Interactions between cattle and biting flies: effects on the feeding rate of tsetse

In Zimbabwe, studies were made of the effect of host behaviour on the feeding success of Glossina pallidipes Austen and G. morsitans morsitans Westwood (Diptera: Glossinidae) attracted to cattle of different age and sex. The mean feeding rates for male and female G. pallidipes attracted to oxen were 60% and 58%, respectively, compared to 33% and 53% for male and female G. m. morsitans. The feeding rate of G. pallidipes varied between oxen and was inversely correlated with a host's rate of defensive leg movements, which, in turn, was positively correlated with the density of Stomoxys spp. (Diptera: Muscidae) caught in the vicinity of the host. Tsetse were significantly less successful in feeding from young cattle. For G. pallidipes, the feeding rate on calves (<6 months) was 11%, whereas for male and female G. m. morsitans the rates were 12% and 20%, respectively. Significantly lower feeding rates were apparent for cattle aged up to 2 years, when the feeding rate for G. pallidipes (31%) was still significantly less than that on mature oxen (68%). Feeding rates for G. pallidipes on adult female cattle were lower than those on oxen (45% vs. 61%). The lower feeding rates in young animals were attributed to higher rates of defensive movements. The results suggest that higher rates of defensive activities by young cattle reduce the risk of them contracting trypanosomiasis.     

Is there safety in numbers? The effect of cattle herding on biting risk from tsetse flies

In sub-Saharan Africa, tsetse (Glossina spp.) transmit species of Trypanosoma which threaten 45-50 million cattle with trypanosomiasis. These livestock are subject to various herding practices which may affect biting rates on individual cattle and hence the probability of infection. In Zimbabwe, studies were made of the effect of herd size and composition on individual biting rates by capturing tsetse as they approached and departed from groups of one to 12 cattle. Flies were captured using a ring of electrocuting nets and bloodmeals were analysed using DNA markers to identify which individual cattle were bitten. Increasing the size of a herd from one to 12 adults increased the mean number of tsetse visiting the herd four-fold and the mean feeding probability from 54% to 71%; the increased probability with larger herds was probably a result of fewer flies per host, which, in turn, reduced the hosts' defensive behaviour. For adults and juveniles in groups of four to eight cattle, > 89% of bloodmeals were from the adults, even when these comprised just 13% of the herd. For groups comprising two oxen, four cows/heifers and two calves, a grouping that reflects the typical composition of communal herds in Zimbabwe, approximately 80% of bloodmeals were from the oxen. Simple models of entomological inoculation rates suggest that cattle herding practices may reduce individual trypanosomiasis risk by up to 90%. These results have several epidemiological and practical implications. First, the gregarious nature of hosts needs to be considered in estimating entomological inoculation rates. Secondly, heterogeneities in biting rates on different cattle may help to explain why disease prevalence is frequently lower in younger/smaller cattle. Thirdly, the cost and effectiveness of tsetse control using insecticide-treated cattle may be improved by treating older/larger hosts within a herd. In general, the patterns observed with tsetse appear to apply to other genera of cattle-feeding Diptera (Stomoxys, Anopheles, Tabanidae) and thus may be important for the development of strategies for controlling other diseases affecting livestock.     

Application of DNA markers to identify the individual-specific hosts of tsetse feeding on cattle

Primer sets for five different ungulate loci were used to obtain individual microsatellite DNA profiles for 29 Mashona cattle from a herd in Zimbabwe. There were 3-13 alleles for each locus and, using the entire suite of five loci, each animal within the herd, including closely related individuals, could be unequivocally distinguished. Wild-caught Glossina pallidipes Austen (Diptera: Glossinidae) were fed on specific cattle and the bloodmeal was profiled 0.5-72 h after feeding. The individual specific sources of the bloodmeals, including mixe meals produced by allowing tsetse to feed on two different cattle, were reliabl identified up to 24 h after feeding. The technique was used in field studies of hos selection by G. pallidipes and G. morsitans morsitans Westwood (Diptera Glossinidae) attracted to pairs of cattle. When the pair comprised an adult and a calf, 100% of meals were from the adult. For some pairs of adult cattle, tsetse were biased significantly towards feeding on one animal, whereas for other pairs there was no such bias. In general, feeding was greater on the animal known to have lower rate of host defensive behaviour. Results suggest that relatively slight differences in the inherent defensive behaviour of cattle produce large difference in host-specific feeding rates when the hosts are adjacent. For flies attracted to pair of cattle, < 2% contained blood from both hosts. The DNA profiling technique will be useful in studying the epidemiology of vector-borne diseases of livestock.     

