Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions.

Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter "crop heterogeneity") can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production.

Landscape configurational heterogeneity by small-scale agriculture, not crop diversity, maintains pollinators and plant reproduction in western Europe.

Agricultural intensification is one of the main causes for the current biodiversity crisis. While reversing habitat loss on agricultural land is challenging, increasing the farmland configurational heterogeneity (higher field border density) and farmland compositional heterogeneity (higher crop diversity) has been proposed to counteract some habitat loss. Here, we tested whether increased farmland configurational and compositional heterogeneity promote wild pollinators and plant reproduction in 229 landscapes located in four major western European agricultural regions. High-field border density consistently increased wild bee abundance and seed set of radish (Raphanus sativus), probably through enhanced connectivity. In particular, we demonstrate the importance of crop-crop borders for pollinator movement as an additional experiment showed higher transfer of a pollen analogue along crop-crop borders than across fields or along semi-natural crop borders. By contrast, high crop diversity reduced bee abundance, probably due to an increase of crop types with particularly intensive management. This highlights the importance of crop identity when higher crop diversity is promoted. Our results show that small-scale agricultural systems can boost pollinators and plant reproduction. Agri-environmental policies should therefore aim to halt and reverse the current trend of increasing field sizes and to reduce the amount of crop types with particularly intensive management.

The syrphids of Serra do Courel, Northern Spain and description of a new Cheilosia Meigen species (Diptera: Syrphidae).

The syrphids (Syrphidae) of Serra do Courel, a mountainous locality of just over 20,000ha at the west end of the Cantabrian Mountains, northern Spain are poorly known. The Scottish based, Malloch Society visited the locality in May 2012 and collected a total of 462 specimens of 98 syrphid species and 36 genera. These represent the first syrphid records from Serra do Courel. The area has many meadows and small woodlands or 'soutos' and these habitats combined were the most productive, 69 spp. recorded. Cheilosia lucense Ricarte sp. nov. is described from Courel and compared with other species of the alpina group. Six other syrphid species were new to the Iberian Peninsula, three of which belong to the saproxylic genus, Brachyopa. In common with studies elsewhere in the Cantabrian Mountains, Cheilosia was the most diverse genus and 21 species were recorded. The syrphid fauna of the Cantabrian Mountains includes 203 species of which 24 are here added and a species checklist provided. 

On the immature stages of some Merodontini hoverflies (Diptera: Syrphidae) from Europe and Africa.

The genera Eumerus and Merodon (Syrphidae: Merodontini) form together the most speciose grouping of hoverflies in the Palaearctic Region. However, little is known about the morphology and biology of their larvae. The few larvae of Eumerus and Merodon that have been uncovered are phytophagous in underground organs of plants (some Eumerus and all Merodon) or saprophagous in a variety of plants' parts (the reminder of Eumerus). In this study, the second larval stage (L2) of Eumerus lyneborgi Ricarte & Hauser, 2020 and both the larva (L2) and puparium of Merodon constans (Rossi, 1794) are described for the first time. Larvae of E. lyneborgi were found in a decaying stem of Cyphostemma juttae (Dinter & Gilg) Desc., 1960 (Vitaceae) in Namibia (Africa), while larvae of M. constans were collected in bulbs of Leucojum vernum Linnaeus, 1753, (Amaryllidaceae) in France (Europe). Morphology of the immature forms was studied by observation and imaging with stereomicroscopy and scanning electron microscopy. The head skeleton of E. lyneborgi larvae was found to be of the filter feeding type, i.e., in accordance with a saprophagous trophic regime, while that of M. constans was typically phytophagous. Variability in certain characters of the M. constans early stages is described and discussed in relation to the adult form and molecular information published in literature. An updated identification key to all known third larval stages/puparia of Merodon is provided.

First Morpho-Functional Assessment of Immature Stages of Pelecocera Species (Diptera: Syrphidae) Feeding on False Truffles.

