Anthropogenic Influence on Moth Populations: A Comparative Study in Southern Sweden

As moths are vital components of ecosystems and serve as important bioindicators, understanding the dynamics of their communities and the factors influencing these dynamics, such as anthropogenic impacts, is crucial to understand the ecological processes. Our study focuses on two provinces in southern Sweden, Västergötland and Småland, where we used province records from 1974 to 2019 in combination with light traps (in 2020) to record the presence and abundance of moth species, subsequently assessing species traits to determine potential associations with their presence in anthropogenically modified landscapes. This study design provides a unique opportunity to assess temporal changes in moth communities and their responses to shifts in environmental conditions, including anthropogenic impacts. Across the Västergötland and Småland provinces in Sweden, we recorded 776 moth taxa belonging to fourteen different taxonomic families of mainly Macroheterocera. We captured 44% and 28% of the total moth species known from these provinces in our traps in Borås (Västergötland) and Kalmar (Småland), respectively. In 2020, the species richness and abundance were higher in Borås than in Kalmar, while the Shannon and Simpson diversity indices revealed a higher species diversity in Kalmar. Between 1974 and 2019, the colonisation rates of the provinces increased faster in Småland. Ninety-three species were found to have colonised these provinces since 1974, showing that species richness increased over the study period. We reveal significant associations between the probability of a species being present in the traps and distinct traits compared to a provincial species pool. Traits over-represented in the traps included species with a high variation in colour patterns, generalist habitat preferences, extended flight periods, lower host plant specificity, and overwintering primarily as eggs. Our findings underscore the ongoing ecological filtering that favours certain species-specific traits. This study sheds light on the roles of climate change and anthropogenic impacts in shaping moth biodiversity, offers key insights into the ecological processes involved, and can guide future conservation efforts.

Differences in phenology, daily timing of activity, and associations of temperature utilization with survival in three threatened butterflies

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperature. The Marsh Fritillary, the Apollo, and the Large Blue differed in utilized temperatures and phenology. Their daily activity patterns responded differently to temperature, in part depending on whether they were active in the beginning, middle or end of the season, in part reflecting interindividual variation and intraindividual flexibility, and in part owing to differences in ecology, morphology, and colouration. Activity temperatures varied over the season, and the Apollo and the Large Blue were primarily active at the highest available ambient temperatures (on the warmest days and during the warmest part of the day). The Marsh Fritillary was active early in the season and decreased activity during the highest temperatures. The relationship between individual lifespan and the average temperature was qualitatively different in the three species pointing to species-specific selection. Lifespan increased with an increasing range of utilized temperatures in all species, possibly reflecting that intra-individual flexibility comes with a general survival benefit.

A window to the world of global insect declines: Moth biodiversity trends are complex and heterogeneous

Moths are the most taxonomically and ecologically diverse insect taxon for which there exist considerable time-series abundance data. There is an alarming record of decreases in moth abundance and diversity from across Europe, with rates varying markedly among and within regions. Recent reports from Costa Rica reveal steep cross-lineage declines of caterpillars, while other sites (Ecuador and Arizona, reported here) show no or only modest long-term decreases over the past two decades. Rates of decline for dietary and ecological specialists are steeper than those for ecologically generalized taxa. Additional traits commonly associated with elevated risks include large wingspans, small geographic ranges, low dispersal ability, and univoltinism; taxa associated with grasslands, aridlands, and nutrient-poor habitats also appear to be at higher risk. In temperate areas, many moth taxa limited historically by abiotic factors are increasing in abundance and range. We regard the most important continental-scale stressors to include reductions in habitat quality and quantity resulting from land-use change and climate change and, to a lesser extent, atmospheric nitrification and introduced species. Site-specific stressors include pesticide use and light pollution. Our assessment of global macrolepidopteran population trends includes numerous cases of both region-wide and local losses and studies that report no declines. Spatial variation of reported losses suggests that multiple stressors are in play. With the exception of recent reports from Costa Rica, the most severe examples of moth declines are from Northern Hemisphere regions of high human-population density and intensive agriculture.

Genetic Color Polymorphism of the Whitelined Sphinx Moth larva (Lepidoptera: Sphingidae)

For a trait to be considered polymorphic, it must fulfill both genetic and ecological criteria. Genetically, a polymorphic trait must have multiple heritable variants, potentially from the same female, in high-enough frequency as to not be due to mutation. Ecologically, in a single wild population, these variants must co-occur, and be capable of interbreeding. Polymorphism is frequently considered in the context of either geographical cause or genetic consequence. However, the incorporation of both in a single study can facilitate our understanding of the role that polymorphism may play in speciation. Here, we ask if the two color morphs (green and yellow) exhibited by larvae of the whitelined sphinx moth, Hyles lineata (Fabricius), co-occur in wild populations, in what frequencies, and whether they are genetically determined. Upon confirmation from field surveys that the two color morphs do co-occur in wild populations, we determined heritability. We conducted a series of outcrosses, intercrosses and backcrosses using individuals that had exhibited yellow or green as laboratory-reared larvae. Ratios of yellow:green color distribution from each familial cross were then compared with ratios one would expect from a single gene, yellow-recessive model using a two-sided binomial exact test. The offspring from several crosses indicate that the yellow and green coloration is a genetic polymorphism, primarily controlled by one gene in a single-locus, two-allele Mendelian-inheritance pattern. Results further suggest that while one gene primarily controls color, there may be several modifier genes interacting with it.

Urban moth communities suggest that life in the city favours thermophilic multi-dimensional generalists

Biodiversity is challenged worldwide by exploitation, global warming, changes in land use and increasing urbanization. It is hypothesized that communities in urban areas should consist primarily of generalist species with broad niches that are able to cope with novel, variable, fragmented, warmer and unpredictable environments shaped by human pressures. We surveyed moth communities in three cities in northern Europe and compared them with neighbouring moth assemblages constituting species pools of potential colonizers. We found that urban moth communities consisted of multi-dimensional generalist species that had larger distribution ranges, more variable colour patterns, longer reproductive seasons, broader diets, were more likely to overwinter as an egg, more thermophilic, and occupied more habitat types compared with moth communities in surrounding areas. When body size was analysed separately, results indicated that city occupancy was associated with larger size, but this effect disappeared when body size was analysed together with the other traits. Our findings indicate that urbanization imposes a spatial filtering process in favour of thermophilic species characterized by high intraspecific diversity and multi-dimensional generalist lifestyles over specialized species with narrow niches.

Faster poleward range shifts in moths with more variable colour patterns

Range shifts have been documented in many organisms, and climate change has been implicated as a contributing driver of latitudinal and altitudinal range modifications. However, little is known about what species trait(s) allow for faster environmental tracking and improved capacity for distribution expansions. We used data for 416 species of moths, and show that range limits in Sweden have shifted to the north by on average 52.4 km per decade between 1973 and 2014. When also including non-expanding species, average expansion rate was 23.2 km per decade. The rate of boundary shifts increased with increasing levels of inter-individual variation in colour patterns and decreased with increasing latitude. The association with colour patterns indicate that variation in this functionally important trait enables species to cope with novel and changing conditions. Northern range limits also increased with average abundance and decreased with increasing year-to-year abundance fluctuations, implicating production of dispersers as a driver of range dynamics. Studies of terrestrial animals show that rates of poleward shifts differ between taxonomic groups, increase over time, and depend on study duration and latitude. Knowledge of how distribution shifts change with time, location, and species characteristics may improve projections of responses to climate change and aid the protection of biodiversity.