Dipteran Taxa Research Articles

Non-canonical odor representation and learning in Dipteran brains

For decades, the vinegar fly Drosophila melanogaster has provided a window into the structure and function of the insect olfactory system, revealing a remarkable organizational correspondence between insects and vertebrates. In both clades, olfactory sensory neurons expressing the same class of sensory receptor proteins exclusively target a dedicated neuropil known as a glomerulus. Here, we review recent evidence from Drosophila and other Dipteran taxa that challenges this canonical view, showing widespread co-expression of olfactory sensory proteins within the same neurons. We discuss the potential consequences of co-expression for early sensory processing in the insect olfactory system. As well, we situate these findings within the broader framework of olfactory learning, highlighting recent findings that suggest a wider importance of the antennal lobe than has been previously appreciated.

Non-canonical odor representation and learning in Dipteran brains

For decades, the vinegar fly Drosophila melanogaster has provided a window into the structure and function of the insect olfactory system, revealing a remarkable organizational correspondence between insects and vertebrates. In both clades, olfactory sensory neurons expressing the same class of sensory receptor proteins exclusively target a dedicated neuropil known as a glomerulus. Here, we review recent evidence from Drosophila and other Dipteran taxa that challenges this canonical view, showing widespread co-expression of olfactory sensory proteins within the same neurons. We discuss the consequences of co-expression for early sensory processing in the insect olfactory system. In addition, we situate these findings within the broader framework of olfactory learning, highlighting recent findings that suggest a wider importance of the antennal lobe than has been previously appreciated.

New taxa of Diptera from China in 2022

New taxa of Diptera from China in 2022

Choice of benthic macroinvertebrate‐based metrics for assessing water quality in the littoral zone under anthropogenic disturbance in southern Lake Kivu (East Africa)

AbstractBenthic macroinvertebrates are widely used to assess the ecological quality of fresh waters. This is because they are in direct contact with the aquatic environment and respond differently to pollutants and changes in the watershed, which are difficult to assess by toxicological or chemical monitoring alone. This study used benthic macroinvertebrate parameters to assess the quality of the nearshore waters of lake Kivu. Twenty‐six metrics covering various aspects of the community were tested using whisker plots to compare their sensitivity in discriminating between reference and disturbed stations. Nine parameters (% EPT taxa, % Diptera taxa, % Chironomid taxa, % Insect taxa; % no Insects taxa, ratio EPT/Chironomid taxa, % moderate tolerant taxa, % very moderate tolerant taxa, Family Biotic Index) were found to be sensitive and were able to discriminate between reference and disturbed stations. All sensitive metrics, with the exception of the percentage of EPT taxa, were positively and/or negatively correlated with the physico‐chemical parameters affected by the changes in the littoral zone. The combined values of the three calculated biotic indices (ASPT, BMWP, and FBI) showed that the biological water quality varies from moderate to good in the reference stations and from average to poor in the disturbed stations. It is concluded that metrics based on benthic macroinvertebrates are effective for assessing water quality in the littoral zone of Lake Kivu in the context of the lack of historical water quality databases and specific tools for toxicological assessment. It is suggested to compare the performance of this approach with others currently used in bio‐indication.

New taxa of Diptera from China in 2021

New taxa of Diptera from China in 2021

Relating environmental variables with aquatic community structure in an agricultural/urban coldwater stream

BackgroundUrban areas are often built along large rivers and surrounded by agricultural land. This may lead to small tributary streams that have agricultural headwaters and urbanized lower reaches. Our study objectives assessed are as follows: (1) landscape, geomorphic, and water quality variables that best explained variation in aquatic communities and their integrity in a stream system following this agricultural-to-urban land use gradient; (2) ways this land use gradient caused aquatic communities to differ from what would be expected for an idealized natural stream or other longitudinal gradients; and (3) whether the impacts of this land use gradient on aquatic communities would grow larger in a downstream direction through the agricultural and urban developments. Our study area was an impaired coldwater stream in Michigan, USA.ResultsMany factors structured the biological communities along the agricultural-to-urban land use gradient. Instream woody debris had the strongest relationship with EPT (Ephemeroptera, Plecoptera, and Trichoptera) abundance and richness and were most common in the lower, urbanized watershed. Fine streambed substrate had the strongest relationship with Diptera taxa and surface air breather macroinvertebrates and was dominant in agricultural headwaters. Fish community assemblage was influenced largely by stream flow and temperature regimes, while poor fish community integrity in lower urban reaches could be impacted by geomorphology and episodic urban pollution events. Scraping macroinvertebrates were most abundant in deforested, first-order agricultural headwaters, while EPT macroinvertebrate richness was the highest downstream of agricultural areas within the urban zone that had extensive forest buffers.ConclusionEnvironmental variables and aquatic communities would often not conform with what we would expect from an idealized natural stream. EPT richness improved downstream of agricultural areas. This shows promise for the recovery of aquatic systems using well-planned management in watersheds with this agricultural-to-urban land use pattern. Small patches of forest can be the key to conserving aquatic biodiversity in urbanized landscapes. These findings are valuable to an international audience of researchers and water resource managers who study stream systems following this common agricultural-to-urban land use gradient, the ecological communities of which may not conform with what is generally known about land use impacts to streams.

