Programme of research for 1976: entomology and environmental protection

SCIEMIFIC AI{D TECTTNICAL ADVTSORY COUTfiTTEE ocP/srAc3. 2 ORIGINAL: ENGLISH January 1976 Third ins Geneva, 2-4 l,tarch 1976 ONCHOCERCIASIS COMROL PROGRAMME IN THE VOLTA RIIIER BASIN AREA PROGRAI'TME OF RESEARCIT FOR 1976 EMOMOIOGY A}ID E}IVTRONMEMAL PROTECTION In the preparaEion of rhe foltowlng reeearch prograrme for 1976 ParEicuLar attenEion lf,as paid co: (a) rhe imediate and long teru neede of the Onchocerclaeis ConErol Programe; (b) association, where appropriate and poeeible, rrith the generat oPeraElonal activities of the Sistrllun Control Operatlone Unlt; and (c) an evaluation of Ehe reeearch currently carried out under establiehed agreements. The research progra*e is again considered under the three headings of: VecEor Ecology, Veccor Control and Envlronoental ProEecEion. I. VECTOR ECOU)GY r.1 The rearing of sin8le seneratione and the developEent of a se eEuatinq colony of S. aamos". High prioriEy will be given Eo che rearing of single generatione in order to obtain idenrifiable material fron wild-caught, blood fed fenales. Inltially, this will benefit the research accivitles planned to colncide wlth the exPected period of re-infestation of the control area in 1976. A Scientifle Advleory Panel l{orklng Group oet in Geneva ftos 20-23 OcEober 1975 to coneider this subJect and a reportl on rearlng Simrliun epecies and the establishment of a laboracory colony of Simrlluo damnosuu was prepared wtrlch highlights the acEion required. In following up Ehe grouprB reco@endatlons, a research entoooLogist, Dr J. Raybould, ie being recruited and a rearing laboratory witl be eetablished at a location ro be selecred early ln 1976. Several locaEions ln Ghana have already been proposed by Ehe 1 OCp/Sep/ZO. t: Reporc on Ehe Scientiftc Advtsory Panel Working Group on Rearing Sim.rllum species and eetablishment of a laboratory colony of S. daonosum. WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SANTE The is8ue of thie document do€s not constatute formal publication. lt should not be reviewed' abst?acted or quoted without the ag?eoment of the World Hoalth Organization. Authors alone a?e responsible for views expressed in signed articles. Ce document no con6titue pas une publication. ll ne doit faire I'oblet d'aucun compte rendu ou r6sum6 ni d'aucune citation aana I'autoriaation de I'Organisation Mondiale de la Sant6. Les opinions exprimdes danE les atticloe signds n'engagent que leurs auteur6. n ocP/srAc3.2 Page 2 National Onchocerciasis Cornmittee and Dr E. G. Beausolel1, Deputy DirecEor, Medical Services, has expressed the desire for the laboratory to be situaced near one of Ghanars universit.ies, ln order Eo encourage the association of personnel therefroo. Prior Eo the selection of any location, Ehe waEer qualicy will be EesEed by a consultant(Or .1. Grunewald, Tropenmedizinisches InstituE der Universitec, Tubingen, Federal Republic of Germany)toen8ureicssu1tabi1icyforthedifferentspeciesof@s.1.foundinthe Programe area. Ideally, porcable rearing chambers should be available in different parts of the re-infestation zone and contact will be maintained with Dr R. Taylor, Center for Disease ConErol (CDC), AElanEa, United StaEes of America, who is currently aEEempting to develop such apparatuE for field use. tlork on escablishing a rearing trough rdas sEarted in Bouak€, Ivory Coast, by Mr J. Mokry from the Memorial University of Newfoundland, St Johnrs, Canada, and it,s con- tinuation will be encouraged. Agreements have been signed wlth Dr R. Taylor and Dr J. Grunewald for the escablishment of a self-perpeEuaEing colony of a speciee of the S. dannosum complex fron West Africa. For thls purpose, eggs are being aupplied to these laboratoriea, eiEher direct from che Programe area or from t,he InstiEuc de Recherchee aur lronchocercose at Bouak6. l{any problems have yeE Eo be solved, not only !iliEh regard to the BEorage and transport of EaEerial fron Africa to laboratories, buE alao to ovipoeiEing, oating and feeding. Some interesElng prellminary seudies on Ehe storing of eggs hrere carried out by Mr Ocran, Chief, Ouagadougou Seccor, Onchocerciasis Control Programe. It is cherefore lntended that the reeearch entomologist in charge of the rearlng laboratory ahould become the focal polnt for studiee tn this field and for the provision of biological EaEeriel outalde the Progra@e area. Noting