Biting behaviour of Tabanidae on cattle in mountainous summer pastures, Pyrenees, France, and effects of weather variables.

In France, during the summer, cattle in mountainous pastures can be highly exposed to tabanid bites. The persistent biting behaviour of tabanids not only causes disturbance, but is also responsible for transmitting diseases, such as bovine besnoitiosis. The purpose of this study was to better identify the level of tabanid annoyance on cattle by means of insect trapping and direct observation of cows. Tabanids were active during the entire daily observation period (10:00-16:00), except for Haematopota sp., which were less active in the morning. The tabanids collected in Nzi traps were generally representative of those that landed on cattle, except for Haematopota sp., as Nzi traps were not very effective for these species. The preferred feeding sites for most species appeared to be cow's legs or udder. Leg stamping was the defensive reaction most related to a tabanid alighting on a host. Generalized linear mixed models showed that the parameters associated with tabanid landings on hosts were related to weather and altitude, but not to landscape structure. Increased landings were mostly associated with the higher temperatures and lower wind speeds at midday, but some differences were observed between species. The results indicate that cattle-protection measures should be taken during the peak of tabanid abundance when climatic conditions favour intense biting activity. Nzi traps set close to livestock were very effective to catch tabanids and could help in reducing the annoyance caused by horse flies.

Spatial and temporal distribution of Tabanidae in the Pyrenees Mountains: the influence of altitude and landscape structure.

In high-altitude summer pastures, horseflies (Diptera: Tabanidae) can be a serious nuisance to livestock, as well as mechanical vectors of animal diseases such as besnoitiosis, an enzootic disease in the Pyrenees. However, the activity of horseflies in mountainous environments is poorly documented. To study the seasonality and distribution of tabanids in the Pyrenees Mountains, a sampling design was set up in two valleys on opposite sides of the mountain, one north-facing and one south-facing, along high-elevation gradients and at different distances from a water body between May and October 2011. The influence of the landscape on species richness and abundance was assessed by taking into account forested and unforested areas in 200 m radii around the trapping sites. Our findings indicated that: (1) The slope, the altitude and the size of unforested patches significantly influenced community composition of tabanids. (2) Altitude had a positive or a negative effect, depending on the species. (3) Species richness and abundance were negatively correlated with large open habitats and positively correlated with patch-shape complexity. (4) Seasonal succession of the most abundant species was observed in both valleys, with a maximum of catches at the beginning of August; however, tabanid activity ended earlier in the southern valley, which was more exposed to sunlight. (5) Philipomyia aprica, Tabanus bromius, Tabanus glaucopis and Hybomitra auripila were active from 9:00 to 19:00 h (GMT+1), with a peak of activity at midday. This paper also discusses the implications of these findings in relation to changes in horsefly distribution and their control in mountainous environments.

Blood-feeding patterns of horse flies in the French Pyrenees.

Horse flies can mechanically transmit Besnoitia besnoiti, the agent of bovine besnoitiosis. Although previously limited to enzootic areas, especially the French Pyrenees Mountains, bovine besnoitiosis is now considered a re-emerging disease in western Europe. To improve understanding of the role of horse flies as mechanical vectors, this study investigated their blood-feeding ecology in the eastern French Pyrenees, in two high-altitude summer pastures whose main domestic ungulates were cattle, and in a wildlife park with native fauna. Species-specific PCR assays were conducted to identify the sources of blood meals: wild boar, horse, cattle (or bison), sheep (or mouflon), goat, red deer, roe deer and izard (or Pyrenean chamois). In La Mouline pasture, tabanids (N=20) fed on red deer (70%) and cattle (30%). In Mantet pasture, tabanids (N=24) fed on cattle (52%), red deer (20%), wild boar (16%), horse (8%) and sheep (4%). In the wildlife park, Tabanus bromius (N=32), the most abundant species collected, fed on red deer (85%), bison (9%) and wild boar (6%). Despite relatively high densities in both the pastures and in the wildlife park, small wild ungulates (izard, mouflon and roe deer) were not detected as a source of blood meals. Only two mixed blood meals were identified in two specimens of T. bromius: cattle/horse for the specimen collected in the pastures, and bison/wild boar for the specimen collected in the wildlife park. Our findings showed that tabanids display a level of opportunistic feeding behaviour, in addition to a preference for red deer, the latter being particularly true for Philipomyia aprica, the most abundant species collected in the pastures.

Olfactory and behavioural responses of tabanid horseflies to octenol, phenols and aged horse urine.

