Tabanid Species Research Articles

Evaluation of DNA barcoding and identification of new haplomorphs in Canadian deerflies and horseflies

This paper reports the first tests of the suitability of the standardized mitochondrial cytochrome c oxidase subunit I (COI) barcoding system for the identification of Canadian deerflies and horseflies. Two additional mitochondrial molecular markers were used to determine whether unambiguous species recognition in tabanids can be achieved. Our 332 Canadian tabanid samples yielded 650 sequences from five genera and 42 species. Standard COI barcodes demonstrated a strong A + T bias (mean 68.1%), especially at third codon positions (mean 93.0%). Our preliminary test of this system showed that the standard COI barcode worked well for Canadian Tabanidae: the target DNA can be easily recovered from small amounts of insect tissue and aligned for all tabanid taxa. Each tabanid species possessed distinctive sets of COI haplotypes which discriminated well among species. Average conspecific Kimura two-parameter (K2P) divergence (0.49%) was 12 times lower than the average divergence within species. Both the neighbour-joining and the Bayesian methods produced trees with identical monophyletic species groups. Two species, Chrysops dawsoni Philip and Chrysops montanus Osten Sacken (Diptera: Tabanidae), showed relatively deep intraspecific sequence divergences (∼ 10 times the average) for all three mitochondrial gene regions analysed. We suggest provisional differentiation of Ch. montanus into two haplotypes, namely, Ch. montanus haplomorph 1 and Ch. montanus haplomorph 2, both defined by their molecular sequences and by newly discovered differences in structural features near their ocelli.

Feeding success and trappability of horse flies evaluated with electrocuting nets and odour-baited traps

The relative capacity of different tabanid species to mechanically transmit infectious diseases was assessed by comparing their feeding success on a horse. Ten species were intercepted with electrocuting nets while approaching and leaving the horse: the most abundant were Tabanus pallipennis, Pseudotabanus silvester and Tabanus townsvilli. Of the tabanid species that managed to bite, the highest proportions of partially fed flies, which could potentially transmit pathogens to their next host, were for T. pallipennis (49%) and Dasybasis oculata (48%), while the lowest was in P. silvester (11%). T. townsvilli and T. dorsobimaculatus did not obtain blood meals, possibly because of their sensitivity to host defensive movements. The study also investigated whether catches from odour-baited traps could reliably predict tabanid activity around horses. The traps caught fewer flies, but captured the same species as the electrocuting nets surrounding a horse. A significant linear relationship between the two was observed for P. silvester, T. pallipennis and T. townsvilli but not for T. dorsobimaculatus. The results also demonstrate differences in trappability among tabanid species.

Alighting and feeding behaviour of tabanid flies on horses, kangaroos and pigs

Successful mechanical transmission of surra between animals by tabanid flies (Diptera: Tabanidae) depends to a large extent on the blood-feeding behaviour of the tabanid species prevalent in the area. We studied tabanid–host interactions in Australia to better predict risk of surra transmission and design intervention strategies. At least six tabanid species were observed alighting on horses, pigs and kangaroos, but the most abundant were Tabanus pallipennis Macquart, Pseudotabanus silvester Bergroth and T. townsvilli Ricardo. The behaviour of tabanids in terms of landing location on the host body, duration of feeding and the proportion completing the blood-meal varied with fly species and host species. The findings predict that some species of tabanid such as T. pallipennis should be better vectors and some species of host such as pigs should be better reservoirs of surra based on the inability of flies to feed to repletion and longer feeding durations. This will result in multiple feeds and increased risk of exposure to the infectious agent, respectively, which increases the risk of transmission. Insecticide treatments should target preferred feeding sites on the host's body.