Learning influences host choice in tsetse

A learning capacity for feeding is described in many insect species including vectors of diseases, but has never been reported in tsetse flies (Diptera, Glossinidae), the cyclic vectors of human (sleeping sickness) and animal trypanosomoses in Africa. Repeated feeding on the same host species by a disease vector is likely to increase the within-species disease-transmission risk, but to decrease it between species. An experiment with cattle and reptiles in a stable provides evidence that the species of host selected for the second blood meal in tsetse flies depends on the host encountered for the first blood meal when the between-meal interval is 2 days. This preference disappears when the between-meal interval is extended to 3 days. The energetic advantages of this acquired preference and its importance in trypanosomoses epidemiology are discussed.     

Host selection by Anopheles arabiensis and An. quadriannulatus feeding on cattle in Zimbabwe

In the Zambezi valley, mosquito females of the Anopheles gambiae Giles complex (Diptera: Culicidae) were collected from a hut containing pairs of cattle distinguishable by known DNA markers. DNA was extracted from the blood-fed mosquito abdomens and primer sets for ungulate and mosquito DNA loci were used to identify the mosquito sibling species and individual host source(s) of their bloodmeals. The 67 mosquitoes comprised a mixture of An. arabiensis Patton (31%) and An. quadriannulatus Theobald (69%). DNA from one or both of the cattle present in the hut was detected in 91% of samples. When the hut contained an adult and a calf, the percentage of bloodmeals from the adult, the calf and adult + calf were 58%, 27% and 15%, respectively; the trend towards meals from the adult host was consistent but not always significant. When the pair of cattle comprised two adults of roughly equal size and age, then mosquitoes generally showed no significant bias towards feeding from one individual. There was no significant difference in the pattern of host selection made by An. arabiensis and An. quadriannulatus but the former had a significantly higher percentage (20%) of mixed meals than An. quadriannulatus (9%). These two members of the An. gambiae complex appear to be less selective in their choice of cattle hosts compared to day-active Diptera such as tsetse and Stomoxys, possibly because the hosts are generally asleep when Anopheles are active and there is therefore less selective pressure to adapt to host defensive behaviour. The slight bias of Anopheles towards older and/or larger cattle may be related to the host's larger surface area.     

The effects of host physiology on the attraction of tsetse (Diptera: Glossinidae) and Stomoxys (Diptera: Muscidae) to cattle

In Zimbabwe, studies were made of the numbers of tsetse (Glossina spp.) and stable flies (Stomoxys spp.) attracted to cattle of different nutritional status, age and sex. Host odours were analysed to determine the physiological basis of these differences and improved methods are described for measuring rates of production of kairomones. Seasonal fluctuations in host weight, related to changes in pasture quality, had no significant effect on attraction of tsetse or Stomoxys. However, both attraction to different individuals and carbon dioxide production by these individuals were strongly correlated with weight, suggesting a possible link. Attraction to the odour from different types of cattle decreased in the order ox>cow>heifer>calf, and oxen were twice as attractive as calves of less than 12 months old. Lactation did not alter the relative attractiveness of cows. Calves less than six months old produced lower levels of carbon dioxide, acetone, octenol and phenols than oxen, but for older calves and cows, levels of production of known kairomones and repellents were similar to those of an ox. Carbon dioxide produced by cattle varied according to time of day and the animal's weight; cattle weighing 500 kg produced carbon dioxide at a mean rate of 2.0 l min(-1) in the morning and 2.8 l min(-1) in the afternoon compared to respective rates of 1.1 and 1.9 l min(-1) for cattle weighing 250 kg. Artificially adjusting the doses of carbon dioxide produced by individual cattle to make them equivalent did not remove significant differences in attractiveness for tsetse but did for Stomoxys. Increasing the dose of carbon dioxide from 1 to 4 l min(-1) in a synthetic blend of identified kairomones simulating those produced by a single ox, increased attractiveness to tsetse but not to the level of an ox. The results suggest that the main sources of differences in the attractiveness of individual cattle are likely to be variation in the production of carbon dioxide and, for tsetse, other unidentified kairomone(s). The biological and practical implications of these findings are discussed.     