the apparent difference in behaviour between laboratory reared adulcs and wild- caught adulcs, it, is considered appropriace for a hietochenical study to be undertaken of the adult Simullum to determlne any difference which oight exist between newly emerged (laboratory ".ra riliEGf,t), nulllparous and parous fenales. Contact ls being nade wich Mr Abdullai Ba, Bamako, l.Iali, who ie currenEly studying the mlcro-anatouy of t.he nerves of Siutrlium larvae. I.2 Llry complex Due emphasts will be given durlng 1976 to diversifying the studies on the S. damrosum complex in order that sEages other than larval can be ldentified by methods alternative to cyEotaxonosy. Ln this regard progress hae been made by Dr Quill6v6r6 under an agreeoenC with OCCGE, Bouak6, in his study of the naxilla in the adult fe-rles, by which he can differentlaEe the'rNi1e/Sirba" group from S. soubrense. In order thac an intensive study could be carried out on che norphologlcal characEeristics of the larvae, pupae and adults of all the speciee of the S. damnosum complex in I'lest Africa, a ConEractual Technical Agreement was established at the end of 1975 wlth Dr B. V. PeEeraon of che BiosysEetratics Research InsEiEute, OEEawa, Canada. A1so, under separate agreements, iso-enzyme techniques are being used by Dr Coker of the University of Ghana, Legon, and Dr H. Townson of the Liverpool School of Troplcal Medicine, UnlEed Kingdon. In Ehe Programe itaelf, Dr C. Vajioe, cytocaxonomist, will cont.inue his study on Ehe disEribuEion of the differenE epecies of Ehe S. damnosum couplex in and around che Programe area, and pursue sEudies t,o try to identify polytene chromosomes in che adult which mighc carry specifie characEers. In aseociaEion with che WHO Division of Vector Biology and Control (WC) an agreenenE is being drawn up with Dr D. G. Bedo of t.he Aust,ralian National Univereity, Canberra, for Ehe study of the C & G banding from oocyt,e nurse cells. During the year, Ehe Contractual Technical Agreement wtth the OrganisaEion de Coordinacion eE Coop6ration pour la luEEe conEre les Grandes Endemtes (OCCGE), Bouak6, will be extended Eo enabre ecological and epideolological studies on Ehe differenc species in selected areas to conEinue, it being appreciated that the fulleaE value from Ehis work will only be realized when the adults can be accurately identified. I IocP/srAc3.2 Page 3 For work to protresB seti8factorlly in every aspect of theee studiee ic will be neeeeeary Eo have relaEed, cype-specific lanrae, pupae and adulte to feed Eo the institutions aeeoclated with this research. It ts incended that such naterial will cooe froa the rearlng laboratory once iE ls established. I.3 S. damnoeuo earpling The nain nork on thia ls being carrled out aE the InsEituc de Recherches eur 1 ronchocercoee, Bouak6, under an agreeaent with the Offlce de la Recherche acientlfique et technique outre Mer (ORSTOI!). Two dlfferent a8pecta are being scudied separately, namely, larval sanpling and aduLt saupling. Becauee of the nature of che studiea, and che need for them co be carried out on spec lee of the S. damnosum coqlex, thig work can only be conducted in areas of West Africa where the dlfferent epeclea are to be found. The team involved ln thlg work in Bouak6 ts applying itself admirably and producing eome lntereeting reeults of value to the Onchocerciaeis Control Programe. Wtrile the oaln objecttve ls Eo develop a suitable saupllng oethod for lanrae and a trapping device for adults, it is obviously essential Eo carry out relaEed research on the general bionomics of che different species. I.3.1 Lanral saqr!!4g: Under an agreenent with the Leopold Institute, Antwerp, Belgiua, Mr P. Eleen has already succeeded in developlng a pronteing artlflcial suPPort of 1ong, narrow plastic sErlpa. He will contlnue sEudtes on the (a) colour and type of oacerial which is most attracEive aB an ovtpositing elte or a lanral eupport; (b) dletribution of larvae in Ehe rrater, particularly as related to depth; and (c) lanral feeding behavlour, e.g., rate of dtgestlon in relaElon to quantlty of oaterial available and waEer apeed. Most of this scudy ia belng undertaken at a fleld station eatabllshed on Ehe l'tarahou6 river, bug l.Ir Elaen will be encouraged to repeac the work in areas wtrere other speciee of the S. daoqqtq coqlex are found. A Conrractual Technical Agreeaent hag algo been eetabliahed sith Dr t{. Cral$, Unlverslty