Search

The majority of Sitka spruce plantations in the UK are managed by clear-cutting and replanting, which leads to the formation of relatively large blocks (5–30 ha) of even-aged, closely spaced trees. These stands are considered to be poor in terms of general biodiversity and vulnerable to outbreaks of insect pests and diseases. In contrast, stands managed using alternative silvicultural systems, such as shelterwood or group selection systems, contain a wider range of tree ages and sizes and have the potential to support greater numbers of other species. If this includes the natural enemies (predators, parasitoids) of pest species, then adopting alternative silvicultural systems might help to reduce current and future pest impacts. To determine whether the greater structural complexity of stands managed using alternative silvicultural systems is associated with an increase in insect diversity and an increase in the abundance of predatory species, we sampled hoverflies (Diptera: Syrphidae) in 5 shelterwood stands, 6 group selection stands and 13 even-aged stands of Sitka spruce at 4 forest sites in mid and north Wales. The larvae of aphidophagous hoverflies are important invertebrate predators in spruce plantations, and hoverfly species richness is often used as an indicator of general invertebrate diversity. Hoverflies were sampled at ground level and in the canopy using yellow pan traps and flight interception traps. 7323 adult hoverflies of 74 species were captured, the majority of these in traps in the canopy. Total hoverfly abundance and the abundance of aphidophagous species were significantly higher ( P

Agricultural intensification is considered to be a major driver of terrestrial biodiversity decline. Resulting loss, isolation and degradation of flower-rich habitats are threatening pollinators. Agri-environmental schemes (AES) aim to counteract these negative effects, including measures to enhance floral resources in agricultural landscapes. The impact of plant species composition on their efficiency to mitigate pollinator loss, however, is largely unexplored. We tested four recommended seed mixtures for their attractiveness to wild bees and hoverflies in a replicated plot design over two consecutive years against the background of the seedbank. Of the 94 available plant species, 14 key plant species were crucial for the whole flower-visiting bee and hoverfly community. Approximately one third of each originated from the seedbank. The four top plants already supported 80% of flower visitors. Although seed mixtures differed significantly in attracting flower visitors at the plot level, the presence of key plants was more important than plant species diversity per se. Seed mixtures showed contrasting attractiveness for wild bees and hoverflies. Identification of plant species exclusively utilised by specific taxonomic groups opens opportunities for assorting plant mixtures for specific ecosystem functions or taxa of conservation concern. Plant species shared by common pollinators are valuable for overall pollinator diversity. The fact that rare and specialised pollinator species were mostly absent, however, substantiates that within 2 years of establishment, flowering resources are not the sole limiting factor in modern agricultural landscapes. Considering additional resources seems indispensable to maximise the conservation of species-rich pollinator communities.

The purpose of the study was to study features seasonal fluctuations in aggregate dynamics density interspecific biodiversity of natural populations of beneficial insects, pests and entomophages host of cereal aphids throughout the growing season of winter wheat in the steppes of Ukraine. Comparative, analytical, field, statistical and mathematical. The results of observations of the dynamics of aggregate density of harmful insect herbivores cereal aphids and their beneficial insect afidofahiv on winter wheat crops. Determined that the highest density of pests in crops of winter wheat was 19 - 110 copies. / 100 bursts of larvae and their entomophagous coccinellide was in the range of 10 to 105 specimens. / 100 bangs сonclusions. Based on our own research suggested making timely monitoring of harmful insect herbivores cereal aphids and their beneficial insect afidofahiv to establish and need chemical protection of winter wheat crops from herbivores. Proposals to make timely route inspection records pest density in two winter wheat growing season: spring, summer and autumn. Keywords: species diversity, natural interspecific populations koktsinelidy cereal aphids, galitsa, hoverfly, zlatohlazky, riders

The genus Eumerus Meigen (Diptera: Syrphidae) is considered one of the most species-rich hoverfly genera. Here, we present two new species, E. montanum Grkovic, Radenkovic et Vujic sp. nov. (Montenegro, Greece) and E. rubrum Grkovic et Vujic sp. nov. (Greece), and one species, E. uncipes Rondani, 1850, recorded for the first time in southeastern Europe. The species are members of three different taxon groups, respectively E. strigatus sensu Speight et al. (2013), E. tricolor sensu Chroni et al. (2017) and E. clavatus as defined here. Diagnostic characters for each of the three taxon groups and descriptions of the two new species are provided. In addition, we employed morphological and molecular data for available taxa of the E. strigatus taxon group in order to corroborate their taxonomical status and systematic position. Finally, we discuss the diversity of these taxon groups (E. clavatus, E. strigatus and E. tricolor) and give a detailed overview of the differences between closely-related species.

Responses of hoverflies (Diptera: Syrphidae) to climate change remain mostly unexplored. Here, for the first time, we investigate the impact of climate change on both presence/absence and abundances of hoverfly species. We used generalized linear models to analyse the relationships of climatic and soil variables with the occurrence and abundance of Cheilosia species on the Balkan Peninsula. Our results show that the ranges of all and the abundances of many species are projected to decrease in the future. Climatically suitable conditions for mountainous species are predicted to generally shift northwards. Species adapted to high mountains are projected to almost vanish from the Balkans and only regions of the Alps would remain suitable for them. We found climatic variables were more important in determining abundance than occurrence. Given that environmental factors differed in terms of their impact on abundance and occurrence, we highlight the importance of monitoring both parameters to ensure effective conservation. Considering the different projected responses of hoverflies to future climate change, as well as their value as pollinators and the increasing threats they currently face, knowledge on their responses to the major drivers of their life-histories is indispensable for proper management and conservation action. We reveal that nationally-designated protected areas are insufficient to conserve the species considered here, both currently and under projected climate change. We recommend implementation of an integrated conservation management plan that can provide a continuum of protected areas along the Dinaric mountain chain to facilitate movement of species to enhance species survival.

