Atylotus Agrestis Research Articles

The Tabanidae (Diptera) of the Greek islands and Cyprus: An annotated checklist with remarks on ecology, zoogeography, and new records on the East Mediterranean fauna

The horse-fly fauna of the East Mediterranean is poorly known and, in some geographical areas, has not been studied for decades. The present study summarizes the results of tabanid collections performed over 30 years in the Greek islands (the Cyclades, Dodecanese, North Aegean and Crete) and Cyprus. In total, 18 species were known from the study territory. The present study reports an additional 10 species. Previously, only 1 horsefly species was known from the Dodecanese islands, 1 from the North Aegean islands, and 2 from the Cyclades. This study has raised the number of species to 6, 7, and 9, respectively. The combined taxa for the three island groups have increased from 4 to 17 species. Specifically, the number of species has increased from 3 to 7 in Crete and from 11 to 19 in Cyprus. Additionally, we report 1 new record from the Greek mainland, 1 from the Levantine region, 2 from Lebanon, and 2 from Israel. Four Afrotropical–Palearctic vector species: Atylotus agrestis (Wiedemann, 1828); Tabanus gratus Löw, 1858b; Tabanus sufis Jaennicke, 1867; and Tabanus taeniola Palisot de Beauvois, 1806; are recorded for the first time from Cyprus, and A. agrestis from southern Italy. Their status as invasive species in Europe is discussed, the four species are illustrated.

In support of morphology: Molecular analysis successfully delineates the Afrotropical genus Atylotus (Diptera: Tabanidae) into species

Previous studies of the horse fly genus Atylotus in the Afrotropics has shown little to no differentiation into species based on the barcoding region of cytochrome oxidase I (COI), largely due to morphological misidentifications. Using field caught specimens and a museum reference collection together with type comparisons, COI and 16S ribosomal RNA sequences were generated from two specimens of Atylotus agrestis, two A. albipalpus, four A fuscipes and one A. nigromaculatus. Phylogenetic analysis of these sequences produced four separate species clades with strong support. The results showed that COI does delineate the species of Afrotropical Atylotus and that misidentifications of specimens is a common problem. Additionally, Atylotus fuscipes is revived from synonymy and given full species status. Finally, a comprehensive review of the COI barcodes, publicly available on GenBank and BOLD is included that highlights some problems with using sequences from public databases.

Seasonal comparison of vavoua, biconical and NGU traps for monitoring of Glossina (Diptera: Glossinidae) and Tabanids (Diptera: Tabanidae) in The Gambia

This work shows the effective trapping method used in catching Glossinidae and Tabanidae species and their distribution in The Gambia. One hundred and eight-six traps were used in this study comprising of 62 Biconical traps, 62 NGU traps and 62 Vavoua traps for 50 trapping days. These traps were baited with at least 4 months old cow urine and acetone and they were deployed at a distance of 100 m apart. A total number of 517 flies belonging to the genus Tabanidae and Glossinidae were captured. This included: Atylotus. agrestis (55%), Tabanus sourcouf (0.4%), Tabanus par (1.2%) and T. taeniatus (1.4%), Glossina morsitan submorsitan (26%) and Glossina palpalis gambiensis (16%). However, Atylotus agrestis and Glossina palpalis gambiensis were the species that were mostly caught in this study. The present study also shows that, Lower River Region was the region with the highest number of Tabanidae species caught (85 catches, mean=20.7 and SD=16.76) while Central River Region-North also had the highest catch of Glossinidae species (52 catches, Mean= 14 and Sd=6.98). Late rainy season (October 2020) and late dry season (April 2020) were the seasons in which the highest number of Tabanidae and Glossinidae species were caught respectively. This study clearly demonstrated that, Biconical trap is the most effective trap that can be used to control the population of both Glossinidae and Tabanidae species in The Gambia.

