South African nose flies (Diptera, Calliphoridae, Rhiniinae): taxonomy, diversity, distribution and biology.

Background: Rhiniinae (Diptera, Calliphoridae) is a taxon of nearly 400 known species, many of them termitophilous. Approximatelly 160 valid species in 16 genera are Afrotropical, with over 60 of them occurring in South Africa. The taxonomy of this group is outdated, as most studies of the South African taxa were conducted 40 to 70 years ago (mostly by Salvador Peris and Fritz Zumpt). Published information on their biology and ecology is also scarce. New information: An annotated checklist of 73 species of Rhiniinae for South Africa was developed, based on the holdings of sixteen entomological collections in Africa, Europe and North America. Over 3,700 specimens were examined, revealing nine new species records for South Africa (Cosminaundulata Malloch, 1926, Isomyiacuthbertsoni (Curran, 1938), Rhyncomyabotswana Zumpt, 1974, R.tristis Séguy, 1933, Stomorhinaapta Curran, 1931, S.malobana (Lehrer, 2007), Thoraciteskirkspriggsi Kurahashi, 2001, Th.sarcophagoides Kurahashi, 2001 and Trichoberialanata (Villeneuve, 1920)). We propose one new combination Eurhyncomyiametzi (Zumpt, 1981) comb. nov. (= Rhyncomyametzi Zumpt, 1981)). Additionally, evidence is presented to remove Rhyncomyaviduella Villeneuve, 1927 stat. rev. from synonymy with Rhyncomyacassotis (Walker, 1849). Relevant novel biological and seasonality information, historical occurrence maps and high-definition photographs for each species are compiled.

Characterization of preimaginal developmental stages of two cryptic South African species of the Merodon planifacies complex (Diptera: Syrphidae: Eristalinae: Merodontini), with differentiation through morphometry analysis.

Merodon capi Vujic et Radenkovic, 2020 and Merodon roni Radenkovic et Vujic, 2020 are two cryptic species belonging to the Merodon planifacies Bezzi, 1915 species complex that have recently been described, with the differences between them being revealed by molecular and geometric morphometry studies of adult specimens. In the present study, the preimaginal morphology of both species is described and displayed, with the material used corresponding to samples taken from bulbs of Merwilla plumbea (Lindl.) Speta plants at two locations in KwaZulu-Natal province (South Africa). The preimaginal stages were compared, looking for morphological evidence supporting species divergence. Linear and geometric morphometric analyses of the larval posterior respiratory process were conducted for the first time and the results of these analyses support the separation of the two taxa. Information about the life cycle and the relation with the host plant is also provided. In addition, we carried out a preliminary study of the adult feeding requirements of the species, based on the description of the mouthparts and an analysis of the pollen present in the gut and on the integument of adults. The results of the study supports a close relationship between the preimaginal stages and plant species of the Hyacinthaceae family.

Estimation of PMI for human remains wrapped in a blanket, with first report of Puliciphora rufipes (Phoridae) and Synthesiomyia nudiseta (Muscidae) outdoors in SE Spain.

The estimation of the minimum value of the postmortem interval is affected by well-known abiotic factors such as temperature and humidity, and others relating to the crime scene (e.g. the presence of direct sunlight or shade, immersion in water). However, there are few published data related to other variables that may exist, such as the presence of different insect species, wrapping of the body, or the presence or absence of maggot masses or predatory larvae. In this paper, a case report is presented in which the corpse of a homeless person was partially wrapped in a blanket. The corpse was found outdoors, in an open area in the province of Alicante (SE Spain). Empty puparia of different species of Diptera were collected during the autopsy. According to the insect development data, the minimum postmortem period was estimated and the influence of different factors, especially the effect of being wrapped in the blanket and the presence of the puparia of different species, was discussed. The entomological evidence includes the first record of Synthesiomyia nudiseta (van der Wulp, 1883) (Diptera: Muscidae) in outdoor conditions, and Puliciphora rufipes Silva Figueroa, 1916 (Diptera: Phoridae), which has not previously been recorded on human remains.

Description of the Third-Stage Larva and Puparium of Platycheirus (Carposcalis) chalconota (Philippi) (Diptera: Syrphidae) with New Information About the Trophic Interactions and Larval Habitats.

