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Les trypanosomoses animales restent une des contraintes pathologiques majeures pour l'élevage en Afrique sub-saharienne. La lutte contre les principaux vecteurs de ces parasitoses (Glossina tachinoides et Glossina palpalis gambiensis) repose sur des systèmes attractifs, dont l'emploi doit être le plus ciblé possible pour être techniquement et socialement acceptables. Les objectifs du projet sont d'identifier les zones d'action prioritaires et en révélant à l'échelle du terroir les points épidémiologiquement les plus dangereux

A parasitological and entomological survey was conducted in the Sideradougou area (south of Bobo Dioulasso, Burkina Faso) in order to identify transmission factors of African trypanosomosis. A total of 3600 tsetse flies (Glossina tachinoides, Glossina palpalis gambiensis) were captured along 120 km of linear gallery forest and half of them were dissected. PCR analysis was undertaken on parasitologically positive flies (161 G. tachinoides, 92 G. palpalis gambiensis) to characterize the different trypanosomes. All the results were integrated in a GIS (Geographical Information System). Spatial repartition of the characterized trypanosomes enabled to recognize different areas with specific patterns of infection. Relations with environmental factors are discussed.

L'objectif du travail présenté ici est d'identifier les facteurs permettant de prévoir la distribution et l'abondance de deux espèces de tsé-tsé (#Glossina palpalis gambiensis#. et #Glossina tachinoides#) dans une zone d'environ 1000 km au Sud-Ouest du Burkina Faso. L'étude associe des enquêtes au sol à des données satellitales à haute résolution (images SPOT). Les systèmes d'informations géographiques utilisés permettent de combiner les différentes couches de données recueillies, toutes géoréférencées, qui concernent l'entomologie (3600 glossines capturées, 1 piège posé tous les 100 mètres sur 120 km de réseau hydrographique), la parasitologie (méthodes classiques approfondies par des analyses PCR), sur les vecteurs et le bétail (animaux sentinelles), le milieu naturel (70 paramètres caractérisant principalement les formations végétales, le cours d'eau et sa fréquentation) et en particulier l'analyse des paysages de vallées, l'occupation du sol et sa dynamique (parcellaire agricole), la distribution du bétail (recensement exhaustif, typologie de producteurs) et les différents modes de pratiques pastorales (ancienneté, sédentarisation, points d'abreuvement). Le croisement de toutes ces couches d'information permet une classification des biotopes favorables. L'évolution des populations de ces glossines est discutée à la lumière des changements environnementaux, révélés à travers une succession d'images aériennes et satellitales. Des différences spatiales apparaissent dans la répartition des vecteurs, dans la nature de l'infection trypanosomienne et dans les hôtes nourriciers. La relation entre le risque de transmission et les densités de ces glossines, qui se révèle essentiellement liée au contact spatial et temporel entre les vecteurs et les bovins, est discutée. Cette approche nouvelle de ce système pathogène complexe permet de mettre en évidence les "points épidémiologiquement dangereux"

La dynamique d'émission de T. congolense souche EATRO 325 (type savannah) est suivie quantitativement et qualitativement par examen microscopique du salivat et de la goutte anale récupérés tous les trois jours selon une méthode mise au point chez G. m. morsitans (mâles et femelles) et G. tachinoides (femelles). Chez ces deux glossines, l'apparition des trypanosomes a lieu à 3 jours dans la goutte anale et à 14 jours dans la salive. Le pourcentage moyen de glossines à salive positive sur la durée d'observation (60 jours) est identique chez les mâles et les femelles de G. m. morsitans (21,30 et 24,50 p. 100). Il est très supérieur à celui des G. tachinoides femelles (12,50 p. 100). Avec l'âge, le pourcentage de salivats positifs tend à s'accroître chez les femelles. L'association de l'examen des deux liquides offre la possibilité de suivre la dynamique d'installation et de maturation des trypanosomes à évolution cyclique chez l'insecte vivant.