of Alberta, EdaoaEon, Canada, for a long-term etudy of the factore governtng detachment and reattachnent behaviour of the lanrae. T.3.2 Adul.r saqling: l{r Bellec, ORSTO}i, will continue to try and develoP a suitable trapping device for 5. da*,osrr!. Most prouiaing resulte have been obtained eo far rlth hla lntenrention trap placed above Uhe rivera. It appears EhaE Progrees with alternative tyPes of trapping devicee wtll be llolted unttl. rcre inforoation has been accum'rlated concernlng the general behaviour and diatrlbution of Ehe S. daurosuo adult fliee, or untit a epeclflc aEEractang hae been found which wilt oake one or other of his developed traPs oore conetsEent- ly efficient. l.tr Bellec will contlnue etudles on all theee asPects and, where aPProPrlate, fur.r her agreeoent6 wl11 be eetablished with tnatitutlons whlch can assisc wlth the develop- menc of aEtractive aubstance8, e.g. pherooonee. In thla regard, contact haa been oade rith the Central taboratorium TNO, The Hague, the Nethertands. The Centre for Overseas Peet Research (COPR), London, haa iadicaced ite willlngnees to tesc dlfferent attractive eubatancea using a special wind tunneL. However, Ehla study can only be carried out when suppliea of s. sum adults are available on the Bpot, e.g. after eatabliehoenE of a self-perPetuatin8 colony. T.4 S. daonosum dlspereal The essentlal work on this subJect wae carried out ln 1975 by two biogeographers from the COPR whoee reporE to WIIO recomended a more inEenslve study to co@ence tn 1977. During 1976, rhe cooperation of COPR will agaln be sought for a study of the clioat{c conditions prevailing in Ehe lower part of the Phase I area froa abouE April Eo October, the perlod wtren re-lnvasion ig ooet likely to occur. Thls rrork wlll be undertaken ln London and all related entoEological inforoation relayed to the biogeographere by the Simrllun Control Operatione uniE. IE was agreed that further etudiea, es outtined in Ehe COPR proposal, wllt be con- sldered only after the reeutte of the reaearch carrled ouE ln 1976 have been evaluaEed. ocP/srAc3.2 paSe 4 II. VECTOR CONIROL II. I Susrep4biligll qesllng AE Ehe second meecing of the Scientific and Technical Advisory Co@itEee (STAC) and the recenE Expert Coosrittee on Insecticide Resistance, the need for a saEisfacEory nechod for EesEing Ehe susceptibility of blackflies to insecticidea $ras hlghlighted as being of Eremendous imporEance. Apart from the Qu6lennec met.hod, which requires Ehe exposure of larvae to very low concentraEions of insecticide in unaerated wat.er in an airconditloned laboraEory for a period of 24 hours, no other method has provided reasonably coneistent resulEs. Regrettably, little progress has been made under the contract with ORSTOM for 1975 and it was decided that che CTA should noE be renewed at Ehis stage. A consult.anE (Dr J. Mouchet, ORSTOM) was recruited for a period of six weeks fron mid- January 1976 to develop studies already lnitiated in West Afrlca, wlth particular emphasis on determlning whether the Qu6lennec Eethod could be nodtfied Eo enable Ehe Eests to be under- taken over a period considerably less than 24 hours. The prolongaEion of this study w111 depend on the reeults obtalned by the consultant. If unsatisfactory, priority will be given to convening a meeEing of epeclalists coobining the disciplines of chemisEry and enEomology Eo recomend a new nethod. TT.2 Insecticide evaluatlon In view of the urgenE need to find a suitable alternative lnsecticlde to AbaEe, research Etarred ac Ehe end of 1975 on chlorphoxim, particular actentlon being paid to its effecE on non-Earget organisms. Thls study is being underEaken under agreemente with OCCGE and Ehe QRSTOM Hydroblological Unit. A hellcopter is being provided from the OCP fleet for che appllcation of tneecticide and the examination of sites dorfirsEreao. A mueh larger-scale trial will be undertaken in part of the Programe area in the dry season and again in t,he rainy Beaaon with the quantiEy of ehlorphoxim available. A nuober of oEher candidate insecticides having been oade available for inltial field Ee6Eing, Dr Stiles, chemisE, \fBC, willvisit West Africa in February to launch Ehe EesEs. These producEs are ALtosid, Sumithion 20% EC, Methyl Dursban, nicro-encapsulaEed formulaEion(Reldan), AbaEe 5O7" weEtable powder, OMS 1804 (25% Dimilln) and OMS 1825 EC 2O%, These will be tested boch for Eheir effect