Rearing and colonization of Simulium damnosum complex and related investigations: April to June,1979.

1 I Subjeott Inetitution: Personaelt Ilate of Submission: Peniod covered: Slgnature of reeponsible offioer: .F /ny**/. TIHO ONCHOCMGTASIS @N[NOI, PBOGRAU}TB REIEANCH REPOHTING. Bearing ancl colonization of Simrliun dannosgq oompl s and ralated inveetigEtloEei rrHo/ocP J.N. Rayboul(l 8th Augustl 1979 April to June; 1979. I aa aataa aaoaaaaaa c0il8ENTS A. Sumary. B. Rearing S. damaosurtn BoIr and related investigatlona. I. &pausion of OCP reariug facilities. 2. Confirmation of a laboratory mating formr 3. The irnprovement of rea.ring teohniques. {. The identiflcation of leared }arvae. C. Preliainary tests with ttsimno Repellent,t ,again st S. damaosura e.lo D. Observatlons on the reoolonigatlon of the Patnpawn River by S. BellaIIOEur[e llhe longevity of 1ocaIly breeding S. dannos[ttr BrI.Er Fr G. Eo I. Jr K. L. Ut populationso Identification of cor+-biting simuliids other than S. daEnosun s.Io Aquatio drosophilid E of the Dtosophila simultvora s,!oupo Suppfy of material to othel workerg. Publioations. ldl scell aneouB aotivltieso Vi sitol s. Worlc plannetl for next quarter.. Aohnowl edgement s. Seferences. llabl es. t A. SUMMARY The limited laboratory mating propensity of S. sotrbr ense was oonfirmed. Some improvements w€r€ made to rearing technigues inclucling the development of an adult collecting device and simplifioation of the aIgal culture medium. Rearing faoilities were establishetl at Natitingu and have already prolr"ided useful results atlclitional to those from Akosombo. A number of new investigations were commenoedr mostly in oollaboration with V.R,A. ttaff. These included an evaLuation of a loca}ly produced repellent, studies on the rate of rocolonization by Sr sum and preliminary work on the Iongevity of S. damno sum s. I'. biting populations. Collections of the Drosophi 1a simulivola group yielded ngw sPeoies but not fiom the OCP area. The suppLy of material to collaborating laboratories oontinued and some publioations ldere finalised. fmportant visitors to Akosornbo includecl the Japanese Mission. B. BEANING S. DAMNOSUi{ S.L. AND NEIAIED INVESTIGATIONS 1. &pan sion of 0CP rearinA faoilities. Early in the period under review, Mr.T. Barro visited Akosombo to obtain th.e necessary apparatus for the establisltment of rearing facilities at Natitingu. He has already obtained suocessful results from thele (see below). In addition tc Akosombo, therefore, both Natitingu and Bobo-tlioulasso are now equipped with rearing facilities. ../ 2. . 22. tqnfirmation of a laborato.ry matin€ form. It was pointed out in my previous report that adults emerging flom pupae oollected at Senchi lapids near Akosombo apPeared, to mate in the laboratory. When subsequontly examinecl, a fen females appeared to be oquying spermatophores. However; as manJl flies appearecl to mate and very few ssomed to be oarrying spermatophores; I begin to doubt my resultso I therefore Bent the speoimens ooncerned to DroJ. Grunewald at the Institute of Tropioal ldediaine in Tubingen. He has sinoe oonfirmecl my reeults and found some more spermatophor.e calrying femaLes amongst some additional material sent to him. 0n the basis of Dr.Vajimers larval identificationsl the flies conoerned are S. soubrense. llhese findi ngs are of particular interest, thereforee because they represent the first record of an identified West Afrioan member of the S. damnosu-,l oomplex msting in captivity. Tlie laboratory colonization of a West African onohooeroiasis veotor now beoomes more feasible. Attempts wi1I be madel thereforer to increase the insemination rate ancl to seleot-out a laboratory mating population. Teohniques developed for non-tropical simuliids and not yet well tested in Afrioar may weII prove usefur for this purpose. The recent agreement between OGp and Dr.J.C. Edman of the Univelsity of Massaohusetts opens up new opportunities in this respeot. The Senchi Bapids near Akosombo ale now undel control and thele is no gualantee that S.soubrense . ./ 3.. 