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A dramatic insect decline has been documented on the grasslands and forests of European or North American mainland. Yet, other parts of the world and other ecosystems remain much less studied with unknown patterns.Using a unique time‐series dataset, we investigate recent trends on abundance and richness of arthropods sampled in Azorean native forest over 6 years (2013–2018).We test the hypothesis that biodiversity erosion drivers are changing the diversity and relative species abundance structure (species abundance distribution, SAD) of endemics, native non‐endemics and exotic species over time. We also examine temporal trends in abundance for each individual species.In contrast with mainland studies, we observed no decline in overall arthropod diversity, but a clear increase in the diversity of exotic arthropods and some evidence of a tendency for decreasing abundance for some endemic species. We also document stronger species turnover for exotic species, but no specific changes in the SAD.We argue that many changes, particularly in unique systems such as islands, will be noticed not at the richness but mostly at compositional level. Special attention should be given to exotic species which are known to be one of the major drivers of biodiversity erosion on islands. [ABSTRACT FROM AUTHOR]

The last 3 years have seen a global outbreak of media headlines predicting a global insect apocalypse and a subsequent collapse of natural ecosystems, a so‐called 'ecological armageddon' resulting in the demise of human civilisation as we know it. Despite the worrying implications of these papers, all studies on global insect extinction to date clearly reflect the Prestonian shortfall, the general lack of knowledge on the abundance of species and their trends in space and time.Data currently available concerning global insect abundance trends invariably suffer from phylogenetic, functional, habitat, spatial and temporal bias. Here, we suggest that to follow the real global changes in insect (and all other taxa) communities, biases or shortcomings in data collection must be avoided.An optimised scheme would maximise phylogenetic, functional, habitat, spatial and temporal coverage with minimum investment. Standardised sampling would provide primary data, on a first step in the form of abundance and biomass. Individuals would then be identified to species level whenever possible, with a morphospecies approach or genetics serving as intermediate steps, complementing or even final steps for non‐described species.If standardised abundance and ecological data can be readily made available, biodiversity trends can be tracked in real time and allow us to predict and prevent an impending global insect apocalypse. [ABSTRACT FROM AUTHOR]

Information on the distribution and vulnerability of invertebrates is often scarce and, as a consequence, this group of organisms is usually neglected in conservation studies. Yet it is possible to reasonably infer ranges and vulnerabilities of species and establish spatial conservation priorities, even with incomplete information. We investigated conservation priorities of hoverflies in Southeast Europe based on species distribution models (SDM) and vulnerability indices., Species distribution models were used to compensate for the lack of knowledge on species ranges. Measures related to geographical rarity, endemism and habitat specialisation were used to assess species vulnerability. Potential distribution and three alternative vulnerability indices were used to calculate two spatial conservation indices: potential Biodiversity Conservation Concern index (pBCC) and potential Biodiversity Conservation Weight (pBCW)., pBCC highlighted areas with a large proportion of highly vulnerable species, even where species richness was low, such as the Danube delta and mid-Aegean islands. It also identified potentially important areas yet-to-be surveyed (e.g. Carpathian mountains), which might deserve future conservation measures. pBCW emphasised areas hosting high richness of both vulnerable and resilient species, such as the eastern Aegean Islands and the eastern part of Crete., We demonstrate that: (i) it is possible to establish conservation priorities at large scales if SDM and simple vulnerability measures are combined; (ii) complementary approaches are necessary to emphasise the importance of areas with different characteristics; and (iii) several understudied areas should be targets of future sampling schemes to confirm their importance for the conservation of hoverfly diversity in Southeast Europe. [ABSTRACT FROM AUTHOR]

Land-use change has profoundly impacted pollinator communities throughout the world. However, the processes through which it acts on pollinator diversity and composition are still poorly understood, especially in highly vulnerable island ecosystems., In this study, we investigated the distribution, abundance, richness and composition of flower-visiting insects to assess their response to land-use change in Terceira Island (Azores)., Flower-visiting insects were sampled over 2 years using a standardised protocol along 50 transects across five different habitats corresponding to a land-use gradient. Insect species were classified as indigenous or exotics. We assessed changes across habitats using multiple diversity indices, species abundance distribution models ( SAD) and species composition metrics (β-diversity), along with plant species composition., We observed that indigenous flower-visiting insects were dominant, both in abundance and species richness, across the entire land-use gradient. Species diversity varied only slightly across the gradient. SADs were lognormal in all habitats, with very few truly common and rare flower-visiting insects and a prevalence of species of intermediate abundance. Species replacement was significantly higher mainly between the two most contrasting habitats (i.e. natural forests and intensive pastures) but was significantly correlated with species replacement of host plant species across the gradient., Our results revealed that the Azorean flower-visiting insect communities were highly simplified across the entire gradient with little difference between habitats. In the absence of strong exotic competitors, indigenous flower-visiting insects expand their range and occupy new anthropogenic habitats, also facilitating the expansion of a large number of exotic plant species. [ABSTRACT FROM AUTHOR]

The objective of this study was to obtain a biogeographical perspective on the hoverfly genus Merodon (Diptera, Syrphidae) based on data from 32 islands in the Aegean and Ionian archipelagoes vis-à-vis the adjacent mainland. In this part of the world, the genus comprises 57 species, out of more than 160 species described worldwide., The importance of eco-geographical variables (area, elevation, distance to the nearest island and distance to the nearest mainland) and the species-area relationship ( SAR) were studied in order to explain patterns of species richness. All tests supported the dynamic equilibrium concept., The area and distance to closest island were found to be the most important drivers of species richness on the Aegean and Ionian archipelagoes. Out of three SAR models evaluated in this study, the exponential function fitted our data best. It was found that a power model with no intercept value ( C = 1) performed even better by using symbolic regression for non-linear equation optimisation., The cluster and null-model analyses performed to detect inter-island similarities and origins of the insular Merodon fauna indicated a clear influence of colonisation history of the species on different islands., The results imply that the current distributions of Merodon species in the study area exhibit the combined effects of historical and present-day processes. [ABSTRACT FROM AUTHOR]

The Finnish Red Lists from 2000 and 2010 were used to calculate for the first time the national Red List Index for the order Lepidoptera and different Lepidoptera families with data from 2245 species., We grouped species according to their primary habitats and analysed each habitat's RLI as well., The overall RLI was significantly negative, reflecting the worsening of the group as a whole in the country., A significant negative trend was found for families Tortricidae, Gelechiidae and Hesperiidae and for coastal habitats., We also report that 76 Lepidoptera species newly established a population in Finland between 2000 and 2010, probably expanding northwards driven by climate warming. [ABSTRACT FROM AUTHOR]