Lord of the Diptera (and Moths and a Spider): Molecular Diet Analyses and Foraging Ecology of Indiana Bats in Illinois

Effective management of endangered or threatened wildlife requires an understanding of how foraging habitats are used by those populations. Molecular diet analysis of fecal samples offers a cost-effective and non-invasive method to investigate how diets of wild populations vary with respect to spatial and temporal factors. For the federally endangered Indiana bat (Myotis sodalis), documenting its preferred food sources can provide critical information to promote effective conservation of this federally endangered species. Using cytochrome oxidase I amplicon sequence data from Indiana bat guano samples collected at two roosting areas in Cypress Creek National Wildlife Refuge, we found that dipteran taxa (i.e., flies) associated with riparian habitats were the most frequently detected taxon and represented the majority of the sequence diversity among the arthropods sampled. A select few arthropods from other taxa—especially spiders—are also likely important to Indiana bat diets in this refuge. A supervised learning analysis of diet components suggest only a small fraction of the frequently detected taxa are important contributors to spatial and temporal variation. Overall, these data depict the Indiana bat as a generalist consumer whose diet includes some prey items associated with particular seasonal or spatial components, along with other taxa repeatedly consumed throughout the entire foraging season. These molecular diet analyses suggest that protecting foraging resources specifically associated with the riparian habitat of Cypress Creek National Wildlife Refuge is essential to promote effective Indiana bat conservation.

New taxa of Diptera from China in 2020

New taxa of Diptera from China in 2020

Health assessment of important tributaries of Three Georges Reservoir based on the benthic index of biotic integrity

China’s Three Gorges Reservoir (TGR) is the largest water conservancy project in the world, and plays a significant role in flood control and water transport. To study the health status of the tributaries of TGR, we set up 175 sampling sites, including 15 reference sites and 160 impaired sites on 36 important tributaries of TGR, and collected zoobenthos at these sampling sites. We selected 26 candidate metrics, analyzed them in terms of the distribution range, discriminant ability and correlation. Eight core metrics (i.e., total taxa, ephemerida + trichoptera + plecoptera taxa, diptera taxa, ephemerida%, trichoptera%, Shannon–Wiener diversity index, dominant species% and filter%) were identified, and then the benthic indexes of biological integrity (B-IBI) was established. The B-IBI was then used to evaluate the ecological status of 36 tributaries of TGR. Among all the sampling sites, “excellent”, “good”, “fair”, “poor” and “very poor” accounted for 5.14%, 13.14%, 28.00%, 44.57%, and 9.14%, respectively. Among all streams and rivers, “excellent”, “good” “fair”, “poor” and “very poor” accounted for 5.56%, 41.67%, 50.00%, 2.78%, and 0%, respectively, showing a general good condition for all tributaries. There was a significant difference in health status between tributaries in the TGR dam and those in its upper reaches. The B-IBI established in this study can capture the health status of 36 important tributaries of TGR. This study does not only enrich the practice of health assessment using B-IBI, but also provides some reference for the evaluation of similar rivers across the world.

Linear habitats across a range of farming intensities contribute differently to dipteran abundance and diversity

Abstract While the value of linear farm habitats for the protection and enhancement of farmland biodiversity in general is known, less is understood about their contribution to Diptera, especially those with different ecological requirements. In this study, we examined the impact of a range of linear farm habitats in agricultural grassland on Syrphidae and Sciomyzidae (Diptera) both of which provide important ecosystem services. Species richness and abundance for each family were measured across five different linear habitat types (dense and open hedgerows with/without adjacent watercourses and watercourses only). While dense hedgerows with adjacent watercourses showed the greatest numbers of Syrphidae species and individuals, open hedgerows with adjacent watercourses had significantly more Sciomyzidae species and individuals than dense hedgerows without watercourses or open hedgerows only. Syrphidae species richness was significantly correlated with the flowering plant species richness of linear habitats, while Sciomyzidae species richness was correlated with a habitat quality score for grasslands adjacent to the linear habitats. Overall, Syrphidae and Sciomyzidae species richness and community composition are shown to reflect a farming intensity gradient with significantly greater species richness for both families on extensive farms. Our results suggest that different dipteran taxa which utilise linear habitats may have different requirements. This has implications for future agri‐environmental schemes in the context of how we assess the conservation value of linear habitats on farmlands.

