Rearing and colonization of simulium damnosum complex and related investigations: October 1979-March 1980

i t 1 Subj ect: Institutlon: Per sonnel: Date of submission: Period covered: }IHO ONCIIOCENCIASIS CONTROL PROGRAMME REStsARCII RBONSING. Eearing and colonization of Simulium damnosum oompl ex and related investigations. ,r./*. J.N. Rqybould. 2n:l ApriI, 1980. October $79 - March 1980. Si€nature of responsible officer: c0i{TENTS A. INTNOIUCIION. B. BEARING AND COTONIZATION. J. Molifications to the rearing system to overcome the effects of power failures. (.) Use of wooden rearin€ troughs. (U) lutomatic switoh-ovel to a battely driven pump. (") Ihe .tautomatic floodingtr method. 2, Attcnpt s to obtain trnatural r oviposition. 3. Rearing work at N3titingou anl Bobo-Dioulasso. 4. Attenpts to obtain S. soubrense for mating experirneDts. 5. Rearing work in U.S.A. using eggs from G:ana. 6. Visit to CornelI end Massachusetts Universities. G. sTUDrEs 0N THE lrrNc rUFT CoLoUBArIoN 0F S.__EI$IAS9SUU FnOr{ BCII FALLS. J. InvestiSations on reared fIies. 2. Studies on wilcFoaught biting fernales. D. PnELIMTNABY B/ALUATTON OF, TETEPHOS (.gn.gre) ELOATTI,TG STRAND DrSPEI'ISERS. & EINAL INVESTICATIONS 0N SIUN0 BEPELLE{To aa a o a a a a a a aaa a a a a a a a a a a a aa '.'t F. G. H. ,Ir J. K. L. u. N. CERATOPOGONIDS AT AKOSO}IBO AND BOTT. UENMITHID PANASITES. DISPAIGI OF MATERIAI TO OTTIER UONTERS. PUBLICATIONS. ETIJCArION AND TNAINING. EqIIPIIEI\m. ATTtrID.\NCE AT MEEIINGS AND vIsITs T0 BEEEAnGI INSIITUTES ETC. ADUINISTNATION. uoflK Fon Nt[T qJAnTEB. ACre{OWLEDqEITENTS. TABLES. "rt A. ININOIUCTION This report ooverg a six monthr period from October I9?l to March 1980. tiithin that timer howsvsp, two and a hal-f months were taken as home leave and about two weeks were spent visiting research laboratolies in two Amerisan Universities. The period available for experimental workt thereforor was limited to three months. Neverthel"ss the long leave period enabled me to clear a back-Iog cf paper-workr writing-up etc. Perhaps the most important advanoe made lecently, has been the developrnent of successful teoini{res for overcoming the effect of power failures on the rearing qysterns. These metliods (two of which were developed.6rlthe advice of I)r. J.B. Davies) are likely to plove ( ParticularIJ valuable during the proposed reinvasion studies latel this Y ear. Another important developttent was the finding that the different (wing-tuft ) oolour forms of S. squamosum do not represnt separate breeiling populations. A11 colour forms were found to be present in flies reared flom a single batoh of eg!s. The main disappointment was my inability to oapitaLize on the di scovely that S. soubrense will mate in the laboratorJ (albeit in smaIl numlers). Conditions of exceptionally hi6$r rainfall resultecl in aIl known (or suspectecl) breeding sites of S. soubrense in Togo and Grana (exoept Senchi Rapids) being flooded out until the time of my departure oD 1eav6r Unfortunately the Senchi RaPids near Akosombor whele a mating populatior wa6 first foundr have not since been recolonized by S. soubrens eo Failure to obtain S. soubrerise material, thereforet made it neteseary to "qn6entrate on the other aspects of research listed (in ttre oontents Iist) on the pleoedin6 Page of this report. .....f2... ,' a 2- As colonization of at least one species in the S. damnosum rcmplex is nolrequired wit,hout delaJrr experimental work direoted to this end will be given urgent priority for the next six months. Ideas developed iluring my recent visit to U.S.A. wiLl no doubt prove to be useful in this r espect. B. NEARING fu'ID COLONIZATICN 'l . Moilif i cations to th e rearin stem to overcome tha effect of Power If I €S. a ) Use of wooden rearing troughs. Bearing troughs made of plastic roofing material (as have boen used hitherto in the OCP area) dry out rapidly when the water flow stops during a powel failure. Many 1&Iv3s die within about 45 minutes and alL aIe usually dead within an hour. lrlooden troughs dry out much more slowly and this is reflected in larval survival. Drling power failures of up to about i1/Z