In this study, the third-stage larva and puparium of the copper-backed fly, Platycheirus (Carposcalis) chalconota (Philippi, 1865) are fully described using stereomicroscopy and scanning electron microscopy from material collected in peach orchards of central-west Argentina. The immature stages of P. chalconota were compared with the third-stage larva and puparium of the best-studied species in the genus Platycheirus scutatus (Meigen, 1822); as well as with the only known Carposcalis immature stages description available for the Neotropical region namely Platycheirus stegnus (Say, 1829). New data on trophic interactions and larval habitats are given: P. chalconota larvae were found feeding on the aphid's species Uroleucon sonchi (Linnaeus, 1767) (large sow thistle aphid) and Hyperomyzus lactucae (Linnaeus, 1758) (blackcurrant-sow thistle aphid) in low vegetation as Sonchus oleraceus (common sow thistle); the species was also found feeding on Myzus persicae (Sulzer, 1776) (green peach aphid) in high vegetation as Prunus persicae (L.) Stokes (Peach trees). The third larval stage and puparium of P. chalconota are described and illustrated for the first time improving substantially the knowledge about the immature stages and natural history of Neotropical Platycheirus, constituting also a baseline for future comparative morphological studies. Despite the efficiency of P. chalconota in the biological control of pests has not been assessed, we think that relevant data presented here can be used in pest management of peach orchards and suggest P. chalconota as an excellent candidate for future studies on the life cycle, prey consumption, efficiency, artificial rearing, and its potential importance as pollinators of Peach crops.

Age-stage two-sex life table analysis of Eristalinus aeneus (Diptera, Syrphidae) reared with two different larval media.

Eristalinus aeneus (Scopoli, 1763) is a suitable candidate for artificial rearing due to its pollination efficiency and subcosmopolitan distribution. However, the high mortality found at the larval stage of this species needs to be overcome. In this research, two different larval media were used to study the life cycle of E. aeneus: brewery spent grain (BSG) from a local craft-beer factory and soaked oat grains (SOG). The age-stage, two-sex life table method was used to analyze the results, which were compared using the paired bootstrap test. The greatest mortality was found at the larval stage with both media. Individuals fed on SOG presented a shorter preadult developmental time (22.05 days) than those reared with BSG (26.97 days). This fact had a direct impact on the total preoviposition period, it being shorter with SOG (34.36 days) than BSG (38.29 days), although the second provided a larger total number of eggs (19,242 eggs) and a faster adult maturation (10.67 days). The population parameters indicated that both populations will display a positive growth under the studied conditions, being the mean generation time (T) significantly shorter when using SOG (38.71 days) than BSG (45.95 days). Despite the preadult results pointing to SOG being a more efficient medium, the promising fecundity values provided by BSG, as well as it's lower cost and ecological benefits, suggest that this second medium could be improved and used as an alternative to SOG in the near future.

Coexistence and intraguild competition of Chrysomya albiceps and Lucilia sericata larvae: case reports and experimental studies applied to forensic entomology.

The larval development of Chrysomya albiceps and Lucilia sericata is a well-known and valuable tool for estimating the postmortem interval (PMI). The third instar larvae of Ch. albiceps are facultative predators of the larvae of other necrophagous dipterans, and this behaviour is undoubtedly an important factor to consider. Both species are found together during human autopsies in Spain and other parts of Europe, where they cohabit, so a precise knowledge of their larval coexistence data is essential. The aim of this study is to investigate their coexistence and the intraguild predation of Ch. albiceps on L. sericata under experimental conditions and in real case reports. To analyse intra- and interspecific competition, four densities were used under controlled abiotic conditions [25ºC, 60-70% RH and 12:12 (D:N)]. The experimental data were compared with data corresponding to their coexistence in natural conditions, so annual activity and forensic case reports for both species were studied. The results indicate that the mortality of immature specimens in both species, the preimaginal developmental time, and adult size were affected by competition. In natural conditions, adult coexistence during the spring-summer period was confirmed. The simultaneity of the two species colonising human corpses is frequent in the studied area, with Ch. albiceps being the dominant species, and L. sericata the relevant species for estimating the minimum postmortem interval.

Global population genetic structure and demographic trajectories of the black soldier fly, Hermetia illucens.