Following a request from livestock owners, a campaign to eradicate tsetse flics was conducted in Dafinso (Burkina Faso) in 1993 and 1994. Traps impregnated with insecticide (Cypermethrin) were laid, and all livestock treated with deltamethrin. In February 1993 (before the campaign), the number of Giossina tachinoides (main species) trapped was 11.7/trap/day. In July 1993 (two months after laying the traps and the first treatment of cattle) the figure was zero. Entomological surveys throughout the period showed a rapid, lasting and almost total disappearance of the tsetse population. During 1994, no tsetse was caught. Livestock owners were actively and financially involved in the campaign from stars to finish. The present exemple shows the importance of cooperation from rural communities for successful and sustainable campaigns against trypanosomiasis

Lors d'experiences menees en 1992 et 1994 sur le site de la Comoe, par le Centre international de recherche-developpement sur l'elevage en zone subhumide (Bobo-Dioulasso, Burkina Faso), les auteurs ont compare l'efficacite des bouteilles et des cages associees aux pieges biconique Challier-Laveissiere ou monoconique Merot, comme systemes de capture pour certaines especes de glossines (Glossina tachinoides et G. morsitans submorsitans) et les Tabanidae. Pour G. tachinoides, la bouteille ne presente un net interet que lorsqu'elle est associee au piege monoconique, mais avec des resultats toujours inferieurs a ceux du piege biconique muni d'une cage. La bouteille avec le piege biconique donne des resultats variables selon les annees, mais au mieux equivalents a ceux de la cage. Les differences entre les systemes sont plus nettes chez les mâles. Pour G. morsitans submorsitans, le systeme piege biconique/cage reste le plus efficace et la bouteille reduit les captures dans les deux types de pieges. Les captures de Tabanidae sont augmentees (parfois doublees) quand on substitue la bouteille a la cage, quel que soit le type de piege. (Resume d'auteur)

Deux expériences sont menées en saison sèche au Burkina Faso sur le site expérimental de la Comoé (zone soudano-guinéenne), afin d'étudier l'influence de la position du sachet diffuseur de produits olfactifs pour Glossina tachinoides et Glossina morsitans submorsitans. Cet essai compare les positions interne et externe du méta-crésol et de l'association méta-crésol/octénol (proportions 3/1) dans des pièges biconiques. La position du sachet n'apparaît pas comme un facteur fondamental d'efficacité des pièges et les résultats obtenus sont variables selon la saison et l'espèce de glossine considérée. Des différences selon le sexe sont également notées. Le rôle de la distance n'a pas été étudié.

Cinq types de pièges sans produit olfactif sont comparés en saison sèche fraîche puis chaude le long de la rivière Comoé au Burkina Faso, pour leur efficacité vis-à-vis de Glossina tachinoides. Le piège biconique Challier-Laveissière donne les meilleurs résultats, alors que le piège monoconique Mérot et le piège F3 se révèlent très peu efficaces; le piège monoconique Vavoua et l'écran-piège fournissent des résultats intermédiaires. Les captures évoluent tout au long de la saison sèche au niveau quantitatif (augmentation du nombre total de glossines capturées) et au niveau qualitatif (prédominance des femelles pendant toute l'expérience, plus nette en deuxième période).

Cette note signale pour la première fois l'existence de chimiorécepteurs sur les ailes des mouches tsé-tsé. Ceux-ci sont principalement localisés sur le milieu de la nervure costale. Leur morphologie est comparable à celle des chimiorécepteurs observés sur les pattes. Leur nombre ne différe pas entre les sexes comme pour les pattes, mais entre les espèces. Ceci suggère un rôle dans la perception chimique proche de l'environnement, par rapport aux chimiorécepteurs des pattes qui semblent impliqués dans le comportement sexuel. L'étude a été conduite sur six espèces ou sous-espèces de glossines.