on Sim.rlium daonosum larvae and non-Ear'get organisns. Should any of Ehese latter insecticides show promise, trials on a larger scale will be underEaken in late 1976. The recruiEnent of a consultant (Dr H. Jamnback, University of the Sgate of New York, Albany, United StaEes of America) to assist in Ehese later trials will be cons idered. II. 3 Biodeqradability of insecEicides Mosr of Ehis work is underEaken ac CDC, AtlanEa. Dr ltilee of CDC has recorded that che half life of Abate in Ehe aquatic environment. is approxinately eight weeks, whereas initial studies with chlorphoxim indicate Ehat iE has a half life of 26 hours ac pH 7. As considerable concern was expressed by the Ecological Panel and some of the partlcipa- ting counEries at the lack of knowledge of the faEe of Abate in the rLvers when applied at weekly intervals, a detailed scudy will comence aE the end of January 1976 wiCh Ehe aesistance of ltiss King of the VBC project Anopheles Control Research UniE (ACRU I) in Kaduna, Nigerla. It is inEended that sanples of waEer be taken over several days Eo Beasure the insecEicide renaining in Ereated rivers outside Ehe conErol area and thaE utrd be collected from different poincs for anaLysis. AE a tater daEe, furEher saoples w111 be collected acroae the profile of the river at different disEances downstream from the point of application. These studies should give some indicacion as to how AbaEe behaves in the river and how it is distrlbuted Ehroughout Ehe aquatic environment. t a a? ocP/srAc3. 2 Page 5 Technlcians will be Erained in the method of collection and exEracEion of che samples,after which a regular Programne of chemical monitoring will be established. Samplescollected will be divided, half being senE ro cDc, ArlanEa, and che other half ro A6RU r,Kaduna, for comparaEive analysis. v,Ihen che 6ystem is established, Miss King will visitGhana and oEher countries, as requi.red, to train technicians in the E.echniques developed. rE is recomrnended that for che aquatic monicoring programtre, Ehe chemical aspecg. shouldbe clearly divorced from Ehe biological aspect, ""p"..t" protocols being drawn up for each,and separaEe agreemeots esE.ablished as necessary. II.4 Insecricide sa feEy for maumals The study being undertaken in zagreb (Dr Plestina) on rhe porenEiaring effecE of Abate andmetrifonate will be complered ac the beginning of 1976. rf chlorphoxim proves to be a suiEable alternaEive Eo Abate and could be considered as alarvicide for the Programme, a study will be initiaEed by the producer in 1976 Eo determineits long-term effeets on rnammals. The fornulation of chlorphoxim provided for rhe Erials Ln L9l5176 has an objectionableodour, thought to be due Eo che type of solvenE used rather Ehan to Ehe insecticide itself.rnformaclon on Ehe long- and short-Eerm coxicity of this formulaEion will be requested fromthe producer by VBC. II.5 UI for insecticide licat ion The rapid release sysEem developed specifically for ocp is proving generally satisfacEoryfor larvicide application throughouc the Progran*" ".".. However, during ex.treme dry seasonconditions, amounEs of less than 0.3 litres need to be discharged fron Ehe hericopter. Thiscan probably be achieved by reducing the slze of an orifice in the sysEem, buc the problem ofemitcing quantiEles less than o.3 litres into a river due Eo wind currents, evaporaEion, eEc.,will have to be investigaced. The easiest solution may be E,o diluc,e the insecticlde priorto its application. As che Progranmre is relying on only one method of treacmenc, some research should beundertaken to establish alternative methods, e.g. ulrra_low volume (ULV) which rnay be moresuitable for formulations different to Ehac of Abare presenEly used. such alternative6 wouldhave Eo be tried wich the assisEance of a consultant (Dr H. Jamnbact) both during E.he dryseason and rainy season, but such trials may have to be postponed uncil 1977. rn order co determine more accurately the discharge of rivers in sEretches where thereare n' 8auges, it is recorunended that che sysEem developed by NASA be tried out in theProgranune area in 1976. conEacE was made wiEh Dr sceinberg who indicated chat modificationsto the apparacus r.lere necessary to enable it to be operaced from helicopters and suggestedthat tests be carried out Eo$rards the end of the yeai. The resulcs obtained will be comparedon Ehe spot by ORSTOM hydrologisEs, using convent-ional