Biology and Control of Tsetse Flies (1)

Mission Entomologique

0.R .S .T .O .&5 o aupres de 1 O .C .C .G .E

JeHamon , A,Challier , J.Mouchet & J,Rageau

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(1) Ce document est bas4 sur un cours fait lors du S6minaire 0.T'tPn.S. .inter+r6gional sur les m6thudes entomologiques de contrble des vecteurs qui a eu lieu en U.R.S.S. en Septembre-Octobre 1965 I1 est diffus6 car il pourrait être utile aux entomologistes devant faire des cours sur les glossines dans les pays d'af- fectation . IC1 conviendrait alors de compl6ter la bibliogra- phie '

nQ Ia 8)iology and Control of Tsetse plies . _.. * .. "... _, . . ..

I' by

J .Hamon -I. , A .Challier', J and J ,Rageau+' Medical Entomologists, Office de la Wecherche

L. Scientifique & Technique Outre Yer

1. IlYTEODUCTIOR .

For centuries human and animal trypanosomiasis have ravaged vast areas of tropical Africa. As recently as 20 years ago sleeping-sickness was considered one of the most terrible of all endemic diseases affecting the African continent, Animal trypanosomiasis,render stock- raising difficult, if not impossible, in *any areas, and in cattle- grazing arieaa bordering on the Glossina zones livestock is weakened and does not supply any draugh$-anima$ (VAU@EL.~&al.,f963 - WILSON & al., - FOED, 11963) .

liesearch efforts undertaken both in the Laboratory and in the field have supplied in recent years better methods of prevention, detection and treatment of trypanosomiasis. During the same period spreading possibilities of the disease have increased through comfiu- nica tion improvements and development ok workers migrations between neighbouring countries (ABEDI & I!AXLLBB, 1964).

Human sleeping-sickness prevalence has been reduced to an extremely low level, but the disease is far from eradicated and many small foci either remain active or even,appear in previously cleared areas. The situation is slightly / ...

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. + Q.L<.S.T.O."F. Team near O.C.C.G.E., P.O.B. 171, Bobo-Dioulasso, Upper - Volta . ++ O.B.S.T.0.:~. 70-74, route d'Aulnay, 93-Bondy, France .

'. . 6etter in West Africa, where the parasite Trypanosoma gambiense has apparently no aninal reservoir, than in East Africa where occurs also T.rhodesiense with both human and animal hosts (ROFBRTSQN, 1963 - WLL- LETT, 1963). Glossina-borne animal trypanosomiasis are always very wides-

pread and hinder econornic developmeni of the majority of African states, ~ Chemotherapy cannot be extended to all domestic animals and has its .l setbacks, including drug resistance of the trypanosomes, Co tsetse fly control has an important part to play in the development oi the bfri- .; caan continent .

2. GEOGRAPHIC DISTRIBUTION OF TSETSE FEfiS . - Glossina sp. infest about 16.000.000 km' on the Airrican mainland. The,ir present distribution has been recently summarized by POBP (1963) but more accurate data for french-speaking states of \?est Africa can be found in MAILL6T i1952), RAGEAU & ADAPI (19SrS)j RICHEM- 3ACH (196%) and FINIBLLB i& al.(P963). Tsetse fly distribution is.,not entirely stable, even in absence of man interference. For exanlple several species retreated from large areas of south-east Africa during the Great Rinderpest of 4896,' and sinc'e this period d.pal1idipe.s and G, morsitans, followed by G.austeni, move slowly south in :!ozambique and .Rhodesia, restoring the situation i,rior to the rin'derpest . In West Africa, during the last P5 years, G.submorsitans has extended northwards its distribution ('dILSOPd, 1958). Such changes in distribu- ir tion are probably of comnon occurence, but escape detection by lack of accurate base data and surveys .

\ Tsetse f1ie.s are classified into three groups, kypifhedi res- I pictively by G.palpalis, C.morsitans and G.fusca; their distributions

are the following ones : I

ni , 2.1. Glossina palpalis group (.. .. The palpalis group includes five species and four sub-species and is'restricted to idest and Central Africa, witb relics in E- thiopia arLd Arabia. L G.tachinoides occurs in the sudanese savannah and in the southern part of the sahelian area of West Africa, with residual foci 'in north-eastern Africa and in the South-east of the Arabian peninsula, It can withstand very dry conditions, but congregates in the dry sea4 son around water holes, residual pools of temporary rivers', and so On. .. 3

G.palpalis and G.fuscipes occur in the forest as well as in the guinean and sudanese savannahs. In the savannahs they are res- 'tricted to the inmediate vicinity of rivers and rivulets. In forested areas also they congregate along watercourses, but not as stric- tly a6 in savannah, using them more for the flight linesthat they ef- fer than for their microclinate, 9

L ,

i G-pallicera occurs in rain forest areas, but can be encoun-

* tered sometimes in the gallery forests of the guinean savannah . G.caliginosa is restricted to the coastal rain forest and to the mangrove areas . G.tachinoides, G.palpalis arid G.fuscipes are the main vectors of the human sleeping-sickness caused by T.gambiense . I

2.2. G.morsitans group . The morsitans group ihcludes seven species and three sub- \ species, all inhabiting savannahs ,

Gjmorsitans complex occurs mainly in sudanese savannahs, with C.submorsitans in Nest and Central Africa, and G.morsitans in East Africa ,

G .longipalpis is restricted to guiniean savannahs and to sou,.. partly deforested areas of the forest zone of +lest Africa . G.austeni is mainly a lowlands and coastal species of East Africa . G,swynnertoni and G.pal1idipes aro highland species of 3ast Africa. The,first one restricted to Kenya and Tanzania. The seconu H is species occurs from-Bthiopia to Yozaanbique and is present in some has the but r coastal areas; it occured in past in ïlata1 has been eradicated there . 4 G .borgesi has been recently described from ?"ozambique (FIXEL .1 1960). G .niorsitans and G.swynnertoni are the normal vectors of the normal vectors of tile second form of human sleeping-sickness, caused 4 by T.rhodesiense; they are also, with G.pallidipes and G.submorsitnnf very importaitt vectors of' several aninal trypanosomiasis (caused by T.brucei, T.vivax, T.congolense) T.rhodesiense has beeil also rece- 1 vered f roin G,pallidipes since 1940 (;-acK1CC'IiAM, 1944) and more recen-

tly froln G.fuscipes (80UTI33N & XOG'E&TSilPJ, 1961 - WICLETT & A1.,1964-I WPEL3TT, 1965) , .. 4

2.3. G.fusca group,'

The fusca group includes 12 species and two sub-species, " Which inhabit mainly densely forested areas . Gknnshi, G.schwetzi, C,tabnniformis, C.haningtoni, G.seve- rini, G.vanhoofi a'nd G,fuscibleuris occur in the Lower guinean forest: sonetimes in very restricted area's 1

G.f~scaoccurs in all forested areas, from Sierra Leone to Uganda and in some of the larger gallery forests of the guinean savannah . G.nigrofusca is widespread in the Upper guinean forest and in the northern gart of the Lower guinean forest, from Guinea to Ugar - da. G.inedicoruiii is restricted to the Upper guinean savnnnah anC forest . G,brevipalpis is very widespread in gallery forests and savannahs of Prlali Bast Africa from Natal to Bastern Congo (Leopoldvil- le) and to Southern Ethiopia and Somalia .

G.longipennis also an eastern savannah species) but Pes- is C tricted to Kenya, Ethiopia Southern Soinalia, South-eastern Sudan, North-western Uganda ar,d Northern Tanzania . The most common species belonging to the fusca group are important vectors of animal trypanosomiasis caused by ?'.vivax and T.congolense (J02DAN,P961 & 1965 a).