L'identication et le comptage des chimiorecepteurs ont ete etablis en microscopie classique et en microscopie electronique a balayage sur les pattes de Glossina tachinoides Westwood, 1850. Les auteurs presentent une carte de repartition des chimiorecepteurs, utile pour les recherches d'electrophysiologie et de comportement. Ces chimiorecepteurs localises sur le femur, le tibia et le tarse sont plus abondants sur les zones ventrales. Cette etude montre que les 3 paires de pattes possedent un nombre similaire de chimiorecepteurs et un important dimorphisme sexuel : 1033 chimiorecepteurs chez le mâle contre 570 chez la femelle. La variabilite du nombre de chimiorecepteurs pour les deux sexes a ete estimee sur la patte prothoracique (Resume d'auteur)

L’accroissement de la demande urbaine en protéines animales se traduit, entre autres, par le développement de filières bovines de production laitière dans les zones périurbaines d’Afrique de l’Ouest. Mais la maîtrise imparfaite des maladies et des parasites compromet la croissance de la production. Une technique de lutte innovante, basée sur le passage régulier dans un pédiluve contenant une formulation aqueuse d’un pyréthrinoïde, pourrait pourtant limiter l’impact des tiques et des glossines, principales contraintes pathologiques en zone subhumide. Cette méthode entraîne l’élimination de la plupart des adultes d’Amblyomma variegatum, la tique la plus nocive dans ces régions, avant leur fixation définitive. D’autre part, un tel traitement permet de diminuer fortement la population des glossines riveraines les plus représentées en Afrique occidentale (Glossina tachinoides et G. palpalis gambiensis) et donc de limiter l’incidence des trypanosomoses. Cette méthode assure ainsi une lutte rapide et efficace à coût réduit car la quantité de produit utilisé à chaque passage est faible. Mais la construction de l’installation, qui peut être utilisée par 400 à 600 animaux, représente un investissement non négligeable que des groupements d’éleveurs ou des investisseurs privés peuvent plus facilement prendre en charge que des éleveurs traditionnels isolés. La mise en place de cette méthode peut ainsi être envisagée dans le cadre d’une politique de développement et d’aménagement. L’intérêt et les modalités de l’appui technique nécessaire sont présentés. Au Burkina Faso, un projet d’appui au renforcement des organisations professionnelles d’éleveurs modernes (Ariope) a de la sorte financé quinze installations dans les zones périurbaines de Bobo-Dioulasso et Ouagadougou.

Trials were carried out in Upper Volta to assess equipment for the application of insecticides as aerosol from helicopters for the control of riverine tsetse flies (G. tachinoides). Flying techniques were developed to direct aerosols in the downwash of the helicopter to tsetse breeding sites close to the water's edge. Good penetration of droplets below the riverine canopy was achieved during the late afternoon and early morning when weather conditions were very stable.

The night resting sites of Glossina tachinoides Westw. were observed in riverine forest at Bara, Bauchi State, northern Nigeria. The flies were marked with an ultraviolet-reflecting paint and released at dusk. They were detected with the aid of an ultraviolet lamp. Most of the flies (84·6%) rested on leaves (68·3% on the upper sides) and on small twigs and creepers (11·5%). The resting heights ranged from ground level up to 6·8 m. The average resting height was highest (2·6 m) in the mid-rains at 20.00–24.00 h; however, at 24.00–04.00 h at the same season the mean height was only 1·6 m. Resting height was lowest (1·3 m) in the early rains. Females were found to rest slightly higher than males and, in moonlit periods, both sexes had a tendency to perch higher. The night resting behaviour of G. tachinoides is compared with that of G. palpalis palpalis (R.-D.), which was investigated in an earlier study at the same location. There is much similarity in the behaviour of the two species, but G. tachinoides selects lower resting sites, and a slightly higher proportion of this species is found to rest on leaves as opposed to small twigs

