Rearing and colonization of Simulium damnosum complex: April to June 1977

ONCHOCERCIASIS OOI(IROL PROGRAMIIM iiESi"ARCH REMRTING Subject: Institutlon: Personnel Date of Submission A. Rearing and colonization of 9!g}!g, e.@ cornplex v'JriolocP J.l'i. Raybould 'l 5th August 1977 period covered April to June 1977. '/' / / responeible Officer .,/. {..... r'.'.... .......,,t- a z -' t-. I CONTE}I-TS Summany The identiflcation of reaned S. dernnosuur complen lanvae '1 . Man-bj-ting S. dramnosum 8i.1. in Ghana. 2. Cow-bitlng S. dannosum s.1. in Ghana and Togo. The identification of larvae collected in the field. The evaluation and improvement of rearing techniquee. Temperatune and oviposltiotl. Blood-feeding adult flies. Dlspatch of matenial to other workers. Training. Meetings. Pergonnel. Wonk planned for next quarten. Acknov,rledgement s . References. Tables. B :.^ ial 1 ,' d. Tt I a a t J. D E F G H I E a a A. SUUIMARY Identlfieatlons of larvae reared during the previous quarter have shown cow-biting S.--O@gSgtr complex females near Akosombo and Lama-Kana to be S. damnosum (Irllfe) and S, sifbanum (Si.rUa), Ideatifications of man-biting flies from Eouth-eastern Ghana are also presented. considerable progress has been made 1n speeding up larvaI development in the laboratory by improved feeding and one tecLurique has been found suitable for rearing adults. The dispatch of material to other workers has continuedt espeeially to the Biosystematlcs Instltute in canada. Mr. Baruo Te1e, chief of the Leo subsector, was successful]y trained in rearlng procedures' Contributions were made to r,vorkshops on onchocerciasis in Accra and Akosombo. 8.. B. rlE IpEI\TIFICaIIQ$ OE:J{EAiIED L D+J4NOSII!4-0Oi\4I'LE( L]\ItVaE Material reared during the prevlous quarter ( see quarterly repont for Decemben to Mareh 1977) nas nolv been ldentified by Dr. Vajime and the results are presented below' 1. Man-blling S- damnosum sJ. in Ghana Resu]ts are given in table I . The few reared larvae from females biting man at Dodi Papase and Asukawkaw road' bridge were not ldentifiable. Results from Aharnansu* on the Vtlawa Riven were S- sanet'iFpuli (Bandama) and S. (tlif e), while those from Asukawkaw femy weresum all@.Asinglelarvarearedfromeggslaid, by a f1y from W11 Fa11s, was li---.EgggILQ-g!1ts (g1ffe)' It Ahamansu WaS tilrongly described as belng on the AsukawkawItlim in my previous quarterly report' .../2 2The ldentlfy of the biting females at eaeh of the three places, therefore, agrees with that of the larvae 1n the nearby breeding sites. 2. Cow-blting S. Oamnosum s .f. in Ghana and Togo. The results given in table 2 represent the flrst ldentifleations of cow-bitlng S. damnosum comploc species. The fac t that S. si anum (Sirta) is biting cow6 at Landa- Pozanda nean Lama-Kana 1s of particular lnterest in view of the four Onchoeerca species found in eattle in the anea (A.M. Denke, personal communicationli, Larvae reared fnom eggs laid by females biting a cow near Akosombo u/ere S. damnosum (I(ife) together wlth a eingle specimen of S. slrbanum (Sirua). Larvae :reared from man- biting females collected at Akosombo were mostly s. brense (Soubre) and a few S. damnosum (tatte I). Identlfications of larvae sampled at vanious times fnom the nearby bneeding site ln the River Volta at Atimpoku are given in tabLe J. It may benseen that damnosum, sirbanum and .g.gg@,@. have alL been collected thene at various times. However, soubrense was in the majority in a sample taken at the end of November 1975, within one and two months respectively of the tlmes at whlch the man-biting and eow-biting flies were collected, The slte at which collections were made from eowe at the village of Tusker, is located between Akosombo, where the man-blting f1ies were eollected, and the breedlng site at Atimpoku. Biting S. damnosum complex females at both places are all believed to come from the breeding site at Atimpoku and dlsappear when control is canried out thene. The fact that s. goubrense was pnedominant amongst larvae obtained fnom . ../3 3man-biting f1ies, but absent amongst those produced by corru-biting lndividuals, woul-cl therefore suggest that this species may be less bovophille than are gg@-U and gigbanum,. This posibllity is ','iort\y of further investagation. c. IDEMIFICATIO N OF I,ARVAE COLLECTT,D ITTOM THE FIELD S-_ de@es-u-U complex larvae vJere col-lected from several locations in the Volta Region of Ghana and have been identified by Dr. Vajime, The results ',vill- be presented in his report together ruith other identlfications from the same area. D. rliE* EVAL-U$1.:rQ_[_ AI{D I},IPROVEI-{ENI OF REARING TECHNISUES It is dlfficult te obtain a precise cornparison of thc different rearing techniques employed because resul-ts are subject to great variation from one experlment to the next, and high larval mortal-ities sometlmes occur suddenly and inexplieably. Nevertheless, oS a result of experiments carrled out during the peniod under review, together with other information obtained earlier, it is novl posslble to rrrake certain generallsations about the various rearing techniques employed so far. u I L thUA rr]arvaI stases Techniques based on the use of 'ci:,-: eompressed air or electro-magnetic stirrers to produce a water current, have been found unsatisfactory for rearing adults. Although Some adul-ts may be obtained they are al-viays very fevr in number and usually very small ln size. Horrever, these slmple techniques require little space ancl are adequate for ::earing Jarvae to the late larva] lnstars. There is then almost invariabl-y a hlgh mortality befone pupation. Beeause it ls the 1arva] stages that are cytotaxonomically identifiable these methods are adeqr.r4te for identifieation purpoaes. .../4 1 l+ A major draw-back in the past has been the slow rate of larval development. Although thene is gr-eat variabilitYr it has normally taken about a month before appreciable numbers have reached adequate size for cytotaxonomic identification. However, by improving the food supply and ensuning adequate water flolv it has been possible to neduce this perlod to about tlvo wecks. Three kinds of food have given good results: unicellular Chlorophyceae (a1gae), a mixture of algae and. bacteria and Tetra conditioning food (a vegetable dlet for tropieal fish). The value of Tetra for feeding simuliid larvae rivas first demonstrated in Newfound.land (Cofto, 1975). Algae used have included a species at first believed to be th]Sre$a, but now thought to belong to another genus, and a species of Anchistrodesmus, The Chlorella-1ike species was cultured in Nakamurat s Ivledium (for Ch1orel1a) . Algae v/ere removed fnom the culture solution by filtratlon before belng added to the rearlng chambers. However, the culture became eontaminated with another a1ga, not yet identified, which completely replaced the Chl-oreI1a-1ike species, The former is therefore no\,l,r being used for feeding the larvae. A genuine Chlo lIa culture has been ordered from the Culture Centre of Algae and Protczoa at Cambridge because thls genus has a very high proteiii content. Old aIga1 eultures become contaminated vsith baeteria r:lhlch teno to float on the surfaee of the cul-ture solution or to sink to the bottom of the eontainer. These bacterla seem to be highly suitable for feeding sirnuliid larvae. Preliminary results suggest that the bacteria ar:e particularly suitable for early stage larvae while algae /5 5provide a better food for larger larvae, 8S i,t,as reported by Fredeen ( t g6t+) . Even if adequate food is provided it is usually stil1 necessary to change the water every fet'r days. 2. Te-ahnislle-s suitgl]e =.gg-L rearins . The most successful method tested for rearing S. damnosum s.1. to the adult stage 1s that of Grunewald (lgll). The modification of Grunewaldr s technique used for rearing }Jast Afriean eytospecies of Sr--QgmnoSgg s.1. (Raybould & Grunewald, 1975) has also -oroved to be satlsfactory for V{est Afnlcan species. This method eonslsts essentially of an inc1ined trough along whieh the vrater is passed, and in whlch the larvae develop, and a purifieation system. The purifieation system through which the water is circulated consiets of a gravel filter, an activated. chancoal filter. and a eontainer with the submerged roots of Ug!-g!gg, sp. (Araceae). In an lnitial rearlng trial using this method and feeding with algae, the flrst pupae urere obtained after 10 days and about ten indivlduals pupated within 12 days. The larvae were then used for a demonstration in Accna and subsequent development could not be pursued. However, further trlals are now in progress and w111 be pnesented in my next report. E TEIUPERATURE AI\ID OUIPOSITION. It has been found that keeplng blood-fed flies at markably reduced temperatures, in an attempt to improve survival, delays egg development. Consequently, ovipositlon eannot be induced after three days as with flies kept at higher temperatures. .../6 n 5F. BLOOD-FEEDING ADULT trT.]ES. Twenty-five out of thirty-one L-39@@ s.1. females, colleeted at Akosombo on 'llth June, were suecessfully fed on a chicken; all but four of these took lange blood mea1s. The flies concerned wene probably