Programme of research for 1976: entomology and environmental protection

!rs a'4*f #,* ri WORLD ORGANIZATION ocP/srAca. 2 ORIGINAL: ENGLISH January 1976 oRGANISATION MONDIALE DE I-N SENTE SCIEMIFIC AI{D TECHNICAL ADVISORY COUMITTEE Third meeting Geneva 2-4 l,Iarch 1976 ONCHOCERCIASIS CONIROL PROGRA},TME IN THE VOLTA RIVER BASIN AREA PROGRAMME OF R3SEARCH FOR 1976 ENTOUOITOGY AND EIII,IIRONMEMAL PROTECTION In the preparation of the followlng research programe for L976 particular attention was paid to: (a) the imediate and long term needs of the Onchocerciasis Control Programe; (b) association, where appropriate and poseible, with the general operationat activities of the Simulium Control Operatlons Unit; and (c) an evaluation of the research currently carried out under established agreements. The research progra'rne is again considered under the three headlngs of: Vector Ecology, Vector Control and Environmental Protectton. VECTOR ECOLoGY 1 The rearing of single generations and the developnent of a self- etuat lnc colonv of S. damosutr High prlority will be given to the rearing of single generattone in order to obtain identifiable rnaterial from wild-caught, blood fed feoales. Initially, this will benefit the research activities planned to coincide with the expected period of re-infestation of the control area in 1976. A Scientiflc Advisory Panel Working Group met in Geneva fron 20-23 October 1975 to consider this subject and a reportl on rearing Simrlium species and the establishment of a laboratory colony of Simllium damnoeum was prepared which hlghltghts the action required. In following up the grouprs reco'n'rendatlons, a research entomologist, Dr J. Raybould, is being recruited and a rearing laboratory will be established at a location to be selected early in L976. Several locations in Ghana have already been proposed by the I OCp/Sep/ZO.t: Report on the Scientific Advisory Panel Working Group on Rearing Simulium species and establishment of a laboratory colony of S. damnosum. I I I , The issue of this document does not constitute formal publication. lt should not be reviewed, abstracted or quoted without the agreement of the World Health Organization. Authors alone are responsible for views expressed in signed articles. Ce document nc constitue pas une publication. ll ne doit faire I'objet d'aucun compte rendu ou r6sumd ni d'aucunG citation sans l'autorisation de I'Organisation Mondiale de la Sant6. Les opinions exprimdcs dans les articles signds n'engagent que leurs autcurg. * a - t'l '.. 't ^,I ',d- a a, ocP/srAc3. 2 PaBe 2 National Onchocerciasis Conmittee and Dr E. G. Beausoleil, Deputy Director, Medical Services, has expressed the desire for the laboratory to be situated near one of Ghanars universities, in order to encourage the associaEion of personnel therefrom. Prior to the selection of any location, the water quality will be tested by a consultanE(Or.f. Grunewald, Tropenmedizinisches Institut der Universitut, Tubingen, Federal Republic of Germany) to ensure its suitability for the different species of S. damnosum s.1. found in the prograffine area. Idea1ly, portable 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 Control (COC), Atlanta, United States of America, who is currenEly attempting to develop such apparetus for field use. Llork on establishing a rearing trough rras started in Bouak6, Ivory Coast, by Mr J. Mokry from the Memorial University of Newfoundland, SE Johnrs, Canada, and its con- tinuation will be encouraged. Agreements have been signed with Dr R. Taylor and Dr J. Grunewald for the establishment ofase1f-PerPetuatingco1onyofaspeciesofth"l@comp1exfromWestAfrica.For this purpose, eggs are being supplied to these laboratories, either direct from Ehe Programe area or from the Institut de Recherches aur lrOnchocercose at Bouak6. Many problems have yet to be solved, not only with regard to the storage and transport of materlel from Africa to laboratories, but also to ovipositingr mrting and feedlng. Some interesting preliminary sEudies on the storing of eggs rilere carried out by !