Distribution of Tabanids (Diptera: Tabanidae) Along a Two-Sided Altitudinal Transect

The pattern of horse fly (Diptera: Tabanidae) distribution and correlations among biodiversity, abundance, abiotic factors, and altitude were determined along a two-sided altitudinal transect. The sampling was carried out on five 3-d periods during tabanid seasonal activity. Linen canopy traps with 1-octen-3-ol as an attractant were used at 20 sampling sites along the transect. The results showed that the qualitative composition of tabanid species can be distinguished by altitude and, especially, between southeastern and northwestern mountain slopes. The peaks of horse fly species richness and abundance were indicated at middle elevations of both slopes, where horse fly distributional groups were overlapping and most rare and infrequent species were sampled. All expected species were sampled according to species accumulation curve. The canonical correlation analysis separated species and sampling sites into three clusters; two were positively correlated with the temperature and the wind but differed in sensitivity toward them, and the third cluster was correlated with the humidity. The horse fly distribution was nonhomogenous, and the distributional patterns were only partially determined by altitude and vegetation. The determining environmental variables were different for each slope: temperature and wind for the southern slope (Mediterranean climatic zone) and humidity for the northern slope (continental climatic zone).

Epidemiologic Questions from Anthrax Outbreak, Hunter Valley, Australia

Epidemiologic Questions from Anthrax Outbreak, Hunter Valley, Australia

Ventral polarization vision in tabanids: horseflies and deerflies (Diptera: Tabanidae) are attracted to horizontally polarized light

Adult tabanid flies (horseflies and deerflies) are terrestrial and lay their eggs onto marsh plants near bodies of fresh water because the larvae develop in water or mud. To know how tabanids locate their host animals, terrestrial rendezvous sites and egg-laying places would be very useful for control measures against them, because the hematophagous females are primary/secondary vectors of some severe animal/human diseases/parasites. Thus, in choice experiments performed in the field we studied the behavior of tabanids governed by linearly polarized light. We present here evidence for positive polarotaxis, i.e., attraction to horizontally polarized light stimulating the ventral eye region, in both males and females of 27 tabanid species. The novelty of our findings is that positive polarotaxis has been described earlier only in connection with the water detection of some aquatic insects ovipositing directly into water. A further particularity of our discovery is that in the order Diptera and among blood-sucking insects the studied tabanids are the first known species possessing ventral polarization vision and definite polarization-sensitive behavior with known functions. The polarotaxis in tabanid flies makes it possible to develop new optically luring traps being more efficient than the existing ones based on the attraction of tabanids by the intensity and/or color of reflected light.

A comparison of trapping methods for Tabanidae (Diptera) in North Queensland, Australia

The ability to monitor the abundance and diversity of tabanid flies over wide areas requires effective and low-cost surveillance methods. Such monitoring activities help to quantify the risk of transmission of pathogens by tabanids. Here we examine the effectiveness and practicality of two types of trap (canopy traps and Nzi traps) and two types of attractant (octenol and carbon dioxide) for monitoring tabanid flies in tropical Australia. The Nzi trap consistently caught more tabanids and more species of tabanids than the canopy trap. It was also more robust and therefore required less maintenance in remote locations. The use of attractants substantially increased capture rates, both of individuals and species, and traps using both attractants were consistently the most effective. However, in remote locations, where it is not possible to check traps frequently, the use of attractants may not be feasible. When attractants were not used, the canopy trap caught very few tabanids, but the Nzi trap remained effective enough to be useful as a monitoring device. In addition, the number of tabanid species caught by the Nzi traps remained high, and included those that were most abundant. We therefore conclude that, in this region, Nzi traps are preferable for tabanid monitoring and that attractants greatly improve their effectiveness. However, for longterm monitoring, especially in remote locations, Nzi traps without attractants are a satisfactory option.

Mutucas (Diptera: Tabanidae) do estado do Paraná, Brasil: chave de identificação pictórica para subfamílias, tribos e gêneros

Foi realizado um levantamento das espécies de Tabanidae ocorrentes em todo o Estado do Paraná, com base em dados da literatura, registros da Coleção de Entomologia Pe. Jesus Santiago Moure depositada no Departamento de Zoologia da Universidade Federal do Paraná (DZUP), registros do Museu de Zoologia da Universidade de São Paulo (MZUSP) e em coletas realizadas durante o primeiro ano do Projeto "Levantamento da fauna entomológica no Estado do Paraná" (PROFAUPAR). Foi elaborada uma chave de identificação pictórica para subfamílias, tribos e gêneros ocorrentes no Paraná. Foram confeccionados desenhos esquemáticos dos caracteres diagnósticos dos gêneros, correspondendo à morfologia da cabeça, asa, abdômen e pernas. São registradas 68 espécies, distribuídas em 23 gêneros, seis tribos e três subfamílias; 28 espécies foram registradas pela primeira vez no estado.

