Invasive species are one of the main threats to biodiversity worldwide and the processes enabling their establishment and persistence remain poorly understood. In generalist consumers, plasticity in diet and trophic niche may play a crucial role in invasion success. There is growing evidence that invasive ants, in particular, occupy lower trophic levels in their introduced range compared to the native one, but evidences remain fragmented. We conducted stable isotope analysis at five locations distributed on two continents to infer the trophic position of the invasive ant Formica paralugubris in the native and introduced part of the range. This species forms large colonies and can be a voracious predator while feeding on sugar-based resources as well. Whereas native populations had trophic positions comparable to that of an omnivore, the introduced populations varied from being honeydew specialists to top predators, or omnivore. Where other ant species co-occurred, there was no overlap in their trophic niches, and F. paralugubris occupied the lower position, suggesting that trophic displacement may enable the coexistence of different ant species. Taken together, our results suggest that shifts in diet associated with changes in the trophic niche of introduced species might mediate invasion success and enable long-term coexistence with native species.

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Switzerland is now home to three invasive alien mosquito species: Aedes albopictus (tiger mosquito), Ae. japonicus (Japanese mosquito) and Ae. koreicus (Korean mosquito). The most important is the tiger mosquito that arrived in Ticino in 2003. Active during the day, it is known to be the vector of dengue fever, chikungunya, Zika virus and filaria of the genus Dirofilaria. Since 2013 it has been discovered in north of the Alps. Its progress continues and it will soon reach French-speaking Switzerland. The Confederation has set up a monitoring and follow-up programme, an expert group of specialists is in contact with the cantonal health authorities to organise the necessary follow-up and treatment. To date, no epidemic (dengue or chikungunya) has occurred in Switzerland, unlike in our neighbours (France, Italy).

Mound-building red wood ants (Formica rufa group) fulfill keystone roles in forest ecosystems, and several species are on the red list of the International Union for Conservation of Nature. Nonetheless, detailed information on their distribution and habitat requirements is lacking, yet needed to evaluate population changes and develop conservation strategies. To assess their status in Switzerland, we studied red wood ant mounds in a nationwide, systematic survey of forests (Swiss National Forest Inventory). We identified key predictors of mound occurrence and mound size related to forest structure, forest composition, climate, and topography. Red wood ants were found to be relatively rare across Switzerland (1.4 mounds per ha of forest), especially at lower elevations (0.16 mounds per ha). Formica lugubris and F. paralugubris were common only in mountainous areas. Few F. rufa and F. polyctena mounds were found countrywide, the latter mostly at lower elevations. Formica aquilonia was restricted to the Engadine region of the Alps. Wood ants mainly depended on slope aspect, climate, forest structure, and conifer abundance, but did not depend on forest fragment size, distance to forest edges, or woody vegetation diversity. Our baseline data will enable population changes of red wood ants to be quantified, to reassess their conservation and protection status. For now, based on their observed rarity, conservation measures for red wood ants seem advisable in Switzerland. Our data suggest that red wood ants are not restricted to large, continuous, or diverse forests. Conservation strategies could thus focus on optimizing the structure of coniferous forests.

Um die Vielfalt und Verbreitung der Waldameisen in Graubünden zu erfassen, wurde im Jahre 2002 in Zusammenarbeit mit dem lokalen Forstdienst eine breite Bestandesaufnahme durchgeführt. Es wurden 546 Proben gesammelt und bestimmt; ausserdem wurden 176 Proben des Schweizerischen Landesforstinventars (LFI4) sowie 555 Beobachtungen weiterer Studien im Kanton erfasst. Es wurden alle sechs in der Schweiz vorkommenden Waldameisen arten gefunden: Formica rufa, F. polyctena, F. pratensis, F. lugubris, F. paralugubris und F. aquilonia. Eine siebte Art, F. lugubris­A2, welche im Jahre 2008 im Schweizerischen Nationalpark (SNP) entdeckt wurde, ist noch nicht offiziell beschrieben. F. rufa und F. polyctena, welche in tieferen und mittleren Höhenlagen vorkommen, machen 6,7 % resp. 3,5 % aller Funde aus. In der montanen Stufe dominiert F. lugubris mit 35,4 %, gefolgt von F. paralugubris mit 26,7 % und F. aquilonia mit 22,4 %. Das Vorkommen von F. aquilonia ist auf das Engadin und auf die Val Müstair beschränkt. Die neue Art F. lugubris­A2 mit 3,8 % der Funde ist bis heute nur aus der Val Mingèr (SNP) bekannt. F. pratensis ist mit 1,5 % die seltenste Art, da sie vorwiegend offene Lebensräume besiedelt, welche kaum erfasst wurden. Dank all dieser Funde, welche den ganzen Kanton inklusive den Schweizerischen Nationalpark abdecken, können wir die ersten detaillierten Verbreitungskarten der Waldameisen Graubündens präsentieren.