{r Ocran, Chief, Ouagadougou Sector, Onchocerciasi-s Control Programe. It is therefore lntended that the research entomologist in charge of the rearing laboratory should become the focal point for studies in this field and for the provlslon of biological naterial outside the Prograrme area. Noting the apparent difference in behaviour between laboratory reared adults and wild- caught adults, it is considered appropriate for a histochemlcal study Eo be undertaken of the adult Sinulium to determine any difference which might exist between newly emerged (laboratory .rrd rifEGtt), nulLiparous and parous females. Contact is being made with Mr Abdullai Ba, Bamako, Mali, who is currentLy studying the oicro-anatory of the nerves of Simulium larvae. I.2 S. damnosum complex Due emphasis will be given during 1976 to diversifying the studies on the S. damrosum complex in order that stages other than larval can be identified by methods alternative to cytotaxonouy. In this regard progress has been made by Dr Qui116v6r6 under an agreement with OCCGE, Bouak6, ln his study of the maxilla in the adult fe-,les, by which he can differentiate the t'Ni1e/Sirba" group from S. soubrense. In order thaE an intensive study could be carried out on the morphological characterj-stics of the larvae, pupae and adults of all the sp ecles of the S. damnosum couplex in West Afri-ca, a Contractual Technical Agreement was established at the end of 1975 with Dr B. V. Peterson of the Biosyst.ematics Research Institute, Ottarnra, Canada. A1so, under separate agreeEents, iso-enzlrme techniques are being used by Dr Coker of the University of Ghana, Legon, and Dr H. Townson of the Liverpool School of Tropical Medicine, United Kingdom, In the Prograrnne itself, Dr C. Vajime, cytotaxonomist, will continue his study on the distribution of the different species of the S. damnosum complex in and around the Programe area, and pursue studies to try to identify polytene chromosoDes in the adult which might carry specific characters. In association with the WllO Division of Vector Biology and Control (WC) an agreement is being drawn up with Dr D. G. Bedo of the Australian National University, Canberra, for the study of the C & G banding from oocyte nurse cells. During the year, the Contractual Technical Agreement with the Organisation de Coordination et Coop6ration pour 1a lutte contre les Grandes Endemies (OCCCE), Bouak6, will be extended to enabre ecological and epidemiological studies on the different species in selected areas to continue, it being appreciated that the fullest value fron this work will only be realized when the adults can be accurately identified. ert ) I \ i : ! I I I a, ocP/srAc3.2 Page 3 For work to progress satisfacEorily in every espect of these studiee it will be necessary to have related, type-specific lanrae, pupae and adulte to feed to the instiEutions associated wlth this research. It is intended that such naterial will come froo the rearlng laboratory once it is established. I. 3 9._9.*os.r, s.rplir,g The main work on this is being carrled out at the Institut de Recherches sur lr0nchocercoee, Bouak6, under an agreement with the Office de la Recherche ecientifique et technique Outre Mer (ORSTOU). Two different aapects are being studied separately, namely, larval sampling and adult saupling. Becauee of the neture of the studi-es, and the need for then Eo be carried out on spec ies of the S. daunosum complex, this hrork can only be conducted in areas of West Africa where the different species are to be found. The team involved in this work ln Bouak6 ls applying iEself adnirably and producing eome interesting results of value to the Onchocerciasis Control Progra*e. Whlle the main objective iB Eo develop a suitable saupllng method for larvae and a trapping devi.ce for adults, it is obviously essential to carry out relaEed research on the general bionomics of the different species. I.3.1 Larval saupling: Under an agreenent with the Leopold Institut,e, Antwerp, Belgium, Mr P. Elsen has already succeeded in developlng a prooising artificial support of 1ong, narro\d plastic strips. He will continue studies on the (a) colour and type of naterial which is most attracti,ve as en ovipositing site or a larval support; (b) distrlbutlon of larvae in the rrater, particularly as related to depth; and (c) larval feeding behaviour, e.9., rate of digestion Ln relation to quantity of ncterial available and lrater speed. Mosr of this study is belng undertaken at a fleld station establlshed on the lGrahou€ river, but Mr Elsen will be encouraged to repeat the work in areae where other epeciee of the S. damnosum corylex are found. A Contractual Technical Agreeoant has also been established with Dr W. Cralg, Unlveratty of