3wiII re-establish itself there in the near future. InvestiEations will be carried out, therefore, using material from Avetonou (near Palime in Togo) which has also shown signs of mating in oaptivity (Grunewald pere. comm.). Identifications by nr.Vajime have shown that S. soubrenso is also included (together with other species) in the breecling population at Avetorollo 3. fhe improvement of learing technigues. lhe algal oulture technique (to supply food for the developing Iarvae) has been much simplified by the use of a liquicl fertilizer malketgq under the name of |tLuwasarr. The replacement of a specially prepared, culture medium by this ready-made solution saves a considelable amount of time. (The suitabil-ity of |tLuwasart for the purpose in question was first demonstrated bv Dr.J.Grunewald of the Institute of Tropical tledicine at Tubingen). An adult oollecting clevice for use with the rearing apparatus has been designed and oonstluctod. It consists essentially of a perspelc cover to the rearing trough onto which one or more perspex tubos (from a WHO adul.t insecticide susceptibility test kit) can be screwed. The oover is painted to exclude light and the flies are attracted by tight into tho unpainted tubes. The end of the trough is closed with netting that allows the passage of waterr Some minor modifications to this design mal be found to be necessary when the device is tested out in praotice. ..f 4., - 4- 4. The identification of r eared larvae. Successful rearing has boen achieved by Mr.T.Barro at Natitingu in spite of soms fe="es resulting flom power failures. rdentifications have so far been obtained (from rl.vajime) for the larval progeny of females from Mo a Mo in Togo. It may be seen from [able L1 that S. sirbanum; S. darnnosum and S. Ecruamosuro were all identified from therel a finding of considerabre intereet in oonneotion with the reinvasion studies. Becent rearing work at Akosornbo has been mainly concerned with flies from Wegbe in the nayi River where Mr.A.K.Akpoboua (consultant) made a special- stufly. The main purpose of this wolk was to identify the pale wing-tufted flies biting man in the Bre&r This proved to be diffiourt beoause they represented onry a very small rcmponent of the biting population. However, the progeny of a f ew f emares were successfurry reared by trlr.akpoboua during his working visits to Akosombo, and aII proved to be S. squamosum (rable 2). Further investigations are requiledl howsvslr to determine whether or not this is the only pare wing-tufted species biting man in the area. The fact that S. damno sulll g. ] . l arvae have been collected nearby (at least on one occasion) su!,gests that it might not be. It may be seon from the table that the progeny of dark wing-tuftecl fries from t.legbe were identified as s.yabenss and S. sanctipaull. This is not the fir st time urat mar[1![!crt*[*fi femaleE have been identified from this site (Raybourcl, tg77) arthough the species is not known to breed rocarl_y in the Dayi River. . ./ J.. 5C. PREIIMINA RY TESIS IIITH IISIMNO il GAINST S. DA}INOSUU S. L. a lhis investigation was oarried out together with MI.a.K. opoku and his assistants in the Publio Health Laboratoryt Akosombo. Noamesi (rgzo) f ound the repell ent rrsimnott, manuf aotured from local plantsrto be fu1ly effective agai nst S. dsmno SB{D E.I r This produot is commeroially malketed by Dr.Noarnesi and it was consialerecl desirable to obtain an independent assessment of its effi oaoy. Tests vlere oarried out by smealing one leg with repellent while leaving the othor unprotectedr and then oomparing oat ohes of S. damnosum s.1. fsmales on eaoh Ieg (Sohmidtr L977). Several eight-hour biting catches near Akosombo indicated that I'simnorr gives a high levol of protection provlding adequate quantities ar.e used. Further t:sts at Boti showed that there is no reduotion in the efficienoJ of the repellent over a tweLve hour period. However' 1 result s wero found to diff er m5'rkedly aooorcling to the tube of repellent used. This would sutgest diffelenoes in the composition of iadividual batches of the produot. In view of this unexpected complioationr the detailed results will be presented in my nent report when this matter has been pursued furthel. ..f6.. 