The fitness of natural enemies should be altered in response to changes in herbivore quality induced by the impact of increased atmospheric CO2 levels on plants. We studied the effect of different CO2 levels on the aphid predator Episyrphus balteatus DeGeer fed either specialist or generalist aphids reared on either of two host plants under laboratory conditions. In the host plant that contains sinigrin (black mustard), elevated CO2 increased the sinigrin content of both host plant and the specialist aphid, but reduced the already very low levels in the generalist aphid. Predator development time increased with elevated CO2, while fecundity decreased. Consequently, individual fitness decreased slightly with increasing atmospheric CO2. Sinigrin significantly decreased fecundity and increased development time of the predator. As a result, fitness was significantly lower too. The consumption rate was influenced significantly by plant and prey solely and the interactions of host plant × prey type and CO2 level × prey type. Further research on the effects of climate change parameters (e.g. greenhouse gases such as CO2, ozone (O3) and nitrogen dioxide (NO2), etc.) separately and jointly under controlled environmental conditions will help to understand the nature and direction of their effects on natural enemies as part of the tritrophic system.

Accumulating evidence shows that landscape fragmentation drives the observed worldwide decline in populations of pollinators, particularly in species of Lepidoptera and Hymenoptera. However, Little is known about the effects of landscape fragmentation on hoverfly (Diptera, Syrphidae) communities. Hoverflies provide varied ecosystem services: larvae contribute to waste decomposition (saprophagous species) and pest control (aphidophagous species), and adults pollinate a wide range of flowers.To determine how the diversity and quantity of resources for larvae and adults affect hoverfly abundance and species richness at three spatial scales, we recorded insect visitors of five target plant species in Belgian heathlands, habitats that have decreased considerably due to human activities.Hoverflies represented the most abundant visitors on two plant species, and the second most abundant visitors (after bumblebees) on the other target plant species. A large proportion of hoverflies observed were aphidophagous species associated with coniferous and deciduous forests. Resources for the larvae and floral resources for the adults influenced interactions among hoverflies and plants, but acted at different scales: larval habitat availability (distance to larval habitat) was relevant at the landscape scale, whereas adult resource availability (floral density) was relevant at the plot scale.Hoverfly abundance and species richness decreased with distance to larval habitat but increased with floral density. Moreover, landscape structure and composition had different effects according to hoverfly ecological traits. Landscape composition influenced aphidophagous but not saprophagous hoverflies, in that their abundance and species richness decreased with distance to forests. Maintenance of the interactions between plants and their hoverfly visitors requires complementary resources at both landscape and local scales.

Since the time of Darwin, biologists have considered the floral nectar spur to be an adaptation representing a high degree of plant specialization. Nevertheless, some researchers suggest that nature is more complex and that even morphologically specialized plants attract a wide spectrum of visitors. We observed visitors on Impatiens burtonii (Balsaminaceae) and measured the depth of the proboscis insertion into the spur, the distance of the nectar surface from the spur entrance and the visitor's effectiveness. The hoverfly Melanostoma sp., with the shortest proboscis, was most active early in the morning and fed on pollen and nectar near the spur entrance. The honeybee Apis mellifera and the hoverfly Rhingia mecyana were the most frequent visitors before and after noon, respectively. Although R. mecyana, the only visitor able to reach the end of the spur, was the most frequent, it did not deposit the largest number of pollen grains per visit. Nectar spurs may function as complex structures allowing pollination by both short- and long-proboscid visitors and separating their spatial and temporal niches. Spurred plants should be considered as more generalized and exposed to more diverse selection pressures than previously believed.

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining both strategies can be an interesting way to maximize pest control. In this work, a 2-year setup involving wheat–pea strip intercropping combined with the release of E-β-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repel aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with the intercropping. The abundance of aphids was significantly decreased, while hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of the aphid-parasitism rate [mummies/(aphids + mummies)] was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides.

Pollinator-driven diversification is thought to be a major source of floral variation in plants. Our knowledge of this process is, however, limited to indirect assessments of evolutionary changes. Here, we employ experimental evolution with fast cycling Brassica rapa plants to demonstrate adaptive evolution driven by different pollinators. Our study shows pollinator-driven divergent selection as well as divergent evolution in plant traits. Plants pollinated by bumblebees evolved taller size and more fragrant flowers with increased ultraviolet reflection. Bumblebees preferred bumblebee-pollinated plants over hoverfly-pollinated plants at the end of the experiment, showing that plants had adapted to the bumblebees' preferences. Plants with hoverfly pollination became shorter, had reduced emission of some floral volatiles, but increased fitness through augmented autonomous self-pollination. Our study demonstrates that changes in pollinator communities can have rapid consequences on the evolution of plant traits and mating system., Pollinators are thought to be a driver of plant diversification, but their effects are difficult to disentangle from those of other biotic and abiotic factors. Here, the authors let plants evolve under different pollination regimes and show rapid and divergent evolution of plant height, floral traits and mating system.