3. BIOLOGY OF TSETSE FLIES . 3.1. Keproduction cycle . . Tsetse flies mate during the days following emergence, when the females are teneral. One insemination is sufficient for the whole life of the female, but ;'*ales mate several times during their lif~ , and probably some females do the same; recent investigations carried out in Upper by one of us (A.C.) on G.galpalis have shown that Volta - non-teneral wild caught females are almost always inseminaled; however the percentage of inseminated females with incompletely filled - spermathecae reaches about amongst teneral flies, against only 51% in flies belonging to. the next two older age groups; so it is very probable that females cf C.palpalis several tisnes during their first days of life. Jemales yresect thsir.:naxinum attractive- ness for males When they are only 3 days old, andiare less attractive with increasing age, although being always able to mate (NkSEi,l95f 5

JOhDBN, 1958 *) * ,Homologous matings are the rule, but sometimes :nating occurs in nature between closely related species; such matings are generally not fertile and can be lethal for the female

The two ovaries are composed of two ovarioleg each, and each ovariole develops in turn (SBUHDERS, 1962 - CWALLIBW, 1963 b). The first ovulation occurs S to'U days after the emergence of the female; the mature ovocyte is not laid, but paskes into the female utr rus where fecundation occurs; then the larva grows inside the uterus, the food being supplied by the "milk glands" of the feaale; the la- te third instar larva is laid on the ground and pupates usually two :..& to five centimeters below the surface, some hours later. Larval development, in utero, takes about 10 days, during which the females bites at least three times, but the first larva is laid when the female is about 16 days old, or moro. Yhen the first larva is laid the I secor,d ovocyte passes into the uterus, and so on. The duratiou; of the pupal life varies from 2Q to 60 days, according to temperature,

The adult can fly some hours after its emergence from the pupariun and is able to bite the following day .,

3.2. Feeding habi,ts .

I.. Both sexes of tsetse flies suck blood and they do not use aiiy other food. They do not ingest usually either water or necter, but seem sometimes able to pierce plants for sucking sap,. They can feed on insects, as one of us (J.R.) has observed for G,palpalis witl- caterpillars . Bach species of tsetse fly exhibits definite feeding preferences, which are directly related to their ,neclical and veterinary importance as pathogen vectors (JOL~DAIJ,1965 a), but the majority . of Glossina sp. are able to feed on a great variety of vertebrates. The kmown trophic preferences are the following (MBITZ, 2963 a), accc ding to 22,640 blood meals identified :

- 6; .swynnertoni, G.austeni, G,fuscipleuris and G .tabaniformis feed mainly' on suids, with bovids and other vertebrate (rhinoceros, hippotmus, porcupine) as secondary hosts ;

- G.morsitans and G.sub.norsitans feed equally on suids sild bovids, warthog ("hacochoerus sp.) being the preferred host; man is also used 6

as host, snainly in Vest Africa by G.sub:norsitans (Jordan, 1965 b);

- G.pallidipes, G.fusca and @.longipennis feed extensively OE bushbuck (Tragelaphus scriptus) and the first and second species bite also suids to soine extent i - C.longipennis feeds mainly on rhinocerosj with giraffe, elephant, buffalo and ostrich as secondary hosts ;

- G.brevlpalpis feeds mainly 011 hippopotamus, suids, buffale and bushbuck ;

- Gopalpalis, G.fuscipes and Gotachinoides feed exteiisively 011 "zn, crocodiles, monitor lizards and bovids, but also sometimes on wild game (FOSTIIR, 3-964); @.tachinoides is particulary infeodated to man and cattle . The behaviour of each species is characteristic and is not entirely depender,t on the availability of different hosts; this view is supported by the fact that commonly occuring animals are not fed don by Glossina, the best example being zebra (Bquus burchelli) in G.morsitans areas of Bast Africa, and waterbucks (liobus sp .) (bd3ITZ, 1963 b) . Few data are available about the adaptability of tsetse flies to a varying host fauna. It is likely that flies like G.morsitans and G.submorsitans, the G.pa1palis group and possibly G.swynner- -toni and G .pallidipes would quickly adapt to changes in f aunz ; however, following the rinderpest panzootio of 1890-1896 the G.morsitnns fly-belts have recessed in 3ast Africa, after almost exter,ninatian of all favourable hosts (FO>UD, l.965). The authropophily of G.palpn- -lis and cf G.tnchinoides increases when the wild fauna and the lives- teck decrease (PAGE & KBCBOïÏktD, 1959 - JOXDAII &: al., k96l. & 3.962 - LAITGEZIDGE & al., 1963). Several species with very restricted feediag habits, such as G.fuscifileurio, G.austeni- and Gotabaniformis (infeodated to suids), G.longipalpis and G.fu:;ca (infeodated to bushbuck and buffalo), arid G.1ongipennis (fcedinE; on rhinoceros, elephant and buffalo), may be very rapidly affected by the remov-al of only a few species. 7 3.3. Bcology . Tsetse fly ecology and its physiological basis have been recentiy reviewed (LANGBIDGE & al., 1963 - WARLBY, 1965 a-E'US3B'L.L, -2 1959, I960 & 1963) and have been the subject in a-recent past of many publications, each of them generally devoted to one or two Glossi- na species .

Bach species of tsetse fly has a specific distribution area, characterized by climate, vegetation and soil, this last elenent being important for larval deposit and pupal survival. The recent studies of BURSEEL (see above) have clearly shown that one of the major limiting factors for the distribution of many species of tsetse. flJes is the relative huri\idity. Adults, which fly ancl cnn select ; their resting-places, can withstand l'ow relative humidities of the general environment, but pupae of ,nany cpecies cannut, and the distribution is under the dependence of the pupal euvelop permeability. The pupae of some species, such as those of rwrsitnns, do not lose zny water within dry soils, whereas pup:.e of several other species, such as palpalis, are easily killed by dessication and require for their development an almost sntura$ed atmosphere, but witbout any free water. Temperature may play a part in 1irilitir:g the distribution, but mainly in extreme conditions

At least in the savannah zones, it is often possible eo distinguish, in the distribution area of each species, three areas (MASII & PAGE, 1953 - PAGB, i961 a - MOUCHBT & al., 2-961 - JACKSON, 1946). - the permanent breeding-sites, where flies ocCTtlr all year round and where they congregate during unfavourable seasons, and usually where they lay larvae ;

- the teinporary breedlng-sites, where flies occur during the most favourable seasons, usually during the rainy season, b-ut where they cannpt survive in the dry season ; ,.

- the feeding-grounds, which are generally open areas, not very far from t,he breeding-sites, where flies can easily detect their hosts and feed upon them; feeding-grounds can extend a few lcilometers a--' round breeding-sites in rainy sens-on, but are usually restricted to their inzmedliate vicinity during the dry season . 8

In each area resting-places of the flies'vary accordiq to environmen$ and to physiological condition of the fly, but they are usually constituted by logs, small' trunks and redium-sized branches, up to some [fleters above the ground. Mowever soríe species, Pike G.swyn-- nertoni and G.pallidipes, rest extensively on leaves by night and on the underside of branches by day (FiABLBY, ~960Sc 1963 a). Sin WOG-

ded savannah areas so:iie species of trees afford better resting-pla- Y ces than others and are regularly selected by the majority of flies.

Tsetse, flies are general1 active only by day time, but some species of the fusca group are also active by night and G.brevipa1- pis exhibits a very chsrqcteristic crepuscular activity, iimediate-

ly after sunset and i;nmcdiately before sunrise (HkitLEY, 1965 b), eG, palpalis and G ..submorsitans bite also scrnetimes by night when distur-

* bed from their resting places (J .H. ,personal observation).

