Report on the meeting concerning the problem of reinvasion: Bobo Dioulasso, 6-7 May 1976

. ORGAIIISATION UOIIDTAIE DE IJA SAN@ v -" i"ogru*t" d,e Inrtte oontre'ltonchocercose Unltd d,e Dutte Anttveotorielle G4--A-c- g)rPoRt oI{ rm WIDssrrNG COI{CERNI}TG IHE I'ITOBT.Tff OF BEIIIVASIO}I BOBO-Or0IIIASS0 6_Z trAy Lyl6 -+f cc: ! t,c l. A rneeting took ple.ce in Bobo-Dioulasso on ll]rursday 6 and Frlday ? May to dlsouss the reirrvasion problera and d::aw up a plan of action to stu(y this phenmm, and deterslrnt ") the causes of the neinvasionb) the source of invatting flies the list of participants and agenda is attached, as annex I 1. D 1 sogigq €ffe:r-r-gqs- -qgi+Ily-eg Dr R. tre Be:re opened the neetin6 and invited the various participants to suanrarize their obsenrations and. give their views on thi.s phenomen. Dr Galus i.ntormed the meeting that ire 19?5 high nuobers of parous flies hacl been obserned on the Band,arna a^nd the treraba rlyerso AJ.thottgh no stud,i-es hatl been rrldertaken on the possible sources of the irrvading fLies it vras genera-Qr felt that they-{rere enanating fronr tire southl or south-west outsitle ihe rrog-Ira@ 8Ireao It- was not clear whether this rruas a step-by-step nlgration or trhether the flies had travelled long tllstanoes transported by wixd. llhe latter theozy does noty however, explaln the age of the migrati:r8 feraales. DrDavj.es pointed out that the canpaigns conductetl in suall areas priorl6 19Zl naa been incomplete antt thls it tras not possible to draw conclusions from the data. On the other terrd, with the exoeption of a few breeding sites rvhich appeared at the beginning oi tfre rairoy season, the complete treatnent of the whole anea in 19?5 and 19?6 sr:$ested a reinvasion. Dr Plullippon saicl that treatuent of the treraba began in 1969 and that rreinvasion hatl been suspected. fron the begJnring. The entonologlcal situatj-on at the present tiine was discussetl. Sub- stantial npnbers of flies vrere alrea(y bei.:rg oau€ht at Pont Routierr However, these catches contain significant nrrnbers of nulliparous flies. As treatnent of the hrown difficult Grechan site hatl taken place, i.t seemed' probable that ttrts was a solgce o,r€a'o Frrrther, at the time very fevr flies nere beir:g caught on the oentral Bantlasa river at Chaussde Niakal and Badi}aha. Mr Walsh Bave a brief accorrnt of the events rvtr:loh ocoumed on the B1ackVolta ln the But region tlurlng L975, In this area a substantial proportion of the catohes consisted of nulliparous flies antl althorrgh no large faj-Lure of treatment I'ras detected j:r the Bui rapids, such is 'che complexlty of th-is i-uoense site that tire posslbility of a local origin for these flies could not be dlscounted. After a gener:a-l clisoussion, it rvas agreed that reinvasion pr"obab\y talces plaoe arurually. [herefone it was llecessary to flnd ansuJers to the foJ-lo'rlng questions: .,.r/,... P-tge 2 1. flhether tLts movement was tafulng place across countly or alon€ the rivers, agtl rvhether lt wa6 wj.rad-assisted or conplete\y active flight' I[tgr were there apparent poi-ntB of concentration? What are the possible sorrr'ces of invading flied? Tlhat ar"e the invadlng cytotYPed If the invadilg flies ere of forest-type could they colonlze the savanna river* 2. 2 4. 