The alkanes (methylalkanes) were analyzed from both sexes of four members of thepalpalis group of tsetse flies,Glossina fuscipes fuscipes, G. palpalis gambiensis, G. palpalis palpalis, G. tachinoides plus onefusca group member, G. brevipalpis, to determine structures, abundances, and the presence of unique or specific methylalkanes. These insects are unique in that trimethylalkanes were major components except in femaleG. tachinoides and both sexes ofG. brevipalpis where 2-methylalkanes were the major components. The identification of novel long-chain tetramethylalkanes, including 11,15,19,23-tetramethylpentatriacontane, a minor component of femaleG. f. fuscipes, G. p. gambiensis, andG. p. palpalis, is reported here. Tetramethylalkanes were significant components of both sexes ofG. brevipalpis. The major tetramethylalkane in G.brevipalpis is 3,7,11,15-tetramethylhen-triacontane. The use of the methylalkanes as taxonomic indicators in tsetse is discussed.

The results of discriminative spraying of endosulfan and decamethrin from a Bell 47G-4A helicopter to fringing riverine forest habitats of Glossina tachinoides in the Komoe Valley, Upper Volta, are described. The insecticides, diluted with diesel oil were applied from the helicopter through a unilateral (left-side) arrangement of four rotary atomisers. Three experimental blocks were each sprayed twice at an interval of about one month, one with endosulfan at individual swath dosages of 100 g (a.i.)/ha, the second with endosulfan at 200 g (a.i.)/ha and the third with decamethrin at 12.5 g (a.i.)/ha. In spite of aerially applied dieldrin barriers there was extensive reinvasion by G. tachinoides during the inter-spray period, consequently conclusions were largely drawn from the data collected before and after the second cycle of insecticide applications. The reinvasion problem is discussed. Endosulfan at 200 g/ha was the most effective in controlling G. tachinoides. Other treatments were less, but p...

The collapse of Glossina tachinoides populations, within a 27-month period of weekly sampling by means of unbaited biconical traps, in two peridomestic agroecosystems is described. Consistent removal of parous flies through trapping and low recruitment of young flies into the population, were largely responsible for unabated decline in the apparent density of both G. tachinoides populations. Reduction in the size of the resident pig population to below five pigs/week/agroecosystem triggered the collapse of both tsetse populations. Some ecological implications of these findings and their possible application in tsetse control are discussed.

The experimental application by helicopter of six insecticides to riverine forest galleries of the Komoe River in Upper Volta against Glossina tachinoides Westw. was monitored for its effects upon non-target organisms, in particular birds, fish, insects and crustaceans inhabiting the experimental area. There was no recognisable mortality associated with applications of these insecticides on birds or fish. Aerosol applications of permethrin and decamethrin produced mortalities in two species of crustacea and very high mortalities occurred from a residual treatment of decamethrin at 12.5 g a.i./ha.

Glossina tachinoides and G. morsitans submorsitans in Niger and C. morsitans morsitans in Mozambique conform to the general pattern of Glossina resting behaviour in that they rest on the woody parts of the vegetation during the day and on the foliage at night. G. m. submorsitans and G. m. morsitans both prefer low horizontal branches as their main day-resting sites, while G. tachinoides rests mainly on the bases of trunks. G. m. morsitans was found to exhibit a 3-phase pattern of resting behaviour: on foliage at night; low down on trunks for a short period after dawn; and on branches higher up for the remainder of the day. No relationship between temperature or relative humidity on the choice and vertical distribution of night resting sites could be found. For G. tachinoides, the microclimatic conditions of its resting sites were more favourable than ambient conditions during the middle of the day.

A biconical trap is described which incorporates a 5 KV electrocuting grid to stun tsetse flies, which then fall via a funnel into a preservative in a tube segregator capable of separating the catch at intervals of 1–24 hours. The trap was effective in Upper Volta and Ivory Coast against Glossina tachinoides (Westw.) and G palpalis s. 1. respectively. A 12 V 45Ah battery allowed continuous operation for over 20 days.

