WHO onchocerciasis control programme research reporting: rearing and colonization of simulium damnosum complex and related investigations: January - June 1982

$ub j eet: Institut ion: Personnel: Date of submissi-on: Period. covered.: Signature of responsible Offic er: i[HO ONCHOCERC]A SI8 CO}:ITROL PRGRA}'118 RESEARCH REPORTTITG '/itlo/ocP J.N. RaYbourld. 20th July e 1982. January - Junee 1982. . . r/.,.rr!. .r::ri{r:ra!:i. . . . -ai :. ,.i @. A. I}TTRODLICTION A}ID SIJ},q,.{ARY i3. REARI'IG AITD COI,ONIZATION STUDIES. 1. Laboratory colonizatlon of ttre Beffa form ofS- soubrens a/5. sanctipauli. 2. Crossing the Beffa fon:t rrrith other menbers of the s. d.anrrosum complex. 3. Laboratory rearirg and i::secticide susceptlbility 'f,ests' 4. A comparison of two n:ethods of inducing ovlpositi-on. C. TNSECTIClDE SUSCSPTIBILITY TESTS. 1. Completion of earlier tork. 2. Current lnve stigat ioi'Ls. STIIDIES ONT HOST PREFEHMiICES OF SITnIG S DAINOSUI'I C OI\.4PLEX FEIF.A.I,ES. E. STTIDIES ON EGG-IiASS DEVEIOPi\MNT OF S Djt\i-{OSUIii S.L. F. OTHIE INVESTIGATIONS. G, PUBLICAT IONS. H. SUPPLY OF I,TATERIAL TO OT}IER liJORKtriRS. I. VISITII{G RESIIARCI:i';iORKERS. J. {'trORii PLAi$NED FOR NEXT QUARTER' , AC]i-C, L;IC]J,:JI[TS. REFERENCES. TABLES. D. 2INTRODUCTION A}ID SI]]$FARY The establ-ishment of tl;o colonles of the Beffa foffn of S. daranosum s.l. r for five and three generations respectlvely, without the chalges in the Sex ratio reported by Sfumons and Edirran (lgaZ) and tire Linprovement ot' adu.lt handling techniques, suggests that long-term colonisation is now feasible. -s mass rearing atteirpt dlrected toitards this end is ttreref'ee planned for the immedlate fubure. ,i' useful ad.vance mad-e dur.ritig the perlod under revier'r, has been the successfii.l cr.oss-mating of Beffa males lvith S. squamosunl feniales. The hybrids rlrere reared. through to the adult stage. This ls of partlcu.lar interest becau.se Beffa and -squanos'ffn are not Io:own to cross in nature. Investigations comparing egg €ertility rates f olloviring tlvo diff erent tnethods of ovlposition i-nducement, have novr been conrple ted.. Rearing is being increasfu:.gly used by OCP in insecticide susceptibllity studies. A collaborative project in thls field involving cross-mating resistant and. susceptible fI1es has commenced a.t Korogho. Insecticide su.sceptibillty studies covered bJ, an agree.'nent betlveen OCP and \IRA, ha.ve norv been extend.ed, to inelude the Pra ai:d Tarro Rivers in south-'','restern Ghana. The flrst results from the Pra are of considerable i-nterest. Stuclies on host preferences of S. C.anrtosu.il s.1. feraales v"/ere redUcecl in value ldren a loca11y breeding population of S. soubrense d.isappeared. H6virever, our techniques 'flere found- to be satisfactory aad 1ire v;ork will be contj-nued. One aspect of earlier investlgations on egg bio1og5r, has been presented for publlcation together with two other recently prepared papers. Increased productivj-ty div'ing tle period under reviers has been largely a-:e to the dedicated and efficient v'rork of those collaborating with ::e, in pa:rticular l':r. F. liord.zifa, l1r. D.A. Boakye atid ''1r. C. Kyorku. lir. i.;orku has now finished his research project and taken up a lectureship al the Uiriversity eg Legon. I{owe./er, 't.le intend to continue our collaboration in the future. 1. LAsORATORY COLOIIIZATIQ{ OF Tiitr BEFFA FORi OF S. SpUBRtr&St/ S. SANCTIPAULI, The for,n of F. sor,.brense/S. sanctipaull hitlerto refeffed to a6 irso/sa" or the i'J-snot formrt has recently been d'eseribed as rtseff at' by rleredi th e t al . ( i, press ) . Two rnulti-generation.al coloni-es of the Beffa f orm tave been estalcllshed and since l-ost. As they represent the f irst caseg of successful- colonization of onchocerclasis vectm s 1n .rfricae our findings are presented" in scme detail in thls r€port. The Kaboua coIon.y. rnmyPrerriousreportitvraspolnted.or:tthataveri/sma11 colony fro:i Kaboua (Ogo 14'i(i, O2o!fitE) (r&* Okpara River, was then 1n its fifth generatlon. Detail-s of the history of the flrst four generations of the colony