With 14 species, Pelecocera Meigen, 1822 is a scarce and small genus of hoverflies (Diptera: Syrphidae: Rhingiini) from the Holarctic Region. Apart from the finding of larvae of Pelecocera (Chamaesyrphus) japonica (Shiraki, 1956) in fungi in Japan, the larval biology of these hoverflies is virtually unknown. The early stages of all Pelecocera species are undescribed. The adults of Pelecocera (Pelecocera) tricincta Meigen, 1822 and Pelecocera (Chamaesyrphus) lugubris Perris, 1839 are found in Palearctic conifer forests with sand dunes. We here report the first morphological evidence of the immature stages of Pelecocera (P. lugubris and P. tricincta), as well as specific data on their breeding sites. Larvae of both species were collected feeding on the hypogean basidiomycete Rhizopogon luteolus Fr. & Nordholm, 1817 in Denmark in 2021. The first larval stage and second larval stage of P. tricincta, the third larval stage of P. lugubris, the anterior respiratory process, and the posterior respiratory process of the puparia of these two species were analyzed and studied using stereomicroscope and scanning electron microscope techniques. The chaetotaxy of the puparium of each species is also described and illustrated. A taxonomic diagnosis of the larvae of the genus Pelecocera is proposed to separate them from the larvae of other genera of the tribe.

Unveiling the Mainland vs. Insular Variability of the Eumerus barbarus Species Group (Diptera: Syrphidae) in the Western Mediterranean Basin.

Comprising nearly 300 described species, Eumerus Meigen, 1822, is one of the most speciose syrphid genera worldwide, and its taxonomic diversity is remarkable in the Mediterranean basin. The Eumerus barbarus (Coquebert, 1804) group consists of four species in the western Mediterranean. Although the phenotypic variability of this species group has been commented on in previous studies, it has never been contrasted with molecular data. In the present work, the morphological variation found in 300+ specimens of this species group from the western Mediterranean is explored and tested against the COI mitochondrial DNA (mtDNA). The highest phenotypic disparity was found in E. barbarus and Eumerus sulcitibius Rondani 1868. The integrative approach has not revealed cryptic diversity within the species E. barbarus but in E. sulcitibius. As a result, a new species close to E. sulcitibius was discovered, Eumerus sardus Aguado-Aranda, Ricarte & Hauser sp. n., from Sardinia, Italy. The new insular species is here described, illustrated, and discussed. A total of twenty-three haplotypes of COI mtDNA were identified amongst the analyzed Mediterranean specimens of E. barbarus, whereas two and five haplotypes were distinguished in the Iberian specimens of E. sulcitibius and Eumerus gibbosus van Steenis, Hauser & van Zuijen, 2017, respectively. Moreover, the first known barcodes of E. gibbosus and Eumerus schmideggeri van Steenis, Hauser & van Zuijen, 2017 were obtained, and the distribution ranges of all species are mapped. An updated dichotomous key to the males of the E. barbarus group from the western Mediterranean is provided.

Combined stereomicroscope and SEM disentangle the fine morphology of the undescribed larva and puparium of the hoverfly Milesia crabroniformis (Fabricius, 1775) (Diptera: Syrphidae).

With over 80 species, Milesia Latreille, 1804 is a hoverfly genus (Diptera: Syrphidae) found in all continents except for Australia and the Antarctica. However, little is known about its life cycle and biology. The three Milesia species for which early stages are known have saproxylic larvae, suggesting that the larvae of all other Milesia species are also saproxylic. The early stages of the three Milesia species occurring in Europe are undescribed. Milesia crabroniformis (Fabricius, 1775), a mimic of the hornet Vespa crabro Linnaeus, 1758, is the largest hoverfly in Europe and is listed as Least Concern in the IUCN European Red List of Hoverflies. We here report the first early stages of Milesia ever found in Europe, describing them and their breeding sites. Larvae of M. crabroniformis were collected in water-filled tree holes of live chestnut trees (Castanea sativa Mill.) in Málaga, Southern Spain in 2020-2021. Various studies based on stereomicroscope and scanning electron microscopy (SEM) techniques have proven useful in diagnosing hoverfly early stages by observation of their fine morphology. Thus, these techniques were also used here to characterize the second (L2) and third (L3) stage larvae of M. crabroniformis, as well as the puparium. A Leica M205C binocular stereomicroscope and a Jeol JSM-ITH500HR SEM were used. The head skeleton and chaetotaxy of the L3 larva were described and illustrated. Adjustments to the diagnosis of the larvae of Milesia are proposed based on the number of hooks from the primary row of the main group of hooks. The new early stages are compared with those of other Milesia hoverflies, as well as with those of the sister group Spilomyia Meigen, 1803. The knowledge of the larval biology and breeding sites of saproxylic insects is useful for implementing forest management measures and species' conservation programs.

Are Appearances Deceiving? Morpho-Genetic Complexity of the Eumerus tricolor Group (Diptera: Syrphidae) in Europe, with a Focus on the Iberian Peninsula.