Descriptions are given of various operational aspects of the dispersal of insecticides, as aerosols and sprays, from equipment fitted to a Bell 47G-4A helicopter, into the riverine forest habitats of Glossina tachinoides Westw. The two aerosol techniques: ‘bilateral’ and ‘unilateral’ and a ‘unilateral’ spray technique, made use of the helicopter main rotor downwash to obtain penetration of insecticide droplets into parts of the G. tachinoides habitats considered important as resting sites. The bilateral technique which involved the helicopter flying above the forest canopy approximately 25 m from the water's edge was easier and safer to execute than the unilateral technique, which involved the helicopter flying over the inner edge of the riverine forest. In future a combination of both types of technique, with some equipment modifications to allow change over from one technique to the other in flight might be more appropriate than using one or the other of the techniques. It was concluded that bo...

Females of Glossina tachinoides Westwood captured three-hourly in biconical traps deployed from 16.30 to 18.30 h weekly in three peridomestic agroecosystems in southern Nigeria from April 1984 to March 1987, were dissected and classified as nulliparous, pregnant, aborted or parous-but-not-pregnant. In all three tsetse populations, the monthly pregnancy rate ranged from 76 to 94% and the abortion rate from 3 to 8% throughout the year. No seasonal or locational differences or evidence of seasonal increase, reduction or cessation in breeding were demonstrated. A significant difference between years with respect to monthly abortion rate during the wet season was possibly due to changes in vegetation structure which is dependent on crop types. It is concluded that the low population density and pattern of seasonal fluctuation in apparent density of G. tachinoides in these peridomestic agroecosystems are due to causes other than seasonal differences in its breeding rate.

The results of a discriminative spray application of decamethrin from a helicopter to fringing forest habitats of Glossina tachinoides in the Komoe valley, Upper Volta, are described. The insecticide formulated as a 2.5% emulsion concentrate was diluted with river water and applied from a Bell 47G-4A helicopter to the fringing forests of a 14 km long stretch of the River Komoe at a dosage of 12.5 g a.i./ha. The insecticide application equipment was so adjusted that when the helicopter was flown at 30 km/h, the effective swath width was about 30 m and the vmd of emitted spray was c.150 μm. Insecticide swaths were applied to the inner edges of fringing forests that were up to 100 m wide. Forests wider than 100 m received an additional insecticide swath. The experimental area was protected from reinvasion by the establishment of dieldrin barriers at its extremities and along some tributaries and woodland/floodplain ecotones. The dieldrin was applied by the same method as was used to apply the decame...

The response of male Glossina tachinoides Westw. to fast neutron and gamma radiations was determined by irradiating 0–36 hr old males using the Standard Neutron Irradiation Facility (SNIF) at the Austrian Atomic Energy Research Laboratory, and the 60 Co Gamma Cell 220 (R) source at the IAEA Laboratory, Seibersdorf. Irradiated males were mated when 6 or 7 days old to untreated, 2–3 day old virgin females for 24–48 hr. After mating, sexes were held separately in groups of 10 in oblong PVC-screen cages. Male survival was recorded for 30 days and pupa production for 45 days. Results showed that the highest neutron dose tested (1·70 krad) produced the same level of sterility (87–89%) as 9 krad gamma radiation. It was estimated that 2–2·5 krad neutron or 10–12 krad gamma radiation would be required to induce 95% sterility. Evidently, neutrons are about four times more effective than gamma rays in producing sterility in this species of tsetse fly. Considering the doses tested that produced the same level of sterility, male survival was similar in both neutron and gamma irradiated groups.

Recent entomological surveys in the Bouafle sleeping sickness focus of the Ivory Coast have revealed that Glossina tachinoides is considerably more widely distributed than hitherto. Some flies were found in the fringing riverine forests of tributaries of the River Marahoue. However, the greatest concentrations were found in villages and settlements where domestic pigs were kept. The southern limit of G. tachinoides now appears to lie one half degree of latitude further south than that reported by earlier investigators. The authors think there is good evidence that G. tachinoides is extending its range eastwards and southwards through and beyond the Bouafle area, and the epidemiological significance of this is briefly discussed.

