Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory of a four-hectare tropical cloud forest in Costa Rica for one year, which yielded 4332 species of Diptera, providing the first verifiable basis for diversity of a major group of insects at a single site in the tropics. In total 73 families were present, all of which were studied to the species level, providing potentially complete coverage of all families of the order likely to be present at the site. Even so, extrapolations based on our data indicate that with further sampling, the actual total for the site could be closer to 8000 species. Efforts to completely sample a site, although resource-intensive and time-consuming, are needed to better ground estimations of world biodiversity based on limited sampling.

Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all extant multicellular European terrestrial and freshwater animals and their geographical distribution at the level of countries and major islands (east of the Urals and excluding the Caucasus region). The Fauna Europaea project comprises about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. Fauna Europaea represents a huge effort by more than 400 contributing taxonomic specialists throughout Europe and is a unique (standard) reference suitable for many user communities in science, government, industry, nature conservation and education. The Diptera–Brachycera is one of the 58 Fauna Europaea major taxonomic groups, and data have been compiled by a network of 55 specialists. Within the two-winged insects (Diptera), the Brachycera constitute a monophyletic group, which is generally given rank of suborder. The Brachycera may be classified into the probably paraphyletic 'lower brachyceran grade' and the monophyletic Eremoneura. The latter contains the Empidoidea, the Apystomyioidea with a single Nearctic species, and the Cyclorrhapha, which in turn is divided into the paraphyletic 'aschizan grade' and the monophyletic Schizophora. The latter is traditionally divided into the paraphyletic 'acalyptrate grade' and the monophyletic Calyptratae. Our knowledge of the European fauna of Diptera–Brachycera varies tremendously among families, from the reasonably well known hoverflies (Syrphidae) to the extremely poorly known scuttle flies (Phoridae). There has been a steady growth in our knowledge of European Diptera for the last two centuries, with no apparent slow down, but there is a shift towards a larger fraction of the new species being found among the families of the nematoceran grade (lower Diptera), which due to a larger number of small-sized species may be considered as taxonomically more challenging. Most of Europe is highly industrialised and has a high human population density, and the more fertile habitats are extensively cultivated. This has undoubtedly increased the extinction risk for numerous species of brachyceran flies, yet with the recent re-discovery of Thyreophora cynophila (Panzer), there are no known cases of extinction at a European level. However, few national Red Lists have extensive information on Diptera. For the Diptera–Brachycera, data from 96 families containing 11,751 species are included in this paper.

From 2019 to 2021, scientific field campaigns have been organised in Corsica by the Muséum national d’Histoire naturelle, the Office français de la biodiversité and the Collectivité de Corse as part of the “Our Planet Reviewed” naturalist exploration programme. This paper presents the context, the state of biogeographical and taxonomic knowledge prior to our expeditions, and the objectives, the methods and the first results obtained. The aim was to establish a modern survey of the species present in a selection of sites representative of different Corsican ecosystems, and to further develop the natural history collections through depositing new specimens and species with associated standard DNA barcodes, useful for their identification. Over a period of three years, nineteen sites were surveyed with a semi-standardised protocol and a large-scale trapping scheme was organised in three of these. Sampling efforts focused on forest habitats at higher altitudes and on coastal dune and lowland marshland habitats. A vast array of methods was used to collect invertebrates, with a specific effort on flightinterception traps and pan traps. A total of 34 experts participated to the field surveys and more than 80 further contributed to the study of the specimens. Occurrence data are available in the Inventaire national du patrimoine naturel (http://www.inpn.fr) and, for specimens processed through DNA barcoding, specimen and DNA sequencing data will be accessible in the Barcode of Life datasystems (BOLD : http://www.boldsystems.org). In early 2023, the assembled datasets included 31,100 occurrence data for 3,900 taxa of terrestrial arthropods, representing a 53% increase in publicly available data for the island. More than 6,800 DNA barcode sequences have been produced for arthropods, representing a 14-fold increase in available sequences of Corsican insects compared to those available before the start of the programme. So far, these efforts resulted in producing the first Corsican records for 148 species and in the description of 12 species new to science.

This paper documents the horse fly fauna collected in lowland rainforest in the southwesternmost part of French Guiana (Mitaraka). During this “Our Planet Revisited” survey nine tabanid species were recorded from French Guiana for the first time:Chrysops ecuadorensisLutz,C. incisusMacquart,Catachlorops amazonicusHenriques & Gorayeb,Chlorotabanus flagellatusKrolow & Henriques,Cryptoylus cauriStone,Phaeotabanus phaeopterusFairchild,Philipotabanus stigmaticalis(Kröber),Stypommisa captiroptera(Kröber) andTabanus amapaensisFairchild. An updated check list of Tabanidae of French Guiana is presented, including 79 species and one unidentifiedChrysops.

Predatory long-legged flies of the genus Medetera are important, but currently understudied, natural enemies of Scolytinae bark beetles such as Ips typographus. Medetera flies lay eggs on beetle-infested trees, where the developing larvae find their prey, but the chemical cues used by Medetera to locate infested trees are currently unknown. To identify odors attracting Medetera signaticornis, a species in Europe, headspace samples were collected at several time-points through different stages of I. typographus attacks on logs of Norway spruce (Picea abies). The headspace samples were analyzed using combined gas chromatography and mass spectrometry (GC–MS), and gas chromatography coupled with electroantennographic detection (GC-EAD) to determine compounds that stimulate M. signaticornis antennae. Antennae of M. signaticornis males and females were found to detect (–)-cis-verbenol, ( +)-trans-verbenol and myrtenol, which are known to be produced by bark beetles. Antennal responses were also observed for verbenene, isoterpinolene, α-pinene oxide, camphor, pinocamphone, terpinene-4-ol, myrtenal, borneol, α-terpineol, geranyl acetone, and verbenone, which are primarily produced by microorganisms, and α-pinene, α-fenchene, β-pinene, camphene, 3-carene, limonene, γ-terpinene, and terpinolene, known spruce tree compounds. In field experiments testing two synthetic blends containing 18 antennal active and two additional compounds 2-methyl-3-buten-2-ol and ipsdienol we observed significant attraction of M. signaticornis within 24 h. These attractive blends can form the basis for development of Medetera monitoring lures for use in future forest and pest management.