Transmitting genes from one generation to the next is the fundamental basis of natural selection and evolution. Understanding the reproductive biology of a species is, therefore, fundamental to understanding how the species evolved and how it is adapted to its environment. In eusocial insects such as the wood ants (Formica rufa group), reproduction is invested in a specialised reproductive caste, which produces both the workers and the next generation of sexual individuals. This chapter introduces the reproductive biology of wood ants, and also gives a general view of the life cycle of a wood ant colony to put the reproductive biology in context.

Wood ants ( Formica rufa group) are the ecological centre of many temperate and boreal forest ecosystems, with influence over ecosystem processes and other organisms. Owing to their dominance and keystone role, there are many reasons why it may be desirable or necessary to sample or monitor wood ants. Most field-based studies are based on exploring the relationships between red wood ants and their environment, be it the effects wood ants have on their surroundings via their nesting or foraging activities, or the effect a changing environment has on the ants. Given their keystone roles with the ecosystem, red wood ants can be useful indicators of ecosystem health, environmental degradation or restoration, or climate change (Torossian 1977b; Sorvari and Hakkarainen 2007b). With many species in Eurasia threatened and those in North America little understood, there is often simply a requirement to assess whether a species is present or not, or whether introductions or translocations have been successful. Unlike most other invertebrates, and indeed even other ant species, most red wood ants build conspicuous and long-lasting mound nests that facilitate their census. However, as for other ant species, this social living presents particular challenges for sampling and monitoring. Careful planning and the application of considered methods are needed to overcome these difficulties. This chapter provides an overview of the sampling methods and approaches that have been directly applied to wood ants, and the theory underpinning them. Where methods or approaches are ineffective or warrant further development, these are highlighted. The goal is to recommend a set of reliable and easy to use methods that can provide accurate and repeatable data, which are comparable between studies. The challenges of studying red wood ants Consideration of life cycle and seasonality Effective sampling or monitoring of wood ants presents considerable theoretical and practical problems. Wood ants are social insects which are patchily distributed and territorial. Moreover, there are seasonal patterns to the abundance and presence of certain castes. The queen (or queens) and some workers are present throughout the year, though not always visibly so. Males and particular stages of brood are present only for part of the year and this can depend on factors such as colony size and age, food availability and local environmental variables.

A noticeable increase in mean temperature has already been observed in Switzerland and summer temperatures up to 4.8K warmer are expected by 2090. This article reviews the observed impacts of climate change on biodiversity and considers some perspectives for the future at the national level.

Aim To improve our understanding of how biological communities assemble, we investigated changes in bumblebee communities in space along an elevation gradient. We assessed how much deterministic abiotic and biotic factors shape community assembly. We focused on proboscis length (influencing the species' dietary regime) and phylogenetic relatedness to investigate if competition and environmental filtering occur in more and less productive climates, respectively. Location Western Swiss Alps. Methods We recorded bumblebee species in 149 plots along a 1800-m wide elevation gradient. We contrasted two major clades of bumblebees, a short-tongued and a long-tongued clade. We calculated the phylogenetic and proboscis-length diversity of the bumblebee communities and compared these observed data with a random distribution to detect clustering likely to be caused by environmental filtering or overdispersion likely to be caused by competition. We compared the prevalence of clustered and overdispersed communities along the gradients of plant species richness (biotic) and temperature (abiotic). Results Under colder conditions, where plant species richness is lower and floral resources are scarcer, the clade with shorter proboscides prevails over the clade with longer proboscides, and communities are functionally and phylogenetic clustered. Under warmer conditions, we found phylogenetic but not functional overdispersion in communities. Main conclusions We show for the first time a strong correlation between phylogenetic relatedness, proboscis length and species distribution along temperature and plant richness gradients shaping bumblebee communities. The low temperatures and low levels of plant species richness limit the dispersal of the species from the long-tongued clade, which have more specialized diets, into high-elevation areas. Competition under warmer conditions may produce communities composed of less closely related species that share distinct ecological preferences. Our empirical results corroborate theoretical expectation as well as experiments on the prevalence of deterministic processes in the most severe and most productive parts of environmental gradients.

Severe environmental conditions filter community species compositions, forming clines of functional diversity along environmental gradients. Here, the changes in functional diversity in ant assemblages with severe environmental conditions in the Swiss Alps were investigated. Eight sites were sampled along an elevation gradient (1800–2550 m). The variation in functional diversity was analysed along an elevation gradient considering four traits: social structure (monogynous vs. polygynous), worker size, pupal development, and nest structure. Ant species richness and functional diversity decreased with decreasing temperature. Species found in colder habitats tended to live in subterranean nests rather than in mounds and exhibit a polymorphism in queen number, either within or across populations. The phylogenetic diversity did not decrease at colder temperature: Formicinae and Myrmicinae occupied the full range of elevations investigated. An insulation experiment indicated that mounds are more thermally insulated against the cold compared with soil. The absence of a mound‐building ant from high elevations probably results from a reduction in the amount of vegetal materials provided by coniferous trees. More severe abiotic conditions at higher elevations act as a filter on ant assemblages, directly through physiological tolerances to the abiotic conditions and indirectly as the vegetation necessary for nest building shifts with elevation.