Pupal sites are selected by fenale tsetse flies and, for

I a sane species and within the same area, their location and relative importance vary from season to seasor. (PTAS& & PAGE, 1953 - CLhS- . GOY, 1961 - JONUE, 1965 b) . Pupae can withstand high relative hutRi- dities but not submersion; high temperatures reduce the length of the pupal period, but too high.temperatures can kill the pupae in some days and even some hours; so pupal sites are usually situated in well-shades places, under logs, .bushes, in hollow trunks, and so on, For same species, such as G.tachinoides alid G.palpnlis, pupalsi- tes caz be entirely man-inade, being provided bj mango and baiznna pln~- tations and even sometimes by graneries, thatch enclosures and other artificial shelters. The depth to which the larvae enter the soil. varies with environmental conditions; in the rainy season the larva can pupate on the ground, or only one or two centimetres below; in the dry seasons the larva can enter five to eigth centimtres bellow /theground before pupating ,

.' 3.4. Tsetse fly survival and population dynamics . Bxcept for their first days of imaginal life, during which the mortality rate is high (1lASH & TAGB, 1953 - I'JBSH & KqkNAGEAM,8965- A.C. personal observation) I adults of Glossina have a high survival rate, in the laboratory as in nature. Average life of two to three months seems to be the rule (;LkL&BY, 3.963 b Oc 1965 a) and survival for 2-54 days has been observed in Gopalpalis; howerver a very small proportion of the population is likely to achieve such extreme age 8e ?AGE, 1953) . 9

Causes of mortality of larvas and pupae are more iaportant because predators are nurilerous : iiisectivo'rous birds, insectivorous insects, and so on; besides mzny insects parasite tsetse pupae :iSip- Cera Eombylidae, Hymenoptera Chalcididae and Nutillidae . Fupae are also easily killed by unfavourable environment chariges . In nature. probably less than half the laid larvae reach the adult stage .

L Tsetse fly densities do not fluctuate very much from one Ø year to another, as long as the environmental conditions romain cons- t. tant. G.swynnertoni has been studied during 23 consecutive years irr Shinyanga area, Tanzania, during wkich the highest density vnlue 'has I been 18 times the lowest one. G.palpalis, which has been- studied during 16 years in Kaduna area, Nigeria, has even more stable poyula- tions in riverine forests, where the highest recorded density was only 3,B tines the lowest ane (G'LkSGQisJ & WBLCET, 1.962 - JOEDAN,f96!3 e).

3.6, Sampling methods . The sampling methods used must be related to the local conditions and to the investigated species, I The most widespread method is based on fly rounds, the fly- catchers moving along standard p.nths under noraalized conditions thro~ the district under inveskigations; results are expressed in fly per unit of length of the paths. The bait ,can be human beings (ifso usually the fly-catchers themselves) or a dornest$c aniri;al, or even i: car moving a& a very low speed, Catches during fly rounds can also .be. carried out on resting flies . Fixed catching stations, used during the whole activity pe- e riod of the flies (sa generally from dnwnito dtask) are also widely use baits being huma.ns , or tethered animals, or specially designed traps.

Moving teams collect nminly unfed hungry flies on the baits, - With a large excess of males, and erieorged and not-hungry flies on their resting places. Standing teams collect a higher proportion of F females, mainly when using traps. Moving car baits are sometimes very efficient for attracting non-man-biting species .

. Very low densities of tsetse flies are always difficult to asse.ss and may even escape entirely to detection . In many instances tsetse control is a very efficient way to stop hunan trypanosomiasis transmission in restricted areas, either alone or aS a complement to chemotherapic neasUres. Tsetse fly control or'better, eradication, is often the cheapest method for pre- venking human or livestock trypanosomissis transmission in areas of

Sudanese and Guinean savaiinzh zones (~-1OCKIM3 & al.,P963) 4

Methods used for tsetse fly cbntrol just before dnd'after the second World War are gradually being replaced by other oms based on residual insecticides applications , and chemosterilization is being investigated. Eut in the past direct destruction, indiscrimina- te and selective clearings, and hosts elimination have been extensively u5sd, soliietimes with fair success (GZQ)V3;1., P96P) .

4.1. Direct destruction of tsetse flies . Direct destruction of tsetse flies by net collection aird glued bnits has not been very efficient in the past, except in Prin- cipe Island where G.palpalis was almost eradicated. Destruction by trapping (Hnrris traps) has been successful in controlling G.i;aPli- dipes in a restricted breeding area of Zululand, South Africa, but results have not been very satisfactory in other areas, Some authors,' like KORBIS (1960, 1961) stress that traps give the best way for catching representative samples of flies, whereas others, like ABEDI ( 1963) and FOSTER (1964), consider traps as very inferior to direct cat'ches. Results depends certainly on the' species involved and on the environmental conditions .

4.2. Tsetse fly control by game destruction . ~,,

It has been observed in the past that tsetse flies and &E- me are of ten associated , and that game elimination, during rinderpest L. epizootics for example, are followed by strong reduction or even disci: pearance of Glossina populations (GLkSGOb7 ¿3 WBLCH, 1962 - U00FF,L565) So gaine destruction hzs been used as a routiric method for tsetse fly control in Bastern and 3outh-eastern Africa, aiid hcs succeeded in clearing mmy thousands of square kilometres of flies belonging to the morsitans grquy, the best known experiment being the Shinyanga one, in Tanzania (@LkSGO%~,1960). This method, which is always used in soine restricted areas, is riot cheap; for exemple fn Southern 18

Xhodesia, during the year 1955, slightly more than 4P.000 heads o? game were destroyed by 800 paid hunters, with au expenditure of W7r00Q rounds of ammunition ( CBOEEBY, 1956 )

Judiciously applied, game destruction can be an economice1 and practical means of trypanosomiasis control, as not only Glossina hosts, but also animal reservoirs of trypanosdmes are destroyed in only one operation. IZowever, as stressed by WBHTZ (1963) and by GLQBriSP, (%!264), the palpalis group of tsetse flies cannot be starved except if reptiles and humans are also eradicated, and the control by starvation

of many species, such as G.swynnertoni, G.austeni, G.fuscipPeuris,G.I_ tabaniformis, G .anorsitans and G.submorsitans, supposes total e1i:nina- tion of suids which consitute a.group more difficult to locate and tb kill than antelopes and big game. Besides, as underlined by DASMAPJN (1962) and by HQCIZXNG & al. (P963), gaine farming car, be more profita- ble in some marginal areas than c~.ttle.-raiqing as a source of meat and skins and also for the tourist in9ustry. So tsetse control by gaine des- qruction is more and more rarely used now .

i3.G. Tsetse fly control by bush clearing . The tsetse ability to withstand seasonally unfavourable climate depends upon the presence of a favourable vegetation community (MkSN,l935). Eushes and trees are widely used by tsetse flies as resting-places; moreover they provide a more or less constant microclima- te ensuring the survival of at least a few females even through the most severe dry seasons (PiAsII & 3AGE,1953); they constitute also very often vital shelters for pupae which can only survive if' the soil is sufficiently shaded, protected from direct insolation and preserved from rapid variations of humidity ànd temperature. "Jan cannot easily alter the climate but he can, at least in savannah areas, alter the vegetation communities that enable the tsetse flies to withstand unfavourable periods of the year . The cleiring of all woody vegetation in a fly-infested area 3arely been used for tsetse fly exadication, but has been extensi- has ,. vely employed to provide barrier areas or to reduce the contact bet- 'ween flies and humans around villnges and water holes, dt river-cros- sings, and along the main routes of communication of humans and cattle (LE ItOUZIC, 1968). Such clearings, called "agronomical $rophylaxis" in french-speaking countries, can be used for cultivstion to be kept ., 12 clear' of trees and busheso They cannot be extended on lar'ge areas in sparsely inhabited zones because they require a larger manpower L -I suppiy than available and are very costly if carried out by adminis- trative agenpies . TI-.owever, for special purposes, clearings and protec- tive barriers have been done up to 100 kilometres long and three kilo- Metres wide, as in Southern Rhodesia . I Selective clearing has been much more extensively used for tsetse fly control. It is based on the tendency of flies, in unfavourable seasons, to congregate in permanent breeding or restirig sites ..that coinprise identifiable plank communities and a comparatively small proportion of the bush-or woodland as a whole, The requireaents of the common tsetse fly vectors of trypanosomiasis have beall described and the types of vegetation most favourable as refuges are known.They must be located before tsetse fly control measures are undertakenhe- lective clearing can be done directly, or by the use of chemicals (de- fi>liants, tree-toxicants,..); it suffers from the saine deficiencies as total clearing; it is a costly measure, the regrowth of bush must be kept down and it is much more efficient in dry areas than in humid ones where it does noelprevent tsetse flies of travelling and resting (PAGE, 1961 b- FOSTER, 1964).