triere presented. and are now sunrnarised in Tables 1 and 3. Forty three F, adults enrerged a:ed r;lore females mabd, blood-fed. and surviv-ed to lay eggs thair d,id. those of earlier generations (fabte 1). Expansion of the colony lvas therefee expected. How€verr of si; egg-batches obtalned, folrr Y',ere infertile and the other tvuo laclr:,ded only 12 ancl &O fertile eggs respectively(1utt" 3). Only ten eggs f'rom one batch hatched although others also developed to the advanced rreye-spot stagert. The d-emise of the colony eaine about lvhen the ten larvae died at an early stage. There lras no shift l-n tbre sex ratlo cturing the life of the colonv and Drs. Il.i. cheke and s.E.o. l'leredith, vuho studied the reared material , foUna no cytotaXonomic or norpholop,ical abnorrnalitles apart f'rom cne Glznslnclromorph in the FJ. The reared adults vJere used. as Vol.r.cher specir,rens vuhen the Beffa for1n was recently described (ileredith etSI. in press). tt. Several atterni:ts v/ere made to coLonize the llono Rlver tseffa population from llear Tetetou (O7o 01 tN, Olo 32'E). .In most cases tr'., adults r','ere reared. successfully and some of the females mated and took blood. SUrvlval \,Vas poor, holrever, and^ moSt flieS s'.rceu;r.bed too early to oviposlt (a situation alread.y reported. by lt - + Simmons et ol. e 1gB2). ITevertheless one colony lffas established and inaint:alned f or three gene rati ons (talte 2). The coloryr was started liith a single feiirale collected as a pupa on 18 or 1g/3/t,2. This f1y m:rted., blood-feo and laid many fertile eggs and 157 Fl adults I'rere reared. Although 15 of the ;f'emales rn€ited arxl 10 of them took blood e only ti'iio survived. to oviposit, prr:ducing 23O and 5O fertlle eggs respectively. Both batches were reared and a total of 136 adults !'/as obtained lnclriding lO femal-es. Twenty-four of the females mated a.ru1 1B took blood bu.t inos-r, soon suceumbed and only three egg-batches lvere obtalned of vihieh one was infertile. The two fertj.le batehes 1ncluded 92 and 1OO fertile eggs respectively, all of which d.eveloped. I{everthe}ess, a total of onJ-y JJ eggs ta tched and only six lara,/ae became ad.uIts. Of the tl;ro males reared., one d.rovrrned. after emergence and. the other refused to mate, so the colony rvas, ]691. In spite of bettir rearlng results and relatively hlgh mating and b1ood.-fccd.ing ratcs, the Bdgba Rapids colony lasted. less long thari the Kaboua colony largcly bccaus c of poor adult survival. Both colol"ius wcrc flnally lost partly because appanertly full-y dcvclopcd cggs failcd to hatch. ::ati+s and blood-fced.j-ng be haviour. Observations madc di:ring our colonization studies rcsulted in improve d. teeirniqucs. l,latlng. The malcs showed. ag€lrcssive mating bchaviour while most fcmales tiiere rcfractory, confj-r,)lng carlier reports (Sfuaaons and Edman, 1982; Slnnnons et +L. , 1982). The mating sequence iras also the samc as ttrat descrlbcd by Slm-mons and E&nan (t9ge). .lating activity v,ras vi-ry variable and be st results were norma1ly obtainc;d. rising tir,lo-d-ay o1d liales not prevlous].y exposed. to other flics. Thc use of young females i-ncreased. the chanso of survival to tte egg-layiirg stage. l,atin,!- activity by the males v.,as us-rally maximal in thc latter part of the day. Active niales sonlctimes mated, with a nu.ober of f emal es in succession and scxne females m:ited. a nr;mbcr of times. 5conscquently, the total numbcr of rnated. females could not be ascertaincd. simply by countl-irg tlr.e number of apparently successful couplings. Howevcr, it vras often posslble to dlfferentlate be twcen individ.uals by neans of size, abflomlnal extension etc. vyhich facilitated the separation of inseminated' f crnal es. tslood-f eedi-ng, Techniques ilsing srnall cages or cloth sleeves for fceding numbers of flics togethcr oi] mari, or animals d.id. not v'uork with the Beffa forn. The single tube me thod, although laborious and time consiilning, was much more Suecessful even ttoUgh Some fe,:,E1es rerirained. motionlcss f or manj/ mlnutes wlthout actually pcnetrat:ng the slcin. Fceding rates tendcd' to be highest in the norning. In spite of ttie diff icr-rlties, five female s lvere even refed after oviposition (taUl-es 1 and 2) and' one of these laid a second. egg-batch rutiich Yras 1nfertl1e' 9isss-s.