Culicoides biting midges and mosquito fauna at three dog and cat shelters in rural and periurban areas in Northern Spain.

The diversity and abundance of Culicoides (Diptera: Ceratopogonidae) and mosquitoes (Diptera: Culicidae) were studied in three animal protection centres (APCs) in Northern Spain between 1 July and 31 October 2018. Four miniature suction CDC light traps (two UV and two standard incandescent bulb traps, both types baited and non-baited with CO2 ) were placed in each APC to compare their efficiency in the collection of these Diptera groups. A total of 1176 biting midges (14 species), 224 mosquitoes (8 species) and 1 black fly were collected and identified by both morphological and molecular approaches. The Culicoides obsoletus complex (C. obsoletus/C. scoticus) accounted for 58.2% of the total collection within the Ceratopogonidae family, whereas Culex pipiens/Cx. torrentium comprised 76.8% of the Culicidae. The input of CO2 in light traps proved largely ineffective in improving the collections of both Diptera groups. UV-light traps were 7.8 and 2.2 times more effective than incandescent light traps in trapping Culicoides and mosquitoes, respectively. Seasonal dynamics differed between both Diptera taxa but captures of both taxa were significantly larger at the beginning of the summer. The epidemiological relevance of the most prevalent species is also discussed.

Seasonality of dipteran-mediated methylmercury flux from ponds.

Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects. We assessed the effects of month and pond permanence on dipteran-mediated MeHg flux (calculated as emergent dipteran biomass × dipteran MeHg concentration) in 10 experimental ponds. Emergent dipterans were collected weekly from permanent ponds with bluegill (Lepomis macrochirus; n = 5) and semipermanent ponds without fish (n = 5) over a 7-mo period (February-August, 2015). We detected a significant effect of month on MeHg flux from 6 dipteran taxa and aggregate MeHg flux, with the highest MeHg flux from herbivorous/detritivorous chironomid midges and predatory midges in March; biting midges, phantom midges and herbivorous/detritivorous orthoclad midges in April; and mosquitoes in August. Aggregate dipteran-mediated MeHg flux peaked in April and then declined throughout the remainder of the summer. We did not detect a significant main effect of pond permanence or a significant month × pond permanence interaction effect on MeHg flux for any of the taxa examined in the present study or for aggregate MeHg flux. Given their ubiquity in aquatic systems and their importance in food webs at the land-water interface, dipterans are important taxa that should not be overlooked as a part of the Hg cycle. Environ Toxicol Chem 2018;37:1846-1851. © 2018 SETAC.

Arthropods Associated with Bovine Carrion in Central Oklahoma

Abstract. The major arthropod taxa visiting carrion in central Oklahoma were enumerated qualitatively. Immature and adult arthropods were collected from beef cadavers throughout decomposition during fall/winter and spring/summer seasons. Arthropods were identified to the most specific taxonomic level possible, and more than 35 taxa of Diptera and Coleoptera commonly associated with carrion were confirmed. As expected, Calliphoridae were the most abundant Diptera during both seasons, followed by Sarcophagidae, Muscidae, and Ulidiidae. Most species of blow flies in fall/winter were the black blow fly, Phormia regina (Meigen), and hairy maggot blow fly, Chrysomya rufifaces (Macquart). P. regina and Cochliomyia macellaria (Fabricius) were the major species present during the spring/summer season. The coleopteran most commonly collected both seasons was the hairy rove beetle, Creophilius maxillosus (Linnaeus), in the family Staphylinidae. Beetles in the families Dermestidae and Trogidae also were collected.

