Modelling the distribution of the invasive Roesel’s bushcricket (Metrioptera roeselii) in a fragmented landscape

The development of conservation strategies to mitigate the impact of invasive species requires knowledge of the species ecology and distribution. This is, however, often lacking as collecting biological data may be both time-consuming and resource intensive. Species distribution models can offer a solution to this dilemma by analysing the species-environment relationship with help of Geographic information systems (GIS). In this study, we model the distribution of the non-native bush-cricket Metrioptera roeselii in the agricultural landscape in mid-Sweden where the species has been rapidly expanding in its range since the 1990s. We extract ecologically relevant landscape variables from Swedish CORINE land-cover maps and use species presence-absence data from large-scale surveys to construct a species distribution model (SDM). The aim of the study is to increase the knowledge of the species range expansion pattern by examining how its distribution is affected by landscape composition and structure, and to evaluate SDM performance at two different spatial scales. We found that models including data on a scale of 1 × 1 km were able to explain more of the variation in species distribution than those on the local scale (10 m buffer on each side of surveyed road). The amount of grassland in the landscape, estimated from the area of arable land, pasture and rural settlements, was a good predictor of the presence of the species on both scales. The measurements of landscape structure – linear elements and fragmentation - gave ambivalent results which differed from previous small scaled studies on species dispersal behaviour and occupancy patterns. The models had good predictive ability and showed that areas dominated by agricultural fields and their associated grassland edges have a high probability being colonised by the species. Our study identified important landscape variables that explain the distribution of M. roeselii in Mid-Sweden that may also be important to other range expanding orthopteran species. This work will serve as a foundation for future analyses of species spread and ecological processes during range expansion

Small field islands systems include a large proportion of the regional orthopteran species pool in arable landscapes

The tendency of species richness to increase with patch area is one of the most robust empirical generalisations in ecology and its logic drives conservation actions. Indeed, preference is often given to conserving large, highly connected areas over small isolated patches. However, small habitats have been shown to be important biodiversity refuges in managed landscapes. Field islands are small remnants of natural habitat patches surrounded by cropland. While their island-like position in a species-poor crop field makes them potentially strategic habitats for biodiversity conservation, they have not received much attention in ecological studies. We investigated how local (i.e. field island area and habitat diversity) and landscape factors (i.e. proportion of arable land) affected orthopteran species richness, community mean dispersal and habitat specificity in 71 field islands in central Sweden. We found that despite low numbers of species per field island, due to their intrinsic small size, taken together, a system of small field island increased species richness and included a large proportion of the regional species pool in the arable landscape in central Sweden. Furthermore, we found that patch area and habitat diversity determined orthopteran community composition in field islands. More diverse and, to a lesser extent, larger field islands benefit sedentary and habitat specialist species. This study shows that more care should be taken to incorporate and potentially also prioritize small and permanent habitat patches in the management of agricultural landscapes. The protection of field islands with diverse habitats may be important for the maintenance of sedentary and specialist species

WWW design code – a new tool for colour estimation in animal studies

BACKGROUND: The colour of animals' skin, fur, feathers or cuticula has been estimated in a large number of studies. The methods used to do so are diverse, with some being costly and not available to all researchers. In a study to measure plumage colour in a bird species, a new method of creating a colour chart was developed. While colour-charts have their own limitations, these can be minimised when they have the following properties: 1) being readily available to the majority of biologists, 2) containing a large array of colours to allow accurate recording and differentiation of subtle colour differences, 3) low cost, 4) adhering to a world-wide standard, and 5) being available in both hard-copy and digital formats to allow for various analytical methods. The method described below satisfies all of these requirements. RESULTS: Colour charts estimated to fit the range of the species' plumage colours were created on the computer screen using web software that allowed for HTML-coding (in this case Dreamweaver™). The charts were adjusted using feathers from dead specimens until a satisfying range of darker and lighter colours were found. The resulting chart was printed out and was successfully used in the field to determine the plumage colour of hand-held birds. CONCLUSION: Access to a computer and printer, and the software to enable the creation of a chart, is within the reach of the vast majority of biologists. The numbers of colours that can be generated should suit most studies, with the advantage of the method being that the chart can be individually tailored to the species under study. HTML colour coding is a worldwide standard, thus the colours used in studies can be described in the methods section of journal articles using the six-digit alphanumeric code. We believe this method is very useful as a low-tech method for future estimation of individual colour