In dry countries temporary control of riverine tsetse flies -has been attempted ;once by use of "obstructive clearing", by felling the trees forming the overhead canopy and blocking the strean-bed to obstruct the tsetse flight-line. The flies could not move freely under shade and either were starved or forced into the open where the climate during the dry season was intelerable (NhSM ¿iSTlBIBTBR, 11957),

With the discovery of modern insecticides it appears that it is generally more efficient eo spray a residual toxicant on the tse tse permanent resting-sites than to destroy them, because tsetse can change of resting-sites when .the p:?eferred ones are destroyed, as see21 in Ankole district of Uganda (HAR@BY"& FILSOM,1961), whereas they do not abandon them after spraving (HOCIIIPITG, 1964) .

4.4. Tsetse fly control by insecticides. I Insecticides can be used as aerosols of teaporary efficacy on huge> areas, or as residual sprays on resting places, traps and ba'its 13 4,d.l. Insecticide aerosols . Insecticide aerosols havi2 a very short residual.effect,if any at and kill tsetse flies 2uring some hours only after their I all, . application, They can control or eradicete the flies only if they are

1, applied on large areas at convenieiit intervals to kill, before their - reproduction, all flies having emerged from pupae since the previous

4 applications. convenient rhythm seem to be about six to eight applis- cations at intervals of two to fou:. weeks (BURNBTT, 1962 b), eccordini:

I to the biology of the local populaCion cf tsetse flies

Aircraft application has the obvious advantage of covering quiçkly large areas, and can be efficient againsq savannah-inhabitingi species like G.morsitans, G .swynnertoni and G .pallidipes; it' is less ' adequate than grounc? jpylication against riverike tsetse flies like -. G,palpalis and G;$uscipes- (ÈURN;ET.T, 1962 b); and is almost impossible to carry out against species living in high forest. Grou,rid application . can be Idone either .with lorry-carried. generators;or with light porta-

I ble mist-blowers (TWOPdSON & al., 1960 - CIIALLIBB & al., 19%) ,

Insecticide aerosols can only be applied some hours a day, jusl after dawn and before dusk, and, sometimes by night, when-air cur-

rents are I duwnwardG ;: dFzrir,g Othe- day-time periods the inseCsticide cloud disperses very rapidly and, if applied by ai'roGaf t , does3-not .. even reach iround level, Only a very small amount of 'insecticide rea- . -,

I ches each individual fly and gravid females, less susceptible to insecticides than snales ,and females of other physiological conditions (BURNETT, 1?6,2 a)., are not eayily killed by chlorinated insecticides; some 0.F. compounds lilcr; fenthion or malûthion might perhaps be more-

efficient, GHQCHCING & al., 1983) . I

For eradication programmes djeldrin, E.H.C. and telodrin

i aerosols have'been used mainly in Bast Africa, with variable results including fair succes (-COCKBILL & al., 1963 - BUICKX, 1965) . Tech.ni- c cal improvemen.ts in -the spraying-designs have permitted to use only very shall amounts of insecticides, averaging i,5 kg. of teloclrin, or 4,5kg ,-of dieldrin.'ber square kilometre. These technical improvements and a better knowledge-of tse%se ecology have decreased the cost of such programmes;'which was very heavy for the first experiments, to around 860 to '1.000 french francs per sq-kilometre now (BURNETT,1962 -.

HOCICIHG & al,, 1.963 - EURNETT i$ al,, 1964). The cost of operations ;d5, be reduced if aerosols are used only for short term control'of tsetse, fly populations in sleeping-sickness foci , .-

I I( i ,,I* 14

4.4 -2. Residual treatment of vegetation , a._ a, Residual treatment of tsetse fly resting-places must be lethal for the fly on short contact for a longer period than the maxi- mum duration of the pupal life. In such conditions only one spr'aying may be sufficient to control the species, and perhaps eradicate it,in

.Y .. an isolated area . . The first residual applications have been aone against riverine speçies, like G.palpalis and G.fuscipes, with habitats restricted to water edge. In larger gallery forests it Is sometimes possible to open pfiths in the forest, which will be extensively used by moving flies; the treatment of sÚch paths may be sufficient to get the control of the flies. The same observations haGe ,been made in dense bush,

where several species, such as G.mc:rs&ta~s"- and G .palpalis, frequent ' piths made by man and áninals and follow avenues and channels occuring thrdu'gh th'e budh; condentrations oi the flies 'occur at ehe intersec- tions ofl the paths; the correspond2ng method of tsetse cont 'I sed' on the opening of pkrallel patts, so le hundreds of metr through dense thickets and wooded rreas, and by treating ,nothing but the paths; this method haslbeen fairly saccessfbl in several areas of Kenya, against G.pallidiyes, G .fuscipes, and G .brovipalp& (l!BOr!iS@N & al., 1960 ) . DUT suspensions arid emulsions, which have been used in the first exp6riments, have usually been rep La'ced by dieldrin emubians, which are assumed to be efficient almost one year, and sometimes more than one -year if applied at 4% (KBZNAGHAN, 1962)'. However, according to BALDBY (1963 & 1964), DDT emulsions have a longer residual effect Chan dieldrin and telodrin (dsobenzan) ones when applied at ;he con- ceritration of 5% and even, in soglie conditions, at concentrations as low as 2,5% (DBVIBS, LS64). Such control procedures are five ta ten tirnes cheaper than bush clearing and of a more permanent effect (Hoc- - KPPaG, A963 - '*acLEPJNAN & AHPCHZSON, 1963 - CHkELIBG, 1965 a) Improvement on the knowledge of tsetse fly resting-places has permitted thesuse of residual insecticides against savannah species like G,morsitaris and.G,swynnertoni, by selective sgraying of the $ioder side of the branches of Acacia trecs in fly-concentrationtareas { (He)CEING, 19611 - CBAlYbJICIC, 1964 - CI-IJXJbJIClf & $al, , 1564 - WOOFF,1965) The cost of the control is then similar to, or &lowerthan,by aircraft fogging, but the work is more.difficalt to plan and supervise. In the

I 1 15 dry season G .submorsitans behave sometines almost like a riverine species and can be controlled by restricted insecticide sprayings (hlAt3LElYfdkP?, k965 - TE’*PLBTON, ,965 - JOL’,DAN, 2.965) . Besidual insecticides have been used also against G.tachinoides in Northern Pfigerin and along the Tchad-Cameroons border, but this fly is not as concentrated as G.palpalia along water-places; so trees and bushes must be treated on a larger width on both sides of the rivers and water-holes (ï?OUCEET & al., 1961 - DAVTBS, 1964 - &!!ac-- LENNAN, 1965 - TIiYPLBTON,1965) * With this species the main difficul- ty is the exact selection of the vegetal communities to be sprayed, which implies a very close supervision of the spraying-teams, and thz accurate timing of the programme, between the end o€ floods and the beginning of the rains, for the breeding-sites neighbouring the Chad

Lake b Residual insecticides are only promising when tsetse fly habitats are restricted, so they have not been used against high forest species. However they have been sprayed with fair success againts G.fusca and G.fuscipes in large gallery forests of the Centrafrican Hegublic (FINBLLE & a1.,1962 & 1963 - YVOiiB & al., 1962) . 4.4.3. Insecticide - treated traps and baits ,

Residual insecticides have been sprayed inside tsetse fly traps to increase their efficacy with limited results. Insectici- des have also been used in combination with attractants, on traps,an * the method is always under investigation.’Studies carried out in Aru- scha; Tanzania, have shown that aqueous extracts of pig skins and bristles are very attractive for G.pallidipes, but not for G.swgnnerto mi; the active principle is soluble in lipid solvents; trays treated wieh this attractant catch two times more G1.pallidipes that untrea- I- ted ones and could be used in combination with either insecticides or chemosterilants (kNONYYOUS, 1965) . 4.5. Biological control . Various attemps have been made in the past to multiply and release naturel tsetse fly parasites (JENKINS, 1964) to control these flies; but the results have not been promising . ‘Trials on hybridization, by cross-mating closely related species, to produce a high degree of skerility in a fly population, have not been successful (GZAS603, 2960) and assume the possibility of raising large nunbers of tsetse flies . 16 Sterilization of flies is possible, e-ither by radiation - or with chemosterilants (IINIPLING, 3.965 - SN1TI-l & DAME, 1963), and field and laboratory investigations have been carried out . The publie hed results are partly contradictory. According to POTTS (f964),mnles sterilized by gamwfia irraGiation are not competitive with normal males the sterilizing doses being nearly the safile as the lethal ones; however DAhIB & al. (1965) have found the pndiosterilized males very competitive, and having a normal survival rate during their first three - LI .. weeks of life CIIADNPCK (i964) has stressed that chomosterilants are L not much more promising than radiations; in his experiments the trea fflent of males alone reduces only by 40% the average iîwnber of produ- ced pupae, apd the survival rate of treated males was considerably reduced; the treatment of females was more efficient, but it seems difficult to reach the female component of wild tsetse fly populations. Nevertheless DA'T i% al. (1965) have published that Tepa - and Metepa-treated males are almost all sterile and that their survival rate is almost normal, the chemicals being applied either on young nales or on pupae. If an efficient contro1 method involving chemos- terilant use is.. discovered, the problem of laboratory massrearing of tsetse flies would have to be solved, which will not be an easy task (P!AILL,C)T, 1958 - MASH, i963 - EVENS, 1964); wide s"ca1e experiments are carried out in South Xhodesia to develop more efficient methods of tsetse mass-rearing than these actualy available .