Diptera as vectors of mycobacterial infections in cattle and pigs

Mycobacteria were isolated from 14 (4.5%) of 314 samples, containing 7791 adult Diptera, which were collected in the Czech Republic and Slovakia in 1997-2000. These flies were collected from three cattle herds with paratuberculosis, two pig herds with mycobacterial infections and one farm that kept both cattle and pigs and that did not have problems of mycobacterial infections. Mycobacterium intracellulare was isolated from Eristalis tenax Linnaeus (Diptera: Syrphidae) captured from a pig herd. Mycobacterium avium ssp. avium (serotype 8) was isolated from flies of the genera Drosophila Fallen (Diptera: Drosophilidae) and Musca Linnaeus (Diptera: Muscidae) originating from a pig herd. Mycobacterium spp. were isolated from Musca spp. and Mycobacterium fortuitum was isolated from dung flies of the genus Scatophaga Meigen (Diptera: Scatophagidae), Musca spp. and Stomoxys calcitrans Linnaeus (Diptera: Muscidae) captured in the same herd. Mycobacterium scrofulaceum was isolated from S. calcitrans from the farm with both cattle and pigs. Mycobacterium avium ssp. paratuberculosis was isolated from Scatophaga spp. collected from pastures grazed by one of the cattle herds and from Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) and Lucilia caesar Linnaeus (Diptera: Calliphoridae) captured in a slaughterhouse, where cattle infected with paratuberculosis were slaughtered. Mycobacterium phlei was isolated from flies of the genus Lucilia captured at a waste bin. These data indicate that mycobacteria may be spread by adult flies that have been in contact with material contaminated with these pathogens.     

Feeding behaviour of Glossina pallidipes and g. morsitans centralis on Boran cattle infected with trypanosoma congolense or T. vivax under laboratory conditions

In field studies, tsetse flies (Diptera: Glossinidae) feed more successfully on cattle infected with Trypanosoma congolense Broden (Kinetoplastida: Trypanosomatidae) than on cattle infected with T. vivax Ziemann or uninfected cattle. Here we describe the first laboratory investigation of this phenomenon. In the first experiment, caged Glossina pallidipes Austen were fed for 1 and 5 min on a Boran steer infected with T. congolense clone IL 1180 and on an uninfected steer. Feeding success was recorded in this way five times over several weeks. The same protocol was subsequently used in three additional experiments with the following combinations: G. pallidipes and a steer infected with T. vivax stock IL 3913, G. morsitans centralis Machado and a steer infected with T. congolense, and G. morsitans centralis and a steer infected with T. vivax. The four experiments were replicated once, making eight experiments in total. In three experiments there was increased tsetse feeding success, measured at 1 min, after a steer became infected (T. congolense, two experiments and T. vivax, one experiment). Analysis of all data combined found no significant differences in tsetse feeding success on the different groups of cattle prior to infection, but after infection tsetse feeding success was significantly greater on the infected cattle (P< 0.001). Trypanosoma congolense infection led to a greater increase in tsetse feeding success than T. vivax infection. The increase in feeding success was not related to changes in the level of anaemia, skin surface temperature or parasitaemia. A possible explanation is the effects of trypanosome infection on cutaneous vasodilation and/or blood clotting in infected cattle. When allowed to feed for 5 min, nearly all tsetse engorged successfully and effects of cattle infection on feeding success were not found.     

Walk-through trap for control of horn flies (Diptera: Muscidae) on pastured cattle

A walk-through fly trap designed in 1938 by W. G. Bruce was tested for two field seasons in Missouri. Screened elements along both sides of the device functioned as cone traps, thereby catching horn flies, Haematobia irritans (L.), as they were swept from cattle by strips of carpet hung from the roof. Horn fly control on pastured cattle averaged 54 and 73% when they were afforded access to the trap. Analyses of Diptera captured in the trap indicated that horn flies comprised the most abundant species; face flies, Musca autumnalis De Geer, stable flies, Stomoxys calcitrans (L.), and others were present in smaller numbers. Cattle were not reluctant to use the trap, and no structural problems were observed during the experiment.     