@- The high mating and Iow blood-fceding rates shown by females of both the ::ono and Okpara River Beffa populatlons, agrce with the f rir|r-r-ngs of Siirmons et a1. (lg}2) urho worked on material from the Saiile jiono Rlver site. The results suggest that these two populations of Beffa a"re i?ore d'iff leult to blood.-feefi than is risual for s. d-ananosum s. str. and- most other members of the comPlex. In splte of poor rearlng results with KaboLla materlal and poor survival e1 Beigba Rapids f11es, both the colonies establisrpd !,,iei'e naintaine d. f or at least a few generations even thoughr sul: jected to extrc,:.re inbreeding. Although poor larval survival, low egg fertillLy xates and 1o'r'r hatch rates, all of v,,hlch oecurrcd at sorne stage, indicated inbreeding depresslon, t,hey coulrl equally tlrel] harle been d ue to other factors gince they not Lr.nccrfl-ronIi/ occur in f lrst generation rearings. Theprod.uetionofcomp}etelyinfertileegg-batc}res by females thought to have mated.r ilaY have been trnrtly d-ue to the iaales lnatlng Inore than once rrith the Sarfle female' At that tirne 'rrre I-i/er'e sti1l cleducing the number of lnseminated 6females from the total nu3.ber of aopare.rtly Successful cor:pi jngs observed. In addition, it ooes not atrrSlear to be icnown 'whether males can SLicceSsfLllly jrrser,:inate a series of females witti whieh they have mated 1n qgtck suecession. The maintenance of the Kaboua colony for five generations notwith- stand.ing the paucity of acililts, pro@es that adult handling techniqr-re S are no!i' adequate. This, togetlrer with the absence of a shift in the sex r"tion (such as that reported by Simmons and Edmafi, 1982) 1n either colony in spite of extreme in breeding, suggests that long-term colontzat,ion of the Beffa f crrn is feasible even itsrng sirnple apparatus. An attempt to produce a more permanent colony 1n Africa by working on a much larger scale is therefore in progress. 2. CROSSITG T:rE .BEi'FA FOR1 ,iuil OTHm ]E:IBIpS OF TIIE s. Di*l,lNOsUl' COLIPLD(. l'/e have recently foirnd that it is qui-te posslble to cross-mate mal-cs of the Beffa form vrittr fenales of otxer members of the S. damnosum ccrnplex. (tnis is contrary to preliminary ind.ications::nentloncd i:i. an earlier report). Although the females are refractory, t,ney are not noticeably more so hhan Beff a f emales th ,:iirselve s. liost cross-mating attenpts Lrave been made using Beffa males and S. squamosum fema.Ies. rJthotlgh the latter are ustlaIly bigger than the former, titls C,oes not prevent mating f rom taking plaee. i'iany appare.'rt1y successful cross-IrEtlngs have been observed in asplrators but rela tlr e1y f evr of :.&he females have survi-ved long enoqgh to blood-feed and lay eggs. Even when egg batches have }een 1aid, some have been completely infertile. ilolrever, a Lotal of four batches laid by eross-mated- females have includ,-.d fert j-le eggs although three of them contained only tvuo, e ight and fifteen sLr.ch eggs. A foUrtfr batch was preclornlnantly fertlle arrdla,rvae vrere reared and. fixed for ehromosotne stud.ies. A ferv 1r.61viflua1s (f O) ?/ere reared' to adults and. the males showed the normal laboratorii nBti-n.g behaviot'u' of pure Beffa ma*Les. Truo of the females were mated. and blood-fed. but both died too early to ovlposit. -v - Thre morphologlcal characters of the hybrld. flies have not yet been studied, iir detail but the adult males appear to have retained the t'J-silot'i mesonotal- pattern of Beff a. 3- LABOTIATCRY REARI-IIG ,{'D INSECTICIDE SI]SCEPTIBILITY TESIE. The rearing of single egg-batch.es, for insecticid.e suscepti-billty tesNg, is bcilg carricd otrt at Korogho in the northcrn Ivory Coast. This work by -'lr. R. Sawadogo und.er Dr. D. Kurtakrs supervision, is succeed.j-ng 1,,/e11 and is mentioned. here as anotler exarlple of the uses to v'hieh laboratory rearlng