5. Dr Ga:nns woulcl unttertalce detailed atudles on the pl{fsiolo$f of flies captusea in the invasion zone to be comparetl rvlth Eaterial from irotential aouroe BrleASr Enphasis would also be plaeed. on the px"esenoe of parasites whioh nlsht give a general intlica'bion of source oreso 2. .Elep-€-&t;ion. for -s$+&-p!;ge:+vgt 2,L gtuEy' of-lopuljt:tion Avnarios in potential depqfhJre zonee, LIr B. Purd.riez tl.esoribetl the najor.iL.Sgggg breetl'ing sites in the area attjaoent to the control zorr€o At ttrl; tfiffie begirurjne of the Lfl6 rei.unrasfonl rrotentia.l departrrre zones are imo'nr on the Banda,rral Sassandra and. oarra[i. .clvers a,nd on certaL:r trj.butaries of the Blaok Volta ln southern Ghs1a. It il,es fleoicle{ to omplete the prosDeotLon of tire Cmoe ald Nzi rivers ancl to urttertalce prospeotion of Rivers [ano antl Pra in south-vrest Ghana. [irls prospection wou1d, l,1trtloate the potential d,epartur€ zones looated betvreen the nlver volta soutL of the volta Lalce irr Ghana and the border with Liberja 1e. the area sj.t ratetl to the south-eastl south and south-west of the Bandalu trdraba. fhe prospeotion wolr.ld be carried o+t durijJlg the next two_wegk; q o* fixetl, vrJn6 aircraft and one he$.oopter (CfiSf , Garms, Walsht Pendr{'ez) ' Ia5.grs* i.nto aocorrnt the data oo}leoted preVious\y on thc other river oourse; bryr-Ilo nouaX6, it was cLecitl'ed to ooncentrate on th€ study of the- {ynanJcs if tfre fere-Ie poputatlon on the lower parts of t}re Bantlarna, t}re Red Bantl.ana and the l{lZL rivers. lhe followlng catching stations lzere selected': Nfzl Dim,boko -Bandana Chutes Gauth.ler Pont dlOLund Kossou Bdor.lrrt & Iaabo Bendana Rouse Danan6oro Banakoro Meruis lhe catchirur tea.ns required qrould. be provid.ed. by 'che l(orhogo Sector-(+ o"toirirrg-boysr-2 chauffeurs) anil rvouj.d. be based at Borratcd (0RS[O{) Mr Sm6 assi-stant-entonoi-ogist rvould be responsible for the zuperrrision and coordina- tlon of -the teams an6 wor.rld provide logi-stical support. l[lvo vehicles would be obtai.:red frorr ggP fuagaclougou (or oavies) . Eaoh iroint rzould be visitetl 2 6ays per rreek: the fei,rales caught the first d.ay rrcrrld be prse:rred in absoLute alcohol for furbher stu6ies; the fenales cou€bt the seoond day ruou-ld be d.i.sseotetl r.ri.bhi.:e 24 hor:rs at Bo,alc6 (OAStOf and VCU). Dr Phtlippon agreed to continue stuclies at Chutes Gauthi.eq Danangoro, Banakoro, and Glte Mernist to r.1grdertalce scientiJic supersrision of the VCti Staff tenporar':.\y worlclng from Boualcd end to prorritte a-Ll tl,ata relevant to this lrwestl€ation' 2.2 neesg4-€ qqg*.te-q^ regles gagLfr- -l"qr-{-qe- -t-o-9-s-t31b-li-olr- tq"et.r.W--€-tLe-.:grgga$A.f-egal=eg Dr J. Bayborld desoribed the studies to be tmdertaken in this field and the nateria-l rLquired. [he neeting ,as infomrcd that lt was planned to set up a labomtory at Krrnasil Ghana, whelre facllities woultt be natle availaLle by the Gove:ment. Certain alfays had, however, been encountered. In a4ctitiont the euppli-es orderetL frur Gensrra had not yet been reoeived. In viel'r of the urgency ,a,./,a, a I aPage "t to initiate this research, Dr Philippon kindly offer"ed the use of faeilltLes at the ORSTOI laboratories, Boualr6. As sufficient material was available in Bouaic6 and at Or.ugadougou to coranence on a maII scaJ-e, it rvas agreed that initiallI Dr Raybould rvould worlc at Bouak6 and move to l(umasi. at a later tl'ate. OCP Genenra would be ::equested rrrgently 'to rnahe every effort to enpedite the strpplies. lhii offer was grateftrlly accepted by Dr Ie Ber"re on bclra-lf of the Progranme. For the ptrrpose of colontzation Dr Rayborfld i:rdicatett that j-nltia1],J he would require at least !O engorged flles and it flas agreed that Mr Sond worrld leave Lmnetl.iate\y for leraba to collect a qrrantity of blood-fed females. Subsequent\y Mr Sanedogo v,rould be responsible for obtai.rring flies for Dr Rayborrld at Pont Routier (trerata). Dr VaJi.ne coirfimetl that forrrth s'ca6e instar corrld. be used for cytotaxo- nouio investlgation although oltler lanrae would be preferable. 2,1 -P-o-s-q-ib+ght of gJre$jng.-flleS--Ep31e!.