6. HEARING FKOBLBfJIS B14D RESEARCH NEEDS . All tsetse' fly control methods suppose a very tho.rough knc ledge of the physilology and ecology of the involved species. Noreover:

* if chemosterilants are promising mass-rearing technics arid mating-habits must be studied. Improverent of our knowledge on the biology and ecology of tsetse flies requires mass marking, release and recaptu- re experiments which also ;imply mass-rearing of staridard speci,.vrlens . The reproduction rate of .Glosaina is very low . ,Fqr example. G.morsitans drops a larva every eigth day at 30°6., every eleventh clay at 2dQ and every twentyfifth day at ICo (JA@K,1939). The best eli- matic conditkons, for Glossina colonies have been defined by 7;IBLLkNB'IIT (1937);temperature must be maintained between 35O and 27OC. for almoe". .. all species; relative huniidity must be high, reaching almost satura- tion ,for the riverine species, such as G.palpa1i.s. The mainte,nance of adults has been done in several types of centainers, including test- tubes (FOSTER, 1C35'9), but for massrearing cages are more handa-b ,Le; 17 Bruce's and Ploubaud's small-sized cages have been used as well as bigger Petana's cage. Preliminary trials carried out by one of us (A .C. ) have shown that environmental conditions such as lightCng shape and volume of the cages, and fly .popuïation .density, may be of a primary importance to eusure normal longevity, behaviour. and reproduction rate ,.

d High insemination rates !nay be obtained in colonies, reaching 97% for G,morsitans ( FOSTEE, 1957) and 88% for G.i~al~alis (PJASB, f955), but the stBrile-male method shall require also a per- ' fect knowledge of the making behaviour. Some data are already avai- hable for G.aorsitans and G.pnlpalis (FOSTER, l957 - NASR,195S-JOEDkT .L95S), but several other economically important Glossina syecies have not been studied yet.

Feeding the adult flies is a very important problem. Too frequent blood meals brini on the groduction ofsmall larvae and indu- ce abortion;the. normal frequency of feeding is two or three tines between two successive lnrvipositions. Guiyiea pigs have been used as 1 . hosts for a long time, but sheep is a better host, ensuring a,better longevity and a high reproduction rate pf the female flies, aïid now goats are also used with success (NASH,.& IZEhlMAGHAN, 1964) . Xepeated tsetse fly biting brings out a skin reaction of the hosts; howover HASII & KBRNkGHliM (f965) have develoRed a method allowing to feed 436 flies every three days on the same geat. Investigations are also car ried out in-lhing the replacement of the host by defibrinated blood: tsetse flies feeding through a aembrane (SOUTHON & COCBHNG,LS63~:a & 1963 b, BIKDBW & BkRLBY,1965). Wo may hope that improvements of the feeding procedures will enable the production of larvae and pupae of , normal weight, without any high mortality of the newly emerged flies: , . which is not always the case, in tsetse fly laboratory colonies (H~ASIJ. r & KBRNAGBAL'J, 1966 ) . Emergence rate from the pupae is also en important factor ir1 the establishment of a Glossina colony. k very high rate has been ob- F tained when larviposition occurs in a layer of dry sand just over wet sand (NASH & al., 1950), for Goyalpalis, but the prablem has to be solved for the other species. 18 7. DXSCUSSION AND CONCLUSIOMS . ! Several methods are available for controlling tsetse flies, but all are expensive and nane of th.em is yet available for densely fo rested areas. Besides tsetse flies can reinvade cleared areas if these a, areas are not isolated from neighbouring tsetse foci, either by natu- I rai barriers or by sprayed ones. Tsefse fly cdntrol, thereforo, must . be planned as a long term programme, on as a wide territorial basis as 'possible Pn many Instances eradication is cheaper than control, on a long range, the new treated areas 'protecting the previously treated

ones . J t Surveys show that where huaan population density reaches 40 inhabitants per kin2 the animal hosts of. tsetse flies bel-unging to the fusca and morsitans groups disappear, and most of the Glossina resting places are cleared; in such conditions tsetse fly vectors of aïrimal tri panosomiasis are usually no longer a problem (FCEZD, 1962), except if "holy W0odlands" occur, like in the Mossi contry of Nest Africa; but such woodlands can be easily cleared from Glossina by insecticides. Ci- verine species of Glossina, which transmit mainly human sleeping-sick- -ness caused by T.gambiense, can survive along rivers but are,very easi ly controlled in such restricted habitats.

.When hunan density Is below 40 inhabitants par km2 tsetse fl control becomes more and more difficult and costly with the scarcity of inhabitants. Despite our technical ability to combat tsetse, flies, .it is still not worthwhile to undertake large reclamation schemes, except in special instances, where soils and climate ax?e:&avourable to intensive agriculture (COCKBILL & alr,L963), or w,hen public health is

, involved .such as in residual foci of sleeping-sickness (W.X:KJS,1962), or for prateetion of cattle during seasonal migrations (FINHELE & alII Ce962 & 1965) I

In other situations insufficient exploitation of the country ,L Will permit tsetse flies to repopulate the cleared areas sooner or later, and the ressources employed for tsetse fly control will hav? been wast'eb .. -. Y9

ABEDI' (Z.H ,) , 1963 .-'Tsetse snmplhe me,thods . knn.Xpt .Liberian 1nst.american Found .trop.Ked .for 1962, 4343 . .

k&Dl (2.M. ) & WILLE11 (L. J .) ,1964 .- Eoadside tsetse hazard in Eibe- ria. Amer.J.tropOr ed.'%+yg.,13 499 504 -9 - .

kNONYYOUS, 196P-1965.- Bast African Trypanosomiasis Eesearch Organi- Fation Beports, 1960. 3.9GP. f962-63 . & 1963-64, Pub1 .East kf r .High Commissian and Bast Af r .Common Services Organisation, Nairobi . mor?Ymus, i965 ,- Tropical Pesticides Research Institute, Annual' Repor'

-01964 Pub1 ,Bast Afr .Common Services Ore., Arushrr, 45 pp,

BALDRY (D.A .T. ) I 1963 .- An evaluation by bioassay of the persistence of DDT deposits on riverine vegetation in the Morthern Guinea savannah vegetation zone of Nigeria and observations on the EaL, tors influencing the availability df deposits to Glossina palpalis (R.D.), Bull.ent.Res,, -54, 497 - 508 . .

BALDRY (B.A,T.), 1964,- An assessinent by bioassay of the comparative toxicity and persistence of dieldrin arid isobenzan deposits on

riverine vegetation in the. Uorthern Guinea.!savannah zone of I ?Ti .. geria in relation to the control of Glossina PalPalis (R.D.).

Bull.ent.Res,, 55, 49 - 52 . I.

BUlCfX (E a J ) , 2965 .- Applications par voie a6rierine de tklodrine dans la lutte contre Glossina morsitans Mestw . au Bugesera (Rwanda) c. C.SIH.Bo~r/C.C.~.k., PUb1.97, 145 - 155

BUHNETT (GOF.), 3.962 a.- The susceptibility of tsetse flies to topical applications of insectici'des. 1x1,- The effects of age and pre-

gnancy on the susceptibility of adults of GlossinaI inorsitans, Bull.ent0Res,53, 337 - 345 .