Evaluation of the relative roles of the Tabanidae and Glossinidae in the transmission of trypanosomosis in drug resistance hotspots in Mozambique

BackgroundTsetse flies (Diptera: Glossinidae) and tabanids (Diptera: Tabanidae) are haematophagous insects of medical and veterinary importance due to their respective role in the biological and mechanical transmission of trypanosomes. Few studies on the distribution and relative abundance of both families have been conducted in Mozambique since the country’s independence. Despite Nicoadala, Mozambique, being a multiple trypanocidal drug resistance hotspot no information regarding the distribution, seasonality or infection rates of fly-vectors are available. This is, however, crucial to understanding the epidemiology of trypanosomosis and to refine vector management.MethodsFor 365 days, 55 traps (20 NGU traps, 20 horizontal traps and 15 Epsilon traps) were deployed in three grazing areas of Nicoadala District: Namitangurine (25 traps); Zalala (15 traps); and Botao (15 traps). Flies were collected weekly and preserved in 70% ethanol. Identification using morphological keys was followed by molecular confirmation using cytochrome c oxidase subunit 1 gene. Trap efficiency, species distribution and seasonal abundance were also assessed. To determine trypanosome infection rates, DNA was extracted from the captured flies, and submitted to 18S PCR-RFLP screening for the detection of Trypanosoma.ResultsIn total, 4379 tabanids (of 10 species) and 24 tsetse flies (of 3 species), were caught. NGU traps were more effective in capturing both the Tabanidae and Glossinidae. Higher abundance and species diversity were observed in Namitangurine followed by Zalala and Botao. Tabanid abundance was approximately double during the rainy season compared to the dry season. Trypanosoma congolense and T. theileri were detected in the flies with overall infection rates of 75% for tsetse flies and 13% for tabanids. Atylotus agrestis had the highest infection rate of the tabanid species. The only pathogenic trypanosome detected was T. congolense.ConclusionsDespite the low numbers of tsetse flies captured, it can be assumed that they are still the cyclical vectors of trypanosomosis in the area. However, the high numbers of tabanids captured, associated to their demonstrated capacity of transmitting trypanosomes mechanically, suggest an important role in the epidemiology of trypanosomosis in the Nicoadala district. These results on the composition of tsetse and tabanid populations as well as the observed infection rates, should be considered when defining strategies to control the disease.

Molecular identification and characterization of medically and veterinary important flies of Bangladesh based on mitochondrial COI gene sequences

Flies are considered serious pests which cause health problems of human and animal, transmitting many pathogenic microbes. Pest management programs depend on proper identification of pests. The present research work is an initiative to identify the medically and veterinary important flies based on mitochondrial COI gene sequences. Eleven species of the fly pests were identified. Among them, four fly species were the first record from Bangladesh. The phylogenetic analysis of retrieved sequences confirmed that the evolution of these species occurred from a common ancestor. Highest AT percentage (69.9%) was found in Haematobia irritans exigua and lowest GC percentage (30.4%) was found in Haematobia irritans exigua. The substitution rate of codon was found 1.88 in 1st position, 0.73 in 2nd position and 1.22 in 3rd position, respectively. Interspecific genetic divergence range of flies sequences was 5-20%. Haplotype network showed that Atylotus agrestis was mostly diverged from its common ancestors by 37 mutational steps. This research is the first molecular approach to identify the medically and veterinary important flies based on MT-COI gene sequences along with the establishment of first DNA barcode dataset for accurate identification in Bangladesh.

Preliminary study on potential mechanical vectors of animal trypanosomes in the Far North region of Cameroon