Eumerus Meigen, 1822 is one of the largest Syrphidae genera in the Palaearctic Region, with the highest levels of taxonomic diversity found in the Eumerus tricolor species group. Despite its high diversity, the interspecific levels of morphological variability can be low. Additionally, some species may show certain levels of intraspecific variability. Hence, species delimitation may become challenging. In this work, we assessed the diversity of the E. tricolor group in the Iberian Peninsula through an integrative analysis of nomenclature, morphology and the 5' (COI-5') and 3' (COI-3') end regions of the Cytochrome c oxidase subunit I gene. Two new species, Eumerus ancylostylus Aguado-Aranda & Ricarte sp. n. and Eumerus petrarum Aguado-Aranda, Nedeljkovic & Ricarte sp. n., were described, and their intra- and interspecific variations discussed. In addition, the first barcodes of Iberian members of the E. tricolor group were obtained, and the distribution ranges of all species were mapped within the study area. The systematic position of the new species is discussed based on the resulting COI-based trees. The male genitalia of Eumerus hispanicus van der Goot, 1966 and Eumerus bayardi Séguy, 1961 were studied and illustrated. A lectotype was designated for Eumerus lateralis (Zetterstedt, 1819). An updated dichotomous key for all known European species of the E. tricolor group is provided. The egg of E. petrarum sp. n. is also described.

Assessing the Diversity and Systematics of Brachyopini Hoverflies (Diptera: Syrphidae) in the Iberian Peninsula, Including the Descriptions of Two New Species.

Five genera of Brachyopini, Chrysogaster Meigen, 1800, Melanogaster Rondani, 1857, Lejogaster Rondani, 1857, Orthonevra Macquart, 1829 and Riponnensia Maibach et al. 1994a are here revised from the Iberian region. Two new species, Melanogaster baetica Ricarte and Nedeljkovic, sp. n. and Orthonevra arcana Ricarte and Nedeljkovic sp. n., are described from Spain, and a third species, Chrysogaster coerulea Strobl in Czerny and Strobl, 1909 stat. n., is reinstated as valid and redescribed. A lectotype is designated for Orthonevra plumbago (Loew, 1840). The holotype of Orthonevra incisa (Loew, 1843) and the lectotype of O. plumbago are described in detail and illustrated. Melanogaster baetica sp. n. is similar to Melanogaster parumplicata (Loew, 1840) in male genitalia morphology, while O. arcana sp. n. is similar to O. incisa in the entirely-pollinose sternum I and the conspicuous incision on the posterior margin of tergum V in female. The first Iberian record of Chrysogaster rondanii Maibach and Goeldlin de Tiefenau, 1995 is provided, whilst Melanogaster aerosa is removed from the Iberian checklist of Syrphidae. Identification keys are presented to the five Brachyopini genera and 18 species now reported from the Iberian Peninsula (Chrysogaster, 6 spp.; Lejogaster, 2 spp.; Melanogaster, 3 spp.; Orthonevra, 5 spp.; Riponnensia, 2 spp.). COI (Cytochrome c oxidase subunit I) barcodes of the two new species plus C. coerulea, Chrysogaster solstitialis (Fallén, 1817), Orthonevra nobilis (Fallén, 1817) and Orthonevra frontalis (Loew, 1843) were successfully obtained from Spanish specimens. A COI-based tree was produced to locate these taxa in a wider systematic framework within the tribe.

A new Eumerus hoverfly (Diptera: Syrphidae) from Namibia and South Africa, with notes on similar species.

Within the pollinator family Syrphidae, Eumerus Meigen, 1822 is a diverse genus with over 70 species recorded in the Afrotropical Region. A new species is described here from Namibia and South Africa. Adults are small to medium size flies, with spur-like expansions in the metatarsomeres 2 and 3. DNA sequences of the Cytochrome c oxidase subunit I (COI) gene were obtained from Namibian specimens. This is only the second Eumerus species documented from Namibia, where it was recorded from The National Botanic Garden, Windhoek. The new species is compared with similar species such as Eumerus vestitus Bezzi, 1912, for which a lectotype is designated. In addition, a new and preliminary morphological concept of the Eumerus obliquus group is proposed and a key to its African species is provided.

Morphological, Genetic and Biological Evidences to Understand Meromacrus Rondani Diversity: New Species and Early Stages (Diptera: Syrphidae).