Insects as past and future food in entomophobic Europe

Insects as food show a large variation in traditional use over the world. This high variation between countries in combination with current ideas of insects as part of a solution to feed a growing global population raises interesting questions. The aim of this paper is to investigate what has been perceived as food historically and how this changes over time with focus on insects. Insects and their products have been used for food and medicine within and outside Europe for as long as we have records. They have not been a staple food but a rare addition to the diet. The frequency of use in Europe, even in times of food crisis, points to reluctance towards this food source. Based on behavioral history and perception of insects as food we suggest the terms entomophobic (insect despising) and entomophilic (insect loving) to describe the eating behavior of societies. If societies are to change their food consumption patterns, new food habits and traditions needs to be created. Altering a predominantly entomophobic society to an entomophilic, changes are needed to take place and many are linked to consumption tradition. Change is likely; history teaches us that aversion to ingredients is possible to overcome

Growth, survival and development of house crickets (Acheta domesticus) fed flowering plants

House crickets (Acheta domesticus) are increasingly being used as food. This has the potential for a more efficient food production that also may benefit agroecosystems. As the first study to compare feeds based on European wild flowering plants as feed for house crickets we examined five common plants known to support biodiversity of wild insects (white clover (Trifolium repens), white nettle (Lamium album), common nettle (Urtica dioica), rough comfrey (Symphytum asperum) and common gypsophila (Gypsophila paniculata). These plants and a control diet were fed as dried and sole feeds ad libitum to one-day-old house crickets for 62 days in a climate-controlled laboratory. Cricket weight, mortality and feed intake were recorded every 7 days. An additional test examined crickets preferences for forages and the effect on maturation and weight, by providing a free choice of rapeseed and wheat meal and either an early- or late-cut red clover (Trifolium pratense) or white nettle for 62 days. Mortality of crickets fed common nettle, rough comfrey and common gypsophila exceeded 80% in first 7 days, so these plants were removed from the trial after 14 days. Survival of crickets on white nettle and control feed was 59% after 28 days and average cricket weight was similar. By day 62, the weight of crickets fed white nettle and white clover was on average 32 mg, compared with 201 mg on control feed. In the free choice test, crickets consumed 15-30% red clover, 31-37% wheat meal and 39-64% rapeseed. Crickets with access to red clover showed a higher (P<0.001) proportion of adults (28%) compared with the control (5%). We conclude that white nettle has potential as feed for house crickets during the early growth stages, and that red clover supplementation increase cricket maturation. Using feeds including white nettle and red clover in cricket rearing additionally benefits to support wild biodiversity and lower feed costs

A clue to invasion success: genetic diversity quickly rebounds after introduction bottlenecks

One of the fundamental questions in invasion biology is to understand the genetic mechanisms behind success or failure during the establishment of a species. However, major limitations to understanding are usually a lack of spatiotemporal population data and information on the populations' colonisation history. In a large-scale, detailed study on the bush-cricket Metrioptera roeselii 70 groups of founders were introduced in areas outside the species' distribution range. We examined how (1) the number of founders (2-32 individuals), (2) the time since establishment (7 or 15 years after introduction) and (3) possible gene flow affected establishment success and temporal genetic changes of the introduced populations. We found higher establishment success in introductions with larger propagule sizes but genetic diversity indices were only partly correlated to propagule size. As expected, introduced populations were more similar to their founder population the larger the propagule size was. However, even if apparent at first, most of the differentiation in the small propagule introductions disappeared over time. Surprisingly, genetic variability was regained to a level comparable to the large and outbreeding founder population only 15 generations after severe demographic bottlenecks. We suggest that the establishment of these populations could be a result of several mechanisms acting in synergy. Here, rapid increase in genetic diversity of few introductions could potentially be attributed to limited gene flow from adjacent populations, behavioural adaptations and/or even increased mutation rate. We present unique insights into genetic processes that point towards traits that are important for understanding species' invasiveness

Road verges are corridors and roads barriers for the movement of flower-visiting insects