DNA fingerprinting of tabanids (Diptera: Tabanidae) and their respective egg masses using PCR – restriction fragment profiling

AbstractPolymerase chain reaction and subsequent restriction fragment profiling analysis were used to associate collected tabanid egg masses with their respective species of adult horse flies and deer flies (Diptera: Tabanidae) in Manitoba, Canada. The ribosomal DNA (rDNA) intergenic spacer between the 28S and 18S ribosomal RNA genes was used successfully to differentiate 34 species of adult tabanids representing five genera: Atylotus (1 sp.), Chrysops (10 spp.), Haematopota (1 sp.), Hybomitra (17 spp.), and Tabanus (5 spp.). rDNA was a suitable molecular target for identifying tabanid species because of the high level of interspecific variation when comparing fragment profiles among different species, and the corresponding minimal intraspecific variation among individuals of the same species. Restriction fragment profiles from 56 field-collected tabanid egg masses were compared with those previously obtained from adults of known species. Egg masses of five species were identified: Hybomitra lasiophthalma (Macquart), Hybomitra nitidifrons nuda (McDunnough), Chrysops aestuans van der Wulp, Chrysops excitans Walker, and Chrysops mitis Osten Sacken. We also provide physical descriptions of these tabanid egg masses along with pictures.

Vasodilatory activity in horsefly and deerfly salivary glands.

Salivary gland extract (SGE) of four horsefly species (Hybomitra bimaculata Macquart, Hybomitra ciureai Séguy, Tabanus bromius L., Tabanus glaucopis Meigen) and one deerfly species (Chrysops relictus Meigen) (Diptera: Tabanidae) were shown to contain vasodilatory activity. Aliquots equivalent to 1, 5 and 10 pairs of salivary glands (SG) relaxed rat femoral artery (with intact endothelium) pre-constricted with phenylephrine. Vasodilatory activity was dose-dependent. SGE of one horsefly species (Haematopota pluvialis L.) did not induce relaxation. The kinetics of vasodilation induced by SGE of four horsefly species differed from the deerfly. These results indicate that tabanid species may produce more than one type of vasodilator to aid blood feeding.

The fossil tabanids (Diptera Tabanidae): when they began to appreciate warm blood and when they began transmit diseases?

A discussion of the known fossil tabanids (Diptera Tabanidae) is presented based on fossil evidence. This includes the origin of the hemathophagy in the Brachycera, more specifically for tabanids. Several tabanid species in the extant fauna are vectors for disease-producing organisms that affect humans and animals. Bacteria, viruses, rickettsiae, protozoa, and filarial worms can be transmitted by them, causing such diseases as anthrax, tularemia, anaplasmosis, various forms of trypanosomiasis, Q fever, and filariasis. However, if tabanids are directly responsible for all of these diseases is not consensual and the known fossil evidence is presented here.

Activity of tabanids (Insecta: Diptera: Tabanidae) attacking the reptiles Caiman crocodilus (Linn.) (Alligatoridae) and Eunectes murinus (Linn.) (Boidae), in the central Amazon, Brazil.

Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02 degrees 45'33"S; 59 degrees 51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kröber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.

Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil.

Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolândia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradão (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%) tabanids from 17 species were caught in the cerradão. The number of tabanid species varied from 7 during winter (July/August) to 15 in the spring (October). Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%). The tabanid peak, in October, coincided with the beginning of the rainy season. The population peak of most species, including those with higher vector potential, suggests that the rainy season can be considered as the period of potentially higher risk of mechanical transmission of pathogens by tabanids to horses in the region.