has been put by OCP. Attenpts to cross males of tlie Beffa forrn with resistant S. soubrense fer,:aIes, frort Chutes Gutier 1n the Bandama River, have al-so started at Korogho. The Beff a population being used. is from Bdgna Raplds in the lllono River in Togo. The purpose of this i-nvestigation, lnitiated by Dr. Kurtak, is to test the insectlcide susceptibility of any hybrid offspring obtained to learn more about the lnherltance of resj-stance. The results will be considered in irgl next report. h. A cor'PaRrsoi{ oF T,Iro lmriIoDs oF rNDUCri'[G ov1P . i:uch of this investigation '/r/as described- in my previous rerort where lt'u,las poilted. ou.t that altrough S.'d.a.mnosun s,1. oviposlts in captivity af ter irraersir-;n in water or decapitatione many infertile eggs are lald.. Egg fr:rtility rates of S. squan'losum v/ere therefore compared after oviposition j-nducemert by immerslon anc Uslng the recent a:rd. more riaturai rrtvtrilight method." of Sliru:ons and Ed ran (t qAZ ) . 3'or further background inf ormation nry prevlous report shourld be eonst:lted. This str,rdy h.as now been completed" and the final results are presented in Tables 41 5 and 6. The tables shov,r that individ,,,a1 egg batches varied g;reatly in fertility iruespective of the indueerne,et techniques useo. l{evertherless, the mean fertillty rates of elg,gs 1a.1cl follolving the d,ifferent metlods of inducement were 37.56% for da1r1i66 ir,snersion, 36.O4% for i,mersion at nlght and. 70,B2o/o for the tlvilist method. It may B- be seen, therefore, that ilre Sirn-r.,ions and Edman technique resulteC in a mean fertj-Iity rate akaost tirrice a.s high as the imnrersion method ancl that resr.ilts wlth the l-atter were not affected by the tlir:e of day at vrhich ir:rmersion lvas carrled out. The diff ercnce between the results obtained. using the tl:o mair, techr:riqucs 1s hlgr:'ly signiflcant (a = 4.6432; P<o.oo1 ). A d.isadvantage of the Si:;nons and E&:ran method is that it must be usecl 1n tke evening after dark, a.1tr ough the flies are ready for stimulation 1n tre ilorning of the third day af ter blood-feeding. The irtmers-i cn tecir-tiquie ma.y tle refore be safel if trp only g::avicl feraa.les available ar"e Iike1y to strccumb du.ring the thirc day. The tl',riligtit method therefore requires testi-ng 1n the morningl in a darl<ened roorn to see vrthether the egg fertility rate remains high. Althoueh tire trnrilight method is convenient for colonization vlrork vuhen man;' fe,,iaIes can simply be left to oviposit over-night, it 1s much less sui table for obtaining single egg batches from pe. rticular f1ies. A modif 1ed a.Dparatus contai,ring a number of separate ovlposition compartmerit s in whlch females could be stjmulated separately and slmultaneously, should therefore be trled". fn addition, the meiliod of Brenner et aL.(tg8o) atso neclulres testing a::rd might l-lreIl- give slmil aT reiruuto the $immons anc E&.,r.aii tecirnique , be ing based on somewhat similar principles . c. n(gECTTCIDE SiiScEpTr;rLrTy TESTg. 1. Coinpletlon of earlier work. The f irst ,two agreen*nts b tv,reen O.C.p. and. \r.R.A. for nur. J-II- Adiamah anrl his asijj.s tant, l'rr. D. Kessie, to d.o susceptibillt;;r tests, coverecl the vorta Region and Kintarnpo area of Ghana and southern Togo. i,irork rellaii:ing .,,ias limitedto a few tests 1n Togo a.c in the Kintampo area. These tests 'riere soon comple ted e$&1t tor those reo.uired at Asubende onthe Rivrer Pru. Breed.ing'1n the pr* talies plaee j,, the dry seascn and it rrias necessai.y to r,uait r_rntil tfp water leveL subsid ecl b efo re I arvae b ecame avail able . Neverthele ss, thete sts required. vTere event i:alt y completed. 9All results arrd. materlal tested have been forvuarded to Dr. i(rrrtak and. l,;i11 not be trresented here. IIowever, no eviclence 'rras obtalned for insectlcide" reslstance 1n the areas eoncerned.. 