Electrophysiological and behavioural responses of females of two tabanid species, Tabanus bromius L. and Atylotus quadrifarius (Loew) (Diptera: Tabanidae), to ammonia, octenol (1-octen-3-ol), phenols and aged horse urine were compared. Electroantennogram (EAG) responses in both species to octenol, 4-methylphenol (4MP), 3-propylphenol (3PP) and a phenol mixture (4MP and 3PP at a ratio of 16 : 1) increased in a dose-dependent fashion. The most effective stimulus was 4MP and synergism between the two phenols may exist. Aged horse urine also elicited strong EAG responses in both species. Using gas chromatography-mass spectrometry (GC-MS) analysis, we identified 29 compounds in horse urine, which included, in particular, ketones, fatty alcohols and phenols, among which 4MP was the most abundant component (~ 80%). Trapping experiments were carried out using Nzi traps baited with various odours. Octenol and the phenol mixture in combination with ammonia increased catches of tabanids by 1.8-2.8 times relative to ammonia alone. Aged horse urine increased catches of T. bromius and A. quadrifarius by 2.2 and 4.1 times, respectively. The high attractiveness of aged horse urine, especially for A. quadrifarius, is not likely to derive from 4MP alone, but from the mixture of various active compounds used in host location.

Behavioural and electrophysiological responses of females of two species of tabanid to volatiles in urine of different mammals.

Urine volatiles from different ungulates (cows, horses and sheep) were tested as bait for tabanids in southeastern France using Nzi traps during the early summer of 2011. Tabanus bromius Linnaeus, 1758 and Atylotus quadrifarius (Loew, 1874) (both: Diptera: Tabanidae) were the most captured species, respectively representing 57% and 41% of all tabanids collected (all of which were female). Horse urine significantly increased catches of T. bromius (1.6-fold) and A. quadrifarius (3.5-fold), and sheep urine significantly increased catches of A. quadrifarius (2.5-fold). In parallel, an electroantennogram (EAG) study was conducted for the first time on these two species, in which EAGs were recorded using 1-octen-3-ol and extracts of the same urine samples used in the field. For T. bromius, the EAG response to 1-octen-3-ol increased quasi-sigmoidally with dose, with a maximum response at ≥100 µg on filter paper. For both species of tabanid, cow and horse urine elicited larger EAGs than did sheep urine. The behavioural implications in host-seeking and feeding habits are discussed.

[Ecology of Stomoxys flies (Diptera: Muscidae) in Gabon. I. First survey in different ecological areas]. / Ecologie des stomoxes (Diptera: Muscidae) au Gabon. I--Premier inventaire dans différentes zones ecologiques.

The stomoxyine flies are hematophagous diptera and potential vectors of various pathogenic agents. Like those of the Afrotropical Region, the stomoxyine flies of Gabon remain nearly unknown. For these reasons, an entomological survey was conducted in a transverse way in eight localities representative of the various ecological zones of Gabon. The survey was based on the use of Vavoua traps. Various environmental factors able to influence the captures were noticed and included into a canonical correspondence analysis. In total, 15,966 Stomoxys spp., belonging to seven species or subspecies, were captured. The apparent densities (DAP) expressed as the number of flies per trap and per day, were highest in Franceville (41), Bakoumba (40), Makokou (25) and Mouila (21). The most abundant species were S. n niger (33.4%), S. transvittatus (33%), then S. calcitrans (17%). The principal factors that could explain the variability of the captures were the degree of anthropisation, the botanical facies (savanna or forest), the presence of wild and domestic fauna and the nature of the vegetal cover of the ground. S. calcitrans, S. niger niger were abundant in the areas where human presence was manifest. S. xanthomelas was present in forest belts. S. transvittatus, S. omega, S. inornatus were ubiquitous species. S. niger bilineatus was found in savannas areas.

Temporal coexistence of dung-dweller and soil-digger dung beetles (Coleoptera, Scarabaeoidea) in contrasting Mediterranean habitats.

The western part of the Mediterranean basin is a transitional biogeographical region for the distribution of the representatives of the main guilds of dung beetles; towards the south, Aphodiinae (dung-dwellers) become scarce, whereas northwards Scarabaeinae (soil-diggers) progressively disappear. The number of species in local dung beetle assemblages is enhanced by this double faunistic contribution. Annual dung beetle assemblages were sampled in two sub-Mediterranean sites, which differed by 600 m in elevation, in order to determine the phenological dynamics related to the way of using dung (dung-dwellers/Aphodiinae vs. soil-diggers/Scarabaeinae and Geotrupinae). Aphodiids were active all year round, although they were affected by summer drought and, at high elevation, by the length of the cold season. This reduced activity was related to an impoverishment of Aphodiinae and to reduced temporal segregation between species. In contrast, soil-diggers were not active all year round and showed different species assemblages in the two sites. An extension of the activity period of these beetles was observed due to the occurrence of cold resistant species at high elevation. Our results suggested that the occurrence of soil-diggers seemingly did not affect the seasonality of dung-dwellers; their local abundance showed no negative correlation and, most importantly, phenological differences between dung-dwellers were always significantly higher than the seasonal differences between dwellers and diggers.