Contribution to the transmission of Onchocerca volvulus by different species of the simulium damnosum complex in the programme area

IWORLD HEALTH ORGANIZATION ONCEOCf,RCI iSTS n\] TEE VOIT,\ CON.IIIOL PROGP.'; iI.E Rr\IER B]',SI}T J.?.f,i ORGANISATION MONDIALE DE LA SANTE O;lIGINirL c Ei{GLISH &P/E\C4,4(ocp/at.+) EXPERT I.DVIS O,],Y C OI,O/TITIM For:rth session E-egtu-a+r.!.F-es.@ql-lesr. COIfMMU'IIO],T TO TIfi Mj,}ISI{TSSIOI{ OF 01.[C}iOCEF.C,\ VOLVULUS BY DIITEiIEi{T SPECIES 0I' Tm SIIVIULIU}.{ D\ICI'I0SUIvl COIIPL}X IN TFIE PROGR{}O{E ANEJ. fn ord.er to understand. the epid.emiological implications of the seasona1aovenentsofthef1ypopuIationsofthe!-l+4ug-@ cornplex, it was necessaxy to d.eterrtine the vectorial role of each vector species and its contribution to the transnrission of _0ncboge..rca volvulus in various bio-clinatic zones in the Prograrute a,rea. In this respect the tvro savaJlna species f "*-lrysuq s.s. artiL S. :i=!a4lro as rrrell as S. squanosuiii were stud,ied.. The stud.ies on the vectorial role of s. @icTIiIIlTlF...S_oulrense were of particular interest as this speciespair d.eveloped. resistance to tenephos and. chlorphoxin in fvory Coast and Gharra (cuittet S-t*a1., 1980, Kurtak.e!*;1L., L9B2) and therefore might represent an inportant operational question. Special stud.ies were undertaken to obtain d.ata on tLre transrnission of .0-yglyullp- by ti:e different vector species. Such data could. not be obtained frorn results of routine d.issections by @P sta"ff because of the d.ifficulties in identifying the ad.ult fenales of the d.ifferent species. Id.entif ications Iclentification of thc flies r+as nad.e accord.ing to norphologic'aI characters such as tlie wing tuft colour (cclour of the setae of the stern vein) (ilurtat< et a1., 19BO), the colou.r of the posteranial hairs and the arculus (lur:g and Peterson, 1980) and the conpaction of the antenna (Qrirt6r6r6 -qJ--4. , 1977). Furthernore tne fenales were categorized. norphor:retrically accord.ing to their thorax length to antenna 1erlgth ratio r,'hich are highest in I =--{gryre.9qp/!r- i-tI!3IIrf , lor.rest in S.-.sanct!pau1_ir{$-.-.s,or.rlc.rense and. inderned.iate in flr--g-qqasfm(carns et ai., f-ge?f Species comp*osltion of biting fly populations The speci-es conposition of biting fly populations caught at vaxious seasons of tire year at various sites in the Progranne area in lvory Coast, Togo and. Benin (figr:re 1) are surnna::ized in Ta.bles 1 arrd 2. 2Seasonal changes of species corupositions were particularly obvious in the Uestern pari of the P::ograome aJtea, .in Ivory Coast. At the begin::ing of the rainy season, s. damnosum/s' SiTb.aSuIr nere the^predo- roinant species, Ie.tokaha, Site ffi l'tarcfr-and-ad t'Iaseadougpu, Site I{t in May,td. J,:ne. trbon July to Noverober the population of S. aam:osuno'/ s. sirbanr:m fenales decreased t"'Tn @"";;""g;;) ""rd f% (fri6-ro-aoueou' ;i;;":' lilr"" rtion,of s' i'a'mrosr:rP'/s, Pirbarrr:ro wag gomernrhat higher-than that of S.jranctipauli/S. soubrensg in 0ctober' dffit; s.-;*r"iir"ti " ; becane the pretlorirr*)I p?*]i: SeaSonal chapges of species composition were also obserned at T6t6tou (Site J) on the River Mono, Togo, whele the proportion.of^ Natural infections 1rhe stuclies cagied out by Traor6 et a1.r(f9gZ) U tvory Coastl.r(f 1,1 at the three sites jn Guinea-savanna (fig,1ae 1) shoved higher infection rates of S. S- sirbarn:m than of S. sanctilaUfileoubrmse,' In S-""*r"tio.Ji76.-to"Ut"".":.t"r.uiea iron 2ol/o in t'tay to aLoost 100% lnS. aawrosum/S. sirbaaun vere founcl' in the Norttr of Benin ai CUasqq (Sit@ .A few- S, eanqtiBuli;:^;;;";""J2-.r-re-gl.,'24/a/st, Ga.ms S! 4., 19BI) reachetl as far Northa:;#"*ffii; ;) "" it! "rr" ,i'rer svst6.