2. Current inve s tirr_at ion-g. A third agreement was recently signed f or iir. Adiamah ald his asslstant to do rnore suscet:rtibility tests in Ghana in the Rivers Pra and Tarro. This lvork- v;ill ontinue to be under my 1ocal sulnrvision 'v;ith tecru*rical d.etails checked" by Dr. D.C. Kurtak. Tests alread-y completed on larvae from the Pra shov,i a somewhat 1o',ver l-evel of susceptibility than is norrnal for most areas. iien€Vere no earlier baseline d.ata are available for tLre area so the slgniflcance of the results w111 irot be evaluated. unti-I the remalning; tests krave been done. D. STIiDIES Or\T IIOST.PREFERENCES OF tsITtr$G S. DAICIOSUIi COTPLEX EE}.IALES. tr'or a considerable period earlier &is year (aetaits may be obtained" from reports of l'ir. G. Fiasorgbor) a rests tant popul"r.tj-on of S. soubrense was breeding in the Black Volta near Bulr west of Kintampo. iiowever, most f11es attacking man lvere f ound to possess tle pale vring tufts of savarula species. The savanna fl1es uiere belleved to be breeding in trlbutaries (soon to be treated) but the question arose as to what the E.-g-oublgnse females were biting. In an attempt to throvr light c,.i this problem, Akarglakoom, near Bul, r/as visitecl durlng the last fevr days in June and eollections l/rere maoe frorn a co!v, a goat, a turkey ancl a guinea fowl. The flies 1rr/ere collected rvlth an aspiratorfunder a /tron nylon-net slung above the anlina]-, Tlie eorners of the net were stipported by po1es, pushed into the sand cLose to the river, and, the sides of the net v,rere; raised. and loi.rered at 15 minute lntervals. A large net was useC for collections from a cour arrd a g@.t lvhile catches from a turkey m.C, a gr.:.i-nea fowl i/ere mad.e usirg a smaller net. The collectfurg period, ';ras flcm 07.3O - 1B.OO a:rd slmultaneous catches were mad_e fro, nan for compafison. - 10 The results are given 1n Tables 7 and. B. It may be seen thai nlany S. d.amnosum s.1. femal-es fed on the cov/, but the goat and. the turlley and the guinea fowl were hardly attaeked.. It is possihle that the vlgorous, jerky movenent s of the goat may have prevented soi'oe flies from feed.ing. llhen various factors such as lovvering of'the net for half the tlme are taken lnto account, the resr;Its fror,r the cow indicate a higher potential blting catch than that taken on man. Smal-l simul-if,tls fed on the turkey and the gulnea fovrl in large numhers butt not on either mamnal. They have not yet been identified" but are thought to include S. Ariseicolle. It may be seen from Ta,:Ie B that tfe vast majority of S, damnosrar s.1. taken from under the nets (i.e. both fed and unfed individlal-s) ana attacking man had paf e vr jrrg tufts. This viras explained when the latcst cytotaxononrlc identif icatl ons of 1arvae frore nea.rly bree d ing-sit e s became availabl e. These showdd that the E -S_oubre_&Sg breedlng in tte maln riy er had. suddenly been replaced by savanna species at the tjme of our lnvestigations. Furtler catehes are required., therefore, wher the S. so.Ubrense return. E. ST TDIES OII EGG-,iA,SS DE\TELJP]IM.]"T OF S. DA]i}TOSiIi S,I,. l,rly. charlss Ky6r1..u, the .i.sc. student f?om tire university of Ghana at Legon, who has been c&rr, i11g out an investigation of simullld eggs uncler nry supervislon, has submitted his li.Sc. thesis. One aspect oi lir. Kyork&ts 'ncrrk has already been ix'esented. for publication in a papcr entitled tiPrelj*mlnary stud.ies on egg-mass devd- opmcnb 1n the Siraulium daFnosum Theo. complex(D:-ptera: slrrr-',lj.idae ) rr . Al tho' gh it is not po ss :-b1e to pre sent lrlv. Kyorkuts fj.ndings in cletail in this report, the sumrnary of the paper is girren belou,r:- ttEgg rnasses of S. d.arnnosum s.1. v/ere investigated experintentally to ex:laln the freq'.rent preserpe of undeveLoped eggs in the loyrer layers. Sample areas of egg masses-intact or rruith tre bottorn layers exposed. - - 11 Ii'./ere lncubated i:r petri dishes, both vrith and wlthout KOLI egg separation treatraent, and in flovring vriater 1n a rearing systei,l. Other samples of exposed bottom layer (e-f,-) eggs li/ere incubated at var-ious 0e levels in boilecl and" unboiled. vyater and the rea.rlng system. Field observations were al so mad.e . lfatural- cleve lopr,rent v,ritjl in e gg-masses d.epend.ed. on their fori:natlon: at