BACKGROUND: The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of farmed insects remain poorly characterised. We present the first comprehensive population genetic characterisation of H. illucens. Based on 15 novel microsatellite markers, we genotyped and analysed 2862 individuals from 150 wild and captive populations originating from 57 countries on seven subcontinents. RESULTS: We identified 16 well-distinguished genetic clusters indicating substantial global population structure. The data revealed genetic hotspots in central South America and successive northwards range expansions within the indigenous ranges of the Americas. Colonisations and naturalisations of largely unique genetic profiles occurred on all non-native continents, either preceded by demographically independent founder events from various single sources or involving admixture scenarios. A decisive primarily admixed Polynesian bridgehead population serially colonised the entire Australasian region and its secondarily admixed descendants successively mediated invasions into Africa and Europe. Conversely, captive populations from several continents traced back to a single North American origin and exhibit considerably reduced genetic diversity, although some farmed strains carry distinct genetic signatures. We highlight genetic footprints characteristic of progressing domestication due to increasing socio-economic importance of H. illucens, and ongoing introgression between domesticated strains globally traded for large-scale farming and wild populations in some regions. CONCLUSIONS: We document the dynamic population genetic history of a cosmopolitan dipteran of South American origin shaped by striking geographic patterns. These reflect both ancient dispersal routes, and stochastic and heterogeneous anthropogenic introductions during the last century leading to pronounced diversification of worldwide structure of H. illucens. Upon the recent advent of its agronomic commercialisation, however, current human-mediated translocations of the black soldier fly largely involve genetically highly uniform domesticated strains, which meanwhile threaten the genetic integrity of differentiated unique local resources through introgression. Our in-depth reconstruction of the contemporary and historical demographic trajectories of H. illucens emphasises benchmarking potential for applied future research on this emerging model of the prospering insect-livestock sector.

Revision of the Afrotropical genus Fainia Zumpt, 1958, with notes on the morphology of Rhiniidae subfamilies (Diptera, Oestroidea).

The taxonomy and diversity of Fainia Zumpt, 1958, an exclusive Afrotropical genus, had not been reviewed recently. The genus included six nominal species, but the status of several of them was debated. Identification of most Fainia species depends on characters of the male terminalia; females are poorly known and, in several cases, are not adequately diagnosed. We conducted a taxonomic revision of the genus and generated identification tools. Based on the study of type material and specimens available in entomological collections in Africa and Europe, we recognise here three of the six species as valid (F. albitarsis (Macquart, 1846), F. elongata (Bezzi, 1908) and F. inexpectata Zumpt, 1973). We also provide an identification key to both sexes, redescriptions of the species, updated distribution records and high resolution photographs of males' and females' habitus and male terminalia. The description of Fainia kagerana Lehrer, 2007a nom. nud. is an invalid nomenclatural act in terms of ICZN Article 13.1.1. Based on examinations of their holotypes, F. sambura Lehrer, 2008 syn. nov. is proposed as a junior synonym of F. albitarsis; F. kirinyaga Lehrer, 2007b syn. nov. is proposed as a junior synonym of F. inexpectata; and Fainia giriama Lehrer, 2007b is moved from the genus Fainia to the genus Rhinia Robineau-Desvoidy, as Rhinia giriama (Lehrer, 2007b) comb. nov.. We propose two apomorphies that support the status of the subfamily Rhiniinae.

Review of Synthesiomyia nudiseta (Diptera: Muscidae) as a useful tool in forensic entomology.

Synthesiomyia nudiseta (van der Wulp, 1883) is a synanthropic muscid found in tropical and subtropical zones around the world. The larvae of this species are a secondary agent of myiasis with necrophagous habits and play an important role in forensic entomology, as they are used as an indicator of post-mortem interval. Adults can be considered vectors of etiological agents such as Escherichia coli and Shigella dysenteriae. Due to its ability to adapt to different environmental conditions, its high dispersal capacity (shown by its introduction to Europe), its predatory habits in the last larval stage and the difficulty of identifying it, a very important goal is to update our knowledge about this species. Therefore, the main objective of this paper is to review the identification, geographical distribution and biology of this species in order to provide better support to investigations involving this fly.

Three new hoverfly species from Greece (Diptera: Syrphidae).

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 Vujic et Radenkovic sp. n. (Pindos Mountains), Paragus thracusi Radenkovic, Likov et Vujic sp. n. (Rhodope Mountains) and Psilota aegeae Vujic, 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 Vujic) have been given. In addition, the taxonomic status of Psilota anthracina Meigen has been discussed.