La différence, entre Zébu et Baoulé, d’attractivité olfactive pour les glossines, a été étudiée afin de savoir si cela pouvait être l’un des facteurs de la trypanotolérance. Si l’urine de Baoulé est plus attractive que celle de Zébu, le résultat est inverse avec l’odeur globale lorsque des poids identiques d’animaux sont utilisés. La faible différence observée (25 %) ne permet pas d’apporter de conclusion sur l’importance de ce facteur dans l’épidémiologie de la trypanosomose.

During conversation with the Resident of Bornu Province, Northern Nigeria, I learned that a former Medical Officer of the district had discovered, some six or seven years ago, a tsetse-fly belt near Mulgue, about 40 miles south of Maifoni, Bornu, and I therefore decided to investigate the locality in July, 1910.

In 1964–65, breeding sites of the tsetse fly G. tachinoides Westw. near Nsukka in south-eastern Nigeria were found in peri-domestic situations (particularly beneath stacked coco-yam tubers and at the base of fences of pig enclosures) and in adjacent farmland (particularly beneath banana and coco-yam plants, under Lantana camara, at the base of farmland fences and around derelict farm buildings). Between them, these sites provide moisture conditions suitable for year-round breeding of G. tachinoides and are not exposed to unsuitably high temperatures (>90°F) for long periods. The night-time resting sites of G. tachinoides in three villages five miles east of Nsukka were sought between May and November 1966 using ordinary torchlight. The most popular resting-sites were dried fronds of oil and coconut palms used for fencing pig enclosures, but a few flies also rested on man-made objects in the villages and on vegetation nearby. Most flies were resting less than two feet above ground level. Day-time observations confirmed the night-time findings. G. tachinoides could probably be controlled, if not eradicated, in the Nsukka area by two applications, a fortnight apart, of DDT emulsion concentrate to pig enclosure fences and pig styes up to a height of 2–3 ft during March–May when the fly population is most concentrated around confined pigs.

A stretch of river with its flood plain, a habitat of Glossina morsitans submorsitans Newst. and G. tachinoides Westw. in the Sudan savannah zone of Northern Nigeria, which is an important cattle-raising area, is described.An effective technique for the eradication of both species of tsetse has been developed, using a single application of a 5 per cent, aqueous suspension of DDT by knapsack sprayer in the places of dry-season concentration of the fly, and on the principal midday resting sites, viz., between ground-level and a height of 5 ft. on tree trunks greater than 6 in. in diameter.

Experiments were carried out to investigate the persistence of toxicity to tsetse of hessian, impregnated with DDT, exposed to the normal weather conditions of the Inland Savanna Region of the Gold Coast; also, to establish a satisfactory method of estimating the loss or change in its toxicity, and to study the effects of impregnation with DDT on the efficiency of tsetse traps.Hessian was impregnated by being soaked for ten minutes in a filtered saturated solution of commercial DDT in kerosene which gave 4·4 g. DDT per sq. ft. and tests were made at intervals with batches of Glossina tachinoides at 15- and 60-second contacts. The comparison of the survival times of these flies compared with those of controls showed an appreciable residual toxicity after 20 weeks full exposure to the weather including 4·26 ins. of rain, a slight toxicity after 30 weeks, and a negligible toxicity after one year including 34·35 ins. of rain. The same preparation could still produce toxic symptoms in tsetse after 15-second contacts when exposed for one year to wind and daylight, but protected from rain and direct sunlight. There was no great difference on the whole between the results from 15-second and 60-second contacts.It was found that survival times lengthened in October when the humidity was high but were shortened in December when the conditions became hotter and drier.A further experiment was carried out with hessian carrying 4·4 g. DDT per sq. ft. and super-impregnated hessian with 7·4 g. DDT per sq. ft. Samples of both were exposed to the weather and others kept as controls. All samples were tested by 30-second contacts with G. tachinoides.It was shown that contact with the super-treated cloth was invariably fatal; the standard cloth had an 82 per cent, toxicity but the flies that received a lethal dose took longer to die on the whole. It was found to be the survival time and not the toxicity that varied with seasonal conditions.A full analysis of the survival times from the exposed samples in relation to those from the control samples showed that exposure to weather during late rains followed by dry season conditions caused only a slight but progressive deterioration of the killing power of exposed DDT-impregnated hessian. This amounted to 10 per cent, in 3–4 months including 7·42 ins. of rain in the case of standard cloth, and 10 per cent, in six months with the same amount of rain in the case of the super cloth.Hessian impregnated with 25 per cent., 50 per cent, and neat DDT emulsion was found to be highly toxic and to retain its efficiency satisfactorily for at least 12 weeks' exposure in the dry season.Hessian freshly impregnated with DDT in kerosene solution caused flies to die more quickly as long as traces of kerosene persisted but moisture, on the other hand, interfered with the action of DDT unless kerosene was also present.An “animal” tsetse trap covered with standard impregnated hessian showed a 40 per cent, superiority in the numbers of G. palpalis and G. tachinoides taken over a period of 20 weeks. Corresponding to the results of the laboratory tests this superiority was lost in October but reappeared in December.Comparisons of catches made by traps covered with standard impregnated hessian and hessian sprayed with 25 per cent. ATSO emulsion showed that, although the emulsion might initially give much better results, its superiority relative to the standard impregnation tended to diminish, especially during the wet season.The increased efficiency of an impregnated trap is more than the measurable amount of the increased catches since flies which have investigated the trap, but have not been caught, are likely to have received a lethal dose of DDT.The application of DDT to traps represents an economical use of the insecticide which can conveniently be applied in sufficient concentration to ensure that brief contacts will be fatal to tsetse over a period of several months.