Alberta, Edronton, Canada, for a long-term etudy of the factors governlng detacbnent and reattachment behaviour of the larrrae. r.3,2 Adult 1 inc : t{r Bellec, ORSTOM, will conti.nue to try and develop a suttable trapping device for S. daurosuu. l{ost prmising results have been obtatncd eo far rdth hls intervention trap ptaced above the rivers. It appears that progresg wlth alternative t)rPes of trapping devices will be llnlted unt11 rcre inforoation hae been accurnulated concerning the general behaviour and dletrlbution of the S. daurosno adult fliea, or until a spectflc attractsnt has been found which w111 nake one or other of hia developed traPe rcre conslstent- ly efftclent. l,lr Bellec w111 continue studies on all theee asPects and, where aPProPriate, further agreements wll1 be eetabllshed with lnstitutions !*rich can aesist wtth the develop- oent of attractive substancee, €.8. pherorcnee. In this regard, contact has been nade wlth the Central Laboratorlua TNO, Thc Hague, the Netherlands. The Centre for Oversees Pest Research (COPR), London, has iodicated its wllllngness to tesE different attractive substancee using a special wind tunnel, Hovever, thli study can only be carried out when suppliee of s damrosum adults are avallable on the spot, e.g. after establishnent of a self-perPetuating colony. T.4 S. <lannog dispereal The essential work on this subject wag carried out in 1975 by two biogeographere from the COPR whoee report to WIIO recormended a more inteneive sEudy to comence in 1977. Durtng 1976, the cooperation of COPR will again be sought for a study of the clinatic conditions prevailing in the lower part of the Phase I area from about April to October, the period when re-invasion ls most llkely to occur. This work wtll be undertaken ln London and all related entomological information relayed to the biogeographers by the Simrliun Control Operatlons unit. It was agreed that further etudLes, as outlined in the COPR proposal, w-111 be con- sidered only after the resulte of the researeh carrled out in 1976 have been evaluated. a at t a ocP/srAc3.2 Page 4 II. II. 1 VECTOR COMROL Susceptibility testing At the second meeting of the Scientific and Technical Advisory Conmittee (StaC) and the recent Expert Cotmittee on Insecticide Resistance, the need for a satisfactory method for testing Ehe susceptibility of blackflies to insecticides rras highlighted as being of tremendous importance. Apart from Ehe Qu6lennec method, which requires the exposure of larvae to very low concentrations of insecticide in unaerated water in an airconditioned laboratory for a period of. 24 hours, no other method has provided reasonably consistent results. Regrettably, little progress has been m,de under the contract with ORSTOI'{ for 1975 and it was decided that the CTA should not be renewed at this stage. A consultant (Dr J. Mouchet, ORSTOM) was recruited for a period of six weeks from mid- January L976 to develop studies already iniEiated in West Africa, with particular emphasis on determining whether the Qu6lennec method could be modified to enable the tests to be under- taken over a period considerably less than 24 hours. The prolongation of this study w111 depend on the results obtalned by the consultant. If unsatisfactory, priority will be given to convening a meeting of speclalists combining the disciplines of chemisEry and entomology Eo recormend a new method. II .2 Insecticide evaluati.on In view of the urgent need to find a suitable alternative insecticide to Abate, research started at the end of 1975 on chlorphoxin, particular attention being paid to its effect on non-target organisms. This study is belng undertaken under agreeoents with OCCGE and the ORSTOU ltydrobiologlcal Unit. A hellcopter is being provided from the OCP fleet for the application of ineecticide and the examination of sites downetream. A much larger-scale trial will be undertaken in part of the Programe area in the dry season and again in the rainy season with the quantity of chlorphoxim available. A number of other candidate insecticides having been nade available for initial field testing, Dr Stiles, chemist, VBC, willvisit l{est Africa in February to launch the tests. These products are Altosid, Suoithion 20% EC, Methyl Dursban, micro-encapsulated foruulation(nelaan), Abate 50% wettable powder, OUS 1804 (257" Dinilin) and OMS 1825 EC 2O%. These will be tested both for their effect on