Temporal comparisons of a site's biodiversity depend on the availability of at least two asynchronous data sets on a bioindicator group. The Sierra de Guadarrama, a mountain range in central Spain has a high biodiversity and representative sites such as El Ventorrillo Biological Station (Madrid province) play an important role in research and monitoring of the Sierra biodiversity. Although unevenly and randomly, hoverflies of the Sierra de Guadarrama have been surveyed for decades, but never at El Ventorrillo. This important group of pollinators, aphid predators and bioindicators was sampled with a Malaise trap at El Ventorrillo from June 1989 to June 1990. A total of 51 species were identified (20 spp. of Eristalinae and 31 spp. of Syrphinae), 22 of which were new to the Sierra de Guadarrama and 17 to the Madrid province. The genera Brachypalpus and Didea were also new to the Madrid province. The Sierra de Guadarrama now has 126 species recorded and the Madrid province 150. Within the Sierra de Guadarrama, El Ventorrillo becomes the second locality in number of hoverfly species recorded after El Escorial (64 spp.). In the Malaise trap catch, hoverflies with zoophagous larvae had a higher representation than those of other guilds, both in species richness and abundance. The results provided here for El Ventorrillo represent a baseline for future biodiversity studies at this site with a similar experimental design, for example, to detect changes in hoverfly diversities along time., This study belongs to the ‘Fauna Ibérica’ Project PGC2018-095851-A-C65A (Ministerio de Ciencia, Innovación y Universidades, Spain).

The various forms of Criorhina ranunculi (Panzer, 1804) in the canton of Geneva (Diptera: Syrphidae) with a key to separate the forms of this species. – The polymorphic species Criorhina ranunculi (Panzer, 1804) comprises visibly at least three different forms in Europe. Two of these forms are now known from Geneva, one of them closely resembling Criorhina pachymera. For the first time a key is presented, separating these two forms from one another and from C. pachymera. Records of C. ranunculi from Geneva are listed. It is concluded that the taxonomic status of the forms of C. ranunculi requires genetic investigation.

Two species of Diptera new for Switzerland (Syrphidae and Stratiomyidae) and complements to the list of Syrphidae of the canton of Geneva. – An ecological and faunistic study of the Moulin-de-Vert nature reserve (Cartigny, Geneva), carried out by Malaise trap from April to July 2019, revealed the presence of two species of Diptera new to Switzerland: Brachyopa obscura Thompson & Torp 1982 (Syrphidae) and Odontomyia annulata (Meigen, 1822) (Stratiomyidae). This study, together with other observations from the canton of Geneva, have added a total of nine new species to the list of Syrphidae in the canton and have confirmed the presence of 16 other species only known from historical records. A number of species recorded at Moulin-de-Vert, such as Criorina pachymera (Egger, 1858) and Mesembrius peregrinus (Loew, 1846), are only very rarely recorded in Switzerland. These results highlight the importance of this site, protected since 1970, and the fundamental role it plays in the conservation of biodiversity on both a cantonal and national scale.

The intensification of agricultural practices contributes to the decline of many taxa, such as insects and weeds. Wildflower species have an important environmental impact on rural biodiversity since plant-pollinator networks play a key role in both landscape aesthetics and environmental functionality. Due to their scarcity and/or disappearance in conventional agroecosystems, wildflowers are now being used in strips to restore the agro-environment. In this study, fifteen wildflower species were sown in order to verify their ecological performance in terms of a plant-pollinator interaction while in laboratory the several chemicals emitted by the flowers were identified. Flowering periods were concentrated in the spring, although flowering periods extended to the hot and dry summer months in some species. An extreme variability was found in terms of quantitative and qualitative pollinator-attractiveness (i.e., bees, bumblebees, hoverfly, bee flies and butterflies). Most wildflower species emit a volatiles belonging above all to one of the several chemical classes. A hierarchical cluster analysis of the different volatile emissions did not fully correlate with the botanical taxa of the respectives wildflowers. Often, single chemical compounds prevailed, such as β-ocimene and limonene among monoterpenes hydrocarbons, santolina alcohol in the case of oxygenated monoterpenes, or (Z)- or (E)-3-hexenol acetate for non-terpenes derivatives. It is believed that these chemical compounds can play an ecological role in plant-pollinator food webs. The hypothesis that the chemistry of the volatiles implies a specialized plant-pollinator co-evolution was confirmed by a significant regression (p

This paper presents the results of the one-year field research into the hoverfly (Diptera: Syrphidae) in Mareschi, in Sant’Antonino di Susa municipality. The sampling activities were performed with Malaise trap, emerging trap, and entomological net. Monitoring was carried out from March to October 2018 in the over-mature alder forest, classified under the Natura 2000 Habitat code 91E0, considered as a priority in EU 92/43 Habitats Directive. Preliminary data from July to October 2017 are also included. Overall, 74 species were recorded, with the first records of 7 species for Piedmont. Some of the observed species in Mareschi are of primary conservation importance, such as Arctophila superbiens (Müller, 1776), Sphiximorpha subsessilis (Illiger in Rossi, 1807) and Temnostoma bombylans (Fabricius, 1805). The use of Syrph the Net analysis and the comparison with other woods in Po Plain confirm the high naturalistic value of the studied area., Fragmenta Entomologica, Vol. 52 No. 1 (2020)

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrus vladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew., This research was partially funded by an Instituto Nacional de Investigaciones Agrarias (INIA) (Project RTA2017-00095) and the Conselleria d’Agricultura, Pesca i Alimentació de la Generalitat Valenciana. J.G.C was supported by the Spanish Ministry of Economy and Competitiveness, Ramón y Cajal Program (RYC-2013-13834) and M.C.A was recipient of grant from INIA (CPD2016-0085).

International audience; For plant–pollinator interactions to occur, the flowering of plants and the flying period of pollinators (i.e. their phenologies) have to overlap. Yet, few models make use of this principle to predict interactions and fewer still are able to compare interaction networks of different sizes. Here, we tackled both challenges using Bayesian structural equation models (SEM), incorporating the effect of phenological overlap in six plant–hoverfly networks. Insect and plant abundances were strong determinants of the number of visits, while phenology overlap alone was not sufficient, but significantly improved model fit. Phenology overlap was a stronger determinant of plant–pollinator interactions in sites where the average overlap was longer and network compartmentalization was weaker, i.e. at higher latitudes. Our approach highlights the advantages of using Bayesian SEMs to compare interaction networks of different sizes along environmental gradients and articulates the various steps needed to do so.