-verr-r?w s', =san9*+Iggly ,S. soubrense fenaies were found" on the M6 River at Md Briclge (Site D) and' ;ffic) i" toso. S. sqBamosup was ttle p_rcdornincnt speoies on the M6 at the two sites. Sl a"#i-u.,-E ri"U*,r- polulations d.ecreased fron nearly 45% to alnos@ Qean during the ralny season.At Tizao-, further south almost all biting flies caught belonged to S- souanosu.m. fboro the 'vJest to the Eastl at Landa Fozancla (Site f), - fAa;Ano-('site G) and B6t6rou (site II) a progressive iacrease in the proportion of S. d.amnosr:ro/S. sirbanum could be obserred. S. d.a,mrosum,/S. s 2.7/o out carried. In both sPeoles the than in the dry season. ected and 1. of 2 O15 pa,rous flies Qo.ilr) d.j.ssected were infective larva1 sta^ses of O. vohmlus. infection rate was higher in the rairry season fbaor6 ot aI_. (f9ge) obserued. a pronounced. zooph-ilic tt3slrPrefereace of S- sanctiilauE/S. .orrt=".r"" wlr-ile only verl' few S' damos,lpn'/sir- Pinun i"rEie i-t". They also forrnd S' sanctiPag+i/S. soubrense females to concentrate near therivers showlng a limited mae"-cy tmisperse fron the water courses. At NtGolodougou in a clistance of 100 metres fron the river only 5. flo of the fenale for:nd close to the water cou3,se were caught. !\:rthe:more, they obSerned' a reduced longevity of S. sancjipauli/S. soublelse^females. Theee observations may erplain tr,e rim s, s?Pcti8*u11(s.=p?rtrinse in thl area investigated. For this species pair tfre MIP calculated' bry . 1y;";-S!}. (ileZl was 10.? for ihe rainy aeason (rnean of {- nonths) and none during the drY season. ,Results of &issectiong of flies caught tturing the rainy season in Togo and Senin ancl analysed by Garms 9!3., (f9eO-e2) and Renz(ryAl) a^re sumnarized. in Table ]. In all cases the infection rateg of S. d.amrosum/S. sirbanr:m were higher than those of S. squanosua'and. trro@er than Iho"" of S. sa$ctipaTfm-ubrense.Theproportionofparousf1ieswithinfectivestagesof9g@was higher in the f1y populatj.ons investigated by Ga.:ms et aI. than in those stud.ied. by Renz. Consequently the estimated number of infective larrraeper 1O0O females also differed consid.erably, particularly in regard. to F. d.amosqg/Q._rsirbarn:n md l:--g@Etsg (raure 7). Eowever, bothpu"i r although showing lower infection rates, ca;ried marry more i-nfective than S. d.arulosum/S. girbarnuo and. S. , squaaosum and therefore plays the most important role in the transmission of O_.lqlU$gg at least jn the eouthernpart of Togo and. Benin. Ihe number of F. sanctippuli/S.. soubr.ense females caught in the northern parts of the two cor:ntries are too sua1l to draw any conclusions. Eowever, as the numbers are very sma1l their veotorial role is certainly limited. 4rpgrimeatgl ilf ecttons hcperinental infections were perfomed in lvory Coast and by Barbiero (tgAZ), Orna, Togo to evaluate the ability of vectors species to transrn-it loca1 and "importedrt fo:sos of 0. voIvulus. In Ivozy Coast fo:mer studies canied. out jn zone (Hrilippon 7977, Qui116v6rd t979t and. others by hod.rhon e.!=!. (l!8r)(igez) and n6z-(rgar) i" the forest and pre-forest showed. an inportant experimental vectorial capacity of [. sanct sou supporting wo:m br:rdens of 11 to 15 infective larvae per fIy. In the humid-savanna Prod thon g! gI. (198r) observed a parasitic load of L-lggglllg*iS. soubre+se fed. on loca1 volunteers of 5 to B third. stege larvae. me propoiifon of infected. flies ranged from 2?/o to 806 tleBending on the microfilarial Ioad. of the voh:nteers. In Togo transmission erperiments by Barbeiro (f9eZ), Oroar (f9ge) and Renz (lggl) have revealed striking differences in the varj.ous parasite- vector complexes in the northern gavanna and. southerrr foregt. 1lhus, the experimental vectorial capacity varied considerably aoongst the diJferent specj.es or species pairs of the complex, in regard. to the ability to ingest ancl support developuent of 0. volvu1us. At land.a Pozand.a (Suaan- savanna), similar rates of infections ana fow parasitic loads were found in popuLation of S. d.amosum,/S. sirbarn:m (infection rate {0-60/o7 parasitic load. 2,2-).2) and rate 411L44%t puasitic load J.z) tea on i Iocaffiffi At Djodji (forest) microlilariae froro a volunteer of the savanna area (Iand.a Pozanda) d.eveloped very poorly in the IocaI population of S.