once or 1n stages. In petri dishes nost top 1a5r6p (t-f,-) eggs hatched v,iithin 2[ ]r.orrs but exposed, B-L-eggs either faileC to hatch or dicl" so in 6-11+ days. Some eggs only devel-oped after transfer to tfe rearing system. In the rearing system ancl after KOH treatmmt (which increased O, access) clerrelopment lras somevrhat faster and. lnore complete. There v/as no hatching after 111 days and no unexposcd B-L-eggs la tched. ..t j-ncreasing 02 Ievels hatch rates 61' ts-L-eggs rose from 2.7/o to 63% but T-L-eggs hatched thro ughout. In the field T-L-eggs hatched in two days and B-L-eggs uncovered after 1 2 hours ha tched. 1n three. Unexposed B-L-eligs were sti1l undeveloped after flve d.ays. The slgnificance and control relevance of the re sults a.re disciissed and fw.ther studles required are ment ioned . fnvestigations on the inheritarc e of wlng-tuft colonization 1n $- squamosui:n and on the tii:ring of adult ecolosion of S. d.amnosom complex species have continued to scme extent d'rrJ-ng the period Under revlev'r. iioyvever, the resUlts have lot yet been fully evaluated a"rrd vri11 be presetted. in later reports. The cytotaxonomic identifi-cations of fleld collected s. damrrosun complex larvae are given 1n j,r. G. Fiasorgborts repor ts. tlJ1 12 G. PU3LICAT IO}TS. The following papers have been prepared.:- Boalrye, D.r,. and P.aybouldr., J.l\'f . The effect of dlfferent methods of ovipo.sition lnducerir.er:t on egg fertility rates in Ell*ul1r',;.f squa,nosum (Enaerleiu) (Dipteral Simullidae ) . Kyorku, C.A. and Raybould-, J.i'[. Preliminary studies on egg-mass developinel:t i:r the Finrul.lum da,nnosum Thso. compl ex ( Oiptera: Simul l iclae ) . Raybould, J.i{. ancl Boakye, D.A. 'r'emporary sma1l-scale eolonlzatlon of the Beffa fonr of l[6 Simrrlirrm dainnostm Theobal-d cornplex (Dlptera: Simuliidae) 1n Africa. H. SUPPLY OF ]IATERI.AL TO OT}iER \//@KERS. Several eonsignments of eggs of the Beffa form of s. d.arcnosum s.1. have been sent to the unive:rsitiy of i,lassaehusetts, cornetr universlty and ii[lnc]res Farm fleld station of the London Sehool of Iiygiene and. Tropical l,ledicine. Reared" specimens of the Beffa f orin have been supplled to CCP colleagues a:rd consurltants. I. VISTTlNG RESEARC}i IiIORKERS. i.ost vislting research workers and consu.ltants coming to Ak-osonbo 1n 19re2 are sched-ured for the seconcl harf of the year. I{o'rieverr rrle have been visited. b;,' several senior mennbers of @P staff during the peri-od under revievr and we were pleased. to recelve Dr. P. Gol-l frorn thc Centre for Overseas pest Research in Lond,on. Dr. C!o1l spent a few da;rs acquaintlng hirlself uvitli rearlng and colonization techniques. J. WORI( PLAIi,NED FOR \]EXT QUARTER. 1 . Attempt at mass colonization of the Beff a f orrn to establish a longi-term colonJ. 2. Collaboratlon with vis it jng consr_rltants. 3. Complet j-on of prograJTri-,le at Korogho (see section B 3.of this rei:ort ) . l+. -13_ Conpletlon of cross-mating and tlming of ecloslon studies. Supervis i-orL of insccticid"e susceptibility lvork. Dispateh of eggs for colonlzatlcn elsewlere. ifriting up earlier worlc. AC Klil O-:ILEDGEI ry 1{I' S I am inoit grateful to all those mentioned in tris reDort for their collaborati on, ad,vise. help or support. In particular I wish to thank llessrs. F. Liordzifa and. D. Boakye for eff icient work tLrroughout; Dr. S. l.Ieredith and l.rr. G. Fiasorgbor for cytotaxonornic identifications; Dr. R.A. Cheke for morpirological data; iir, T. Sa:'ro for collecting material; Dr. D.C. Kurtak and .,es$rs. J.ij. Adiamali, R. Savr,ad.ogo and C. Kyorku for their friendly collaboration and Messrs. J.K. Opoku and K. I(podzo for typ:-ng tiris report. I am indebteC to Dr. E.'1. Samba, Dr. E. Philipponr Dr. J. Gruneyva-ld and Dr. L.K.A. Derban for their continuing supnortl to V1?A and VLRDP for acconulodation at Akoso''rbo and to the Ghana lliaistr.jr of llealth for send lng Daniel Boakye as a rcsearch assistant. REFEREI.ICES Brenner, R.J. , Cupp, E.Y. & Bernardo, 1{.J. (198O). Laboratory coloni-zation an,-1 life tar:le statistlcs for geognaphic strains of Slmullr:,-n decoru.r,r (Oiptera: Slmuliidae ). Tropenmed. Parasi-t. , 31-, 487-497. Iteredith, S.E.O. e Cheke, R.A., Garirs, R. Variati.on andd,istribution of forms of Siir:uLium soubre4se and gen-c-!]paull ln i,?est Africa. Ann. t*fgg_!,{ed.r_Parasit., In trIr esrt. Siinmons, K.R. r RayboUld- J.Id., l\lspsflith, S.E.O. and. Gmms, R. Ideltifieaticn of a laborator5r ma.ting fcnm of the Slmuliun dalurosun Theobald ccmplex in ilrest Afrlca. tr, 6. 