An entomological study was carried out in the Far North region of Cameroon – historically known focus for animal trypanosomosis and declared tsetse free in the late 1970s – to determine the potential mechanical vectors for trypanosomes and their spatial preference in this region. Thirty-one Nzi traps were installed at 6:30–8:00 a.m. in Goulfey, Madiako canton and Darack karena in Logone and Chari Division, as well as in Guidiguis, Kalfou and Maga-Guirvidig in two other divisions. They were visited after 10–11 hours of exposition. The sampling lasted one day. A total of 20,084 hematophagous flies (865 Stomoxys and 19,219 tabanids) were collected. Stomoxys niger was the only Stomoxyinae species caught, whereas five species of tabanids were collected: Atylotus agrestis, A. albipalpus, A. fuscipes, Tabanus taeniola and T. biguttatus. A. agrestis was by far the most prevalent species (92.7%), followed by T. taeniola (7.1%). The apparent densities of 50.1, 409.4 and 1499.0 tabanids per trap per day in Guidiguis, Goulfey and Madiako canton, respectively, were significantly different (p = 0.0002). Tabanids were more abundant in campsites than in pastures and water points. Atylotus agrestis seemed to be the major potential mechanical vector of trypanosomes in the area.

Horse flies and their seasonal abundance in El Tarf Province of northeastern Algeria.

The horse flies of El Tarf Province, northeastern Algeria comprise 15 species within two subfamilies (Chrysopsinae and Tabaninae) belonging to five genera (Atylotus, Chrysops, Dasyrhamphis, Haematopota, and Tabanus). The genera Chrysops, Dasyrhamphis, and Haematopota are represented by two species for each, while the genera Atylotus and Tabanus are represented by four and five species, respectively. Seasonal abundance was assessed from mid-March until the end of September, 2017 for the trapped species. Haematopota pluvialis and Tabanus autumnalis appeared in April and lasted until September with a peak in May. Atylotus agrestis appeared in May with the highest density and lasted until September. Atylotus fulvus, Atylotus kroberi, and Haematopota italica emerged in April with peaks in May, while Chrysops flavipes appeared in March, reaching its peak in May and June, declining in July, and disappearing thereafter. Atylotus flavoguttatus, Chrysops mauritanicus, and Dasyrhamphis tomentosus appeared in April with a peak in June, then disappearing in August. Tabanus nemoralis started to appear in April with a peak in May and disappearance after July. Dasyrhamphis algirus, Tabanus bromius, and Tabanus eggeri started to appear in May. Both Tabanus eggeri and Dasyrhamphis algirus peaked in June and July, whereas T. eggeri lasted until the end of September. Tabanus tinctus was observed in June with a peak in August and lasted until September.

Alighting of Tabanidae and muscids on natural and simulated hosts in the Sudan

Alighting of horse flies (Diptera: Tabanidae) and non-biting muscids (Diptera: Muscidae) was studied at Khartoum, Sudan, using black cylindrical models mimicking a goat, calf and cow. Flies were intercepted by attaching electrocution grids or clear adhesive film to models. Alighting sites and defensive behaviour were also documented on hosts through observation. Female Tabanus sufis (Jennicke), T. taeniola (Palisot) and Atylotus agrestis (Wiedemann) were the main tabanids captured. Muscids landed in equal numbers on all sizes of models. They had a strong preference for the upper portions of both models and hosts. Landings of T. taeniola and A. agrestis increased with model size, but not so for T. sufis. T. taeniola and A. agrestis scarcely alighted on the legs of models whereas 60-78% of T. sufis did so. Landings of T. sufis on artificial legs did not vary with model size. Landings of all tabanids on the lower and upper portions of a model increased with model size. For both hosts and models, most tabanids (88-98%) alighted on the lower half and legs. Most muscids (63-89%) alighted on the upper half. Landing of tabanids on the cow was 34.9 and 69.3 times greater than that on the calf and goat, respectively. These results are discussed in relation to strategies for the control of blood-sucking flies associated with farm animals using either insecticide-treated live baits or their mimics.