Horseflies (Diptera: Tabanidae) from Protected Areas of the Yucatan Peninsula, Mexico

Examination of horseflies deposited in the Coleccion Entomologica Regional of Universidad Autonoma de Yuca Merida, Yucatan, Mexico (CER-UADY) and Instituto Nacional de Diagnostico y Referencia Epidemiologicos, Mexico City, Mexico (INDRE) collections revealed a significant number of species and new localities from the Peninsula of Yucatan (PY). Previously published information is summarized, and new information about tabanid species reported for PY is presented, with emphasis on the most important protected areas within the biotic province of Yucatan: Celestun, Cuxtal, Dzilam and Ria Lagartos (Yucatan), Calakmul (Campeche), Sian Ka'an and El Eden (Quintana-Roo). Over 5,000 specimens collected by netting, human bait, Malaise traps and light traps were examined. A final list of 29 species, 17 representing state records and three representing PY records, is provided. One species is also reported for the first time from Mexico. Species diversity by state is as follows: Campeche, 19 species, 10 new state records; Quintana Roo, 23 species, 2 new state records; Yucatan, 22 species, 9 new state records. The 29 species reported for the biotic province of Yucatan represents more than 14% of the species known from Mexico. Most of these species have Neotropical or amphitropical affinities. Species showed wide distribution ranges within the biotic province of Yucatan, probably related to climatic and orographic homogeneity, which define the limits of the province. Key words: Tabanidae, Peninsula of Yucatan, Mexico

Abondance relative des tabanidés dans la région des savanes de Côte d'Ivoire

L'existence, l'abondance, la dynamique saisonnière, les préférences écologiques et la diversité des espèces de tabanidés ont été évaluées par des captures d'insectes à l'aide de pièges Nzi. L'étude a été menée durant quatre saisons dans quatre types de sites (savane, forêt, galerie et parc) et dans quatre localités des deux principaux départements d'élevage du nord et du nordouest de la Côte d'Ivoire, Odienné et Korhogo. Seize espèces de tabanidés appartenant à quatre genres ont été identifiées pour un total de 3 104 spécimens capturés. Les espèces numériquement les plus abondantes ont été Tabanus taeniola Palisot de Beauvois, 1807 (avec 26,4 p. 100 des captures), T. par Walker, 1854 (15,6 p. 100), T. laverani Surcouf, 1907 (14,9 p. 100) et Chrysops distinctipennis Austen, 1906 (12,3 p. 100). Les espèces les moins abondantes ont été Atylotus albipalpus Walker, 1850 (6,9 p. 100), Chrysops longicornis Macquart, 1838 (6,9 p. 100), T. brumpti Surcouf, 1907 (4,8 p. 100), T. gratus Loew, 1858 (3,7 p. 100), At. agrestis Wiedemann, 1828 (2,5 p. 100), At. fuscipes Ricardo, 1908 (1,8 p. 100), Ancala necopina Austen, 1912 (1,5 p. 100), T. biguttatus Wiedemann, 1830 (1,4 p. 100), T. ricardea Surcouf, 1906 (0,5 p. 100), T. boueti Surcouf, 1907 (0,4 p. 100), T. pluto Walker, 1854 (0,3 p. 100) et An. fasciata Fabricius, 1775 (0,2 p. 100). Le maximum de captures de tabanidés a été observé en galerie et le minimum en forêt. Les captures ont été plus importantes dans l'Odienné que dans le Korhogo. Le pic d'abondance s'est situé en mars, à la saison sèche chaude, sauf dans la localité de Korondougou, où le maximum a été observé en juin (saison des pluies). D'autre part, 2 471 stomoxes ont été capturés, dont 70,7 p. 100 de Stomoxys niger Macquart, 1851 et 29,3 p. 100 de S. calcitrans Linnaeus, 1758. Les stomoxes, avec seulement deux espèces, ont représenté près de 45 p. 100 des insectes piqueurs capturés et devront être pris en considération dans l'évaluation de l'impact des insectes piqueurs sur le bétail.

Betrequia ocellata Oldroyd (Diptera, Tabanidae, Rhinomyzini) blood feeding on Caiman crocodilus (Linnaeus) (Crocodylia, Alligatoridae) in Manaus, Brazil

In Central Amazonia the tabanid Betrequia ocellala Oldroyd, 1970 was recorded for the first time blood feeding on caimans during an experiment in September/October 1996 at Ducke Reserve, Manaus, Brazil. Among different available hosts (Caiman, horse, duck and human) B. ocellata was observed only on Caiman crocodilus (Linnaeus, 1758), suggesting specific blood feeding on crocodilians. The adult flight season, diurnal blood feeding period and flight stratification are presented. Other tabanid species feeding or landing on caimans are also recorded.