Modelling the effect of feeding-related mortality on the feeding strategy of tsetse (Diptera: Glossinidae)

Abstract. Free-living haematophagous insects risk death through host grooming responses or through increased susceptibility to predation whenever they take a bloodmeal. In this paper we investigate the effects of these risks on the feeding strategy of tsetse. A model is presented that allows for death of tsetse by starvation if they do not succeed in feeding within a fixed time (set at 6 days in the first instance) and for mortality specifically associated with feeding. In addition there is background mortality that applies to all flies at all times.
The model is used to compute the individual life-time fertility (number of female puparia per female) as a function of the probability of obtaining a meal (indicated by field data to be very high, usually > 0.85 per day) and the day on which flies start to search for a meal. We suggest that the feeding strategy that would be selected for is that which allows the maximum reproductive output. The model shows that this strategy involves making no attempts to feed for 3–4 days after the previous meal and then attempting to feed with the greatest possible probability until a meal is obtained. The predicted feeding interval, obtained independently of any trapping data, agrees closely with all previous estimates from field studies using a variety of methods. Preliminary results from a laboratory experiment reveal an increased risk of predation of recently fed as compared with hungry tsetse. The lower the actual feeding mortality the more frequently will flies be able to feed should conditions so demand. It is adaptive, however, for tsetse to delay attempting to feed for as long as they can, which is made possible by the near certainty of locating and feeding on a host within 1 day, using their sophisticated sensory systems.     

Effects of host grooming on louse populations

Grooming behaviour by the host is increasingly recognized as an important determinant of feeding behaviour by blood-sucking arthropods. In general, grooming activity increases as a function of attack rate which, in some cases, provides a density-dependent limitation on the success of blood feeding. In turn this can lead to density dependence in population parameters of the arthropod, and can affect transmission of some arthropod-borne parasites in a similar way. But although insect-host interactions at this level are now being revealed in a variety of blood-sucking groups, such as mosquitoes, tsetse flies and triatomine bugs (see Box I), they are perhaps most clearly seen in, populations of ectoporositic insects such as lice, which ore permanently subject to defensive grooming behaviour by their hosts. As Durno Murray discusses here, host grooming has been a dominant factor in the evolution of lice, not only at the morphological level but also in terms of reproductive strategy.     

Behavioural responses of stable flies to cattle manure slurry associated odourants

Stable flies (Stomoxys calcitrans [Diptera: Muscidae] L.) are blood‐feeding synanthropic pests, which cause significant economic losses in livestock. Stable fly antennae contain olfactory sensilla responsive to host and host environment‐associated odours. Field observation indicated that the abundance of stable flies increased significantly in grasslands or crop fields when cattle manure slurry was applied. Major volatile compounds emanating from manure slurry were collected and identified. Behavioural responses of stable flies to those compounds were investigated in laboratory bioassays and field‐trapping studies. Results from olfactometer assays revealed that phenol, p‐cresol and m‐cresol were attractive to adult stable flies. When tested individually, attraction was higher with lower dosages. Stable flies were most attracted to blends of phenol and m‐cresol or p‐cresol. Traps with binary blend lures caught more stable flies in field trials as well.     

Host preferences of tsetse (Diptera: Glossinidae) based on bloodmeal identifications

An enzyme-linked immunosorbent assay (ELISA) was developed to identify the origin of vertebrate blood in the guts of 29 245 wild-caught flies of eleven Glossina species from various ecological zones of Africa. Depending on the quality of the bloodmeal samples, 62.8% of the samples were identified and could be assigned to a host-group (e.g. ruminant), family (e.g. Bovidae) or species (e.g. Bos spp.). A total of 13 145 samples (44.9%) was identifiable up to the species level. With a few exceptions, the present results are in agreement with earlier published reports. Glossina austeni and G. fuscipleuris seemed to have a distinct feeding preference for Suidae (mainly bushpig). Glossina morsitans ssp. fed mainly on Suidae (mainly warthog), although local variations were observed and in some areas hippopotamus or ruminants replaced the warthog as the main host. Bushbuck seemed to be the principal food source for G. longipalpis and G. fusca . Glossina pallidipes fed mainly on ruminants (buffalo, bushbuck and cattle) but, depending on host availability and location, Suidae were also important hosts. Hippopotamus was identified as the main source of blood-meals for G. brevipalpis . The main hosts for G. longipennis were Suidae (mainly bushpig) and not rhinoceros as had been reported 40 years earlier. The opportunistic feeding behaviour of the palpalis tsetse group was confirmed. The results showed that changes in environment, fauna and host availability may result in modification of tsetse feeding patterns.     