Biting flies and Trypanosoma vivax infection in three highland districts bordering lake Tana, Ethiopia

An epidemiological study was conducted to determine the prevalence of trypanosomosis in cattle, small ruminants and Equidae, and to identify biting flies; potential mechanical vectors of trypanosomes in the three districts of Bahir Dar Zuria, Dembia and Fogera, bordering lake Tana, Ethiopia. About 1509 cattle, 798 small ruminants and 749 Equidae were bled for the prevalence study using the buffy-coat method and the measurement of the hematocrit value. Sixty-six NGU and 20 monoconical traps were deployed for the fly survey. The results indicated the presence of trypanosomes in 6.1% (92/1509) of the cattle with a maximum during the late rainy season (9.6%) than the early dry season (3.6%) at Fogera district. Prevalence at the district level varied from 4% to 9.6%. Only one sheep (1/122) and one goat (1/676) were found positive for T. vivax-like trypanosomes and none of the Equidae was positive. All the trypanosomes encountered in cattle belong to the single species of T. vivax. The PCV was negatively associated with detection of T. vivax (21.6% in infected versus 25.4% in non-infected cattle). A total of 55,398 biting flies were caught of which 49,353 (89.08%) belong to Stomoxys, 4715 (8.51%) to horse flies and 1330 (2.4%) to Chrysops species. There was no tsetse fly. Species identification has indicated the presence of Atylotus agrestis, Chrysops streptobalia, Stomoxys calcitrans, S. nigra, S. pulla, S. pallida, S. sitiens, S. taeniata, S. uruma, Haematopota lasiops and Hippobosca variegata. The overall apparent density was 214.7 flies/trap/day. Seasonal comparison showed higher fly catches in the late rainy season than the early dry season. This study indicated that T. vivax infections culminate in cattle at the same time as mechanical vectors such as Stomoxys sp. and Atylotus agrestis. Therefore, attention towards T. vivax infection in cattle is essential to control the impact of the disease on productivity. A further study on biting flies is recommended.

Mechanical transmission of Trypanosoma vivax in cattle by the African tabanid Atylotus fuscipes

An experiment was carried out in Burkina Faso to evaluate the potential for mechanical transmission of Trypanosoma vivax by the African tabanid Atylotus fuscipes. The experiment was carried out in a corral ( 10 m×10 m) completely covered by a mosquito net ( 12 m×12 m and 2.5 m high). Eight heifers (cross-bred Zebu X Baoulé), free of trypanosome infection, were kept together with two heifers experimentally infected with a local stock of T. vivax. An average of 539 A. fuscipes per day, freshly captured with two Nzi traps, were introduced into the mosquito net from Day 1 to 20, to allow mechanical transmission of the parasites among cattle. Daily parasitological examinations (BCM) of cattle blood samples indicated that six of the eight receiver heifers were positive from days 9, 10, 15, 16, 19 and 29. Mechanical transmission of T. vivax by A. fuscipes was demonstrated unequivocally in close to natural conditions, at a high rate (75% incidence over a 20-day period) under a mean challenge of 54 insects per heifer per day. These results, in addition to previous demonstration of mechanical transmission of T. vivax by Atylotus agrestis, confirm that mechanical transmission can be a significant route of infection.

Mechanical transmission of Trypanosoma congolense in cattle by the African tabanid Atylotus agrestis