1. An account is given of the development of strains ofTrypanosom gambienseinGlossina tachinoides.Complete development with infection of salivary glands and hypopharynx occupies from 12 to 40 days and upwards, according to the strain of trypanosome used and the temperature conditions during development.2. It is shown that the first or intestinal phase of development is passed within the extra-peritrophic space and that the lumen or intra-peritrophic space of the gut is not involved.3. The importance of the proventricular infection as an index of maturing infections is stressed, and it is shown that filamentar crithidia are always present in this organ in the later stages of infection when infection of salivary glands is taking place. It has been proved that these filamentar crithidia may constitute up to 20 per cent. of flagellates in the proventriculus and are partly responsible for the further migration to the salivary glands.4. An account is given of the infectivity toG. tachinoidesof twenty-six strains ofT. gambiensefrom epidemic and endemic sleeping sickness areas in Northern Nigeria. None of the twenty-six was proved to be non-transmissible and twenty-five of the strains gave Total Infectivity Rates in the tsetse of from 0·9–10·5, the Cyclical Developmental Rates ranging from 0·6–9·8.5. No evidence has been obtained that strains ofT. gambiensefrom chronic cases of human trypanosomiasis in endemic areas are less transmissible by tsetse than strains originating in epidemic areas.6. An account is given of experiments in whichG. tachinoidesinfected withT. gambiensewere exposed to 37° C. for varying lengths of time. The effect of high temperature during the infecting period is seen in a marked and constant increase in the proportion of tsetse infected. In the case of one strain a total infection rate of 77·8 per cent. was obtained with true cyclical development in 73·5 per cent. of the tsetse used.7. It is suggested that the temperatures at which experimental tsetse are infected in the laboratory withT. gambienseare excessively low, and an investigation is to be made into the optimum climatic conditions for development of the trypanosome in the fly with a parallel attempt to correlate this with the climatic conditions under which wild tsetse become infected in nature.

THE chromosomes of several species of tsetse-fly have been studied by Itard1. These include Glossina tachinoides Westwood and Glossina morsitans orientialis Vanderplank (Glossina morsitans morsitans Westwood in the terminology adopted by Itard). Glossina morsitans orientalis is one of the two main tsetse-flies which occur in Rhodesia, and so I thought it worthwhile for comparison to study the other, Glossina pallidipes Austen. The G. m. orientalis material used by Itard originated in Rhodesia.