Diversity of Stomoxys spp. (Diptera: Muscidae) and diurnal variations of activity of Stomoxys indicus and S. calcitrans in a farm, in Wang Nam Khiao District, Nakhon Ratchasima Province, Thailand

A study of species diversity of Stomoxys spp. and diurnal variations of activity of the most abundant was performed during a one year period at a local dairy cattle farm in Wang Nam Khiao District, Nakhon Ratchasima Province, Thailand. Four species of stomoxyine flies were morphologically identified, including Stomoxys indicus Picard 1908, S. calcitrans (Linnaeus 1758), S. sitiens Rondani 1873 and S. uruma Shinonaga and Kanao 1966. The most common species were S. indicus (50.2%) and S. calcitrans (49.5%). S. sitiens and S. uruma were found in small proportions (< 1%). The number of flies captured was significantly different among the three seasons with the greatest number in the rainy season (mean = 66%; df = 2, P < 0.05). The variations of diurnal activity were observed during different period of times (06:00 to 18:00) during three seasons. Both sexes of S. indicus and males of S. calcitrans showed unimodal activity pattern in cool and summer seasons. But a bimodal activity pattern was recorded in rainy season. For females S. calcitrans, a unimodal peak of activity was observed in cool season and a constant variation of activity all along the day in summer and rainy seasons, with an increase from the morning to the evening. A better understanding of stomoxyine fly behavior, especially the daily flight activity, can assist in prioritization and design of appropriate vector prevention and control strategies.     

Molecular identification of bloodmeal sources and trypanosomes in Glossina spp., Tabanus spp. and Stomoxys spp. trapped on cattle farm settlements in southwest Nigeria

The interactions of host, vector and parasite in bovine trypanosomiasis transmission cycles in southwest Nigeria are not yet well understood. Trypanosoma (Trypanosomatida: Trypanosomatidae) species infection prevalences and bloodmeal sources were determined in transmitting vectors of the genera Glossina (Diptera: Glossinidae), Tabanus (Diptera: Tabanidae) and Stomoxys (Diptera: Muscidae) collected using Nzi traps in cattle settlements in southwest Nigeria. Sequenced cytochrome B mitochondrial DNA segments obtained from vector digestive tracts identified bloodmeal sources from eight host species, namely human, cattle, hippopotamus, giraffe, gazelle, spotted hyena, long‐tailed rat and one unidentified species. Overall, 71.1% [95% confidence interval (CI) 63.0–78.1], 33.3% (95% CI 21.9–47.0) and 22.2% (95% CI 16.2–29.9), respectively, of Glossina, Tabanus and Stomoxys flies were positive for trypanosomes. The observed trypanosome species were Trypanosoma vivax, Trypanosoma congolense, Trypanosoma brucei, Trypanosoma evansi, Trypanosoma simiae and Trypanosoma godfreyi. Trypanosome DNA was more prevalent in tsetse (34.8% Tr. vivax, 51.1% Tr. b. brucei, 5.2% Tr. congolense, 4.4% Tr. simiae and 24.4% mixed infections) than in other flies and the main determinants in all flies were seasonal factors and host availability. To the best of the present group's knowledge, this is the first report of Trypanosoma species in Tabanus and Stomoxys flies in Nigeria. It indicates that vector control programmes should always consider biting flies along with tsetse flies in the control of human and animal trypanosomiasis.     

Effects of stable flies (Diptera: Muscidae) and heat stress on weight gain and feed efficiency of feeder cattle.

Cattle respond to the feeding of stable flies, Stomoxys calcitrans (L.), by bunching to protect their front legs. This bunching can increase heat stress which indirectly accounts for much of the reduction in cattle weight gains. We used fly-screened, self-contained feedlot pens which allowed regulation of fly populations feeding on cattle. The indirect fly effects (bunching and heat stress) accounted for 71.5% of the reduced weight gain. The direct effect of the biting flies and energy loss involved in fighting flies accounted for 28.5% of the reduced weight gain.     

Effect of host behaviour on host preference in Stomoxys calcitrans

Field observations suggest that, in the U.K., cattle are the preferred host of Stomoxys calcitrans (L.), followed by horses. Differences were observed in the numbers of flies feeding on individual animals both in the field and under controlled conditions. Analysis of the behaviour of four Friesian calves under attack from S. calcitrans in controlled conditions revealed that the differences in the levels of attack between individual hosts are dependent on the reactions of the host when under attack. Those hosts which respond vigorously by tail flicks, foot stamps and head-swings suffer less from attack by S. calcitrans than their more placid contemporaries.     