Simulium damnosum larvae and non-target organisms. Should any of these latEer insecticides show promise, trials on a larger scale will be undertaken in late 1976. The recruitment of a consultant (Dr H. Jamnback, University of the State of New York, Albany, United States of America) to assist in these.later trials will be cons idered. II. 3 Biodegradability of insecticides Most of this work is undertaken at CDC, Atlanta. Dr Miles of CDC has recorded that the half life of Abage in the aquatic environment is apProxinately eight weeks, whereas initial studies wirh chlorphoxim indicate that it has a half life of 26 hours at pH 7. As considerable concern was expressed by the Ecological Panel and some of the participa- ting countries at the lack of knowledge of the fate of Abate in the rivers when applied at weekly intervals, a detailed study will cor"mence at the end of January 1976 with the assistance of Miss King of the VBC project Anopheles Control Research Unit (ACRU I) in Kaduna, Nigeria. It is inEended thaE sampLes of r^7ater be taken over several days to measure Ehe insecticide remeining in treated rivers outside the control area and that mud be collected from different points for analysis. AE a laEer date, further saaples will be collected across the profile of ttr" river at different distances downstream from the point of applicaEion. These studies should give some indication as to how Abate behaves in the river and how it is distributed throughout the aquatic environment. l t IocP/sTAc3. 2 Page 5 Technicians will be trained in the method of collection and extracti-on of the samples, after which a regular Programne of chemical monitoring will be established. Samplescollected w111 be divided, half being senE to cDc, Atlanta, and the other half to ASRU I,Kaduna, for comparative analysis. When the system is established, Miss King will visitGhana and other countries, as regui.red, to train technicians in the techniques developed. It is reconrnended that for the aquatic monitoring programtre, the chemical aspect shouldbe clearly divorced from the biological aspect, separate protocols being drawn up for each, and separate agreements established as necessary. LI.4 Insecticide safe ty for manunaIs The srudy being undertaken it Zagreb (Dr plestina) on the potentiating effect of Abate andmeErifonate will be completed at the beginning ot 1976, If chlorphoxim proves to be a suitable alternative to Abate and could be considered as alarvicide for the Programme, a study will be initiated by the producer in 1976 to determineits long-term effects on marunals. The formulation of chlorphoxim provided for the trials in L975/76 has an objectionableodour, thought to be due to the type of solvent used rather than to the insecticide itself. rnformation on the long- and short-term toxicity of this formulation will be requested fromthe producer by VBC. II.5 Equipment for insecticide application The rapid release system developed specifically for oCP is proving generally satisfacroryfor larvicide application throughout the Prograrme area. However, during extreme dry seasonconditions' amounts of less than 0.3 litres need to be discharged fron the heticopter. Thiscan probably be achieved by reduclng the size of an orifice in the system, but the problem ofemitting quantities less than 0.3 litres into a river due to wind currents, evaporaEion, etc., w111 have to be investigated. The easiest solution may be to dilute the insecticide priorto its application. As the Progranrne is relying on only one method of treatment., some research should be undertaken to establish alternative methods, e.g. ultra-Iow volume (ulv) which rnay be moresuitable for formulations different to that of AbaEe presently used. such alternatives wouldhave to be tried with the assistance of a consultant (Dr H. Jamnbact) both during the dry season and rainy season, but such trials may have to be postponed until 1977. In order to determine more accurately the discharge of rivers in stretches where thereare no gauges, it is reconunended that the system developed by NASA be tried out in theProgranrne area in 1976. Contact was made with Dr Steinberg who indicated chat modificationsto the aPPeratus were necessary to enable it to be operated from helicopters and suggestedthat tests be carried out tor^rards the end of the year. The results obtained will be comparedon the spot by ORSTOM hydrologists, using