Carnivorous plants are major predators of small insects in some habitats. Because traps of carnivorous plants are serious threats for small insects, it is probable to evolve a mechanism to sense a cue of carnivorous plants and avoid being trapped. However, such a sensing behavior of small insects has never been described. Here we report that a hoverfly species Sphaerophoria menthastri, a major pollinator species of carnivorous sundew Drosera toyoakensis, exhibits a behavior to sense a cue of trap leaves and avoids landing there. In a quadrat (5 m × 5 m) where D. toyoakensis and other non-carnivorous plant species co-occur, we observed behaviors of hoverflies approaching D. toyoakensis and other plants. The numbers of approaches to trap leaves, flowers of D. toyoakensis, flowers of non-carnivorous Lysimachia fortunei and leaves of Poaceae and Cyperaceae were 9, 60, 52 and 54, respectively, and the numbers of landings to those four organs were 2, 55, 49 and 49, respectively. When S. menthastri approached trap leaves, almost all individuals successfully avoided landing there by 1 or 2 hesitation behaviors. These findings suggest that S. menthastri can sense the cue of trap leaves during an approach.

1. The status of pollinating insects is of international concern, but knowledge of the magnitude and extent of declines is limited by a lack of systematic monitoring. Standardized protocols are urgently needed, alongside a better understanding of how different methods and recorders (data collectors) influence estimates of pollinator abundance and diversity. 2. We compared two common methods for sampling wild pollinating insects (solitary bees, bumblebees and hoverflies), pan traps and transects, in surveys of 1 km countryside squares (agricultural and semi‐natural habitats) and flowering crop fields across Great Britain, including the influence of local floral resources (nectar sugar availability or crop flower density) on the insects sampled. Further, we compared the performance of recorders with differing expertise (non‐specialist research staff, taxonomic experts and non‐expert volunteers) in applying methods. 3. Pan traps and transects produced compositionally distinct samples of pollinator communities. In the wider countryside, pan traps sampled more species of solitary bee and hoverfly. In flowering crops, transects recorded a greater number of individual bumblebees, but fewer species. 4. Across all taxonomic groups and countryside and crop samples, transects generally had lower rates of species accumulation per individual collected than pan traps. This demonstrates that differences between methods in estimating richness are not due to sampling effort alone. However, recorders possessing greater taxonomic expertise can produce species accumulation data from transects that are almost commensurate with pan trapping. 5. The abundance and species richness of pollinators (except solitary bees) on transects in the wider countryside was positively related to the availability of estimated nectar sugar. In crops, pollinator abundance responses to flower densities were idiosyncratic according to crop type, but overall the response was positive and negative for transects and pan traps, respectively. 6. Given these taxonomic and context‐specific differences in method performance, we assess their suitability for monitoring pollinating insect communities and pollination services. We discuss the relevance of these findings within the context of achieving standardized, large‐scale monitoring of pollinating insects.

Methyl salicylate (MeSA) is an herbivore-induced plant volatile (HIPV) known to attract the natural enemies of herbivores in agro-ecosystems, however, whether this attraction leads to an increase in natural enemy functioning, i.e., predation, remains largely unknown. Here, we monitored for 2 years (2011&ndash, 2012) the response of herbivores and natural enemies to MeSA lures (PredaLure) by using sticky and pitfall traps in cranberry bogs. In addition, European corn borer, Ostrinia nubilalis, egg masses were used to determine whether natural enemy attraction to MeSA leads to higher predation. In both years, MeSA increased adult hoverfly captures on sticky traps and augmented predation of O. nubilalis eggs. However, MeSA also attracted more phytophagous thrips and, in 2012, more plant bugs (Miridae) to sticky traps. Furthermore, we used surveillance cameras to record the identity of natural enemies attracted to MeSA and measure their predation rate. Video recordings showed that MeSA lures increase visitation by adult lady beetles, adult hoverflies, and predatory mites to sentinel eggs, and predation of these eggs doubled compared to no-lure controls. Our data indicate that MeSA lures increase predator attraction, resulting in increased predation, thus, we provide evidence that attraction to HIPVs can increase natural enemy functioning in an agro-ecosystem.

The phytophagous hoverfly genusMerodonMeigen, 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, theserrulatusspecies group ofMerodonis 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 theM. serrulatusgroup, along with the available distributional data. Moreover, descriptions are provided for seven new species, namelyM. defectusVujić, Likov & Radenkovićsp. nov.,M. disjunctusVujić, Likov & Radenkovićsp. nov.,M. mediumVujić, Likov & Radenkovićsp. nov.,M. nigrocapillatusVujić, Likov & Radenkovićsp. nov.,M. nigropunctumVujić, Likov & Radenkovićsp. nov.,M. opacusVujić, Likov & Radenkovićsp. nov., andM. trianguloculusVujić, Likov & Radenkovićsp. nov.In addition, the taxaM. serrulatus(Wiedemann in Meigen, 1822),M. bequaertiHurkmans, 1993,M. hirsutusSack, 1913,M. kawamuraeMatsumura, 1916,M. sacki(Paramonov, 1936) andM. sophronHurkmans, 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 toM. serrulatusis revised and a new synonymy is proposed:M. tenerSack, 1913syn. nov.(junior synonym ofM. serrulatus). The identity ofM. trizonus(Szilády, 1940) could not be assessed as the type specimens are lost. Thus, the nameM. trizonusis considered asnomen 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.

