmental variables.  We did not detect any declining trends in total moth biomass of moth functional groups, and most groups were stable over time. Moreover, biomass increased for species using coniferous trees, lichens, or mushrooms as hosts, multivoltine species, as well as monophagous and oligophagous species feeding on trees. We found that length and temperature of the growing season, winter climatic conditions, and habitat structure all partially explained variation in moth biomass. Although boreal moth communities are rapidly changing due to species turnover, in terms of total biomass they seem to contradict the trend of dramatic insect declines observed globally. This may lessen the immediate possibility of negative bottom-up trophic cascades in boreal food webs.