Basic tools for setting environmental flows at the regional scale: application of the ELOHA framework in a Mediterranean river basin

AbstractEcological limits of hydrological alteration (ELOHA) framework aims to set limits of hydrologic alteration based on empirical hydroecological relationships built along flow impairment gradients. These relationships can be specific for different natural flow regime types. The object of our study is testing the ELOHA method in the Ebro River Basin. Seven flow alteration–ecological response curves were obtained in the present study as preliminary guidelines for developing and calibrating environmental flow standards in the Ebro River Basin. For continental Mediterranean‐pluvial flow regime mean monthly flow in March was related to Plecoptera abundance (ELOHAs ±21% from baseline), and high flow magnitude and frequency were closely related to Plecoptera, Ephemeroptera and Trichoptera richness (ELOHAs for high flow magnitude and frequency were +18 and +54% the reference central value respectively). For nivo‐pluvial flow regime, high flow magnitude was found indicative of macroinvertebrate biodiversity and Coleoptera abundance (ELOHAS −12 and +23% from central reference value respectively). And for pluvio‐oceanic flow regime, mean monthly flow in January was indicative of the proportion of Gastropoda, Oligochaeta and Diptera taxa (GOLD index) (ELOHA +17% from baseline). These hydrological limits are endorsed by recent international reference works. Flow alteration–ecological relationships presented here were constructed from real monthly flow data records and macroinvertebrate samples at family level. ELOHA values obtained in this study pretend to be a starting point for implementing an environmental flow regime program in the Ebro River Basin. Copyright © 2016 John Wiley & Sons, Ltd.

The female reproductive tract of Grallipeza sp. A (Diptera: Micropezidae)—large ventral receptacle substitutes for spermathecae convergently in small and widely separated dipteran clades

The internal female reproductive tract of a Neotropical species of stilt-legged fly (Diptera: Micropezidae: Grallipeza sp. A) is described and illustrated with microphotography. Special emphasis is given to the massively enlarged sclerotized tubular ventral receptacle and an almost complete reduction of the spermathecal capsules, suggesting that sperm storage has been shifted from the spermathecae to the ventral receptacle. This constitutes a remarkable convergence with analogous developments in other dipteran taxa. The published information on the internal female reproductive tract of other Micropezidae is reviewed, and the evolutionary history of the condition in Grallipeza sp. A is reconstructed and related to evolutionary processes likely involving sperm competition and cryptic female choice. The presence of paired accessory glands in Grallipeza sp. A is confirmed.

Meio- and Macrofaunal Communities in Artificial Water-Filled Tree Holes: Effects of Seasonality, Physical and Chemical Parameters, and Availability of Food Resources.

ObjectivesIn this study we investigated the dynamics of meiofaunal and macrofaunal communities in artificial water-filled tree holes. The abundances and, for the first time, biomasses and secondary production rates of these communities were examined. The experimental set-up consisted of 300 brown plastic cups placed in temperate mixed forests and sampled five times over a period of 16 months to determine the impact of (i) seasonal events, (ii) physicochemical parameters, and (iii) food resources on the tree hole metazoans.OutcomesMetazoan organisms, especially the meiofauna (rotifers and nematodes) occupied nearly all of the cups (> 99%) throughout the year. Between 55% and 99% of the metazoan community was represented by rotifers (max. 557,000 individuals 100 cm-2) and nematodes (max. 58,000 individuals 100 cm-2). Diptera taxa, particularly Dasyhelea sp. (max. 256 individuals 100 cm-2) dominated the macrofaunal community. Macrofauna accounted for the majority of the metazoan biomass, with a mean dry weight of 5,800 μg 100 cm-2 and an annual production rate of 20,400 μg C 100 cm-2, whereas for meiofauna mean biomass and annual production were 100 μg 100 cm-2 and 5,300 μg C 100 cm-2, respectively. The macrofaunal taxa tended to show more fluctuating population dynamic while the meiofaunal dynamic was rather low with partly asynchronous development. Seasonality (average temperature and rain intervals) had a significant impact on both meiofauna and macrofauna. Furthermore, bottom-up control (chlorophyll-a and organic carbon), mainly attributable to algae, was a significant factor that shaped the metazoan communities. In contrast, physicochemical water parameters had no evident influence. 23.7% of organism density distribution was explained by redundancy analysis (RDA) indicating a high dynamic and asynchrony of the systems.