The genus Merodon Meigen (Diptera: Syrphidae) is distributed throughout the Palaearctic and Ethiopian regions, and is characterized by a large number of species groups comprising taxa with subtle morphological differences. The taxonomic status and identification of many species still requires clarification. The adults of Merodon species are well studied, especially since various recent publications successfully used an integrative taxonomic approach, combining morphological and molecular information. The immature stages of this phytophagous genus, however, remain understudied, with the descriptions of larvae and/or puparia published for roughly just 5% of species. Considering both published and new data, this study aims to review and to re-evaluate the main diagnostic morphological characters of the preimaginal stages and to assess the importance of these traits as taxonomic tools for delimitation within the genus. Features distinctive among different species are mostly associated with the posterior respiratory process, pupal spiracles and cephalopharyngeal skeleton. Potentially diagnostic features are recognized for four well-supported lineages (putative subgenera) within the genus Merodon (avidus-nigritarsis, albifrons+desuturinus, aureus and natans) defined by adult morphological and molecular characters; however, no clear pattern is achieved for all studied taxa at this level. Furthermore, certain characters previously considered as species-specific turned out to be rather ambiguous. This study confirms the need for both more species and more specimens of Merodon immature stages to be examined and compared in order to obtain better supported conclusions.

In October 2017 an international expedition to Cyprus was made in order to collect hoverflies (Diptera: Syrphidae) and to improve knowledge of the local fauna. In twelve days, numerous localities were visited in a wide range of habitats, where Syrphidae were collected by hand net. Malaise and pan traps were placed in some sam-pling localities around the Troodos Mountains. In total, 52 Syrphidae species were collected, 23 of which represent new species records for the island and another three belong to undescribed taxa. Newly obtained DNA data from the genera Merodon and Ceriana indicate a large interspecific morphological variation within Merodon sp. nov. 1 and support the recent split of C. glaebosa Van Steenis Ricarte, 2016 from C. vespiformis (Latreille, 1809).

As a result of the study of the hoverfly subtribe Xylotina in Korea, we have recognized the following 14 Xylota species, including eight new to the Korean syrphid fauna (marked with asteristks) and three new to science: X. abiens, X. amaculata*, X. atricoloris*, X. coquilletti, X. filipjevi*, X. fo*, X. ignava, X. pseudoignava*, X. spurivulgaris*, X. tarda*, X. umbrosa*, X. hauseri sp. n., X. orientiflorum sp. n., and X. xanthotarsis sp. n. Among these species, we clarified the identities of three previously confused species, X. coquilletti, X. spurivulgaris and X. fo, which had been collectively identified as a single species, X. coquilletti, in the Korean literature. In addtion, we provided unequivocal characters to separate two sibling species pairs based on their external characters including genitalic structure (X. hauseri sp. n. vs. X. umbrosa; X. pseudoignava vs. X. xanthotarsis sp. n.; X. filipjevi vs. X. tarda). In order to aid accurate identification of the Korean Xylota, diagnoses, descriptions, and color photographs of external structures including male genitalia are provided. For the taxonomic key, we included all the Korean genera of the subtribe Xylotina (Xylota, Brachypalpus and Chalcosyrphus).

Many animals use motion vision information to control dynamic behaviors. For example, flying insects must decide whether to pursue a prey or not, to avoid a predator, to maintain their current flight trajectory, or to land. The neural mechanisms underlying the computation of visual motion have been particularly well investigated in the fly optic lobes. However, the descending neurons, which connect the optic lobes with the motor command centers of the ventral nerve cord, remain less studied. To address this deficiency, we describe motion vision sensitive descending neurons in the hoverflyEristalis tenax. We describe how the neurons can be identified based on their receptive field properties, and how they respond to moving targets, looming stimuli and to widefield optic flow. We discuss their similarities with previously published visual neurons, in the optic lobes and ventral nerve cord, and suggest that they can be classified as target-selective, looming sensitive and optic flow sensitive, based on these similarities. Our results highlight the importance of using several visual stimuli as the neurons can rarely be identified based on only one response characteristic. In addition, they provide an understanding of the neurophysiology of visual neurons that are likely to affect behavior.

Despite the fact that migratory insects dominate aerial bioflows in terms of diversity, abundance, and biomass [1, 2, 3, 5, 6], the migration patterns of most species, and the effects of their annual fluxes between high- and low-latitude regions, are poorly known. One important group of long-range migrants that remain understudied is a suite of highly beneficial species of hoverfly in the tribe Syrphini, which we collectively term “migrant hoverflies.” Adults are key pollinators [7, 8, 9, 10] and larvae are significant biocontrol agents of aphid crop pests [11], and thus, it is important to quantify the scale of their migrations and the crucial ecosystem services they provide with respect to energy, nutrient, and biomass transport; regulation of crop pests; and pollen transfer. Such assessments cannot be made by sporadic observations of mass arrivals at ground level, because hoverflies largely migrate unnoticed high above ground. We used insect-monitoring radars [12] to show that up to 4 billion hoverflies (80 tons of biomass) travel high above southern Britain each year in seasonally adaptive directions. The long-range migrations redistribute tons of essential nutrients (nitrogen [N] and phosphorus [P]) and transport billions of pollen grains between Britain and Europe, and locally produced populations consume 6 trillion aphids and make billions of flower visits. Migrant hoverfly abundance fluctuated greatly between years, but there was no evidence of a population trend during the 10-year study period. Considering that many beneficial insects are seriously declining [7, 10, 13, 14, 15, 16, 17, 18, 19], our results demonstrate that migrant hoverflies are key to maintaining essential ecosystem services.