7. Ann. trop. med.. Parasi-t. In press. 14 - Slmrnons, K.R. ,l Edrnan, J.D. (t 9gZ). Laboratory colonization of the human onchocerciasls vector Sir:nuliurm d.amnosu.m eoi:rplex (Oiptera: Simuliidae) using an enclosed, gravity trougir rearing system. J. iled. Entomol ., j-2, 117-126 . H 0) o ,o 'd(sg o a q) s +J q-.1 H 0) rl(d c q) .o .+) ,d. l{r5..Or-q{ .P r{O rlO(dE rlo6 F{OH =0)ox,o rl rl O) cd> oc6 r{S b0op ' r{gX oboO +)r{a hE c)do = d'-to oPd r{cs ,!4 q{ &Crlt Pxgo)g{ OOo.d .r{ O@.q o dp rld rl (sGq{A dod Or{o >q)o. o> 'd' Eo o orda&oo o{J a(do >dd F{q)t cuF rl r{OOrlC 5r{H -d EI fl EI 14l HI Erl 8l HI EI *l EI : trld cq F o idodg lr^{trE rl, rrt (t (U(5 lBAf', C{ moc r{ r{ 45 r{ 0) +r@sl F{ b0c6O Ui0)6.F4d \o AIJ f.OJ o lJ'\ c! a x o S{gg d .d o {J c5 o o p o z, o\\or\ I gI ord4()Otr sp($b06q)E]Ed r (5 OD .J{)0 .c1Ht)--+ro 6'-;+{ if,.-.-l i-) 'igulc ,il- L { tq c\I C\l N \o c\J rd o H ofi a o? r I r rd 0) f4 oz o\ rr\ M\ r-- ()lq{ Ol O "d rllodl .+r E odolZ=14 I h6 = AI rn fc\ *a rlPdr-l .P' ode{< c!o AJ rn rq olOJ o\ fa\J I oul !1 rt +:I cdr{I H-l! 6,5lr"-< o\o C\lc\t o \o t-C\I (I) +)Or{ r{,d{d =< @ rr\ r o o.r rl^\ +.\o H o 'rl +Jd F. c) !{rld ib't.<i6lor: q) I Fin'lF{ tr E Fq ol Fq fi-\ r\ JH LN14 0)c{ .r{ 4J rlOpog F{ b0rdo b0a)i{ t'l p( (Jl C)P+)oeat o o OOfc\ lr\N -. nt (J'oc) Ou+, +)fi cr +.sl{NO >,rncr5 r- .(-r, I ([l() s CJp CU'd Fa 0) l.t@d@otr]fi c\J c! r{d(l+) oo ,qHo\+)o6r{ Pq .rl +) b0 t{ h0(l) Etl fr{ \ ol OJ ff\ C\I I (; 9+ 0)' ffi. oJ7: I oq) F,r o o @ o 0)q{ tij r{ oo6 .P E o-cd 0)Z,F"fa' lr\ J ot I *o -l{:(dr-l P5 o(3H< .r r-- rc\ \o tl \o @ o rl(U c a) o\\o o(\ N a o rl(s = I rn @ \o co AJ d o .-l € 6 l-{ 0) Hq) o (, 0) €dPOOp{trrl o 5O c6rlAt{ Er{(doo@ AFqOcd ft{ clf4 rq 14 a .q o € Cds o oP xodao rlg 'rlB(6o q,{ H _!d +rdttp q.{ C) o(d ts0t{(.) CU rl r{ rlq+ 'ds)(JOatg'ddoOS{(Dp, 0) @(t) b0 ob0 ,d 0) a -{*)o@(o H= f'l FT Fq H () a @ h0ftl q{ o o +) cd Frl a +)Ht 'iJ @ o\ i- 'do H(d 0)& rd 0) .r{ d ^o)a6 r{ t't +)i(dd.drl odE+Jprtf\ Jo t'.\ .o rlv()d oogd&c)(6{J oo(d?,tE a {J F{ d(d dcu 0)OJ '-{vd dq) ocd cdF1 ocd& t-I @ +) rtt(J Cd o\ 'd0)L(6 0) G a +) rltd(6 rqJ 'd a)f{ cU q) & al rdio1 !o13{r q)(drl sd (l)0) H(d d$ (s *:-{ d .od L1(,cs 0)P'dooP -l-qdooq) o(do .dgb -{0 0 0) b00)O >J€ -{Aj (ooz r-ldP(,lo h0Hb0\frl o) r-{q{ .-l o.Pot1 oa)A fzl r-J \o c\l5 q) r{ rlJ@PJCr\F{ C{ rr\o\\q-{ r LngrcO H OJ TT\ LN f-- ol O. 'r\C)c\l . x\o@trgI o o az o\ r{ o\\o r,n 0) r{ ..r{()of ..1-{zz0)\\q{c{o d .r-5H a 0)tr o b0+) b0(6Hto d dpo (dp d 6 CH 6p. 0) a d a o d o .r'l {J Cd F.l 0)dq) o o+ r{ CS +)g 0) F{ Cd tu r Fq c\l 14 rr\ fi{ 5f4 tr\ft{ rd G) +) a o o +) o( il ra\ f=llj cq H Flv TrTo . IAELE- l+. X'erti11ty of g. ggg.4.gsum eggs la1d by females induceil to ovipoelt _ by -IryerqF@-,a,elet-Lg the dav-timq--Fate of eggs Date raid n"trli"atil No. %Infertile Fertl]eNo. Lald. .]\To.Fertile 1 2 3 lt 5 6 7 B 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3o i-! 32 33. 3l+ 35 36 37 58 39 l+o ,1'. 't o. Bl tt It 9.1 1 .Bl il il ,l 23.11 .81 tl il il It 29.11 ,81 It ll 10.12.8'1 tt tl ll lt It tt 11 .1 2.81 It tt il 23.12.82 il 1. 1.82t, 'l 0.1.82 It It 5.3,82 il 15.3.82 il il ll ll 16 0 15 5 0 o 83 o 0 0 o 0 o 0 o t+71 399 o o o o o o o 158 (t.l) [7:si (r 9.t ) (6g.5)(50.t ) (55 .l) 535 217 489 302 320 l+25 352 640 531+ 256 231+ 283 206 238 338 205 265 112 289 312 378 l+56 B9t 287 136 6lg 652 4CI+ 309 270 B6 191+ 195 529 531 215 212 Z6l+ 112 490 251 B9 1B 197 251+ 21 318 t+43 zl+ 1 I z4 138 z9 9B 7B 2 32 0 230 t l+8 311+ 209 713 7 5B 529 158 85 T5 238 7 z6 1 37 5l6 o 1l+ 108 B ZBI+ 128 l+tl 105 55 4ol+ 3l+ 197 51 0 255 210 ll+5 177 140 z6o 2d1 233 11? 