From 1993 to 2008, criminal investigations were conducted in the western part of Switzerland with special attention to blowfly and flesh fly species in order to estimate the post-mortem interval when requested by the police authorities. Flesh flies were found in only 33 cases out of 160. Five species of the genus Sarcophaga were identified (S. africa, S. argyrostoma, S. caerulescens, S. similis and S. sp.). The main species found on corpses (larval stage) was S. argyrostoma. The thermal constant (K) calculated for this species in Switzerland is 380.6 ± 16.3 (mean ± S.D.) degree-days. With the exception of S. caerulescens, found three times in the larval stage on corpses, the three other species are of minor forensic importance. S. argyrostoma is found during summer and indoors. This species colonises dead bodies, usually the same day as blowfly species, and it could be used to estimate the post-mortem interval. Other species are discussed in the light of current knowledge on their biology and ecology. It is recommended that voucher material be deposited in a museum, allowing further studies by relevant specialists, thereby helping investigators and avoiding misidentifications.

Wood ants in Switzerland: situation and outlook of a monitoring The authors summarise their state of knowledge about wood ants and their role in the forest ecosystem. They also describe the situation in Switzerland, their past development and their conservation status. In several regions, mainly in the Plateau, wood ants seem to diminish, despite their total protection since 1966. The reasons for this regression are not well known, but the fragmentation of forest habitats in the Plateau region and direct damage to ant nests seem to play a certain role. A new project in which the development of wood ant nests is monitored in Swiss forest reserves (Formica-Forêts-CH) was recently started in the Swiss national park. It is to be extended, in collaboration with the forest services, over the whole of Switzerland.

Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability.

The mite Varroa destructor is a global challenge for apiculture and accurate quantification crucial for adequate and timely pest management. However, foraging ants are regularly found in hives and may interfere with mite diagnosis. Here, we quantify for the first time the impact of ants. We expect lower mite numbers on bottom boards with foraging ants and that estimates of phoretic mites are ant independent. From July to August 2007–2009, the experiments were conducted with 64 queenright honey bee colonies (predominantly Apis mellifera carnica, Table I). One apiary was used for 3 years, but each time, new colonies were monitored. All colonies (~11 frames of bees, 6–10 brood frames) were housed in Dadant hives (12 frames) with bottom board inserts for mite quantification (Imdorf et al. 2003) and placed in groups of four or five each on hive stands with four steel polders (50 cm aboveground). All colonies were treated in summer and fall using formic and oxalic acid (Imdorf et al. 2003). To quantify the impact of ants, we added traps (water-filled buckets [∅=20 cm]) to each of the four steel polders of the hive stands. At least once a month, water was refilled, and the surrounding vegetation was cut. The controls remained without traps. Quantifications were conducted weekly by removing the bottom board inserts and counting all mites and ants. In 2009, we also collected weekly 200 bee workers from the brood nests of 18 colonies for 8 weeks to evaluate the number of phoretic mites following Ritter and Ruttner (1980). For that purpose, nine colonies received traps (= treatments), and nine remained without (= controls) for 4 weeks; then, the groups were exchanged by relocating traps. Thus, we obtained from the same colonies mite infestation loads from both bottom board counts and phoretic mite estimates with or without ant traps. We also monitored all stands to investigate whether they were exposed to ant foraging. Ants were collected for taxonomic identification using morphometrics (Seifert 2007). We performed Kruskal–Wallis and Mann–Whitney U post hoc tests to compare ant and mite numbers. To test whether there is a regression between ant and mite numbers, we constructed a Linear Mixed Model (LMM), with log-transformed V. destructor numbers as the dependent variable, log-transformed ant numbers as fixed effect and colony as random effect, resulting in normally distributed residuals:

Because of their beneficial impact on forest ecosystems, European red wood ants (Formica rufa group) are protected by law in many European countries and are considered to be among the most reliable bioindicators of forest stability. However, their taxonomy has been much debated and, unfortunately, it is too often neglected. This happens mainly because the morphology-based method for species delimitation requires lots of time and experience. We therefore employed 9 microsatellite loci and mitochondrial DNA (COI gene) to verify the power of genetic markers for red wood ant species delimitation and to investigate the cryptic diversity of these ants within the Eastern Swiss Alps. We analyzed 83 nests belonging to all red wood ant species that occur in the Swiss National Park area. Genetic data indicated that these species represent different genetic pools. Moreover, results showed that Formica aquilonia YARROW, 1955 and F. paralugubris SEIFERT, 1996 often hybridize within the Park, confirming that these two species are genetically very close and could have diverged only recently. Nevertheless, microsatellites also revealed that one entire population, located in the Minger Valley and morphologically identified as F. lugubris ZETTERSTEDT, 1838, is genetically different to all other analyzed F. lugubris populations found within the same area and to other red wood ant species. These findings, confirmed by mitochondrial DNA analyses, suggest the existence of a new cryptic species within the Eastern Swiss Alps. This putative cryptic species has been provisionally named F. lugubris-A2. These results have a great importance for future conservation plans, monitoring and evolutionary studies on these protected ants.