BackgroundAngiosperms employ an astonishing variety of visual and olfactory floral signals that are generally thought to evolve under natural selection. Those morphological and chemical traits can form highly correlated sets of traits. It is not always clear which of these are used by pollinators as primary targets of selection and which would be indirectly selected by being linked to those primary targets. Quantitative genetics tools for predicting multiple traits response to selection have been developed since long and have advanced our understanding of evolution of genetically correlated traits in various biological systems. We use these tools to predict the evolutionary trajectories of floral traits and understand the selection pressures acting on them.ResultsWe used data from an artificial and a pollinator (bumblebee, hoverfly) selection experiment with fast cyclingBrassica rapaplants to predict evolutionary changes of 12 floral volatiles and 4 morphological floral traits in response to selection. Using the observed selection gradients and the genetic variance-covariance matrix (G-matrix) of the traits, we showed that the responses of most floral traits including volatiles were predicted in the right direction in artificial- and bumblebee-selection experiment, revealing direct and indirect targets of bumblebee selection. Genetic covariance had a mix of constraining and facilitating effects on evolutionary responses. We further revealed how G-matrices evolved in the selection processes.ConclusionsOverall, our integrative study shows that floral signals, and especially volatiles, evolve under selection in a mostly predictable way, at least during short term evolution. Evolutionary constraints stemming from genetic covariance affected traits evolutionary trajectories and thus it is important to include genetic covariance for predicting the evolutionary changes of a comprehensive suite of traits. Other processes such as resource limitation and selfing also needs to be considered for a better understanding of floral trait evolution.

The current study was continued from March 2016 to April 2017. The specimens of the genus Scaeva Fabricius were collected from different localities of Balochistan. Two species Scaeva albomaculata Macquart and Scaeva selenitica Meigen were identified and described. Saeva albomaculata Macquart is first time recorded from Balochistan province of Pakistan and Scaeva selenitica Meigen is new country record. These species were identified on the bases of morphological characteristics, body coloration, male and female genitalia. The identification and description of these new records will serve as an important contribution in the insect fauna of Balochistan and Pakistan. Furthermore both the identified species are aphidophagous on serious pests of various crops so these can be used for the biological control of various pests. Keywords: Balochistan; Hoverfly; Scaeva Fabricius; Syrphidae http://dx.doi.org/10.19045/bspab.2019.80069

Various organisms, especially arthropods, are able to live as parasites in ant nests and to prey upon ant broods without eliciting any aggressive behaviour in the hosts. Understanding how these intruders are able to break the ants' communication codes in their favour represents a challenging and intriguing evolutionary question. We studied the chemical strategies of three European hoverfly species, Microdon mutabilis (parasitic on Formica cunicularia), M. analis (parasitic on Lasius emarginatus) and M. devius (parasitic on L. distinguendus). The peculiar slug-like larvae of these three species live inside ant nests feeding upon their broods. Gas chromatography-mass spectrometry analyses show that: 1) these parasites mimic the host brood rather than the ant workers, although each differs distinctly in the extent of chemical mimicry; 2) isolation experiments indicate that after 14days the responsible cuticular hydrocarbons (CHCs) are not passively acquired but synthesized by the fly larvae. Additionally, Microdon larvae show an array of protective structural features, such as a thick and multi-layered cuticle, retractable head, dome-shaped tergum and a flat and strongly adhesive "foot" (sternum). This combination of protective chemical and structural features represents a successful key innovation by Microdon species, and one that may facilitate host switching. The results of a preliminary adoption analysis confirm that Microdon larvae of at least some species can readily be accepted by different species of ants.

The hoverfly,Eupeodes corollae,is a worldwide natural enemy of aphids and a plant pollinator. To provide insights into the biology of this species, we examined its population genetic structure by obtaining 1.15-GB random genomic sequences using next-generation sequencing and developing genome-wide microsatellite markers. A total of 79,138 microsatellite loci were initially isolated from the genomic sequences; after strict selection and further testing of 40 primer pairs in eight individuals, 24 polymorphic microsatellites with high amplification rates were developed. These microsatellites were used to examine the population genetic structure of 96 individuals from four field populations collected across southern to northern China. The number of alleles per locus ranged from 5 to 13 with an average of 8.75; the observed and expected heterozygosity varied from 0.235 to 0.768 and from 0.333 to 0.785, respectively. Population genetic structure analysis showed weak genetic differentiation among the four geographical populations ofE. corollae, suggesting a high rate of gene flow reflecting likely widespread migration ofE. corollaein China.

The 16 world species of Sphecomyia Latreille are revised, including seven previously undescribed species (S.cryptica Moran, sp. n., S.hoguei Moran, sp. n., S.interrupta Moran, sp. n., S.oraria Moran, sp. n., S.pseudosphecomima Moran, sp. n., S.sexfasciata Moran, sp. n., and S.weismani Moran, sp. n.). Descriptions, redescriptions, male genitalia photographs, distribution maps, and an illustrated key for all Sphecomyia are presented. DNA barcode data are provided for all 16 species with a cytochrome oxidase subunit I gene tree presented and discussed. Sphecomyiastat. rev. is redefined to represent the monophyletic lineage of species within subtribe Criorhinina possessing a bare, medial vitta extending ventrally from the oral margin in both sexes, a bare gena, a bare katepimeron, a scutellum with at least anterior margin densely pruinose, an anterior ventral half of vein C before crossvein h without setae, and a narrow intersection of vein R1 with vein C. Three species groups of Sphecomyia are identified: the S.vittata group which possess pruinose scutellar vittae, the S.pattonii group which lack pruinose scutellar vittae, and S.metallica (Bigot), a hairy bee mimic with a completely pruinose scutum. Criorhinatsherepanovi Violovitsh is resurrected and transferred, along with Criorhinaaino Stackelberg, to the genus Sphecomyia: S.tsherepanovi (Violovitsh), comb. n. and S.aino (Stackelberg), comb. n.Criorhinametallica (Bigot) is designated as the senior synonym of C.lupina (Williston), not junior as improperly treated, and transferred to Sphecomyia: S.metallica (Bigot), comb. n. The species Sphecomyiafusca Weisman, S.nasica Osburn, and S.occidentalis Osburn are transferred to Criorhina Meigen: C.fusca (Weisman), comb. n., C.nasica (Osburn), comb. n., and C.occidentalis (Osburn), comb. n.

