Furcantenna malayana
sp. nov.
is described from Peninsular Malaysia, based on a single female collected in 1962. The other two known species of this genus are also known from single specimens, from ...Southeastern China and Nepal. A key to the species is given, and the taxonomy and distribution of the genus are discussed.
The species of the hoverfly genus Paramixogaster Brunetti, 1923 from the Oriental Region are revised. The resulting number of valid species is 15, of which the following four are described as new: P. ...halmaherensis Reemer, sp. nov. , P. jubata Reemer, sp. nov. , P. kodaiana Sankararaman & Reemer, sp. nov. , and P. sulawesiana Reemer, sp. nov. Three new synonymies are established: Paramicrodon decipiens de Meijere, 1917, syn. nov. is a junior synonym of Microdon vespiformis de Meijere, 1908; Paramixogaster wegneri Keiser, 1964, syn. nov. is a junior synonym of Ceratophya indica Doleschall, 1857; Microdon subpetiolatus Thompson, 2020, syn. nov. is a junior synonym of Microdon contractus Brunetti, 1923. Paramixogaster huoi Reemer, nom. nov. is introduced as a replacement name for P. trifasciatus Huo & Zhao, 2022, which is a primary homonym of P. trifasciatus Ssymank & Reemer, 2016. Neotypes are designated for Paramixogaster icariiformis Pendlebury, 1927 and Myxogaster variegata Sack, 1922, and a lectotype is designated for Microdon vespiformis de Meijere, 1908. An identification key to the species and diagnoses for all species are provided.
The immature stages of hoverflies of the subfamily Microdontinae (Diptera: Syrphidae) develop in ant nests, as predators of the ant brood. The present paper reviews published and unpublished records ...of associations of Microdontinae with ants, in order to discuss the following questions. (1) Are all Microdontinae associated with ants? (2) Are Microdontinae associated with all ants? (3) Are particular clades of Microdontinae associated with particular clades of ants? (4) Are Microdontinae associated with other insects? A total number of 109 associations between the groups are evaluated, relating to 43 species of Microdontinae belonging to 14 genera, and to at least 69 species of ants belonging to 24 genera and five subfamilies. The taxa of Microdontinae found in association with ants occur scattered throughout their phylogenetic tree. One of the supposedly most basal taxa (Mixogaster) is associated with ants, suggesting that associations with ants evolved early in the history of the subfamily and have remained a predominant feature of their lifestyle. Among ants, associations with Microdontinae are known from subfamilies Ponerinae, Dolichoderinae, Formicinae, Myrmicinae, and Pseudomyrmecinae. These subfamilies comprise more than 95% of all ant species. Interestingly, no associations are known with “dorylomorph” ants (army ants and relatives).
Evidence for declining populations of both wild and managed bees has raised concern about a potential global pollination crisis. Strategies to mitigate bee loss generally aim to enhance floral ...resources. However, we do not really know whether loss of preferred floral resources is the key driver of bee decline because accurate assessment of host plant preferences is difficult, particularly for species that have become rare. Here we examine whether population trends of wild bees in The Netherlands can be explained by trends in host plants, and how this relates to other factors such as climate change. We determined host plant preference of bee species using pollen loads on specimens in entomological collections that were collected before the onset of their decline, and used atlas data to quantify population trends of bee species and their host plants. We show that decline of preferred host plant species was one of two main factors associated with bee decline. Bee body size, the other main factor, was negatively related to population trend, which, because larger bee species have larger pollen requirements than smaller species, may also point toward food limitation as a key factor driving wild bee loss. Diet breadth and other potential factors such as length of flight period or climate change sensitivity were not important in explaining twentieth century bee population trends. These results highlight the species-specific nature of wild bee decline and indicate that mitigation strategies will only be effective if they target the specific host plants of declining species.
Significance Growing concern about bee declines and associated loss of pollination services has increased the urgency to identify the underlying causes. So far, the identification of the key drivers of decline of bee populations has largely been based on speculation. We assessed the relative importance of a range of proposed factors responsible for wild bee decline and show that loss of preferred host plant species is one of the main factors associated with the decline of bee populations in The Netherlands. Interestingly, species foraging on crop plant families have stable or increasing populations. These results indicate that mitigation strategies for loss of wild bees will only be effective if they target the specific host plants of declining bee species.
Understanding species distributions and the factors limiting them is an important topic in ecology and conservation, including in nature reserve selection and predicting climate change impacts. While ...Species Distribution Models (SDM) are the main tool used for these purposes, choosing the best SDM algorithm is not straightforward as these are plentiful and can be applied in many different ways. SDM are used mainly to gain insight in 1) overall species distributions, 2) their past-present-future probability of occurrence and/or 3) to understand their ecological niche limits (also referred to as ecological niche modelling). The fact that these three aims may require different models and outputs is, however, rarely considered and has not been evaluated consistently. Here we use data from a systematically sampled set of species occurrences to specifically test the performance of Species Distribution Models across several commonly used algorithms. Species range in distribution patterns from rare to common and from local to widespread. We compare overall model fit (representing species distribution), the accuracy of the predictions at multiple spatial scales, and the consistency in selection of environmental correlations all across multiple modelling runs. As expected, the choice of modelling algorithm determines model outcome. However, model quality depends not only on the algorithm, but also on the measure of model fit used and the scale at which it is used. Although model fit was higher for the consensus approach and Maxent, Maxent and GAM models were more consistent in estimating local occurrence, while RF and GBM showed higher consistency in environmental variables selection. Model outcomes diverged more for narrowly distributed species than for widespread species. We suggest that matching study aims with modelling approach is essential in Species Distribution Models, and provide suggestions how to do this for different modelling aims and species' data characteristics (i.e. sample size, spatial distribution).