The trypanosomes pathogenic to livestock in Africa ( Trypanosoma congolense, Trypanosoma vivax, and Trypanosoma brucei) are mainly cyclically transmitted by tsetse ( Glossina). However, T. vivax, can also be mechanically transmitted by haematophagous insects. Laboratory studies have demonstrated the mechanical transmission of T. congolense, but confirmation of this under natural conditions was necessary. An experiment was therefore carried out in Lahirasso, Burkina Faso, in a corral completely covered by mosquito net, to avoid exposure to tsetse. Eight receiver heifers, free of trypanosome infection, were kept together with two donor heifers, experimentally infected with local stocks of T. congolense. On average, 291 Atylotus agrestis, freshly captured in Nzi traps, were introduced into the mosquito net daily for a period of 20 days to initiate mechanical transmission among cattle. Daily microscopical observation of their blood indicated that two of the eight receiver heifers became infected with T. congolense from days 42 and 53. Mechanical transmission of T. congolense by A. agrestis was demonstrated unequivocally with a 25% incidence over a 20-day period of exposure under a mean challenge of 29 insects/animal/day. These results, in addition to previous reports, demonstrate the ability of A. agrestis to transmit T. vivax and T. congolense to cattle in Africa by mechanical means. Efforts to eliminate cattle trypanosomosis should therefore consider the eventual persistence of disease as a result of mechanical transmission of trypanosomes by tabanids. Index descriptor and abbreviations: Trypanosoma congolense ( Trypanosomatidae) is a pathogenic trypanosome found in wild and domestic herbivores, principally in cattle ( Bos taurus, Bos indicus, and cross-breds), in Africa. It is cyclically transmitted by tsetse ( Glossina, Diptera); however, mechanical transmission by biting insects may also occur. The present study demonstrates unequivocally the mechanical transmission of T. congolense to cattle by one of the most common African tabanids, A. agrestis. The main conclusion is that tabanids are able to transmit T. congolense; however, the incidence of transmission was lower than in studies carried out under the same conditions with T. vivax. Better models of mechanical transmission are required to understand why, on the one hand, epidemiological studies support the mechanical transmission of T. vivax but not T. congolense, and, on the other hand, experimental studies confirm that both species can be mechanically transmitted. Our studies suggest that the epidemiology of trypanosomosis in cattle involves tabanids, and hence, the eradication of tsetse-flies in Africa will not necessarily lead to the eradication of trypanosomosis in domestic livestock. ADT, apparent density of insects per trap per day (mean number of insects caught in one type of trap per 24 h of trapping); D, day; NS, not statistically significant

Trypanosoma vivax: mechanical transmission in cattle by one of the most common African tabanids, Atylotus agrestis

The role of mechanical vectors in the transmission of African livestock trypanosomes has always been controversial relative to tsetse flies, their cyclical vectors. An experiment was carried out in Burkina Faso to demonstrate mechanical transmission of Trypanosoma vivax by one of the most common tabanids in Africa: Atylotus agrestis. Eight heifers (crossbred zebu × Baoulé), free of trypanosome infection, were kept in a corral covered by a mosquito net, together with two heifers infected experimentally with a local stock of T. vivax. On average, 324 A. agrestis, freshly captured with Nzi traps, were introduced daily over 20 days. Parasitological, PCR and serological examinations were carried out regularly to assess infections and levels of parasitaemia. Microscopic examination of buffy-coats indicated that five of the eight receiver-heifers were infected on days 8, 13, 32, 41, and 48. PCR results indicated that these five heifers were already infected by day 13. Mechanical transmission of T. vivax by A. agrestis was demonstrated unequivocally, at a high rate (63% in 13–20 days). Conditions of transmission in this experiment are discussed in terms of natural rates of challenge. The importance of tabanids as mechanical vectors of T. vivax should be re-considered, in light of these results. Creation of tsetse free zones in Africa will generally lead to the disappearance of T. congolense, T. brucei, and most often T. vivax as well; however, in areas where T. vivax can be mechanically transmitted, clearance of tsetse may not be sufficient to eradicate livestock trypanosomosis. Index Descriptor and Abbreviations: Trypanosoma vivax (Trypanosomatidae) is a pathogenic trypanosome found in wild and domestic herbivores, principally in cattle ( Bos taurus, Bos indicus, and crossbreeds), in South America and Africa. In Africa it is principally cyclically transmitted by tsetse flies ( Diptera). In America it is only mechanically transmitted by tabanids (Tabanidae). The present paper describes the mechanical transmission of T. vivax in cattle by one of the most common African tabanids: A. agrestis. The main conclusion is that not only tsetse can transmit T. vivax in Africa, consequently the epidemiology of trypanosomosis in cattle is also tabanid dependant, and, the eradication of tsetse flies will not necessarily lead to eradication of T. vivax. ADT, Apparent density of insects per trap per day (mean number of insects caught in one type of trap per 24 h of trapping); PATTEC, Pan African Tsetse and Trypanosomiasis Eradication Campaign; RHD, rate of hematocrit decrease; D, day; ELISA, enzyme linked immunosorbent assay; NS, not significant (in terms of statistics); PCR, polymerase chain reaction