Pollination is a critical ecosystem service underpinning the productivity of agricultural systems across the world. Wild insect populations provide a substantial contribution to the productivity of many crops and seed set of wild flowers. However, large-scale evidence on species-specific trends among wild pollinators are lacking. Here we show substantial inter-specific variation in pollinator trends, based on occupancy models for 353 wild bee and hoverfly species in Great Britain between 1980 and 2013. Furthermore, we estimate a net loss of over 2.7 million occupied 1 km2 grid cells across all species. Declines in pollinator evenness suggest that losses were concentrated in rare species. In addition, losses linked to specific habitats were identified, with a 55% decline among species associated with uplands. This contrasts with dominant crop pollinators, which increased by 12%, potentially in response agri-environment measures. The general declines highlight a fundamental deterioration in both wider biodiversity and non-crop pollination services., Pollinator loss is a concern but data on their status is lacking. Here Powney et al. use occupancy modelling to estimate the degree of loss in wild bee and hoverfly species across Great Britain, and report a 55% decline in upland species and a 12% increase in dominant crop pollinators.

The adaptive benefits of individual specialization and how learning abilities correlate with task performance are still far from being well-understood. Red wood ants are characterised by their huge colonies and deep professional specialization. We hypothesized that red wood ants Formica aquilonia form aversive learning after having negative encounters with hoverfly larvae differently, depending on their task specialization. We tested this hypothesis, first, by examining whether hunters and aphid milkers learn differently to avoid the nuisance of contacts with syrphid larvae, and, second, by analysing the difference between learning in ‘field’ and laboratory-reared (naive) foragers. During the first interaction with the syrphid larva in their lives the naive foragers showed a significantly higher level of aggressiveness than the members of a natural colony. Naive foragers applied the ‘mortal grip’, ‘prolonged bites’, and ‘nibbling’ towards the enemy with a significantly higher frequency, whereas members of both ‘field’ groups behaved more carefully and tried to avoid encounters with the larva. The aphid milkers, who had a negative experience of interaction with the larva, being ‘glued’ with its viscous secretion, behaved much less aggressively in the follow-up experiments after ten minutes and even three days, thus exhibiting the shaping of both short- and long-term memories. However, both ‘field’ hunters and naive foragers demonstrated no signs of aversive learning. These data provide some new insights into the relationship between task specialization and learning performance in ants. Given our previous results, we speculate that scouts and aphid milkers are the most cognitively gifted specialists in red wood ants, whereas hunters and guards are rather brave than smart.

Diaphorina citri (Hemiptera: Liviidae) is a notorious citrus pest that vectors a bacterium that causes huanglongbing, a lethal citrus disease. Studies evaluating the potential of buckwheat (Fagopyrum esculentum), alyssum (Lobularia maritima), phacelia (Phacelia tanacetifolia), and California poppy (Eschscholzia californica) as insectary plants for conservation biological control of D. citri were conducted in California citrus orchards. Field studies assessed flowering phenology and attractiveness to hoverflies and other natural enemies, hoverfly oviposition on D. citri colonies, and the effect of potted alyssum and predation from hoverflies on the mortality of D. citri nymphs. Laboratory studies quantified lifetime consumption of D. citri nymphs by individual Allograpta obliqua (Diptera: Syrphidae) larvae, the only hoverfly species attacking D. citri in the field. Results indicated that alyssum and buckwheat possessed a short sowing to flowering time (30–33 days when sown in March) and attracted 10–20 times more syrphids than California poppy. No hoverflies were observed feeding from phacelia. California poppy was marginally attractive to hoverflies, and failed to attract ladybugs, parasitoids, or predatory wasps. When alyssum was present in an unsprayed citrus orchard, the number of hoverfly eggs laid on D. citri colonies and abundance of predators was 3.5 times and 2.5 times higher, respectively, when compared to control plots lacking alyssum. Consequently, 10% more D. citri nymphs survived to adulthood in the control plots compared to alyssum plots. In the laboratory, individual A. obliqua larvae consumed, on average, 421 D. citri nymphs before pupation. Results demonstrate that A. obliqua is an important and voracious predator of D. citri nymphs, and that alyssum and buckwheat show potential as insectary plants for conservation biological control of D. citri.

The foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), has become a significant pest in horticulture as it can build high populations from 10 to 18 °C, when no commercially available biocontrol agent is efficient. The American hoverfly, Eupeodes americanus (Wiedemann) (Diptera: Syrphidae), has demonstrated good active flight, oviposition, and larval voracity at low temperature. In the present study, the efficiency of a banker plant system using the American hoverfly was evaluated in a cage experiment (enclosed space) and commercial greenhouses (open environment) at production temperatures (heating temperature was 18 °C). The results demonstrate that banker plants with the American hoverfly provided an adequate control of foxglove aphid populations in both environments. In a cage experiment, the predator used the banker plant for nutritional resources and successfully developed and reproduced on them. Green pepper plants infested by foxglove aphids and exposed to hoverflies show a significantly lower abundance of aphids by the end of the trial, compared to the control cages. In commercial greenhouses (real situation), adult hoverflies were able to mate, locate infested plants, and oviposit. Subsequently their offspring provided an efficient control of aphid populations after 6 weeks. This study demonstrates the high potential of a banker plant using hoverflies in greenhouse environments. It also demonstrates the importance of studying new potential biocontrol agents.