noors most Iarvae (in wooden troughs) survive and recove! when the water flow is resumed. Wooden rearing troughs will therefore be used for routine work in the OCP area in futurel but it will be necessary to avoi'd kinds of wood that produce toxic materials. ( (r) Automati c stlitch-over to a batt ery driven pump. Ihis teohnique whicir uses a sin61e pole solenoid operated switcn to-bring a battery-run pump into operation as aoon the mains power supply ceasesl is the best of the three methods. ['he water flow is maintained thloughout the durations of the power failure enabling the larvae to continue to feed normal]y. The method i s, however, expensive, reqriring two centrifugal pumps and a battery as weII as the solenoid operated switch' f 3... t I- 3- ( c) tne "qqtornslic floodingrr method. This adaptation of the rearlng teclinieue was suegested by D!. J.B. Davies and has proved to be particularly successfnl. The learing apparatus is modified to include a rearing trough positioned rilside a plastic bin. A centrifu€aI pump conveyE water from tne bottom of the bj-n to the bottom of a second bin placed at a hi€her level. The upper bin filIs with water and nverflows into an outlet pipe Ieading to the top of the rearing trough in the lower bin down which the water flows. Drring a power failurer the water in the upper bin flows back tirrough the motor into the lower bin ( contaitring the rearing troueh to wirioh the larvae are attached) filling it with watel. The Iarvae remainatt*ilbdtl'to the trough although deeply submerged in still water. They wave about and sJ.owly move up the trough to near the water surface. Virtually all Iarvae survive for several hours or even overnight. I'lhen the power supply resumes, the lowel bin is almost emptied of water as the upper bin is fil-Ied. The larvae are ternporarily exposed. They respond by becoming firmly attached which results in their not being washed awal when water flow along ttis trough j.s resumed via the overfl-ow pipe from the upper bin. An alditr.onsf advantsgs of this excellent techniquer is that it is easy to fit an adult collecting device to a lid covering the Iower bin. f 4... ' f ' I-4- 2. Attempts to obtain Itnatural rt oviposition in the laboratory. ItNaturalr'oviposition in captivity, where the gravid females actively select an oviposition site, has been obtained with s. d.ecorum at cornell and Massachusetts universities in the unitetl States. This has not Y et been achi ev ed f or S. damiro sum s. I . Sxperinrents have recently been carried out in which the techniques used suocessfully in the U.S.A. have been aPPlied to the S: damnosum oomplex, so far without 6rccess. Although some fsnales do oviposit under these conditionsr they a!'pear to do so only when they accidentally become trapped in water. TLrey do not appear to deliberatelJ select an oviposition site. 3 Rearing work at Natitingou ancl Bobo-Dioul osso. These important investigstions carried out by M,:ssrs. T. BarIo and SawadoSo respectivelyl were referred to in my plevious report' Mr. Barrors work has also been well presented in a separate report (Barr.o t 1977) which incluiles discussion of future research requiromerltso Irlost of the realed larvae has now been identified by 3r. Charles vajime. The results are of paltic,;IaI interest in relation to the reinvasion probrdllo They are presented in !r' vsjimers recent report and will not be reiterated here. 4. Attgnpts to obtain S. soq brense for mating experiments. [he discovery that S. soubrense mates in the Iaboratory (albeit in small numbers) made its 1s'iroratory colonization feasible. Unfortunatelyr however; .the specisg has since failed to return to Senchi rapidsr near AkoEombo where the original mating population was found. Att empts to obtain 5. soubrense during the rainy season last year failed becauss the known breedrng - sites in fogo were .....f )... 