-t-tj=rg .ghp-l}-o-c-qt-BEggt3. A vector eollec'bor infected with g.lgofg&W. wou-Ld. be used. at Pont Routier to obtain infec'i;ett flies so that studies coultl be nad.e to asgertain whether these (invading) flies corrld transelt the savanna strain of the parasite. 2.4 }[ele-o-t'oloAioElSe-t-a- Iegtfl4e-+-!g[gi96i.t.o.1-t-o- .eIAIySS--e. -Lo;s-t-errorr, -!&s-.r,-+sv.+@ It wae recalied tirat during 1975 two consultants from the Centre for Overseas Pest Researoh, trondon, IIK hact studied. 'bhe neteorological situation in eonjunction with data provi-ded by the entomological evah:atlon tea:ns and had attenptett to ana\rse the movei,rents of irigratixg S. !ry. However, the pattem of eddt catclres rxrdertaken ln 1975 proved ir:adecluate for firrn conclusions to be drawn regarding possible links between 'l;he moveuent of flies and neteorologioal factors. Dr l*Iagor had ind.icated that additional all-day catching stations lvere necessary to obtain aclequate clata for bio-clfunatic studies. It was agreecl to try to ude#lo as Ear\y daily catches as possible at additioiul sites in line with Dr l,tagorls proposal. tr'or this ltrrrtrrose i.t would be necessary to hire vector collectors for 2 days a week over a period of 2-3 months. Ihis had presented certain acli:ri-nis'crative fittficulties in vievr of lIIIOt recnritment procedures but it was agreed tl:at the uatter woultl be further discussed nith the Persoru:el Urrit to seek a solution. It was agreed by the meeting that aerial planlcbon nets attached to aircraft might provide valr.rable infomation. Having esbablished that the aerlal oontrqotor (Evergreen HeLicopters) worrld. be willi-ng to r:nd.ertal:e such trialsit was agreed that OCP Geneva would be requestetl to urgetrtly finalize the oontractua-l agreement and. make arrangements for Dr Rainey to visit the ?rogra.me area as soon as possible. D3 ${rrnga reportecl on his meeting r.rith lir Baldy at 0].fl1 who had. agreed to collabo::ate with the Progra.uTee in regularly providiry meteorological forecasts. Contact had also been nucle with ASECItrA who had agreecl 'bo provid.e uaps of laBther oonclitions affec'bi.:ng the Prograrame o,Te&r 2r5 Urse gf the_B_elmett teclmique Dr Davies rei:orted. on the visit of Dr Berunett to Bouakd in April and the discussions which took place between Dr Beiure-bt, Dr Ph-ilippon and himself. Dr Ber:ne'ct believed that he cotrlcl ittentify the qr:antity of traoe elenents in a f)y utilizing x-rqy fluorescence spec'i:roscopy (mS) . Howeverl it lvorrld be neceseqzXr to obtain as naJgr sainples as possible fron a source area, which couId. be a countzyt a riyer rystem, or one loeality. Fron ttrttt source B0 sa:uples rvould be requlretlfor a valid. statistical analysis each rvith up to 100 specinens. A sirall sanple of flies frorn the invad.ed area worrld be needed. for comparison with the invadingflies. Dr Bennett utillzed absolute propyl alcohol for the prese:rration of the f1ies, howeverl Dr Davies was investigating r,rhether absolute ethyl alcohol wouLd. be a satisfactory substitute. Subes forbhe speci-:nens should be nade fron polyetllylene' and not gJ.ass. . , ../ , . .. DPage + fhe meeting felt that t]uis work rdght prove valr.nb1e and l;hat a research contract shon-Id be established vrith Dr Bennet-i; for this purposeo Dr Philippon, Davies ancl other workers had already collec'bed material whioh was being presenred in ettryl alcohol for transraission to Dr Belnett on cornpletion of the contracttral anrangementso 2.6 Eeatneqt- of- go-t-e-n;.b-i=aJ- -{egag@--aogeS, It was agped 'bhat having followed the developnrent of r"ei.::vasion for about slx r.,reeks, a1r experj-uental control of tlre lower reaches of the Bandamar belovr l(ossou dan vrould be considered. Dr Philippon pointed out tiEt owir€ to the natq-ra,} populatlon