Intra-puparial development in the hoverflies Eristalinus aeneus and Eristalis tenax (Diptera: Syrphidae).

The intra-puparial development of 150 pupae of Eristalinus aeneus (Scopoli, 1763) and Eristalis tenax (Linnaeus, 1758) was analyzed. Individuals were obtained from the sixth laboratory generation kept under artificial rearing conditions at the facilities of the University of Alicante (Spain). The experiment was conducted at 25 ± 1°C temperature, 50 ± 5% relative humidity, and 12:12 hr (L:D) of photoperiod. Groups of 10 pupae were collected every 6 hr over 48 hr, after that period, pupae were collected daily until the adult emergence. They were fixed in 5% formic acid and preserved in 70% ethanol. Fixed pupae were dissected and photographed. The chronology and morphological changes that take place during the intra-puparial development in both species were analyzed and compared. Five phases were observed: prepupa, before 6 hr; cryptocephalic pupa, between 6 and 24 hr; phanerocephalic pupa, between 24 and 30 hr; pharate adult, after 30 hr; and the adult imago, restricted to the very end of the development process just before adult emergence. In total, the intra-puparial development lasted 189 ± 4 hr in E. aeneus and 192 ± 3 hr in E. tenax, with the pharate adult the longest phase (some 81% of the total developmental time). These data can be used to develop accurate cold storage protocols during artificial rearing of both pollinator species, avoiding critical events during the development and increasing survival.

The puzzling mitochondrial phylogeography of the black soldier fly (Hermetia illucens), the commercially most important insect protein species.

BACKGROUND: The black soldier fly (Diptera: Stratiomyidae, Hermetia illucens) is renowned for its bioconversion ability of organic matter, and is the worldwide most widely used source of insect protein. Despite varying extensively in morphology, it is widely assumed that all black soldier flies belong to the same species, Hermetia illucens. We here screened about 600 field-collected and cultured flies from 39 countries and six biogeographic regions to test this assumption based on data for three genes (mitochondrial COI, nuclear ITS2 & 28S rDNA) and in order to gain insights into the phylogeography of the species. RESULTS: Our study reveals a surprisingly high level of intraspecific genetic diversity for the mitochondrial barcoding gene COI (divergences up to 4.9%). This level of variability is often associated with the presence of multiple species, but tested nuclear markers (ITS2 and 28S rDNA) were invariant and fly strain hybridization experiments under laboratory conditions revealed reproductive compatibility. COI haplotype diversity is not only very high in all biogeographic regions (56 distinct haplotypes in total), but also in breeding facilities and research centers from six continents (10 haplotypes: divergences up to 4.3%). The high genetic diversity in fly-breeding facilities is mostly likely due to many independent acquisitions of cultures via sharing and/or establishing new colonies from field-collected flies. However, explaining some of the observed diversity in several biogeographic regions is difficult given that the origin of the species is considered to be New World (32 distinct haplotypes) and one would expect severely reduced genetic diversity in the putatively non-native populations in the remaining biogeographic regions. However, distinct, private haplotypes are known from the Australasian (N = 1), Oriental (N = 4), and the Eastern Palearctic (N = 4) populations. We reviewed museum specimen records and conclude that the evidence for introductions is strong for the Western Palearctic and Afrotropical regions which lack distinct, private haplotypes. CONCLUSIONS: Based on the results of this paper, we urge the black soldier fly community to apply molecular characterization (genotyping) of the fly strains used in artificial fly-breeding and share these data in research publications as well as when sharing cultures. In addition, fast-evolving nuclear markers should be used to reconstruct the recent invasion history of the species.

Revision of the Merodon serrulatus group (Diptera, Syrphidae).