Wild bees, hoverflies and wasps are valuable ecosystem service providers in agricultural systems through pollination and biological control, and their species richness, abundance and reproductive success well indicate ecosystem health. However, they are often limited by foraging and nesting resources that are major drivers behind their steep decline. Although agri-environmental measurements improve resources for these groups, their wider landscape-scale impacts are basically unknown. Here, we questioned whether 2–3 years old, sown set-aside fields could have a potential in enhancing pollinator and predatory wasp communities at the landscape scale in a Central European agroecosystem. We measured reproductive success and parasitism of cavity-nesting bees and wasps by trapnests throughout the vegetation period, and sampled bee and hoverfly communities by colored pan traps in mid-summer, comparing landscapes with and without set-aside fields. We measured the effects of increasing distance from set-aside fields, the effects of share of different habitats and flower resources, and the effects of increasing set-aside field percentage area at landscape scale. The landscape scale effects of set-aside fields varied among taxa and/or at different time scales. Reproductive success of cavity-nesting bees and wasps was positively related to the presence of set-aside fields in the landscape and together with the number of cavity-nesting bee and wasp genera increased with the proportion of set-aside fields. Species richness or abundance of bees or hoverflies showed no difference between landscape plots with or without set-aside fields in the mid-summer period according to the pan trap samples, and flower abundance and distance from the set-aside fields had only a limited effect. Set-aside fields had no effect on either the most abundant wild bee species or on composition of species of intermediate abundance. Our results suggest that reproductive success of cavity-nesting bees and wasps can be enhanced by additional flower resources and nesting habitats through set-aside fields at the landscape scale. Other wild bees and hoverflies can be less sensitive to the presence of set-aside fields according to our results that might need different conservation approaches. But this might also suggest that such landscape-scale benefits of set-aside field management might be measureable only with samplings covering the whole vegetation period. We argue that well-defined measures specific to spatial scale and target groups are mandatory and should be adapted to the different histories and local contexts of agricultural landscapes in Europe to strengthen ecosystem service provider insects and have the highest benefit for agricultural production.

Food webs centered on aphids contain networks of species, some directly related to prey characteristics, others mediated via the characteristics of the host plant. These tritrophic interactions can be even more extensive and complex when ants are present in aphid colonies. This study investigated how the presence of ants ( Cataglyphis aenescens Nylander and Formica cunicularia Latreille) in colonies of a generalist aphid ( Myzus persicae Sulzer) can influence (i) the performance of an important generalist aphidophage (the common hoverfly Episyrphus balteatus DeGeer) feeding on aphids growing on two host plants that express different levels of the glucosinolate sinigrin ( Brassica napus L. and Brassica nigra L.); and (ii), the oviposition of the aphidophage on ant-free versus ant-tended aphid colonies. Individual fitness was calculated from performance measures, and the number of eggs laid by gravid females used as a measure of preference. Ant presence significantly reduced the survival rate of predator immature stages, but there were no significant effects of host plant (sinigrin content), and host plant did not interact with ant presence. Female fecundity was significantly reduced by ant presence and varied between host plants, but these factors did not interact significantly. Syrphid females avoided ovipositing in the presence of ants, independent of plant species. Overall, the presence of ants in aphid colonies reduced predator performance and reduced oviposition by hoverfly females. Therefore the ant-aphid interaction is important in biological control as it influences the distribution of aphidophagous syrphids within the habitat.

The feeding habits of the generalist arthropod predators in agroecosystems are often difficult to determine, as they are small, mobile and live among the vegetation or in the soil. DNA-based gut-content analysis is a powerful tool that enables the study of arthropod predator–prey interactions. Predation on two of the main pests of Mediterranean lettuce crops, the lettuce aphid, Nasonovia ribisnigri, and the western flower thrips, Frankliniella occidentalis, as well as on Collembola, the most abundant non-pest prey, was studied. Generalist arthropods, like hoverflies, anthocorids (Orius spp.), coccinellids and spiders were collected in lettuce plots in two seasons (spring and summer) and analysed by conventional PCR using N. ribisnigri, F. occidentalis and Collembola-specific primers. Our results showed that in spring the main pest was N. ribisnigri, which was consumed by hoverfly larvae and coccinellids. In summer, the main pest was F. occidentalis, which was mainly predated by Orius spp. followed by hoverfly larvae. Spiders, which fed mainly on Collembola, did not seem to contribute to control of either target pest. This study offers a deeper knowledge of the trophic relationships present in Mediterranean lettuce crops, laying the groundwork for implementing biological control programmes based on the conservation of natural enemies.

The hoverfly Eumerus tricolor is morphologically very similar to the females of cuckoo bees of the genus Sphecodes Latreille. This hoverfly was observed in two localities in central (Certoryje NNR, Czech Republic) and southern (Kladhas, Greece) Europe together with females of these cuckoo bees at nest sites of the bee hosts ( Lasioglossum Curtis) of the cuckoo bees. Females of E. tricolor were sitting on the ground, slowly flying low over the ground and walking on the nesting site. This can be interpreted as Batesian mimicry of Sphecodes . This Eumerus species is the only European hoverfly of this genus with a very similar colour pattern to Sphecodes , and it also prefers the warm and sunny slopes and/or rocky steppes where Sphecodes are abundant. Within red-and-black hoverflies, E. tricolor is the only species showing this behaviour. It thus uses not only morphological but also behavioural mimicry.