methods. permission wilI be obtainedfrom the aerial contraccors to undersling the equipment on che helicopters. rn order co obtain uP-to-date information on rlverine discharge aE key poinEs, lc isproposed that a trial should be undertaken with a gauge equipped with a radio-t.ransmitE.er.This could use either wF, wiEh the information being collecred by plane or heticopger nearche scene, or HF, which is very rare and rmrch more expensive but r^rould enable che informationto be received directly aE the operationat headquarters. The transmitcer could be progranmedEo send ouE the coded information aE a regular time each day or be switched on by . "ig.r.ffrom headquarEers whenever informacion is required. This particular study is being forlowedup in collaborarion wirh oRsroM hydrologisrs in paris and others. I aocP/srAc3.2 Page 6 II.6 Biological control It is unlikely thaE a meE.hod of biological concrol, which might be used in OCP on a small or large scale, might be developed in che inunediace fuEure. The WHO Division of Vector Biology and Control and The Incernational Developmenc Research Centre, Canada' (IDRC) are supporEing the main insciEuEions and personnel already engaged in sEudies of blackfly parasites. However, OCP will keep icself fully informed of developmenEs and consider any assistance which may be required Eo promote this crork. TI,7 EnvironmenEal man lac ion White the more intensive study for physical modificacions proPosed by Dr A. Hess(Consultant) in 1975 awairs implementaEion, it is reconrnended chat smaller scale studies might be undercaken in 1976. In this regard, Ehe descrucEion of che imPortant breeding site aE Niampourou rnay be considered by che OCP personnel torking in association with che Public Works DeparEmenE. This siEe is on a disused causeway and a sEudy will be carried ouE Eo determine whether removal of the strucEure will result in exPosing other Potential sites. Many of rhe breeding sites in the Whice Volta in Ghana could probably be similarly modified to greatly reduce che scope of Ereatment necessary during the dry season. The implications of such modificaEions could be reviewed by a shorc term consultant, possibly a hydrological engineer, during the dry seaaon in 1976. III. ENVIRONMENTAL PRCTIECTION III.1 Acute effecEs of insecticides The acute effects of che range of candidate insecEicides on non-target organisms will be evaluaEed in 1976. Initially scudies will be undertaken to Ery co develop a laboraEory technique which will produce resulEs similar Eo Ehose normally found in natural conditions. It may be expecEed that the majoriEy of this work will be underEaken in Bouakd under an agreement wich the ORSTOM Hydrobiological Unic, where a device for in siEu testing in Ehe river is being tried. SEudies on Ehe shorE- and long-term effects of insecticides on fish are being carried ouE in CDC, Aclanta. The Cencre for Overseas PesE Research, United Kingdom, submiEted a proposaL in 1975 for a research prograrme in Ghana to study, in detail, the effects of Abace and other candidate insecticides on a number of species of fish comnon to WesE Africa. The Ghanaian auchoriEies are interesced in cooperaEing in this research prograsme and funds are being soughr. by COPR. IE is anEicipaEed Ehat this sEudy will comrnence during the firsE half of L976, wiEh certain financial assisEance and cooperaEion from OCP, and will lasc several year8. III. 2 Long-Eerm effecEs of inseccicides on non-Ea rset or qan].sms The aquaric moniEoring progranme is being conducted by the ORSTOM Hydrobiologieal Unit and the InstiEute of AquaEic Biology, Achimota, Ghana. In January L976, a $rorking group was convened of those involved, togeEher with a Temporary Adviser (Or l,t. Pugh Thomas, University of Salford, UniEed Kingdom) and Mr Duppenchaler, OCP staciscician, with the objeccive of reviewing the acciviEies to daEe, finalizing the formaE of the recording forms and coding them for comPuter storage and analysis. This programme rrill- contlnue in 1-976. At rhe beginning of L976 a Temporary Adviser, Dr R. Wallace of the Freshwater InsEiEute, Winnipeg, Canada, cotlecCed data from rivers not included in Ehe normal monitoring Programme. This will be repeaced towaEds the end of L976 and beginning of 1977. Towards the middle of L976 the resulcs of che moniEoring Prograflme will be analysed and a reporE prepared for submission Eo the Ecological Panel. { ,