Roads and road verges can potentially have opposite impacts on organisms that move through the landscape. While road verges can be habitat for a large number of species, and have been proposed to act as dispersal corridors, roads can act as barriers to movement. This duality of roads and road verges has however rarely been assessed simultaneously, and it is unknown to what degree it depends on the amount of traffic on the road and on the habitat quality of the road verge. We used fluorescent powdered dye to track movements of flower-visiting insects along roads with varying traffic intensity, and in verges with contrasting habitat quality (flowering plant species richness and flower density). Insect movements along road verges were more frequent than movements into the adjacent habitats, indicating that verges act as corridors. The frequency of movements that required crossing the road was lower compared to the frequency of movements that did not, suggesting that roads are barriers. The movement patterns were independent of traffic intensity, but the barrier effect was stronger when the road verge had a higher density of flower resources. The effect of roads as a barrier and of the road verges as corridors were independent of each other. Our results suggest that flower-visiting insects tend to remain longer in road verges with high density of flowers and we therefore suggest that managing road verge habitats for an increased plant diversity will mitigate the known negative impacts of roads on insect populations

Translocation of a sand-associated blister beetle (Apalus bimaculatus) due to urban development in Uppsala, Sweden

The blister beetle (Apalus bimaculatus, Coleoptera: Meloidae) is a beetle managed for conservation in Sweden. The species inhabits at-risk ephemeral and patchily distributed sandy habitats and are dependent on stable colonies of the bee species (Colletes cunicularius) on which it parasitizes. The beetle is not considered threatened at a global or European level. It has previously been categorized as Vulnerable (VU, 2000) and near threatened (NT, 2005 & 2010) in the Swedish National List, but are now considered as Least Concern (LC, 2015). The change in categorization is due to that more populations have been found, which is believed to be an effect of overlooked populations in the past. The species is still considered as declining in the country, due to a general decrease in area of suitable habitat e.g. from sandpits becoming overgrown after excavation has ceased, and when sand dunes and other sandy areas are used for human development. The beetle population in this project has until now inhabited a sandy area between pine-dominated forest and areas used for human activities. The site is in Uppsala, Sweden, and it is located in a part of the city previously little used for human development but where major building work is planned and ongoing

Bumblebee queen mortality along roads increase with traffic

Managing road verges to promote diverse and flower-rich plant communities has been proposed to mitigate the decline of pollinating insects caused by the loss of natural and semi-natural habitat. There is, however, a concern that flower-rich road verges can be ecological traps for pollinators as insects might be attracted to a habitat where there is a risk that they are killed by traffic. Therefore, we investigated the combined effects of traffic intensity and flowering plant diversity in road verges on the mortality and behaviour of bumblebee queens. The probability that an observed bumblebee queen was dead almost quadrupled when traffic increased from 100 to 6000 vehicles per day and tended to be lower when the flowering plant diversity in the road verge was high. Further, the number of nest-seeking bumblebee queens decreased dramatically with increasing traffic intensity in sites with low diversity of flowering plants, but not in sites with high diversity. Based on published data on bumblebee colony densities in different habitat types, we estimate that between 0.2 % and 32 % of all bumblebee queens present in our study landscapes were killed by traffic. We conclude that the flowering plant diversity in the road verge neither mitigates nor exacerbates the mortality from traffic. Road verges often provide pollinators with a high abundance of resources in florally poor landscapes. We therefore advise management to prioritise plant diversity along roads with low traffic intensity

“Screwed from the start”: How women perceive opportunities and barriers for building a successful research career

After finishing the PhD, the researcher enters a stage in their early research career where more independence is expected. Within a relatively short time period, the researcher needs to gather research experience and support in the form of tangible resources as funding, and intangible resources like access to research networks, close collaborations, and mentorship to support their next career stage. How resources are allocated are therefore important determinants for the success of researchers. However, research shows that the resource allocation decisions in academia are biased in favor of men, with many of these gender biases that influence the success of research careers increasing. In this study, we asked women employed as early-career researchers (WECRs) about how they view their opportunities and potential for long-term success within academia, and how this relates to the resources that they have access to. We found that the WECRs were given few resources and support, and that they perceived that finding resources important for their career was up to themselves. The noticeable male dominance in who receives resources and positions within the university and the lack of women as role-models signals to WECRs that they are not wanted in academia. The WECRs suggest several ways to improve the possibilities for a successful research career for women on more equal terms as their male collegues: these include transparent processes for resource allocations, equal opportunity officers in all hiring processes, and mandatory gender training for all senior research and administrative staff. All the actions suggested are within the control of the university