7tr)- flooded out by exceptionally heavy rain. How6rrs1, priority is now being given to this aspect of the wolko A visit to an S. soubrenee bteedin g site at Tetstour on the Mono River in Togol at the end of March this Jear, yielded larvae ( tfrat were f ixed for cytotarononnio identification) and pupae of S. damnosurn s.1. However, the aclults that e:nerged from the pupae collected sliowed no signs of mating in captivityr suggesting that soubrense wasabeont at that time. An irrigation soheme near Afienya close to Accra was aI60 vrsited without suGoosg. A furthel Bearoh for possible nearby bleeding sites of S. eoubrense in southurn g13na wilL be made at the beginning of Aplil. If this is unsuccessful, I will move to Atakparne for a while for studieB on Iaboratory msting before muXtigenelational realing is attempted at Akosombo. A.e Atakpame is oLose to a number of known 5. soubrense breeding-sitesl there is a good ch6ns. of sufficient material being available. 5. Rearing work in U.S.A. ueing eg€s from Ghana. Several consignp ente of 5. damnosum s.I. eggs from Grana havo been sent to 3r. J. Edman and Mr. K.B. Simmons of the University of Massachusetts wiro have a contract with OCP. Results with the filst consigrunent (S. ElluamgEum) tt"re been described in a report by Dr. Edman. The eggs alrivsd in less thsn one week and a reasonable hatch was obtained. The Iarvae were reared up to mid late instals whon thsy stopped Srowing and died. A very 6maII numbar did pupate' trgrthel triale are required to determine r*hether the oomplessed ai! systenr used ia unsuitable for the S. damnosum complex (as is suggested by our expelience in Africa) or whether the water ternperatOle (t9oC) ......f 6... t-5- was too Iow. It is also possible that nutritional conditions were not suitable. Nevertherlessl it is satisfying that even this leveL of success rru.Lhiev,:d witir the first consignment of eggs dispatched. 5. Visit to Cornell and Ma ssaohuset t s Univ ersiti es. Drring the seooncl half of January I visited Dr. E.W. Cuppts laboratory at Cornell Universrty and Dr. J. Edmants laboratory at the University of lttassachusett s. At both laboratories col-oniee of S. decorum have been successfully established. The visit proved to be very informative and worthwhile and has given me Eeveral new ideas. Howsysl, tletails will not be given hele because a comprehensive report has already been plesented separately. C, STUDISS gry lHE I,IING-TIJFT CoLoUAATIqT 0F S. SqUAMoSIJM lo Investlgations on reared fIies. This investi6atiorl w2g carried out in collaboration with I)r.3. Kurtak. With the exoeption of S. squaltosum, West African onchocevciasis vectorg mal be Bepalatetl into ttg6Isstrr oI rtsavannahrr cytospecies aocording to the dark or pale colouration of the tuft of hails on the stem vein of the wing. The wing tuft col our ation of s. squarno sum t howeverr m4y be paler dark or mired. fhis lenders identification clifficult (Garms, 19?8) and complicates reinvasion studies. Drs. Peterson and DanB (to whom much material has been sent for morphologi cal stuay) h3v e suS,fested that'tsquamosumr miglrt be two distinot but closely related speciesl notmal variauts of one epecies squalllosum - rslslss.or the dark form could be a hYbrid of f7 ... -7 - rn an attempt to shed some light on this enigma; single egg batches of S. squanosum from Boti Fal1s were reared separately. Wing tuf t colours of the f ernal e parent and adult pro:,eny were scored by Dr. Kurtak using the following qystsn: A = all pale hairs B = pale with up to 5 dark hairs C = mixed pale and dark hairs D = dark with up to 5 pale hairs E = all dark A oomparison of parents and progeny si:ows the following: Par ent Progeny oo oovrogeny ++ A B B E 28 4E 2E 1ar6E 1B 1B' 1D 1A-8, 1E ZCt 1D, 6E Although the numbers ar6 very small (4 parent adults and e9 progeny) the results do intlicate cIBarly that tlre different types of wing tuft can occur in tne offspring cf a single fIy and do not represent separate popul2trons of the cytospeciesl and that the character is expressed differently in males and fernales. 