S. damnosum s.S. (see Table 3). This single experiment suggests that at least wild caught flies of this species are not diffieult to feed. in the laboratory. cl. plsplfcH OF NATryIAL To O[Im. VIOmERS. Fantleurar attention has been paid durlng the present quarten to the supply of adequate matenlal to Dr. Peterson of the Biosystematics Reseanch rnstitute, ottavtra, canad.a. S. darrutosum s.1. eggs for rearing work have been dispatched to Dr. Gnunerruard at Tubingen in Germar5r. special postal aruangements have now been made to reduce dellvery time to Tubingen to three days. rt 1s hoped, therefore, that aI1 future eonsignments of eggs wilr anrive in a viable eonditj.on. Pneserved S. damnosum eomplex larvae of various cytospecles (for use in the WHO entomol-ogists refreshen eourse) have been dispatched. to Dr. crosskey at the Natural Hlstony Museum, London. Larvae for eleetnon mienoscopy have been sent to Mr. Williams at Livenpool Universlty. H. &LUlIg. Mr. Barno Te1e, chief of the Leo subseetor, spent about one rnonth at Akosombo fon training in r.eaning teehniques. He showed great interest in the work and is now fu11y competent to rear lanvae fon identification from eggs lald by reinvading S. damnosum s.1. females. .../7 Jd I. @' A demonstration of rearing techniques was presented at the Yiest African College of Physicians Onchocenciasis Workshop in Accna on 5th to Bth Ju]y. An lllustrated talk and laboratory demonstration was given at a workshop on "Education for protection against schistosomiasis and onehoeereiasj-Str at Akosombo on tth to lOth Ju1y, Mn Tony Opoku, a very experienced teehnician at the Fublic Health Laboratory here in Akosombo, is now eol-laborating with me on most projects. A resultant increase in researeh productivity is already apparent. K WORK PI,ANNED ND(T O.UARTER. In addition to a contlnuation of the long-term programme itemiseO under this heading in earlier quarterly reports, the following projects will- be undertaken: - 1. The supply of identlfied materlal at al-l stages of development to Dr. Peterson of the Blosystematics Researeh, Institute, Ottawa, Canada. 2. Studles on the veetor potential and host preferences of S. sanctipaull (Bandama). Flies fed on an lnfeeted person vril-l- be rnaintained in the laboratory and the subsequent development of the paraslte foLlowed. The training of tlvo entomologists, Mr. Vrlilson and Mr. Asigri, from the Ghana Ministny of Health. 3. EEBE@,.a ACKNOWLEDGEME}{IS I am grateful to Dr. .C. Vajime for all l-arval ldentifieations, to lvfu.. A. Opoku for assistance in the laboratory and in the fiel-d and to Mr. J.F. Yv'alsh for his help and. advlce during and after his visit to Akosombo. RE]FERENCES. Co1bo, M.H. (lgl6). Larval slmuliid rearing. Annual Repont, Research Unit on Vector Pathology, Memonial University of Newfoundland, p.11. Fredeen, F.J.H. (tg6t+) . Bacteria as food for blackfly larvae (niptera: SimuLiidae) in laboratory culture and in natural streams, @., !8, 527-5t+8. Grunewald, J. Die Wdrochemischen l-ebensbedingungen der praimaginal-en stadien von Boophthora ervthrocephala De Geen (Diptera: Simuliidae). 2. Die entwlcklung einer zuoht unten experimental-I en b edingungen. ?)L, 232-21+9. Z^ Tro Parasit. Raybould, J.N. and Grunewald, J. (lglil. Present progress towards the laboratory eoloni zat'ton of Afrloan Simuliidae (Oiptera). Tropenmed. Parasit., 25, 1 55-1 68. l.\ trHH -o EqZ r-tH .Zl o trlZAH C!@\o rf\ N\o la\ LC\ trlA^A14HdEl!m550oa@.- a =DA^oEl =Fl4dI)F{@rQ2- a NJ H FlD -{ap.i < r+ts B3 #.8 a o\ =5l- fifrEfrHHaa U) J zDa a) Zra d.}-l <Hdz a o\ zoH HHaI =oo af'lHo 14 P{a @ @Jo c{ N 8HB >N dgffzAe \o co rr\ LN Gd o atr{ fqAoOl(h{oo< . f-l E-1 Fl2fi f*- C\t f-f.- C\ e\i f- Ir_ (\ C\' l-- Ir- N.\ o C{ r-N |-- f*- €r- a tr] i,lHH ffH Ff, F1o() f--l-- (\ C{ |..l-- r.q fa\ N a F1Fl * H Ff = o Eq =oao\) trla il 'd HAoA .{ MB>4&gltir i-l a fal trl c) =A.cHgE(EMtoD<ao <ft tr{oa l'1rqil()<I ,x=Dtr] oFqa azg fl q) .rl .r- C6 o l.{ A hp dq) .d +t .rl P cq) o .-l o FI 0) = 0)(d F{d rl 0)tH + H A a& fl& r4g & S H d =O C) @1 ho zoHFHaI =o C) a tr]Ho trI P-{ a) trlH *{H + ? TABLE 2. , THE S I T N S SOURCE OF FEI\4ALES NO. NOT IDEI{TIFIED 24 + I,ANDA- POZANDA NEAR I,AMA-I$RA TUSKER NEAR AKOSOMBO 6 + Collected and brought to Akosombo by Dr. Denke. rAE&E f. S. SIRBANUM ( srRBA) S. DAMNOSUM(ivrrn)DATECOLLECTED EGG BATCTMS i,AID I,ARVAE REARED 1628/3/77 2 22 115 376t+28& 2e/1/77 MPOSlTIO S MPOKU SPECIES COMPOSITION SOURCE OF i,ARVAE DATE COLLtrCTED S.DAMNOSUM S SIRBANUI\,I S. SOUBR]JNSE RI\TER VOLTA AT ATIMPOKU 20/5/7 6 51+ 26 30/t1 /76 10 17 I B/5/77 1l+ 30/5/77 7