Seasonal changes in abundance and gonotrophic age of host-seeking Tabanidae (Diptera) from a subarctic Labrador peatland.

Canopy and Malaise traps continuously sampled host-seeking female tabanids throughout the 1990 and 1991 flight seasons at Iron Arm Fen in subarctic Labrador. A total of 19,426 tabanids representing 3 genera and 18 species was collected. Subsamples of each daily catch were dissected to determine gonotrophic age. Horse flies (mainly Hybomitra spp.) accounted for 96% of all tabanids; the remainder were deer flies (Chrysops spp.). Hybomitra arpadi (Szilady) and Hybomitra aequetincta (Becker) were the dominant species, comprising 60.6 and 24.8% of collections, respectively. They were also among the 1st species to emerge (in early July) and persisted for the entire flight season (until mid-August). Seasonal abundance for each species varied between the 2 yr of study. Both H. arpadi and H. aequetincta were obligately anautogenous at Iron Arm Fen. Seasonal changes in the gonotrophic age structure of host-seeking females of these species indicated a mid-July emergence peak in 1990 and an early July peak in 1991. Among the other tabanid species collected at Iron Arm Fen, Hybomitra lurida (Fallen) and Hybomitra zonalis (Kirby) were facultatively autogenous, whereas Hybomitra pechumani (Teskey & Thomas), Hybomitra hearlei (Philip), Hybomitra frontalis (Walker), Hybomitra astuta (Osten Sacken), Chrysops zinzalus (Philip), and Chrysops nigripes Zetterstedt were obligately autogenous during their 1st ovarian cycle.

Responses of horse flies (Diptera: Tabanidae) to Jersey bullocks and canopy traps baited with ammonia, octenol, and carbon dioxide.

The attraction of females of six species of tabanids to stanchioned Jersey bullocks, unbaited canopy traps, and canopy traps baited with either octenol (1-octen-3-ol), ammonia (NH4OH), a combination of ammonia and octenol, or 5 kg of dry ice (CO2) was studied. A randomized Latin square design (treatments x sites x days) was used. Species diversity and number of flies captured in canopy traps unbaited or baited with octenol, ammonia, or the combination of octenol and ammonia did not differ significantly. Females of Tabanus americanus Forster, T. fuscicostatus Hine, and T. lineola F. were captured more frequently in CO2-baited canopy traps than on Jersey bullocks, but the reverse was observed for females of Leucotabanus annulatus (Say). The number of females of T. pallidescens Philip and T. wilsoni Pechuman collected from CO2-baited canopy traps and bullocks did not differ significantly.

Mechanotactile and olfactory antennal sensilla in four species of female tabanids (Diptera)

Abstract This paper reports the loci, structure and numerical distribution of various types of mechanotactile and olfactory sensilla in four species of female tabanids, i.e., Tabanus rubidus, Tabanus striatus, Haematopota dissimilis, and Tabanus subcinerences. It was observed that sensilla chaetica were confined to scape and pedicel, while sensilla basiconica were confined to the first segment of flagellum. Sensilla trichoidea and sensilla stellate were distributed over all the segments of flagellum in all four species of tabanids, although they were present in maximum number in the first segment. The significant difference in the total number of various types of sensilla in different species has also been observed.

Evaluation of Pyrethroid Ear Tag and Spray Treatment of Cattle Against Horse Flies (Diptera: Tabanidae)

Permethrin and fenvalerate ear tags, and fenvalerate sprays (0.01 and 0.02%) were evaluated against tabanids under field conditions in Louisiana. Residual concentration of insecticide in the hair from the head, side, back, abdomen, front and back legs of steers was measured after each fly collection period by gas chromatography. Mortality rates were reported relative to the feeding pattern of species of tabanids studied and insecticide concentration of different body regions. A total of 2,922 females belonging to three Tabanus species were collected. Mortality rates were 3% in controls, 9% in permethrin tag, 15% in fenvalerate tag, 67% in 0.01% fenvalerate spray and 79% in 0.02% fenvalerate spray treatments.