BURNETT (G.P.), 1962 b.- Eesearch.. in Bast Africa on the control of tsetse flies from the air: Agricultural Aviation, 5, 79-87: I._ ao 1. , ' .:t BURNETT (G.F.), CHADWICK (i?.R.)3 YTLL5L7 (A.U.D.) & BEESLEU. (J.S.S.), _. . -i664.- kirqraft applications of insecticides in Bast Africa...... XIV.- Very-low-volume 'aerosols of "dieldrin and isoberizan for the control of Glossina morsitans Westw. Bull.ent .Res ., .I 55 539 -9 537 - .

BURSE,EL (a .) , 1959 .- The water, balance of tsetse flies. Trans .T: .3nt Sdc.Zond.,, 'kL1,- 205 - 235 ...... BURSELL (E.), í.960.- The effect of temperature oil the consumption of fat during pupal development in Glossina . . Bull .ent .Zes ., 51 583 - 598.

BUIX3EiCL (B .) , 1965 .- Tsetse-fly physiology: a review of.receiit advances and current aims. Bull.Or6.mond.Saaté0, 28, 1903 - 709, .., ('F.A.), 1955.- The natural history of tsetse flies. Eond, Sch.ISyg. & trop.iced., Tliemoir noiO, 816 pp.

C€-3ADb?ICK (f.R.), a,- study of the resting of Glossina i964 iì.' sites swynnertoni kust. in 'Florthern Tariganyika; bull .ent .Res'. , 55, ". 23 - 28 0' . * . >i CHADWICK (P.E.), 1964 bo- Sffeet of two chemosterilants. on Glossina i morsitans . Nature, (Lond .) , e,299 - 300 . ,.

' ($

CHBLLXEB (A. ) , E963 .- SensibilitB de Glossina palpalis gambiensis Var - derplank A949 au DDT et à' la dieldr&e, :deterktine'e au moyen la trousse stEndard O..; .S . pour moustiques adultes . @ull.Si>:; Fath.exot., 56, 519 - 533 .

' CEAELIBB. (A-.'), .l'965a .- Campagne de Putte contre Glossin6 palpalis gambiensis Wanderplank, dans le foyer de,Bamako (ZQpublique du Mali). SeptiGmne enquête en saisoil sèche, du 8 au 22 Pevrisr -1965. Docutxent ronéotypé .O.C .C .G .B. ; .Bobo-Dioulasso . 22 CHALLIER (A ) , i965 b .- L' &valuation de 1 age physiologique chez .. Glossina palpal& gambiensis Vanderplank 1949 . ,Bull .Soc Path.exot., sous prGsse .

CHALLXER (fi.), BYRAUI) (i .) & DBDEWANOU (E.), L964.- Btude de l'effet de 1'HCH nébulis6 sur une population de Glossina.. palpalis ._.. gambiensis Vanderplank 194,9,dans une galerie forestihre ( Kankala'ba, k6publique de Haute-Volta) . Document roneotype 0 .C .G .G .B., Bobo-Dioulasso .

CBOBLBY J.E.), 2.955,- Annual report of the director of tsetse fly

operations for the year ending I 30th Septembre, 1955. -* Xhode sia agric. da., fi3 , 637 - 656.

I. COCKBILL (G.F.), LOWMQkB (D.'iF.)& PBBLPS (R.J.), 1963.- The control of tsetse flies (Glossina : Diptera, 'uscidae) in a heavily -. . infested area of Southern Zhodesia by means of: insecticide discharged from aircraft, followed by setelemeni of indige- nous people . Bull.ent.Res., E, 93 - 106

3k';IE (D.A.), DBAN.(G.J.W..) &! FO2D (J.), 1965.- Investigations of the sterile male technique with Glossina morsfkans. C .S .I .Z.T C.C.T.A., publ. 97, 93 - 96 .

DkSPdAI'U$.. (R.P.), 1962.- Came ranching in efrican land-use planning. B&Pl.epiz;Dis.Afr,, 10, 13 17 I_ - . 1.

DBYVIBS 11964,- The eradication of tsetse in the Chad River SyS- tem of Northerm Nigeria, J,appl.Bcol,, A, 387 - 403 .

EVENS (F+) *~96~.-Ltelevage des glossines. SUU. .Org,mond,Sant6. ,& 521 - 525 . EVENS (FJ~-.J.C..) & NIBM@GIEBRS (c.J.E.J.), i954.- Kecherches sur 1'6- levage et la biologie he Glossina palpalis mar'tinii. 3. Pnst .R.Sc .nat .Belgique, >:&me s6r ., 3, 63 pp .

FINELLE (F.), DBSROTOUiZ (J.), PVORB ('2.) & RENNER (l:~.), 1962.- Essai de lutte contre Glossina fusca,.par pulv6risation de dieldri- ne, en- XBpubliqu'e Centrafricaine, Rev,Blev,l:T6d ,vét.Pa.vS -*ttrop -Y15 247' - 253. 22

FINELEB (F.), ITBED (J.), YVQEB (Y.) & bACOTTf.3 (E.), i963 ar- BQpar- ., , . .-. tition des glossines en R6publique Centrafricaine. Btat ac- tuel des connaissances . Kev.Blev." ed .v6t .Fays trop., f6, 337 - 388 . , ...... PPNELLB (P. ) , LfiURBNT (J. ) & BYWAUD (J.F'. ) , 1965b .- Note compl6men- - taire sur un essai de lutte contre Glossina fuscipes en R&i.u-. 6 blique Centrafricaine. Rev,Slev.'-Qd.v6t .Fays trop ., -,16 ~''17w. 418 .

FORD (J.), 4962.- African wildlife and the tsetse fly-borne diseases, .. . Bull.epiz.Dis .Afr ., i0, 9 - 12 ..

FOXD (J.), ~963,-The distribution of the vectors of african pathoge- ' nic trypanosones. Bull.Brg.mond.Sant6, -928 653 - 669 . .. FORD (J.) 1965 .- Distribution of Glossina and epideniological pat-

terns &n the african trypanosomiases J .trop .'Ced .I-T.yg 3 .-"&. ,. . 61," . zu. - 225

FQSTER (R.), 19s7.- Observations onvlaboratory colonies of, the tsetse .clLes Glossina morsitans Idestw and Glossina austeni Mewstead .. . Parasitology 47> 363. - 374. '

]FOS-TBR (5. ) , 11964 .- Contributions to th& epidemiology of human slee-

ping sickne.5~in Liberia :a bionomi'cs of the .vector Glossina palljalis (E.D.) in a forest habitat . Bull.ent.i.\es,, E, 727 - 744 .

' FRAGA DE AZEVEDO (J.), DA COSTA PHlMBO (E.), AZAUJO kBi.BU (t ,i'.DB) &- TRAVASSOS ~BIITOS DIAS ( J .A .1, 1960 .-'CriaçAo' de Glossina mor- * sitans West . no laboratoria. An .Inst .Xed .troo . ( Lisboa), 19

CAS@WBN (U.), 1945.- 'Eds Glossines de l'Afrique Occidentale frangaisc- * Acta tropico, suppl. 2, 127 pp., Bale .

GTSIGY (U.), 1948.- Elevage de Glossina PalPalis. Acta tr¿)Dica, 5,

." GLJEXOW (J.F.), I.960,- Shinyanga : a review of $he..work of the tsetsa

' . . :. I research laboratory. B.Afr.a~ric,Furest.J1,, 26, 22-34, 23

GLASGO%? (J.P.), 196i.- Seasonal changes in the breeding places of 1, Glossina morsitans morsitans- Westwood. k.cta tropica?, 252 - 254 .