conventional methods. permission will be obtainedfrom the aerial contractors Eo undersling the equipment on the helicopters. In order to obtain uP-to-date information on riverine discharge at key points, it isproposed that a trial should be undertaken with a gauge equipped wiEh a radio-transmitter.This could use eiEher VHF, with the information being collected by plane or helicopter nearthe scene, or HF, which is very rare and much more expensive but would enable the informationto be received directly aE the oPerational headquarters. The transmiEter could be prograurnedto send out the coded information at a regular time each day or be switched on by . "igrr.ffrom headquarters whenever information is required. This particular study is being followedup in collaboration with oRsroM hydrologists in paris and others. J ocP /srAc3 . 2 Page 6 II.6 Biological control It is unlikely that a method of biological control, which might be used in OCP on a smaII or large scaIe, might be developed in the irnnediate fuEure. The WHO Division of Vector Biology and Control and The lnternational Development Research Centre, Canada, (fOnC) are supporEing the main institutions and personnel already engaged in studies of blackfly parasites. However, OCP will keep itself fully informed of developments and consi-der any assistance which may be required to promote this work. TI,7 Envi-ronmental manipulation While the more inEensive study for physical modifications proposed by Dr A, Hess(Consultant) in 1975 awaits implementation, it is reconrnended that smaller scale studies might be undertaken in 1976. In this regard, the destruction of che importanE breeding site at Niampourou nray be considered by the OCP personnel working in association with the Public Works Department. This site is on a disused causeway and a study will be carried out to determine whether removal of the structure will result in exposing other potential sites. Many of the breeding sites in the tr{hite Volta in Ghana could probably be similarly modified to greatly reduce the scope of treatmenE necessary during the dry season. The implications of such modifications could be reviewed by a shorE term consultant, possibly a hydrological engineer, during the dry season in L976. III. ENVIRONMEMAL PROTECTION III. 1 Anrrfp cffctl' ts of insecticides The acute effects of the range of candidate insecEicides on non-target organisms will be evaluated in 1976. Initially studies will be undertaken to try to develop a laboratory technique which wiLl produce results similar to those normally found in natural conditions. It may be expected that the majority of this work will be undertaken in Bouak6 under an agreement with the ORSTOM Hydrobiological Unit, where a device for in situ testing in the river is being tried. Studies on the short- and long-term effects of i-nsecticides on fish are being carried out in CDC, AElanta. The Centre for Overseas PesE Research, United Kingdom, submitted a proposal in 1975 for a research prograrrEne in Ghana to study, in detail, the effects of Abate and other candidate insecticides on a number of species of fish common to West Africa. The Ghanaian authorities are interested in cooperating in this research programme and funds are being sought by COPR. It is anticipated that this study will commence during the first half of L976, with certain financial assisEance and cooperation from OCP, and will last several years. IIL2 Long-term ef fects of insec Eicides on non-target organisms The aquatic monitoring programe is being conducted by the ORSTOM Hydrobiological Unit and the Institute of Aquatic Biology, Achimota, Ghana. In January L976, a working group was convened of those involved, together with a Temporary Adviser (Or U. Pugh Thomas, University of Salford, United Kingdorn) and Mr Duppenthaler, OCP statistician, with the objective of reviewing the activities to daEe finalizing the format of the recording forms and coding them for comPuter sEorage and analysis. This programme wil1 continue in 1976. At the beginning of 1976 a Temporary Adviser, Dr R. Wallace of the Freshwater Institute, Winnipeg, Canada, collected data from rivers not included in the normal monitoring Programne. This will be repeated towatds the end of 1976 and beginnLng of L977. Towards the middle of L976 the resulEs of the monitoring Prograflme wilI be analysed and a report prepared for submission to the Ecological Panel. I