2. Studies on wild-caught biting fsnales. Investi€ations on this subject by John Adiamah and his team from the PubIic HeaIth Labor3tory at Akosombo have continued to date. .....f8... BThe geasonal shift from a predominance of pale tufted females to one of dark tufted flies was less apparent last y:ar than in 1978. ilowever, tlte result s aIe difficult to interpret because weather conditions were quite different. In addition, a collecticn of larVae obtained from Boti in July w:.s fou:rd not to be pure squamosum as is usua11ythecase,butamixtureof.WandyahenSe.Further consiCeraiicn of the significance of 1:.st yeals results, thereforeg will be deferred until othor larval collections made in 1978 and 1979 are identifi ed oytotaxonomi cally. D.P MINANY E'\IALUAIICN OF TE[\{EPHOS ABATS CONTRCLI ED A T a Temephos controll ed lef ease ttfloating strandrt di spensels (pCOfnO 1?O?F) manuf actured by Ihvirorrmental Chemicals Inco. r were sont f or testine by Dr. Gardalelli of tne Envi rouncnt'; Mana8ement Labor3tory r Akron UniversitY. Itwasdecidedtotesttiris,levicein3gtreamnearthelower size limit sometimes inhabitod bY S. squamosum. As the stream at Tsatsadu Fa1ls near Hohoe was at a low ebb in early March but still breeding heavrly, this strsam was olrosen althoug.r it is in faot a yahense ra ther than a sguamosum site. One device was placed in a fast flowirrg stretch of strearn on 3rd llarch and a second device was positioned a few yards upstrearn iD relatively slow water. When exarnined on llth Marchr numerous ]3rvae and pupae were found in olose ploximity to the floatinS strand dispensers. the dispenser positioned in fast flowing water even had small larvae attached to .....f9... Y -9- its surface. Although it would be possible to test t;,is detice more precisely under laboratory oonditions uslng artificial rearing systemg, this would not ssem to be worthwhile in tire light of t-ris prelimin3ry result unless the insecticide lelease rate can be greatly accelerated. E. FINAL INVESTIAATIONS ON SII![.IO RSELIEOT. Bef ors f s3vi-nE the Publi c Health La ror3toly at ,lkosombo to joi:t OCP, i{r. Opoku with t}rs help of frrs assistauts completed a preliminary evaluation of Simno-repellent i.n consul tati.ou with rnyself . It was pointed out irr my previous report that Cifferent batohes of Simno €ave diff erent resul -us. Consequently Dr. r'troamesi tried to standardise tlie formul3,tion. It may be seen frcm the TabIe that a batch prepared in i'Iovember was found to be about 97/i, eftecti-.re a€,ainst S. damnosufi so1. females. Tests with two different batches of the base oil showed it to be pOf, etteotive i.n both cas€so It would appear therefore that the base oil is fu1Iy effective but suffers a sli€ht loss of effoci.ency when mixed with other comporrsnt s to produca a cr earno Neverthel ess the best f ormul ations of repell ent cream are almost as good as the oil anC i'nore suitabl e for r€gular use. Mr. 0poku al so fou:rd Simno-repoll ent to be ef f ecti../e against mosqui boes and bitrng-mid€,es but the results are not rel evant to OCP and will not be plesented hers. F. CERATOPCCONIDS AT AKOSO'4BO A}iD BOTI. It vras mentioned in my previous report tbat biting midges ( ceratopogoniCs) had been collected bitrng rnan at rlkcsornbo ard Boti FaIIs. These have now bcen identified by Dr. J. Boorman ...../'f0... - 10- of the Animal Virus Research lnstitute in En8land. llhe speoimens fron Boti Falls are Culiooides (a weIl-known man biting species that transmits Acantl.ocheilonerna) and the 1ittle known C. inornatipennis. The Akosonbo specimens were Forci ia (Las:-ohel ea) 1ef anui and C. nnurphyi both of which are littIe known. In Australia Lasiohel ea species have b:en sirci,rn to be vec[ors of 0nchocerca gibsoni of cattf e. The Possibilr-ty thst rriest itfrican LasC.ch eI ea mi tht be a vector of O. volvulus would be worthy of investi€ation. Although unlikely to be of mucil practical impoltance inthi.Slespect,tlrgymiShtconceivablyfunctiollasusefullaboratorJ ho st s. C. MERMIfiIID PARASITES. Mermithid par asit es of S. damnosum s.1. are of some interest to OCP as potential bioto6'ica1 control agents arrd indicators of possibl e sou1lce areas of rs-invading fIies. Merrnit-,ids f rorn S. sq+e4eEqm in the Akrurn Hiver have all been identif i ed b;'" Dr. C . Poinar ,s Q3sterotnermis Ieberrei. It is of interestr thereforet that thsy appe3r to occur j.n two colour f ormss