59tfu 54 zl+7 178 280 78 1'to l+91+ 319 73 32 79 158 194 l+gz 526 179 212 250 h 482 l+5.9 l+1 .o 3.7 55.2 75.1+ l+.9go.3 59.2 4.5 o.l+ 10.3 l+8. B 1l+.1 41 .2 23.1 1.O 12.1 o.o 79.6 47,t+ 83.1 l+5,8 BO. O 2,11 l+2,7 82,8 2l+.2 21 .O 76.1+ 88.2 8.1 13.4 o.5 7.O o.g 15.7 0.0 5.3 96.1+ 1.6 ; i [t:?] z 10.7 )2oo (5e.9) ? [ki] 0 4 (o.B) o 0 o 0 o Total 1,382 (l.t; 13,603 5,184 8,619 37 "6 * fhese are percentages of the total number of eggs produced. TABLE 2 tr'ertllLty of S. squaqogr].m eil;gs laid by females lnduced. to ovlpoeltby lmmersion in a tube of water at niqht F1v No. Fate of eggs Date laid *"r.li"utZ) No. Traid. :ffi;---_--m; T"FertileFertile lnfertile 1 20.'1 0. 81 2rt3,J+ rr 5 22rl O.81 6il 7 29,10,81 Bil gtt13 , 11 rt 12 tr 13 tr14 9.1 1 .8115 23.11 .8115 rr17 rr 18 il1g 29,11 .81 20ll21 'l O.1 2. 8'l 22 rt21 11 .12.81 zl+ rr25 23,1 2.81 25 tt 27 It28 9.1 .82 29 tt 30 rr31 '3Z 9.2.8233,34 15.3,8235,35 rr 37 rt 38 rt 39ill+O rr o 0 2o(1 O .1) n o o 47 (5.s) 5t+7 (87 .2) 282(77,1 ) o *7 (53.2) o 0 0 247 (58.8 ) o o 0 o1 (o.! ) o 0 o o o 0j (o.5) o1 (o.l+) 0 1 [S:? j 155(52.5) 177 (26. )) o o 0 88 (:1. o ) 97 Q7 .3) 0 4a1 590 175 l+zz 201 2L+B 643 BO Bl+ 183 138 481 l+45 207 389 576 287 t+35 162 254 l+25 500 235 189 48o 437 6l+5 5sl 286 170 1+93 359 140 495 211 415 559 179 396 258 17 31 95 100 l+t 239 '1 00 5 3 162 31 427 L+o5 0 2018l B6 10 1 13 l+13 475 11 34 4t 298 .,3 o 102 0 4sz 352 79 B 6 326 228 21 5 3L+ 385 559 BO 322 160 9 543 75 B1 21 101 54 4o 207 188 l+93 201 423 161 237 13 25 224 155 439 139 632 653 r84 170 l+t 17 61 t+87 205 B9 131 158 390 221+ l+.2 5.3 5l+.3 23.7 20.l+ 96.1+ 15.6 6,3 3.5 BB.5 22.5 88.8 91 .o o.o 51 .7 14.4 30.O 2.3 o.5 5.2 97.O 95.o l+.7 18.0 8.5 58.2 2.O 0:o 35.70.0 91 .7 95,4 56.1+ 1.6 2.8 78.5 53.5 11 .7 1.5 13..2 Total 1,904(12.18) 13,7311 l+,95o 8,784 36.O Fertill ty of by s@'l. g. S,gggg.gum eggs laidthe Simmons and Edman by females lnduced to ovlPoslt technique Flv Fate of e,,'r.ES No. Laid nr''ert1Ie Irrf erti le Fertile llo. Date laid No.Retained(% ) 1 20.1 0. 81 2tl 3 22,1A.81l+ rr 5,6 29 .10.81 7llBrrg, 1 O J0;1 0.Bl11 9.11.81 12 il13 ,1l+ 29.11 .81 15 rr 16 il17 1O.12.81 18 rt 19 It 20 rr 21 il22 1 1 .T2.8123,24 rr25* 26 tt27 'l 0.1 .82 28 rr 29 rr 30 rt31 rt32 9.2,8233,3l+ 15.3,82 35 rt36 tr 37 rr 38 rr 39 rrl+O rr 5 2 1 1 5 5 1 ) il 5 a 9 o1 (: o 3eQ 1(( o o o o 0 38(1 .0 .5 .l+ .1 .1 .6 .7 .2 .5 .4 .4 .3 .8 .1 "7 l8 o o o eB( o o 16( 2l+( 71( lu( 12( 4( 11( l+1 ( lo( o ft o 26( B( ( 0 0 0 22( 4( 5ll t+7 0., 16 27 5 81 26 B 2 o 1 12 47 I 'l 9 2 7 0 4ta 319 268 1 1l+ 6tz 319 6l+o 537 6+t 59o 537 67t+ 283 258 295 160 302 118 2Ol+ l+11 563 690 55t 291+ 143 529 l+14 276 208 255 278 L+53 292 228 290 57t+ 1.l+B loo )+72 331 360 184 l+3 6 5lB 310 6sg 4go 500 386 51t+ 602 ?39 245 157 157 21 15 72 155 l+zl 645 615 66 47 521+ 139 45 161 36 257 13 231+ 185 257 515 52 295 354 227 5B 135 225 108 3l+ 9 I 47 141 301+ 23 7z ll4 13 138 3 281 103 132 276 1l+2 l+5 36 228 96 5 275 231 l+7 219 21 l+50 5B l+3 33 59 96 5 118 10L 85.1 57.7 I 6.1 5.3 94,g 97.2gg.B 91 .3 78. 0 55,9 95.7 89.3 84.5 95.o 53.2 98.1 1.o 12.7 35.3 36.o 74.8 93.5 9l+.5 22.5 32.9 99.1 33.5 16.3 -77.1+ 14.1 92.5 2.8 80" 1 B'l .1 BB.5 Bg.7 35.1 98.3 75.O 69.5 l+ o o o Total 1,896(1 t.o) 15,279 1O,821 4,458 70.8 ================================ =================================== ===== Numbers of d.omestic anlmals !AEL_U. *g. 1}ry s.1. and other slmuliids biting man and -at-Effinyakrom during one-day bitlng catches S. damnosum s.1. Other slmuliids Date Fed LInf ed. Fed Unf ed i otff Turkey Man 22.6.82 il il 33l'19 r+ | tt 6l+ 0 119 19 ,: 1B J+B Goat Gulnea-Fow1 Iiilan 23.6.821 2 I " 'tIOt6 iil I 109 o u?vurlrgq-r' vw r I t iran ! " * F 1les attacklng man \tlere tubed. before feed.ing. Numbers of Pale and darkblting man and- from nets over TABLE 8 wing-tufted $. 1}gm{L9sum s.1. collecteddomestic animals. {, Conslderable numbers of flies had mlsslng wing tufts and a few were 1ost. Vrrtng Tuf t a "r""""** Fil Balt Subject Date Pale Dark Total Collection Oow Turkey Man 22.6 . 82 ll il l+o 16 61 o ^(1 fedt(l unfed 3 52 21 6l+ Goat Guinea-Fow1 Man 23.5 "82 il il 1l+ 3 108 o 0 I 19 6 109