Bumblebees in Europe have been in steady decline since the 1900s. This decline is expected to continue with climate change as the main driver. However, at the local scale, land use and land cover ...(LULC) change strongly affects the occurrence of bumblebees. At present, LULC change is rarely included in models of future distributions of species. This study's objective is to compare the roles of dynamic LULC change and climate change on the projected distribution patterns of 48 European bumblebee species for three change scenarios until 2100 at the scales of Europe, and Belgium, Netherlands and Luxembourg (BENELUX). We compared three types of models: (1) only climate covariates, (2) climate and static LULC covariates and (3) climate and dynamic LULC covariates. The climate and LULC change scenarios used in the models include, extreme growth applied strategy (GRAS), business as might be usual and sustainable European development goals. We analysed model performance, range gain/loss and the shift in range limits for all bumblebees. Overall, model performance improved with the introduction of LULC covariates. Dynamic models projected less range loss and gain than climate‐only projections, and greater range loss and gain than static models. Overall, there is considerable variation in species responses and effects were most pronounced at the BENELUX scale. The majority of species were predicted to lose considerable range, particularly under the extreme growth scenario (GRAS; overall mean: 64% ± 34). Model simulations project a number of local extinctions and considerable range loss at the BENELUX scale (overall mean: 56% ± 39). Therefore, we recommend species‐specific modelling to understand how LULC and climate interact in future modelling. The efficacy of dynamic LULC change should improve with higher thematic and spatial resolution. Nevertheless, current broad scale representations of change in major land use classes impact modelled future distribution patterns.
At the local scale, land use land cover (LULC) change strongly affects the occurrence of bumblebees. However, at present LULC change is rarely included in models of future distributions of species. We compared models of climate‐only covariates to models with added static and dynamic LULC covariates. Dynamic models project less range loss and gain than climate only projections, and greater range loss and gain than static models. We recommend species‐specific modelling to understand how LULC and climate interact in future modelling.
Atmospheric nitrogen deposition and other sources of environmental eutrophication have increased substantially over the past century worldwide, notwithstanding the recent declining trends in Europe. ...Despite the recognized susceptibility of plants to eutrophication, few studies evaluated how impacts propagate to consumers, such as pollinators. Here we aim to test if soil eutrophication contributes to the temporal dynamics of pollinators and their larval resources.
We used a temporally and spatially explicit historical dataset with information on species occurrences to test if soil eutrophication, and more specifically nitrogen deposition, contributes to the patterns of change of plant and pollinator richness in the Netherlands over an 80 yr period. We focus on bees and butterflies, two groups for which we have good knowledge of larval resources that allowed us to define groups of species with different nitrogen related diet preferences. For each group we estimated richness changes between different 20‐yr periods at local, regional and national scale, using analytical methods developed for analyzing richness changes based on collection data.
Our findings suggest that the impacts of soil eutrophication on plant communities propagate to higher trophic levels, but with a time‐lag. Pollinators with nitrogen‐related diet preferences were particularly affected, in turn potentially impairing the performance of pollinator‐dependent plants. Pollinator declines continued even after their focal plants started to recover. In addition, our results suggest that current levels of nitrogen deposition still have a negative impact on most groups here analyzed, constraining richness recoveries and accentuating declines.
Our results indicate that the global increase in nitrogen availability plays an important role in the ongoing pollinator decline. Consequently, species tolerances to soil nitrogen levels should be considered across all trophic levels in management plans that aim to halt biodiversity loss and enhance ecosystems services worldwide.
The species of the Neotropical hoverfly genus
Reemer, 2013 are revised, based on morphological characters with aid of mitochondrial DNA barcodes. The resulting number of valid species is increased to ...31, of which the following seven are described as new:
Reemer,
,
Reemer,
,
Reemer,
,
Reemer,
,
Reemer,
,
Reemer,
, and
Reemer,
Two new synonymies are established:
Curran, 1925,
and
Curran, 1925,
are both junior synonyms of
Fabricius, 1805. A neotype is designated for
Sack, 1921. This neotype, which has been reared from an ant nest, also represents the first case of a larval record for this genus. In some species, most notably in
(Fabricius) and
(Curran), discrete and distinct colour morphs are recognized, with strongly differing colouration of wings and abdomen.
The flower fly genus Afrosyrphus Curran, 1927 (Diptera, Syrphidae) is revised and a new species, Afrosyrphus schmuttereri sp. nov., from Kenya and Uganda is described. Diagnoses, illustrations, DNA ...barcodes and known distributional data are provided for the two species of this genus, as well as an identification key. A critical review of the published literature is also provided.
Ubristes rex sp. n., a hoverfly of the subfamily Microdontinae (Diptera: Syrphidae) is described from northern Brazil (Roraima). A diagnosis and a key are provided for distinguishing this species ...from the other three known species of Ubristes, which are all Neotropical. Information on distribution and habitat of all known Ubristes species is summarized. A brief comment is made on the decision to describe this species based on a single female specimen.
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