GLRSG@d (J.P. ) , 1963 .- The distribution and abundance of tsetse. Int o Ser .l;ionogr ,Pure & kppl ,Eiol. y .Zaology, 20, 2.41 pp. Fergamot. Press. GEASGOFJ (J .P. ) & UBLCI-3 (3.xi. ) , 1962 .- Long-term f luctuations in num-* bers of the tsetse fly Glossina swynnertonb Austen. Bull, ent.Res,, 53, 129 - 137 ,

GLOVER (P.ñ,), L963,,-.The tseCse problem in Northern Nigeria. Pa%:: News Agency (B.A.) Ltd, Nairobi, 383 pp.

GLOVER (P.E .f , 1964,.- A review of recent informations on game tsetse3 relationship, Proc .Ist.Int .Congr .Parasit. I Aome, sous pres-> se.

BARLEY (J.I .C. ) , 1960 .- A review of entomological research carried out by Bast Bfrican Try no 5 oiniasi s Rese ar c h $Org anis a t ion , .. Rpt .7th .Commonwealth ent .Conf., Londofi . '.. .. HkXLBY (J.y: .E. ) , 1963 .- New trends in, entomological research in try- > panosomiasis. Eu11 .Org ,mend .Sante, 28, 825 i 830 .

PIARLEY (J.pi.B.), 1963 b.- Age and infection rate of female Glossina attacking cattle at Lugala . B .A .T .k< .O., 'ïteport J_g62-J-s63

28 - 29 . II

HkRLEY (J.n* .B. ) I965 a .- Seasonal variations in age and infection rate of Glossina fuscipes, C .5. X .i< .T. /C .C .T .I;. , Fubl, 97, 93, - 92 . ,.-

HAELLEY (J.Fh.S.), i965 b .- Activity cycles of Glossina pallidipes Aust., Gopalpalis fusciyes Newst, and G.brevipalpis I\leWSt. Bull.ent.3es., 56,. 2-41. - 16G .

ISAHLEY (J.?*.B .) & ~IL$OPl (E.D. ) , 1961 .- kn experiiitent.. .. .in the use Of discriminative clearing for the control of Glossina morsitans .'rIestw in. Ankol,a, Uganda.. Bull .ent .Res., '=, 561. - : 576, . . . ., ...... ,. ., -.. HOCKING (IC .S .) , i961 .- Discriminntive application of insecticide a- ', '. :gainst Glossina morsitans West.. . Bull .ent.Bes., 2,17-22", .. .: I,. ,. .~...... HOCKIIG (Ji .S. ) , 1964 .- Recent advances in the control"".of tsesse flies.) l?roc'.L2kh.Hnt .Congr .Brit., London,. sous presse ., . ... "., .. '.A .I

HOCKIrk (IC .S. ) ,* LA?!&RTOT-j ( J .P.. ) &. LEHXs (I3 .A. ) *, 1963 .-'Tsetse-f Py .con- L trol and eradication . piu11 .arg .mend .Santk, a8 y 811-8a3 . Li JACK ($?,Id.), 1939.- Studies in the physiology and behaviour of Glos- sina rnorsitans Westwood. h5em.Dep.t .hgrid .Bhodesia, &, 203 pp

JSC$$3OIi *(C .TE.N. ) 1945 Cor:.iparative studies on the habitnt require- .. ,., .- .. , .. .. , ...... ments of 'tsetse.fly species . J .anim.Eco~e, 14, 46-61 +

JENKINS (D.W .), 1964.- Pathogens, parasistes and predators of medi- cally .important arthropods. Annotated list and .bibliography. Bull .Or,g .mond .§ant&, 30 Suppl ., 17 - 2i.

(A*' .), 1958.- The mating behaviour .of females of Glossina palpalis (R .D. ) in captivity. Bull.ent.Res., 4-5, 35 - 43.

(A.K.), 11961.- An assessment of the econornic importance of the tsetse species of Southern Nigeria afid the Southern Cameroons

based on their trypanosome infestion rate and ecology. I_Bull ent.Res., 52, 431 - 441.

(Li.7-.), 1965 a.- The hosts of Glossina as the.main factor affecting tryphnosofle infection rates of tsetse flies in Nige- ria . Trans .li .Soc .trop .¡!Led .Hyg. , 59, 423 - 431

' JCGDAl'4 (A.. .), 1965 e .- Long-term fluctuptions in numbers of a pop- lation of Glossina palpalis (K.D. ) : sixteen years' observations C.S.I.Z.T./C.C.T.B., Publ. '97, 85 .- 90..

JOSDAR (,!i.'.), LBS-JOHBS(E.) & WEITZ (E.), 1962.- The ,naturnl host

of tsetse-flies in Northern IJigeria. I Ann .trop .,?!Ted.Parasit .,' -?56 450 - 441 .. 25

ICBRKAGFIAN (R.J.), 2962.- kn experinent Ln the contra1 Of Glossina palpalis over a limited area. J .trop .T.ed d3yg., 66, 146-15Q7

IIIGBEi< (C.D.) & IILKLBY (J.)?.B.), L965.- A fibrine membrane for Pre- ding'Glossina E .A ,T.R .O. tmnuc.1 Beport, 1963 - 1964, 45 . L

1\ ICNSPLITG (E .F .) i i963 .- La sterilisation d'insectes msles comme moyec 'I possible d'obtenir 1'6radieatîon de la mouche tse-tS6. , WIHO/Vector @ontrol/27, Gen&ve .

LANCiUDGE (W.P.) ICEliNAGHAN (X.J.) & GLOVER. (F.E.), 1963!.- A review of recent knowledge of, the ecology of !;he main vectors Of trypanosomiasis. Eull.Org.mond,Santf?, 28, 671 - '701 .

LE XOUZSC, 1948 .- La prophylaxie: 'agronomique. Un moyen de lutte pour 1' 3 l'assainissement des r6gions infestees, Eu11 .m6d .A.@ .F.

' 5, 117 - 122 . .. P!cDOMALD (N.A.), l.960.- The laboratory rearing of Glossina morsitans I submorsitans Hewst . in Piorthern I'tSigeria. C.S.I.k.T./C!C. TA. .$ publ. 62, 247 - 261 .

?MAC KIGHAN (1.w .'), 1944.- Rhodesian sleeping sickness' in Eastern U-

ganda . Trans.I.:,Soc.trop.Paed.Byg., & 49 - 61. m ,I PAACLET'JNAN (K. J .R .) i965 .- Repor$ on results from inseçticidal contro? projects for the eradication of Glossina in the sudan vege- tational zone in Northern Nigeria. C.S.I.Ii.T;/~,,C'.TrA.,

k Publ. 97, 125 - 132

v PIIACLLBNNAN (IC'.J.i<.) i3 kETCI2PSON (P.J.), 1963.- Simultaneous control of three species of Glossina by.the selective appliqation of \ insecticide . Bull.ent.Kes,, 54, 199 - 212 .

la' I NAILLOT (L. ) , i962 .- Carte de repartition gc5ogrg4 en A.B.P. Q.It,3.T.0.P~;.t Faris . .. MAILLOT (I, ) , 1958.- Eievage de Glossina f,uscipes quanzensid Fires a Erazzavil$., Eull. I.Z.C., 15 - îG, 85 - 90 .

idELLANDY (a.), 1937,- Experimental work on reproduction in the tsetse fly, Glossina palpalis. Farasitology, __29, 131 - 141 36

NIOUISI. . '(K.B..S.), 1966.- Trapping as a means of studying the game tse-

. ts\e, Glossina yallidipes Aust. Bull'.ent.Res.; -?51 533 - 557,

-FROIQi<:IIS (1i.R.S.)) 1961.- Effectiveness of traps in tsetse surveys in . the Liberia rain-forest. Am:J:trop.~'"ed.I-Eyg., 10, 905 - 913

l\dIOXitIS (1Z.B .S ,) ~ 1962,- Focal nature of an epidelnic diseae . !Vature

HOUCHET (J.) , DELAS (ti. )& 'YVQRB (f .) , 196:. .- La campagne exp6rimenta- le de lutte contre Glossina tachinoides Hest. à Logone-Birni (R6pubPique du Cameroun et W6bublique du Tchad) . Bull .soc Path.exot,,*, 895 - 892 .