Meromacrus is a genus of conspicuous syrphids with saprophagous larvae, ranging from the southern United States to Argentina and Chile. However, this genus is in need of a taxonomic revision. Adults reared from larvae collected in Mexico and Peru, and other material available at different institutional collections were examined. Meromacrus cactorum sp. nov., from Peru, Meromacrus yucatense sp. nov., from Mexico, their puparia and breeding sites were described. A key to Meromacrus puparia is provided. The holotypes of Meromacrus canusium, Meromacrus gloriosus, Meromacrus laconicus and Meromacrus melmoth were also examined. The name Meromacrus draco is proposed as a junior synonym of M. gloriosus. Larvae of M. cactorum sp. nov. were found in decaying columnar cacti in Peru, while those of M. yucatense sp. nov. in a rot-hole of a Ceiba pentandra stump. Obtained results on both taxonomy and biology of these species serve as a first step towards a revision of the entire genus.

A checklist of the Syrphidae (Diptera) of Spain, Andorra and Gibraltar.

Hoverflies are relevant to pollination, predation, phytophagy and decomposition processes and they are also used as bioindicators. The numerous recent advances in the study of Spanish hoverflies and the absence of species lists for the Spanish provinces prompted us to update the national catalogue and fill in the gap at the provincial level. Andorra and Gibraltar are also included in this review. A total of 421 species of 72 genera are included in the present catalogue (417 species in Spain; 86 in Andorra; 43 in Gibraltar). León (182 spp), Salamanca (143 spp), Madrid (134 spp), Ciudad Real (124 spp) and Huesca (121 spp) are the Spanish provinces with the highest numbers of species recorded. The Balearic Islands have 81 species and the Canary Islands 41, with one and 11 endemic species respectively. The richest hoverfly genera in Spain are Cheilosia (56 spp), Merodon (40 spp plus 1 sp from Gibraltar) and Eumerus (38 spp plus 1 sp from Gibraltar), all of them being Eristalinae; within the Syrphinae, Paragus is the richest genus (18 spp). The possibility of elaborating regional (provincial) species lists from the information provided in the present study also contributes to 'Syrph the Net, the database of European Syrphidae' as a tool for assessment of habitat conservation in Spain.

Two new species of Quichuana Knab (Diptera: Syrphidae) from the paramo ecosystems in Colombia.

Two new species of Quichuana Knab (Diptera: Syrphidae), Quichuana citara Montoya & Wolff sp. n. and Quichuana nigropilosa Montoya & Ricarte sp. n. are described from highlands of the Colombian Andes. Images of type material, including drawings of male genitalia are provided. An adjustment for the latest identification key for the Quichuana species and distribution maps for those species occurring in Colombia are given.

A review of the early stages and host plants of the genera Eumerus and Merodon (Diptera: Syrphidae), with new data on four species.

The genera Eumerus and Merodon (Diptera: Syrphidae) have a high taxonomic diversity (300+ species altogether), but life histories of most species are unknown. In addition, these hoverfly genera are recognised to be pests (ornamental plants and vegetable crops). In this paper, early stages of four hoverfly species are described, Eumerus hungaricus Szilády, 1940, Eumerus nudus Loew, 1848 and Merodon geniculatus Strobl, 1909, from Spain, and Eumerus strigatus Walker, 1859, from California, USA. Larvae of E. nudus were obtained from swollen roots of Asphodelus cerasiferus J. Gay. Larvae of E. hungaricus were found in bulbs of Narcissus confusus Pugsley. The host plant of the examined specimen of Eumerus strigatus is unknown. Larvae of M. geniculatus were reared from bulbs of different species of Narcissus L. Scanning electron microscope imaging was used to study and illustrate the anterior respiratory processes, pupal spiracles and posterior respiratory processes of the new early stages. A compilation of all available information on the early stages and host plants of Eumerus (21 spp.) and Merodon (15 spp) is provided, as well as an identification key to all known larvae/puparia of these genera. Eumerus elavarensis Séguy, 1961 is proposed as a new synonym of E. hungaricus and first data of this species are reported from Austria, Bulgaria, Spain and Turkey. In Eumerus, larvae are alleged to rely on the previous presence of decay organisms, but in the larvae of E. nudus the sclerotisation and size of the mandibular hooks suggest that this larva can generate decay from intact plant tissue.

Revision of the West-Palaearctic species of the tribe Cerioidini (Diptera, Syrphidae).