6- D. OBSffiVATIONS ON TITE RECO ZATION OF TIIE P NPAWN RIUEN BY sa This work was carried out by Mr. J.H. Adiama]r and his team in the PubIio HeaIth Laboratoryl Akosombo, in conoultation with myself. Difficulties in the identification of S. Bsuamosum render its role in the reinvasion phenomenon not sasy to determine. rnformation on the late of reoolonization of S. ssuamosu-n breecling-sites after the resumption of river-flow is therofore of parl-cuLar intslsst. Beoause the breeding population of S. darnnosojD s.I. in the pawnpawn River at Boti Farrs (soutLoasteln Ghana) is virtualry pure S. Sgualnosum r this site lras ohosen for preliminary observations. A11 breetling areas in the pawnpawn crose to and incruding Boti Falls had ceased to flow by late February, Lg79. Consequently no biting adults wero captured during ths period February to ealry lrlqy, 1919. 0n 10th 4pril there was no breeding by ar\y simuliids in any }cnown sitss close to Boti Falls. River flow reoommenoed at Boti on rlth May and a larva1 search on 22nd Mav vierded a singr" r.rr3!31 s. "d"oui "rdS. unicolnutum. Two days Iater, three eflg batobes and some larvae of the S. darnnosum complelr, presumed to be S. SgUamOstun r wele found above the falls and S. adersi lalvae were encounteled further upsteam, Nearby downstrsam sites yielded numerous larvae and even pupae of S. sgUamo Sum, S. uni oornuturn and S' adersi. Later prospections on 2!th and 31st lt{ay revealed incleased breeding and the presence of pupae at Boti. 0n May llst, 86 females were captured during a biting catch at Boti. ..f7.. 't- [he observed recolouisstion of Boti ps]fs was unexpeotedlyrapid.Itseemsliketythatbreedirrginthe downstream sites comuenced. a l-itt1e earlier tiran at Boti FaI1s enabLing the latter to be recolonized immediately aftertheresumptiorrofrivelflow.I{errtyearprospections wiII be carriod out for greater distanoes, both up and down strear, to yield further information on this aspeot' These results differ from those of Hynes (fgff) who obselved that rr3fter two or three woeks tity Elggllg larvae ma;t app€artr. Possibly, howover, the liver sometimes risos more slowly; taking longer for the flow-rate to become adequate for breedinS' E. THE LO}Iffi\J:tTY OF LOCALL Y BRSE,DING S. SUM S.L. ATIOI{ During the dry season, the senchi and Kpong rapids in the VoIta Hiver reprosent the onIY o ilamrrosum s.I. brceding_sites a CL' ns31 [kosombo. The locaI biting population' thereforel completely disappears after the cotttrol of these breeding-sitos' In the rainy season, howeverl breedinS also occuls in some small st r ealns. control of the volta River breeding-sitcs is discontinuous. Abate is atlded by V.R.A. at weekly intervals for two or three months and then treatment is stopped until the return of a biting population necessitates its resumption' It should therefore be possiblel at least in the dly seasont to tletsxmine the longevity of ttre 1ocal biting population by regular biting eatches and dissections followirig the reeumption of control' As Dr.Kurtak has pointed out, Belleo Tlaps oould also be used in such a study to yield valuable information on egg numbers and physiol ogi cal &fl,€o ..f8.. BS. damnosum 8.1. femalos recently reached a higit biting density in tho area and oontrol was commenced' on lth June' As this was in the rainy s3ason, thero