Sreen and whiti sh' I willnothavetimetopursuethismatterfurtherbutDr.Undeenof B.U.V.F.1 St. Johns, Newfoundlandr may be able to do so uhen he PaJs a working visit to tnis Iaboratory later i-n the y'rar' H. DISPA TC[i OF M4TERI T[ TO OTHEA I.CBKERS. one ol more consignmants of s. damno sum s.1 . e5,g,s hav e been 4isp3tcJeed to tne Bltomology Department of Massactrusetts (see section 8.2.5 above) and Cornell Univorsities in the U.S.,!. and t.le London gr ah alTri i ,....f'l l..o tschoot of Tropical Medicine. AduIt specimens were plesented to of the iiiatural Hi story Museum, London and +'he Zoolog'v Department Legon llniversitY r Accra. of I. PU 3I.I CAIIONS ltre following two publications appeared in press during the period under review. one is a+r account of my work witrr oCP wliile the oliler is a more general review of Onchocerciasis Veo'ior6' Raybor:Id, J.Il. r Vajime, C' G.1 Quill L"Z'", D" Barro' T' and Sawadogor R. ($19)' fhe laboratory maintell'u1ce and TealingofSimuliumdamnos,amcomplexspeciesasaresealoh tool for the 0nchocerciasis Control Programmer Parasit.10r 499-504. Baybouldr J.N. arrd'v{hite, G'B' (fg?f)' The discribution' bioi:omils andcontrolofOnchocerciasisVggtorsinEast.r\fricaand Yan en. Trop ennoed. Parasit. t J9, yJ}-.549 J. E"iUCATI ON AN D TRAINING AlectureonOCPwasgiventothe]vi.Sc.Parasitolog;courseatthe London sc-.ooI of Hygiene r.ld Tropical Medicine during mJi leave and to agroupofPostgracuateMedicalstudentsfromthemedicalfacultyat I,egon 3fter mY return tq Gh3na' K. EqJI PM,1{T Scientific suppltgls were visited during my leave for the '11 - staff Trop 9d. some further orders were made as a resi'It ofofpurcnase/eQr:if m':nt and my visit to I-r.S. A. L. ATTE{DTN CE AT M5EI'IN iS -AND VISI TS TO RESEABCH TNSTINJT ES Drring my leave the Drtomology lepartment at the London School ...../12... 12- of l{ygiene and Tropical Medic:-:,e and the Natural History Museum in London were visited on several occasions for discussions. Meetings of the Eoyal Society of Tropical Medicine were attonded and a visit was made to the Animal Virus Research Institute at Pirbright. I also attended tlre inaugural lecture at Iegon university in Febru3ry entitled "Research in Trcpi cal Insect Sci erlce. rl Three cays were spent i;r oua..adougou earlJ in Marcli for discussi.)ns on my future work programme arld other matters. M. ADMINISTRATICN. Various administrative duti'es have tended to itrcr€asB' These have usually been unavoidable owing to poor telep.tone oommunications between la,nale and Accra and urte iact that I can be oon"acted by radio and am based fairl; close to Accra. N. WORK FOR IIEXT 4JARTER. ( r) As it is resui red that I estal:lish a colonY of S. soubrense (tfie only laboratory m3ting species known in W. Africa) witirout delay, the next six mcnths will be spent on experimental work directed to that €rd. Preparaticn of publications wilI therefore be deferrcd' (z) When S. squamosum returns to Boti FaI 1s more egg ba+.ches will be IeaIed. separately to furthc1. Investi4ate the inheritance of wing tuft co1 our at i- on i n that spe ci es. ACKNOWLEDCEMENTS I a.rn grat e fuI to Dr. J. B. Iavi es f or valuebl e aCvi cei to Messrs. T. Barro and Ro SawadoSo for rearln€ work at NatitinSou and Bobo-Dioulasso respectively; to Dr. C. Vajime and Mr. Fiasoribor for , . . , . f I ]. . . I )1l - oytotaxorromic identifications; to Dr. D. Kurtalc for his ocllaborationl; to Messls. A.K. Opokul J.H. Adiamah and others in the Akcsombo Pub1io HeaIth laboratorJ for carrying out investiSations of interest to O.C.P.; and to Drs. J. Boorman and G. Poinar fol the identification of oeratopogonids and mermitliids respectively. I am esPecially grateful to Mr. F. Mordzifa for his enthusiagtic assistance both in the lsborstory and in the field. The Volta River Authority and VoIta Lake Besearoh and Dev'etoPment Ploj ect have kindly continued to provide laboratory aocommodation and certain other facilities witnout which tlis work could not have been oarried out. . .i' a Eq trl () F Ft Ff ;lf.I o.F]E @ R Fl Ho F] rn Frl Hic E{ a Rf'IHFl A{ O. 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