Recently, reports of insect declines prompted concerns with respect to the state of insects at a global level. Here, we present the results of longer‐term insect monitoring from two locations in the Netherlands: nature development area De Kaaistoep and nature reserves near Wijster. Based on data from insects attracted to light in De Kaaistoep, macro‐moths (macro‐Lepidoptera), beetles (Coleoptera), and caddisflies (Trichoptera) have declined in the mean number of individuals counted per evening over the period of 1997–2017, with annual rates of decline of 3.8, 5.0 and 9.2%, respectively. Other orders appeared stable [true bugs (Hemiptera: Heteroptera and Auchenorrhyncha) and mayflies (Ephemeroptera)] or had uncertainty in their trend estimate [lacewings (Neuroptera)]. Based on 48 pitfall traps near Wijster, ground beetles (Coleoptera: Carabidae) showed a mean annual decline of 4.3% in total numbers over the period of 1985–2016. Nonetheless, declines appeared stronger after 1995. For macro‐moths, the mean of the trends of individual species was comparable to the annual trend in total numbers. Trends of individual ground beetle species, however, suggest that abundant species performed worse than rare ones. When translated into biomass estimates, our calculations suggest a reduction in total biomass of approximately 61% for macro‐moths as a group and at least 42% for ground beetles, by extrapolation over a period of 27 years. Heavier ground beetles and macro‐moths did not decline more strongly than lighter species, suggesting that heavy species did not contribute disproportionately to biomass decline. Our results broadly echo recent reported trends in insect biomass in Germany and elsewhere.
We present the first multigene phylogeny focused on Eristalinae (Diptera: Syrphidae) utilizing a dataset containing 120 flower fly species from across all four subfamilies and representing 13 out of 16 tribes. Eight genes were used in the construction of the phylogeny: mitochondrial cytochrome c oxidase subunit I and the nuclear genes 28S ribosomal DNA, Alanylt RNA Synthetase, the carbamoyl phosphate synthase domain of CAD, Period, RNA-binding Protein 15 (RBP–15, 5’), Casein Kinase 1 and TULP for a total of ~6.7 kB of data. Eristalinae is recovered as paraphyletic with strong support for the elevation of Cerioidini, Merodontini and Volucellini to subfamilial status. Deineches, Flukea and Malometasternum render Criorhinina paraphyletic with respect to the type genus Criorhina. A clade with Criorhina, Matsumyia and Sphecomyia is strongly supported. The generic concept of Criorhina is paraphyletic, while Sphecomyia is monophyletic and Matsumyia is monophyletic but requires expansion. Evidence supports the resurrection of Romaleosyrphus and the creation of new genera. Criorhinina (stat. rev.) is restricted to contain Criorhina, Matsumyia, Romaleosyrphus and Sphecomyia. Thirteen changes to the higher classification of Syrphidae are proposed.
1. To study insect decline, an important threat to biodiversity, long-term datasets are needed. Here we present a study of hoverfly (Diptera: Syrphidae) abundance and diversity in a Dutch forest, surrounded by other forests, and analyse the variation in insect numbers over four decades.2. Between 1982 and 2021, abundance decreased by 80%. Until 1990, abundance showed a strong decrease of 10.9% per year, mainly in nationally rare species with carnivorous larvae exposed to air. From 1990, abundance stabilised, whereas from 2000, a second period of strong decline of 9.0% per year occurred, mainly in very common species.3. Species richness also declined strongly between 1979 and 2021: the total number of species observed in five monitoring days dropped by 44% over those 43 years.The characteristic set of dry-forest hoverfly species disappeared over four decades.4. The number of nationally rare species observed at the study site declined from 19 to 9 early on, in a period (1979)(1980)(1981)(1982)(1983)(1984) that coincided with intense nitrogen input and acidification caused by agriculture in the same region. The more recent decline is likely also caused by factors from outside the forest, as forest management and conditions remained constant. 5. Continued influx of nutrients and pesticides at a regional level, as well as climate change are possible causes of the decline. Research is needed to quantify their relative effects.
An ongoing investigation on the Greek hoverfly fauna using adult morphology has revealed new species within three genera. In this study, the knowledge of the Mediterranean hoverfly fauna has been enhanced by describing the following species: Cheilosia candida Vujić et Radenković sp. n. (Pindos Mountains), Paragus thracusi Radenković, Likov et Vujić sp. n. (Rhodope Mountains) and Psilota aegeae Vujić, Ståhls et Smit sp. n. (Lesvos island). Diagnosis of new species, as well as identification keys to the Mediterranean species of the subgenus Convocheila Barkalov of Cheilosia Meigen and the European species of the genus Psilota Meigen have been provided. Additionally, mtDNA COI barcodes for the members of the Psilota atra group (except Psilota nana Smit et Vujić) have been given. In addition, the taxonomic status of Psilota anthracina Meigen has been discussed.
The 34 species of Australian Psilota are revised, with 26 new species described (Psilota aislinnae Young sp. nov., Psilota alexanderi Young sp. nov., Psilota apiformis Thompson and Young sp. nov., Psilota auripila Young and van Steenis sp. nov., Psilota azurea Thompson and Young sp. nov., Psilota bicolor Young and Ferguson sp. nov., Psilota brunnipennis Young sp. nov., Psilota calva Young sp. nov., Psilota darwini Young sp. nov., Psilota flavoorta Young and van Steenis sp. nov., Psilota fuscifrons Young sp. nov., Psilota livida Young and van Steenis sp. nov., Psilota longipila Thompson and Young sp. nov., Psilota mcqueeni Young sp. nov., Psilota metallica Thompson and Young sp. nov., Psilota nigripila Young sp. nov., Psilota occidua Young sp. nov., Psilota pollinosa Young and van Steenis sp. nov., Psilota purpurea Thompson and Young sp. nov., Psilota smaragdina Young sp. nov., Psilota solata Young and van Steenis sp. nov., Psilota spathistyla Young and van Steenis sp. nov., Psilota spinifemur Young sp. nov., Psilota viridescens Young and van Steenis sp. nov., Psilota xanthostoma Young sp. nov., Psilota zophos Young sp. nov.) and one new record for Australia (Psilota basalis Walker, 1858). Previously described Australian species are redescribed, with the males of Psilota auricauda Curran, 1925 and P. basalis (Walker, 1858) described for the first time. Six previously described species (Psilota erythrogaster Curran, 1926, Psilota hirta Klocker, 1924, Psilota queenslandica Klocker, 1924, Psilota rubra Klocker, 1924, Psilota rubriventris Bigot, 1885, and Psilota shannoni Goot, 1964) are morphologically indistinguishable from related species. P. erythrogaster, P. rubra, and P. rubriventris are therefore treated under the Psilota cuprea (Macquart, 1850) species complex while P. hirta, P. queenslandica, and P. shannoni treated under the Psilota tristis Klocker, 1924 species complex. Lectotypes for the following species are designated: Coiloprosopa nitida Macquart, 1850, Merodon muscaeformis Walker, 1852, Orthonevra basalis Walker, 1858, Psilota coerulea Macquart, 1846, and Psilota viridis Macquart, 1847.
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