uas a possibility of a smalI contribution to the biting poputstion from some small styeams not subjected to oontrol. Iitrevertheless; in the hope that some preliminary indioation of longevity could be obtainedr several biting catohes wera carried out with the helP of v'R'A' staff during the ten days after treatment. The results of this very preliminary and supelficial investiSation indicated that the biting population fo1I by about Bol; between the thirtl and sixth day after treatment and from the sever.rth to loth days very fcw flies were collected. Bearing in mind that some adults were probably emerging from pupao for at least two days after treatmont (tire punae not b,:ing killed by the inseotioirie), these results suS,gest a survival of only one or two gonotrophic cycles for most fomales. A more thorough investigation on the lines mentioned above will be undertaken during the next tlry s€ssorlo F. IDENIIFICATION OF COW-BITING SIMULIIDS CT}IEB THAN S. DAMNOSUM S.L. The small number of cow-biting simuliids oollected by Ir.Denke from f6t6tou and 0kpahoue in Togol and referred to in an earlier report (.luly-leoember, 19?B) have been identified as s. !gI}.".. such cow-biting specles ale of interost as Fossible vectors of parasites also transmitted by members of the S. damnosum oomPlex. G. AOUATIC DROSOPHILIDS OF THE DROSOPHILA SIMULIVORA GROUP My oollection of aguatic drosophilids of thc Iro so ila simulivora group was given to Ir'1,' Tsacas (Laboratoiro Qsn6tiquo Evolutivesl Paris) for identification ..f9.. de Biologie et -9- when I met him during my leaveo These lemarkable flies are of particular interest because they eat Simulium eggs and might have a possible use as biological oontrol agents (Tsacas and DiBney, 191d. At least two and possibly three new spooies were incLuded in my matelial but none of these were from the OCP area. H. SUPIEY OF MATSRI TO OTIIER WOBKMS Adults of S. squamosurn were supplied to Dr.R.Garms for compslison with wild-caught fries in his reinvasion studies and to Drs.P.[. Dang! and B.Vr Petelson at the Inst11o1" ot Biosystsmaticsl 0ttawa. A fow specimens of other simuliids wore present sd to Dr.R. Crosskey during rny Ieave in England. Eggs of s. damnosurn s.1. were dispatched to f)r.J. Grunewald at the Institute of Tropioal Meclioine at Tubingen and to D:r., M.Pudney and Miss Meredith at the London and Liverpool Schools of lropioal Medicin6 lsrpectively. Dr.Grunewald has reported that eggs dospatched ea,rly in Maroh arrived in particuJ-arly good conflition and were successfrrlly reared to adults in groat nufibers. I, PUBLICATIONS The following papels on work carried out for OCp were published or in press duling the period under reviews- Omar, M.S.1 DonJre, A.M. and Raybould, J.N. (tglg). fhe development of 0nchoceraa oohengi (Nematoda: Filarioidea) to the inf octive stage in Simuliurn darnno sum s.1. with a note on the histochemical staining of the parasite. Published but not yet s€enoTlopenmed. Parasit. ...f:.o... -I0- PUB!,I_QAIME (cont d. ) . Rayboulds J.N. (tgfg). A new simple technrque for rearitrg the darnno summ prog€ny from singl e females of the Simulium Theobald oomplor. wtro/ vBc/ 7 9 .7 L 4 ana }[HO/0I'rcHo/? 9. r 48. Rayboulcll J.II. (tgly). P1.esert progress toviar6s the laboratory oo1 oni zation of members of the Simulium darnnoeum compldr. In: Blackflics: the futurs for biological methods in intsgl3f,ed control. Ed. M. Laird. In press. Raybculdl J.N., Vajime, C'G,1 Quill6v6r1 , D.r Barror T. and Sawad,ogo, R. (tylg). The Iaboratory maintenanoe and rearing of Simulium damnosum comploc speoiss as a research tool for the Oirchocerciasi s Control Progr sIIilIlgo Tropenmed. Parasit. In press. In addition to the above the following Papers on onohocerciasi.s vectors in Africa outside the CCP area were also published or in pr ess! Grunewaldl J., Grunewaldl 8.3'1 Raybould; J.N, and Mhiddin, H.K.1 (tglg). The hydro-ciremical and physical characteristics of tho breoding sites of tho Simulium noavei Roubaud sroup u'a t?I"?gift*"u crabs in tho Eastern Usambara Mountarns in Tanzania. Internat. Rev. Ees. Hydrobiol. , 64, 71-88. Raybould; J.N. and lrJhits, G.B. (tglg). The di stribution, bionomios and control of onchocerciasis veotors (Diptera: Simuliiclae) in Eastern Africa and Yemen. WHO/VBC. In pross. ,,f :-],-, -11 - J, MISCETTANMU S AC{IIITIES: It was trcntioncd in my previous loport that aclministrative dutiss had tended to increase with the periodic breakdown of teleJ'hone communications betwsen Tamale and Aocra. This situation has oontinued. During my leave the opportunit;- was taken to diEcuss my work with professional colleagues. The Natural History Museum tu London was rrisited on several occasions for this purpose and a very briof vi.sit was rnade to the River Laboratory near Wareham. Certain items of equipment were also purchased 6uring my I eave. K. Iiitsrmas Members of the Japanese Mrssion spent two days in Accra and akosombo. Their visit was appreciated and an effort was made to give them as comprehensive and informaf,ive a prograrnrne as possibl e. Dr. P. Reit*r Gonsultant, arrived towards the end of June for a few weeks workiug visit. Reference to his investigations will be made il my noxt report. Other visitors included Professor A.B. Sta glof Kumasi university and Director of rurPa (rnstiiute of E:tomology aad Parasitology of Africa) I Dr.M..p. selvicel Head of the Department of Medical Entomology at the Liverpool School of Tropical Medicinsl members of the Board of Directors of the Volta Rivor Authority and a representative of the British Council. ..fL2.. -L2- [. }IonK PtaMfE"n Fon Nu(T QUAnTER 1) (") Studies on laboratory mating by S. soubrense (t) Continued -:earch for other laboratory mating gpecies. 2) Furthor roaring work at Natitingu and Bobo-dioulBSEoe 3) fnvostigation of the inheritance of wing-tuft colouration in S. squamo gllJll r 4 Complotion of tests on rtsimno Repollentttr 5) Continuation of collaborative programlnes with V.R.A.Priority will be given to ths first itern. M. ACKNOWLENG EI{ENTS I arn grateful to IroG. Vajime for all larval identifications; to Dr.R.W" Crosskey for identifying adult simuliiils; to nr. L. Tsaoas for identifying alrosophilids; to Xr.J. Grunewald for valuable advicel to Dr.5.K,Noamesi for his cooperation;to Mr.T. Barro for rearing larvael to Mr. A.K. Akpoboua for results from the Bivel Dayi; to Messls. J.H. Adiamah, A.K. Opoku and other members of the Public HeaIth Laborato..y staff for their collaboration in a number of important investigations; to Lir.F.Mordzifa fol his assistance throughout and to Mr.A.S.E Danso for doing al1 my typing. I am indebted to the Volta River Authority and the Volta Lake Resealch and DeveLopment project for Iaboratory aocommodation and to aII thoso in O.C.p. and V.E.A. whose continuod support has made my invsstigations possible. ...f !3.. fa -'t1,- NEEENEII cE5 Hynes1 Jeu (fgZf)I :Innual river in southeln Glianar oycles of maoro-invertebrates of Freshwat. Biol. r 5r 71-83' Noamesir G K, (rgzo)r Preliminary roport orr a new ropollent ilsimnort against blackflios and othor biting inssstso Ghana Med. J. % 3y43. Rayboulde J.I[. (fgff). Tho speoieE colnposition of man-biting S. dalll[osutlll so] r population f rom certain Iooa1ities in Ghana and Togo. Quarterly report to 0.c.P.e oot-Doc.1977t 4. Schmitlt, M.L. I Lg77. Relative cffectiven-iss of repellsnts agai nst Si ium alnno sum (Dipturr: Simuliidae) and Glossina morsitans (Dipt"or: Glossinidae) in Ethiopia. J. Med. Ent' Honolu1u Llt 276-278. a lIsaoas, f,., and DisnoJl1 R.H.L. of Eeophif-e- ( Oipt ora: Simulium Iarvae (DiPt., 350- l? 7. (igZ+). Tvro new Af rican sPecies Drosophilidss whose larvae feod on Simuliidae). Tropenmed.Parasit . 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