fluctr.rations, and the lilceJy delay between tr"eatauent at the source a11d its effect at the d.istant arrival zone, it would. be necessary to r.rndertalce 3 or 4 'breatment cycles. It was decid.ed that prospection of the trower Bandarn" rvouJ.d. be r.mclertaken to map the treatment points. Other-netholg [1r J.F. Ilalsh i-ntroduced a discussion on marlcj.ng and recapture extrleriraents. It vras generally agreed 'chat direct martcilg of adult flies is relatively easy and can yield. value.l:Ie restrlts, erg. the worli of ftt(tltlgO isr Caneroon. However, for the rec-,uirements of i;he Prograiirre it seeraed r.mtiJtelV to provicle a satis- factory teclrniquer os, owing to the large areas under stu(y, narking of several mi].lion arlult flies lzould be necessary. Dr Philiirpon and irlr BeIIec brought up the cluesi;ion'of n:arlcing the larvae either with a radio-active tracer or fluorescence. ?relimlnary trials had been r.rndertaicen v-l'ith the 1a'cter and it lvas agreett by the neeting that frrrther j.nvestlgatlon of the concentration/ti-me requirecl to afleqr.rate\y maflf lartae vrould be trorttrrvhile. ltlo large experi-nents oould be envisaged duri.ng the pr"esent season. I.5Esrei.o:f .o-t-r.eSS-qr-o"lo--g4"og4g4gef .19I7-:l€7.? A rLiscussion toolc place on futr:-ne research ne6ds and. stutlies in progresso Dr PhIlippon spolce of the general proEranroe of activj-ties of ORSIOM, Bouak6. Llr Bellec desoribed adult tr:apping methods and, erplained the results that had been acluleved ryith aLrrntnir.ua traps. ilr Elsen described stud.i.es on the assessrnent of lanral populations and. Prograrme staff were particularly interested. in the fiJrdlry of Ia:rrae in deep uater. Experi-ments on the larra1 feed.ing activities were also reported. Dr Qui-Llevere spolce about h:is recent work on the morpholory of adults of di-ffer"ent cytotypes. In closing the nneeting Dr le Ber:re thanlced aII those present for their contribution to the pnooeedings. On behalf of OCP, irlr lYalsh expressed apprecia- tion to Dr Ptr-illppon and his colleagues for thier participation j.:l the neeting antt 'bbeir t ssJ.stance and oooperation in the research studies on the reinrrasion phenomeno It 'aras general\r agreed by aII participants that this lud been an excelrtioru-lly valuable neeting and that it worrld be d,esirable for such meetings to talce place at regular iltenrals. Dr R. Ie Be:re Ch-l.ef Vector Control Unl.t fOR.SIIOM. Boualc6tu--.!d Vector Control Unit Sectors Dr B. llr C: IIIr P. l4r B. Dr D. Philippon Be1lec EIscn Pend.riez Quillevere . Le Berre . cliff . Davies . Hendericl:x . Simaga . Vajime R. Villars . lIaIsh IrIr P. Pangalet llessrs Ch. Gbohor A. Messrs J. 0u,6d.raogo, Ilr [i. 0cran I4r G. Zerbo Mr A. S6k6t61i Annex f Son6, R.. Sawadogo T. Awotto MEETII{G OT TIM PROBT]TM OF ILEINVASIO}I VCU Bobo-Dioulassor 6-7 tlaY 1.976 € -=-=-- - = -= - =- = -=-=-= - AGT}IDA Discussion of the problem of the reinvasion expected' in L976(anaI|sis of the initial results) Plan of action for the study of the reinvasion Z.L population cLyrnanics in the potential d.eparture uones 2,2 Possibility for migrating femaLes to transmit the ':localrr parasi.te. 2.3 Rearing of blood-fed. females from FI larvae to establish the cytotaxonomic identity of the rnigrating femalcs' 2,4l{eteorolo6icald'atarecluired.toforccastorto analyze a gs-t-e-a1o;e1, the reinvasion. 2,5 Use of the Bennett technique. 2.6 Treatment of potcntial d'eparture zoncs' 2.7 Other methods. Discussion of rescarch .?ro8?alnmes for 1977-1979. LIST OF PARTICIPAI{TS WIIO Consultants Garms Raybould t 2, , a Dr R. Dr J. DrR l:r ts DrJ l{x J DrB DrC I.[iss tir J Baraako Bobo I(orhogo llatitingou Tanale Ouaga.dougou Secretariat I{essrs II. Traor6, E. Sanon i