The phytophagous hoverfly genus Merodon Meigen, 1803 (Diptera, Syrphidae), which comprises more than 160 species distributed in Palaearctic and Afrotropical regions, can be differentiated into multiple groups of species that harbor high levels of hidden diversity. In this work, the serrulatus species group of Merodon is revised, providing an illustrated key to species, a detailed discussion on the taxonomic characters and a morphological diagnosis, including also the first data about the preimaginal morphology of this species group. The study includes characteristics of the 13 species of the M. serrulatus group, along with the available distributional data. Moreover, descriptions are provided for seven new species, namely M. defectus Vujic, Likov & Radenkovic sp. nov., M. disjunctus Vujic, Likov & Radenkovic sp. nov., M. medium Vujic, Likov & Radenkovic sp. nov., M. nigrocapillatus Vujic, Likov & Radenkovic sp. nov., M. nigropunctum Vujic, Likov & Radenkovic sp. nov., M. opacus Vujic, Likov & Radenkovic sp. nov., and M. trianguloculus Vujic, Likov & Radenkovic sp. nov. In addition, the taxa M. serrulatus (Wiedemann in Meigen, 1822), M. bequaerti Hurkmans, 1993, M. hirsutus Sack, 1913, M. kawamurae Matsumura, 1916, M. sacki (Paramonov, 1936) and M. sophron Hurkmans, 1993 are redefined and redescribed. Following a detailed study of the type material sourced from different entomological collections, the status of all available taxa related to M. serrulatus is revised and a new synonymy is proposed: M. tener Sack, 1913 syn. nov. (junior synonym of M. serrulatus). The identity of M. trizonus (Szilády, 1940) could not be assessed as the type specimens are lost. Thus, the name M. trizonus is considered as nomen dubium. The monophyly and composition of this species group are assessed through Maximum Parsimony and Maximum Likelihood analyses of the mitochondrial COI and nuclear 28S rRNA gene sequences.

A world review of reported myiases caused by flower flies (Diptera: Syrphidae), including the first case of human myiasis from Palpada scutellaris (Fabricius, 1805).

Rat-tailed larvae of the syrphid species Palpada scutellaris (Fabricius, 1805) are documented causing an enteric human myiasis in Costa Rica. This is the first time that the genus Palpada is recorded as a human myiasis agent. We report a 68-year-old woman with intestinal pain and bloody diarrhea with several live Palpada larvae present in the stool. Using molecular techniques (DNA barcodes) and both electronic and optical microscopy to study the external morphology, the preimaginal stages of the fly were unambiguously identified. An identification key to all syrphid genera actually known as agents of human and animal myiases is provided for larvae, puparia, and adults. Moreover, a critical world review of more than 100 references of Syrphidae as myiasis agents is also given, with emphasis on the species with rat-tailed larvae.

Predatory behavior of Synthesiomyia nudiseta larvae (Diptera: Muscidae) on several necrophagous blowfly species (Diptera: Calliphoridae).

Intraguild interactions play a prominent role in sarcosaprophagous communities, so intraspecific and interspecific competition phenomena between fly larvae take place. Synthesiomyia nudiseta is a species that has recently been recorded on human corpses in Europe, and it has been cited in forensic cases in Spain and Italy. The mature larvae are known to be facultative predators on necrophagous fly larvae, but their role as predators is unknown. The aim of this paper is to investigate the predatory behavior of S. nudiseta on the most abundant blowfly larvae in sarcosaprophagous communities in southwestern Europe (i.e., Chrysomya albiceps, Lucilia sericata, and Calliphora vicina). Intraspecific and interspecific competition experiments were carried out to study the effect of this species in the necrophagous diptera community. First-instar larvae were placed in plastic cups with the same amount of pig liver (15 g) at different densities (50, 100, 150, and 300 individuals/cup). Mortality in blowflies increased when S. nudiseta larvae were present: up to 98.40% in Ch. albiceps, 89.60% in L. sericata, and 84.93% in C. vicina. Pre-imaginal developmental time and adult wing size were analyzed and compared under each of the intraspecific and interspecific conditions; both variables were affected by competition in all cases. The implications of the presence of S. nudiseta for sarcosaprophagous community dynamics and its effect on the estimation of postmortem interval (PMI) are discussed.

Review of the Merodon albifasciatus Macquart species complex (Diptera: Syrphidae): the nomenclatural type located and its provenance discussed.