Vecteurs potentiels de <em>Trypanosoma evansi</em> chez le dromadaire au Tchad oriental

Le Tchad oriental est une région d’élevage du dromadaire. La trypanosomose à Trypanosoma evansi (ou surra), maladie transmise mécaniquement par divers insectes hématophages, y est répandue et touche en priorité les cheptels transhumants. Une enquête entomologique a été réalisée dans sept sites représentatifs afin de préciser l’épidémiologie de la maladie dans cette zone. Quatre sites (Koukou Angarana et Djogori au Sud, Oum Chalouba et ouaddi Fira au Nord) ont été associés à une forte prévalence de la maladie et les trois autres (Abdi au Sud, Am sak et ouaddi Fama au Nord) à une faible prévalence. L’enquête s’est basée sur l’utilisation de 15 pièges biconiques Challier- Laveissière et de cinq pièges Nzi avec des relevés à 24 et 48 h. Trois séries de piégeages ont été effectuées afin de tenir compte des variations saisonnières. Divers facteurs pouvant influer sur les captures ont été relevés et inclus dans une analyse statistique multivariée. Au total, 1 272 stomoxes, 945 tabanidés et 226 hippobosques ont été capturés. Chez les tabanidés, l’espèce dominante a été Atylotus agrestis ; les autres espèces ont été Tabanus gratus, T. taeniola et T. biguttatus. Les trois principales espèces de stomoxes identifiées ont été Stomoxys calcitrans, S. sitiens et S. niger. La majorité des hippobosques identifiés ont appartenu à l’espèce Hippobosca camelina. Les principaux facteurs qui expliquaient la variabilité des captures étaient la nature du piège, la saison et la latitude. Le piège Nzi a été plus efficace pour la capture des tabanidés et des stomoxes. La période de capture la plus favorable a été le début de la saison sèche (novembre à janvier) pour Atylotus agrestis, les stomoxes et les hippobosques. Tabanus gratus a été surtout capturé en fin de saison sèche (février à mai) et en saison des pluies (juin à octobre) et Tabanus taeniola en saison des pluies. Les hippobosques ont été plus fréquemment capturés au nord de la zone étudiée et T. gratus et T. taeniola au sud. Une corrélation entre le nombre d’insectes piqueurs capturés en saison sèche et la prévalence du surra a été relevée avec les deux types de piège. La forte prévalence du surra dans les cheptels transhumants s’expliquerait par un effet cumulatif, les animaux étant en contact avec le pic d’Atylotus agrestis au Nord à la fin de la saison des pluies et au début de saison sèche et avec une entomofaune piqueuse se maintenant dans les zones d’accueil du Sud (novembre à juin). Chez les petits transhumants et les semi-sédentaires du Nord, l’impact du surra tiendrait à la nature de la zone fréquentée, celle-ci autorisant ou non le maintien de populations d’insectes hématophages en saison sèche.

Notes on Tabanidae (Diptera) that are Surra vectors or pestiferous with description of a new species of Tabanus from India

A new species of Tabanid fly, Tabanus hisarensis, sp. nov., collected from Hisar (Haryana) is described and illustrated. This is related to Tabanus sufis Jaennicke and Tabanus kurahashii Inaoka and Burger and is characterised by having a broad frons and transverse basal callosity. Notes on morphology, distribution and biology of Atylotus agrestis (Wiedemann), Atylotus virgo (Wiedemann), Haematopota roralis Fabricius, Tabanus dorsilinea Wiedemann, Tabanus rubidus Wiedemann, Tabanus striatus Fabricius and Tabanus triceps Thunberg are also given. These species are common blood feeding pests of horses, mules, cattles, camels and other livestock and some of them (A. agrestis, T. dorsilinea, T. rubidus, T. striatus) are proven vectors of Surra disease of livestock in India.