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass (Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat (Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia National Park (CA, USA), where detailed, long-term records of stock management were available. We sampled paired grazed and control wet meadows that contained both habitats. There were moderate negative effects of grazing on vegetation, and effects were greater in sedge than in reed grass. Conversely, negative grazing effects on arthropods, albeit limited, were greater in the drier reed grass, possibly due to microhabitat differences. The differing effects on plants and animals as a function of habitat emphasize the importance of considering both flora and fauna, as well as multiple habitat types, when making management decisions. Sedge supported twice the overall arthropod abundance of reed grass as well as greater diversity; hemipteran and dipteran taxa were particularly abundant in sedge. Given the greater grazing effects on sedge vegetation, greater habitat provision for terrestrial arthropods, and value as aquatic arthropod habitat, the wetter sedge assemblage is worthy of additional consideration by managers when planning for grazing and other aspects of land usage.

The influence of natural flow regimes on macroinvertebrate assemblages in a semiarid Mediterranean basin

ABSTRACTThe investigation of flow–ecology relationships constitutes the basis for the development of environmental flow criteria. The need to understand hydrology–ecology linkages in natural systems has increased owing to the prospect of climate change and flow regime management, especially in water‐scarce areas such as Mediterranean basins. Our research quantified the macroinvertebrate community response at family, genus and species level to natural flow regime dynamics in freshwater streams of a Mediterranean semiarid basin (Segura River, SE Spain) and identified the flow components that influence the composition and richness of biotic assemblages. Flow stability and minimum flows were the principal hydrological drivers of macroinvertebrate assemblages, whereas the magnitude of average and maximum flows had a limited effect. Perennial stable streams were characterized by flow sensitive lotic taxa (Ephemeroptera, Plecoptera and Trichoptera) and intermittent streams by predominately lentic taxa (Odonata, Coleoptera, Heteroptera and Diptera). Relatively minor biological changes were recorded for intermediate flow regime classes along a gradient of flow stability. Seasonal variation and minimum flows are key hydrological components that need to be considered for river management and environmental flows in the Segura River basin and other Mediterranean basins. The anthropogenic modification of these parameters, due to both human activities and climate change, would probably lead to significant changes in the structure and composition of communities in perennial stable streams. This would be characterized by a reduction of flow sensitive Ephemeroptera, Plecoptera and Trichoptera taxa and an increase in more resilient Odonata, Coleoptera, Heteroptera and Diptera taxa. Copyright © 2012 John Wiley & Sons, Ltd.

The decomposition of rabbit carcasses and associated necrophagous Diptera in Kuwait

Rabbit carcasses were used to compare rates of decomposition and associated assemblages of Diptera at four discernable habitat types in Kuwait; a country of a region with a paucity of such reference data. Carcasses in an urban habitat showed faster decomposition (as measured by percentage weight loss) than in agricultural, coastal or desert habitats, even with accumulated degree days (ADD) as the explanatory variable (t=2.73, df=34, p=0.010) to compensate for temperature differences. Taxa of Diptera at the four habitats became more similar as decomposition progressed, suggesting such differences between habitats were not marked. The occurrence of Chrysomyia megacephala and Lucilia sericata had not previously been recorded in Kuwait.

Aggregation in cattle dung-colonizing insect communities

Background Ruminant dung is a highly ephemeral, patchily distributed resource, which is utilized by a diverse community of invertebrate species. This ecologically important community may be affected adversely by insecticide and endectocide residues in the faeces of treated cattle. The aim of the present work was to quantify the aggregation of the insects colonising cow-dung in cattle pastures and test the hypothesis that the dung-pat community assemblage observed is the result of stochastic colonization events. Methods Fresh dung from dairy cattle was used to construct arrays of standardised, 1.5kg, artificial cow pats in cattle pastures. Batches of ten pats were placed out each week for 24 weeks, between May and October in 2001. Pats were left exposed in the field for seven days, to allow colonisation. Pats were then brought back to the laboratory and insect colonizers were collected and identified. Results Individual pats contained on average, only half the number of insect taxa present in an entire batch put out at any one time. Among six representative taxa of Diptera and four of Coleoptera, significant levels of intraspecific aggregation were observed in all but one (Mesembina meridiana), with the abundance of most taxa within pats approximating a negative binomial distribution. A simulation analysis was used to show that the observed relative frequency of taxa within pats does not differ from that expected by chance if colonisation is a random binomial event in which each species colonises a pat independently of all other species. Conclusion The highly aggregated distributions observed in this study highlight the need for relatively large sample sizes when attempting to assess the abundance and distribution of individual taxa in cow dung. In addition, the results suggest that the aggregated populations of even highly abundant insects will be more susceptible to the deleterious effects of insecticidal residues in dung than if they were evenly distributed, if by chance they colonize a pat containing insecticidal residues from a recently treated animal.