The West-Palaearctic cerioidines (Syrphidae: Cerioidini) are revised, including species of the genera Ceriana Rafinesque, Primocerioides Shannon, and Sphiximorpha Rondani. Three new species are described, Ceriana glaebosa van Steenis & Ricarte sp. n. (Cyprus), Ceriana media van Steenis & Ricarte sp. n. (Afghanistan and Iran) and Ceriana skevingtoni van Steenis & Ricarte sp. n. (Armenia, Azerbaijan and Iran). The following names are proposed as junior synonyms: Cerioides caucasicus Paramonov, 1927 [= Ceriana conopsoides (Linnaeus, 1758)], Ceria binominata Verrall, 1901 [= Sphiximorpha garibaldii (Rondani, 1860)], Ceriana worelli, Bradescu, 1972b [= Sphiximorpha garibaldii (Rondani, 1860)] and Sphiximorpha hiemalis Ricarte, Nedeljkovic & Hancock, 2012 [= Primocerioides regale Violovitsh, 1985]. Identification keys, biological data and distribution maps for the studied taxa are provided. Conops vaginicornis Schrank, 1803 is discarded as a synonym of Ceriana conopsoides and should be considered as nomen dubium.

Bee (Hymenoptera: Apoidea) and hoverfly (Diptera: Syrphidae) pollinators in Pannonian habitats of Serbia, with a description of a new Eumerus Meigen species (Syrphidae).

The diversity of bee (Hymenoptera: Apoidea) and hoverfly (Diptera: Syrphidae) pollinators from ten localities in Vojvodina, Serbia was surveyed. Among different types of Pannonian habitat (grasslands, heathland and scrub, woodland and forest habitats) all localities were categorised as forest and steppe. They were in protected areas, mostly undisturbed by human activity. Censuses of pollinators took place from 30 March to 10 October, 2014. We recorded 218 pollinator species; 135 bee species (42 Halictidae; 32 Apidae; 29 Andrenidae; 24 Megachilidae; 7 Colletidae; 1 Melittidae) and 83 species of hoverflies. We describe a new species of hoverfly, Eumerus pannonicus sp. nov., and compare it to other similar species. Based on our study, the Special Nature Reserve of Pasnjaci Velike Droplje is critical for the conservation of this new Eumerus-being only found at this locality-and other species such as Chrysotoxum lineare (Zetterstedt), which is rare in Europe and protected under Serbian legislation. The highest numbers of bee species were recorded in the Deliblato and Subotica sand areas (40 and 32, respectively), while Fruska Gora Mountain and the Vrsac Mountains harboured the highest number of hoverfly species.

Neotropical Copestylum Macquart (Diptera: Syrphidae) Breeding in Fruits and Flowers, Including 7 New Species.

Ten species of Copestylum (Diptera: Syrphidae) were reared from fruits and flowers in Costa Rica, Ecuador and Trinidad. Seven were new and in this paper, we describe them, their development sites and the third stage larva and/or the puparium of all ten species. One new synonym is proposed, Copestylum pinkusi (Curran) [= Copestylum cinctiventre (Curran)]. Similarities and differences between these new and other Copestylum species, suggest they separate into two groups, referred to as the Vagum and Cinctiventre species groups. Features characterising these groups for both adult and early stages are assessed. Each species was also distinguished using adult and early stage characters. Within the Vagum group, adults were more disparate morphologically than the larval stage; this was reversed in the Cinctiventre group. Adult colour patterns are probably cryptic in function and for disguise. Vagum species have disruptive marks, while the Cinctiventre species have reflective colours. Biologically, the groups are almost distinguished by larval development sites. Vagum species use predominantly fruits and have a larval stage that is relatively generalised in form and habit. Cinctiventre species are confined to developing in flowers and the larva is more specialised. A key to both adult and early stages of all ten species is provided.

Nematocera flies recorded in Serra do Courel, northwest Spain, May 2012 (Diptera: Anisopodidae, Blepharoceridae, Cylindrotomidae, Limoniidae, Pediciidae, Tipulidae and Trichoceridae) including descriptions of two new species of Limoniidae.

During May 2012 Diptera were sampled in the Serro do Courel area of Lugo Province, Galicia, northwest Spain. The authors of this paper, members of the Malloch Society (see website) are active in attempting to understand the detailed ecology of flies. Much of this work is through targeting larval stages often with an emphasis on saproxylic situations. By rearing adults from larvae direct relationships between them and their detailed habitat requirements are established. The list of nematocerous Diptera that were sampled includes 36 species two of them new to science and records of six others new to the Iberian peninsula are provided. We describe Lipsothrix galiciensis Hancock & Hewitt sp. nov., and Prionolabis pjotri Hancock sp. nov. of the family Limoniidae and provide a key to adults of European Lipsothrix species. Such results from this brief opportunity indicate the potential of the area for further field work in these and other families of Diptera.