. NASH (Tek.V ,) , i933 .- The ecology of Glossina morsitans, 'r.lestw. ,and

..I., two possible methods for its destruction. . Eull.ent.Wes 9-224 107 - 195

NASH (T,A.I *) & PAGB (W.A.), P953.- The ecoPo&y of Glossina palpalis

I. . . in Northern Nigeria. Trans.~~,ent.Soc.eond, 184, 7% - 169.

NBSR (T .A .-< ) , 1956 ,- The fertilisation of GlossinQ. palpalis in cap- -. . tivity, Bulf.ent.Res., Q6, 357 - 368, , ..

../ .I 'I. , .. NASI1 (TOA.I'? .) ? e963 .'-' Fr'ogre'ss and problems in the 'establishment and .. maintenance of laboratory colonies of tsetse flies. Bull.Org...... ' ' mond,Sant6, $8 , 83& - .836. " ...I 1. , .. NASH (T1A.i. .) '&'ICERNAGBAN (R.i.), 'i-984.- The feeding of hematophagous insects on goats arid sheeps. Techniques .for .host restraint and

cage apElication.,, knn.trop.; ed.Parasit. 58, 168.- 17'0, .. NASE (T .A .?A. )& IBWNAGE-TAN (R .J .) , 1955 .- The weighi and viability of puparia of Glossina austeniy in relation to the conditions pro-

. vided for pupal development.. knn.trop.r"d,'E.arasit = - - --..--...-_.. ._.._ . ., =, 226 234 .

NASH..-.( T,,A.,;"., ) , KERNAGHAH. (3.J. ) & WEIGET (A .I .) , , 1965 .- k method for . .., ...... , . ... .--.. .. Che prevention' of skin reac6ions-in gdats used far .l[leedirLg tsetse flies, Glossina sspp. ann.troy,r~ed,Farasit.) 59, 88-94.

- .. , 27 NASE (T.A.T"-.), PAGE (M.A.), JORDAN (A.? .) & PETANA (W.),. 1958.-The rearing,of Glossina palpalis in the laboratory for experimental work. C.S.IC.9.T./C.C.T.A., publ,..",L, SC3 - 550 .

NASH (T.A .M. & STEIPJBR (3.0.),1957.- The effeCt of obstructive clearing on Glossina palpalis (2: .D. ) . %Sul1.ent .Res ., 423, 323-539.

0.6: .5. 1961 - Comité d'experts de' la trypanosomihse. Premier rapport o Org .mond .Santé Sér .Ra&p .techn ., -*247 60'..> pp .

O.'~..S. 1965 .- Késistarice aux insecticides et lutte contre les vecteurs Treizieme rapport du Co!;;ir6 0.7:'.S. d'experts des Insecticides . Org ,mond .Santé 4r.'Rapp .techn.., 2.65 i79 1181 _I - .,

PAGE (N.A .) , 1959 8 .- The ecology of Glossina 1onaipalDis Wied.in SOL" thern Nigeria. BulE,ent.i

$1 PAGE (N.A.), 1959 b.- The ecology of Glossina balpalis (R.D.) in Sou- thern Nigeria. Bull .ent .Res. ,x,SI7 - 633,.

' PAGE (W,h.) 13 McDONkLD (W.A.), 3.959,- An assessment of the degree of pnanfly contact exhibited by Glossiaa,palpalis at water-holes in Northern and Southern Nigeria. Ann.trou.-'ed.%arasit,, 53,262- i65 . r,. PIRDS (F.A .), P9GO .- Uma nova espécie de glossina do "grupo morsitans" (Dipt,era, T%uscid*ae)Glossina borpesi sp.nov. Bol .Soc .Est .?.,rioCam-- bique, 1 - 7 .

FOTTS (N.H,), 1964.- Camma-irradiation of Glossina yuparial stages and control. Proc .L2th .Int .Congr .Bnt, , Londori, 'sdus presse

RkGBkU (J.) & ADAM (J.F.), 1953.- X6partition des giossines au Came-

roun français. ~~ev.Elev.i~éd,v~t.Paystrop., e6, 73 - 78 . .. RPCKBNEACB (A.), 1961;- Cartes de r6partition des Glossines en kfri- que occidentale d*expression fransaise . 0.2 .S .T.Q.;x' . 6d .,Fari8 -

i28 . XOBEX

!% da: a further study of the epidemiology, ... of the d$sease among .. fishermen and peasant cultivators .. Bull..Org .mond.Sant&, ZS, 627 - 643 .

SOUTIEOR (H.A.N.) & COCKIlVG (K.E.), 1963 bo- Fertilisation of glossina morsitans in laboratory. in fS.B.T.E.0. Report, 1962 - i963 y 33 - 54 .

SOUTHOI~ (H .A .U .) & RBBBKTSUI4 (D.B .K. ) y 1961.- Isolation ,.of Tryoanoso- ma rhodesiense from Wild Glossina palpalis Nature (Lond.),

-7189 410 - 412 .

. TEJYIFLETON (K.G.) I 1965.- hn attempt to eradicate Glossina tachiuoides Westw. and Glossina inorsitans submorsitans Newst .. in an area

.._. of endemic sleeping sickness in TJorthern Iiigeria by the use of residual insecticides. C.Srl.P.T./C.C.T.k., Fub1.97, 167 - 169 . I B ” I.

.THOMSON (W.E..F.), GLOVSN (S.E.) & TXUX’iiP (E.C.), 1960.- The extermina- w tion of G.pallidipes fron an isolated area on Lake Victoria

with the use of insecticides. . I C.5.Il.~.T.,/C.C.T.A., pao b 62, 303. - ::O8 i

VkUCHL (&:,.A.), WADDY (B.B.), kNBRA3E DA SILVA (“.A.de)& PONS (V.E.), I963 .- 2.<&partitionde la trypanosomiase africaiae chez l’homme et chez les animaux Bull.Qrg.mond .Gant&, 28, 545 - 594 . 29

I l WITZ (E,), 1963 a,- The feeding-habits of Glossina, Bul1.Org. , I mond.Sant&, 28, 733'- 729 e

CJBITZ (E, ) ,1963 b .- Immunological relationships between af rican trypanosomes and their hosts. knn.:?ew .York Acad .Sciences, =, R 403 - 408 . :I 1 WILL;BTT (I:*c } y 1953 The laboratory aaintenance of Glossina -Pa- P) .- rasitologx, 43, 158 - AL30 .

WILLET" (1C.C .)-, 1963 .- Some principles of the epidemiology of human trypanosomiasis in kf rica . Bull ,Org .mond .bante, 28, 645 - 652 . WHLLBTT (K.@.), 1965.- Some observations on the recent epidemiology of sleeping sickness in Nyanza region, Kenya, and its relation to the general epidemiology of gambian and rhodesian sleeping sickness in Africa J Trans +E.Soc'.Ved .Myg ., 59, 374 - 394.

WILLET (K.C.), :ZcPdBMQN (J.P.), ASBCROFT (¡..To) & BAIC3X (JeRe),L964,- Trypanosomes isolated from Glossina palibalis and G.pallidiDes . in Sakwa; Kenya. Trans.W.Soc.trop."ed.KyE., 5 39P - 396

VILLON (8.G.) , 1958 .- ZCecent advances of Glossina inorsitaris submorsitans in Northern Rigeria. C .S .I .k .T ./e .e .T. A ., PUbl .4l, Y 67- 3E9 , < WILSON (S+G.), i4IORRIS (K.R.S.), LEWIS (1.3.) & KEROG (E.), 1963.-The effects of trypanosomiasis on rural economy: with special refe-

$1 rence to the Sudan, Bechuanaland and West Africa. Eull.Orq, 3 mond.Sant6, 595 - 613.

WOOF (u .It. ) y 1965 .- The eradication of Glossina unors,itans morsitans 5 Westw. in knkole, Western Uganda y by dieldrin application. i C.S.I.R.T'./C.C.T.A., Pub1.97, 157 - 166 .

YVORB (F. ) , DBSBOTOUB (J. f , LLAUKBPIT (J. ) & FENBLLLH (P. ) ? 1962.- ES- sai d'assainissement drune zone infestbe par Glossina f uscirjes Newst. en lt6publique Centrafricaine . Uev.3lev: Bd ,,v6.t,,S2a.vS trop., 15, 405 - 410 .