Identification of Tsetse (Glossina spp.) Using Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry

Glossina (G.) spp. (Diptera: Glossinidae), known as tsetse flies, are vectors of African trypanosomes that cause sleeping sickness in humans and nagana in domestic livestock. Knowledge on tsetse distribution and accurate species identification help identify potential vector intervention sites. Morphological species identification of tsetse is challenging and sometimes not accurate. The matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS) technique, already standardised for microbial identification, could become a standard method for tsetse fly diagnostics. Therefore, a unique spectra reference database was created for five lab-reared species of riverine-, savannah- and forest- type tsetse flies and incorporated with the commercial Biotyper 3.0 database. The standard formic acid/acetonitrile extraction of male and female whole insects and their body parts (head, thorax, abdomen, wings and legs) was used to obtain the flies'' proteins. The computed composite correlation index and cluster analysis revealed the suitability of any tsetse body part for a rapid taxonomical identification. Phyloproteomic analysis revealed that the peak patterns of G. brevipalpis differed greatly from the other tsetse. This outcome was comparable to previous theories that they might be considered as a sister group to other tsetse spp. Freshly extracted samples were found to be matched at the species level. However, sex differentiation proved to be less reliable. Similarly processed samples of the common house fly Musca domestica (Diptera: Muscidae; strain: Lei) did not yield any match with the tsetse reference database. The inclusion of additional strains of morphologically defined wild caught flies of known origin and the availability of large-scale mass spectrometry data could facilitate rapid tsetse species identification in the future.     

Spatio-temporal distribution of tsetse and other biting flies in the Mouhoun River basin, Burkina Faso

In the Mouhoun River basin, Burkina Faso, the main vectors of African animal trypanosomoses are Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood (Diptera: Glossinidae), both of which are riverine tsetse species. The aim of our study was to understand the impact of landscape anthropogenic changes on the seasonal dynamics of vectors and associated trypanosomosis risk. Three sites were selected on the basis of the level of disturbance of tsetse habitats and predominant tsetse species: disturbed (Boromo, for G. tachinoides) and half-disturbed (Douroula for G. tachinoides and Kadomba for G. p. gambiensis). At each of these sites, seasonal variations in the apparent densities of tsetse and mechanical vectors and tsetse infection rates were monitored over 17 months. Tsetse densities differed significantly between sites and seasons. Of 5613 captured tsetse, 1897 were dissected; 34 of these were found to be infected with trypanosomes. The most frequent infection was Trypanosoma vivax (1.4%), followed by Trypanosoma congolense (0.3%) and Trypanosoma brucei (0.05%). The mean physiological age of 703 tsetse females was investigated to better characterize the transmission risk. Despite the environmental changes, it appeared that tsetse lived long enough to transmit trypanosomes, especially in half-disturbed landscapes. A total of 3021 other biting flies from 15 species (mainly Tabanidae and Stomoxyinae) were also caught: their densities also differed significantly among sites and seasons. Their relative importance regarding trypanosome transmission is discussed; the trypanosomosis risk in cattle was similar at all sites despite very low tsetse densities (but high mechanical vector densities) in one of them.     

The role of cattle as hosts of Glossina longipennisat Galana Ranch, south-eastern Kenya

Abstract. Glossina longipennis were recorded visiting and engorging on cattle in an enclosure and on a single ox in a crush using transparent electrocuting nets in an incomplete ring. Of the total flies caught, 3–6% of males and 5–6% of females in the total catches were engorged (a feeding success rate of up to 16.6% and 12.6%, respectively, depending on assumptions made about the proportion which had an opportunity to feed). Direct observation of tsetse from an observation pit showed 57% landing on the front legs, 13% on the hind legs, and 11 % on the belly of the host. The largest number of bloodmeals was taken from the front legs, although only 14% of landings there terminated in feeding; a higher proportion of the flies alighting on the hind legs and flank succeeded in feeding (28% and 21% respectively). Glossina longipennis were attracted to targets baited with ox odour from an underground pit in a dose-dependent manner. Odour of humans was much less attractive to G.longipennis than that of oxen (for equivalent biomass). Analysis of bloodmeal samples from tsetse caught in two sites on die ranch showed that G.longipennis preferentially feeds on suids, bovids and hippopotamus.