The Palaearctic Merodon geniculatus species group (Diptera, Syrphidae: Merodontini) currently comprises six Western Mediterranean species and four species with Eastern Mediterranean distribution. One of this group species, Merodon albifasciatus Macquart, 1842, is the only Merodon species listed from the Oriental Region. We discovered the lost holotype, which fit morphologically with European Merodon females of the M. albifasciatus species complex confirmed here and that occurs in the Palaearctic region. An integrative approach to the taxonomy of M. albifasciatus based on morphological and molecular evidences revealed the existence of two additional closely-related species in the Eastern Mediterranean area, M. luteofasciatus Vujic, Radenkovic Ståhls sp. nov. and M. neofasciatus Ståhls Vujic sp. nov.. The females of these three species can only be separated by molecular and distributional data. With the aim of stabilising species concepts within the complex, the taxon distributed in mainland Greece, including the Peloponnese was associated to the old female holotype of M. albifasciatus. The identity of Merodon fractipes Paramonov, described from Rhodes Island (Greece) as subspecies of M. geniculatus Strobl in Czerny Strobl, could not be resolved as the type specimen is lost. Thus the name M. fractipes is suppressed as nomen dubium. We discuss the distribution of the species of M. albifasciatus complex, identify host plants of M. neofasciatus, and provide an identification key to males of Eastern Mediterranean species of Merodon geniculatus group.

Checklist and distribution maps of the blow flies of Venezuela (Diptera, Calliphoridae, Mesembrinellidae).

A checklist of the 39 species of blow flies (Calliphoridae and Mesembrinellidae) so far known to occur in Venezuela is provided, based on a thorough literature review and the examination of ca. 500 specimens deposited in the main entomological collections of the country. Data from the literature and museum collections were used to generate distribution maps for 37 species. Three species are recorded from Venezuela for the first time: Chrysomya putoria (Wiedemann, 1830), Mesembrinella spicata Aldrich, 1925 and Mesembrinella umbrosa Aldrich, 1922.

Where Is My Food? Brazilian Flower Fly Steals Prey from Carnivorous Sundews in a Newly Discovered Plant-Animal Interaction.

A new interaction between insects and carnivorous plants is reported from Brazil. Larvae of the predatory flower fly Toxomerus basalis (Diptera: Syrphidae: Syrphinae) have been found scavenging on the sticky leaves of several carnivorous sundew species (Drosera, Droseraceae) in Minas Gerais and São Paulo states, SE Brazil. This syrphid apparently spends its whole larval stage feeding on prey trapped by Drosera leaves. The nature of this plant-animal relationship is discussed, as well as the Drosera species involved, and locations where T. basalis was observed. 180 years after the discovery of this flower fly species, its biology now has been revealed. This is (1) the first record of kleptoparasitism in the Syrphidae, (2) a new larval feeding mode for this family, and (3) the first report of a dipteran that shows a kleptoparasitic relationship with a carnivorous plant with adhesive flypaper traps. The first descriptions of the third instar larva and puparium of T. basalis based on Scanning Electron Microscope analysis are provided.

Phylogeographic patterns of Merodon hoverflies in the Eastern Mediterranean region: revealing connections and barriers.

We investigated the phylogeographic patterns of Merodon species (Diptera, Syrphidae) in the Eastern Mediterranean. Ten species were sampled on five different islands and mainland sites as a minimum. All samples were screened for their mtDNA COI barcode haplotype diversity, and for some samples, we additionally generated genomic fingerprints. The recently established zoogeographic distribution categories classify these species as having (1) Balkan distribution; (2) Anatolian distribution; (3) continental areas and large islands distribution; and (4) with wide distribution. The ancestral haplotypes and their geographical localities were estimated with statistical parsimony (TCS). TCS networks identified as the ancestral haplotype samples that originated from localities situated within the distributional category of the species in question. Strong geographical haplotype structuring was detected for many Merodon species. We were particularly interested to test the relative importance of current (Aegean Sea) and past Mid-Aegean Trench) barriers to dispersal for Merodon flies in the Aegean. We employed phylogenetic ß-diversity (Pß total) and its partition in replacement (Pß repl) and richness difference (Pß rich) to test the importance of each explanatory variable (interisland distance, MAT, and island area) in interisland differences using partial Mantel tests and hierarchical partitioning of variation. ß-Analyses confirmed the importance of both current and past barriers to dispersal on the evolution of group. Current interisland distance was particularly important to explain the replacement of haplotypes, while the MAT was driving differences in richness of haplotypes, revealing the MAT as a strong past barrier whose effects are still visible today in the phylogenetic history of the clade in the Aegean. These results support the hypothesis of a highly restricted dispersal and gene flow among Merodon populations between islands since late Pleistocene. Additionally, patterns of phylogeographic structure deduced from haplotype connections and ISSR genome fingerprinting data revealed a few putative cases of human-mediated transfers of Merodon spp.