- squa&osUg (infection rate 6/*Ldp6, parasitic 1oad., L-r). Ilowever, n:-&ofif-ari.ie from a Ioca1 r'forestrr volunteer developed. relatively well in the 1ocaI populations of S(infection rates 2O'fi, parasitic loacl {.9-5.1). S irom Djodji and T6t6iou (pre-forest) supportla & S. soubrense of microfilariae of volu:rteers of the forest zone and from the savanna zone. fhe was the 4 infection rate and. parasitic load. withtrforestrt microfilariae 6l-65910 and. 4.1-7.8 infective larvaer with 'rsavannarr microfilariae figures weTe ,1-45% and' 4.2-9.6 infective la.rvae. Previous stud.ies on the histocheraical differentiation of Onchocerca laryae in S. daronosun connplex species in the OCP area have revealed that the proporTios,sE irfective larvae, morphologlcally ind.istinguishable but enzymatically separable from O. volrmlus varied- greatly ln the &ifferent regions of-tfr" erog3aeff;;;A? Ga,rms flef ). The propor- tion of non-lp@g larvae and the flies carlTing them were highest in the West and d.ecreased. progressively to the eastern areas of the Prograrone. fhe overall percentage d.istribution of infective larvae enzlrmatica3-Iy separable fron S_Jg!151!gg. from positive flies caught-in Togo averaged8.91t they were for:nd in 8.ry6 of the flies dissected (0nar l9B2). However,thepercentaged.istribrrtionofnon.@1arrraevariecI' greatly jn the flies of the d.ifferent catching sites. At Landa Pozancla(situ i') trr" percentage of larvae,/flies concerned was lQ.2/9.? whereasit fdteiou (Site.t) ii was 2,4f4.O. A11 species and species pairs investigated., S. da.mrosum/S. sirbarrunr E:.-ggll@ and F. sa9ctipalJ-iS. soubrense cffi-stages of non-gglg1$ filarial species. C presence of non-volvu1us filarial larvae indicates the zoophilic tenrierrcy of the species or species pai-rs and their involvement jn the transmission of ani-mal filariae in both the savanna and forest areas ln Togo. Conclusion Since progress had been mad.e recently toward.s identifyrnq fenaLes of the S. aamnosun complex by using morphological characters (Qui116v6rdg!,1.,msr9}o,Dangand-Peteisonr9eo,Ga.:enss-eI:'19B2) it tecane possible to d"ete::nine the vectorial capacities of single cytospecies or species pairs j.:: mixed. populations. Such investigations were of particular interest in Ivory Coast ancl in Togo and. Benj-rr because of the d.ifferent bioclimatic zonation and. the variety of S. d.a.mrosum complex species. Special attention was paid. to the species pair S. sanctipauli/S. soubrense. With the appearance of resistance to temEphos and chlorphoxim of this species pair the questlon arose whether the females of those flies no:ma11y occ\rrl$g in the forest and pre-forest zone arld being potential vectors there, would also be potential vectors of 9:-@ of the sava;nna axeas particularly inprotected savarma areas of the OCP which they invad.e cluring the rainy season. 5Although S. sanctipauli/S. soubrense was found to have a high experimentat v@ in rnunia sava.nna areas in Ivory Coast (Frodthon e g., LgBr) their natgral vectorial capacity is ve11r 1ow and theilplEy-hard.Iy any role in the transmission of 9. volYlr}us, i1 iti" r=et (tiaor6-et al.-, l9B2). The 1ow vectorial capacity, although highly receptive to saGnna 0. volvulus microfilariae, is due to a pdrol*""d. zoophilic behaviou-rr a reduced longevity and a reduced' potential to disperse from rivers. Lxperir:nental infections have shown a high receptiveneql of 0.. volvulus of both the forest and. savanna area by S. sanct In Togo and Benin the results.by Gar"ms S! gl. (f9gO-eZ), Barbiero Oqaz). omir Ogez) and nenz (198J) suggest that the species pair il-"*"t+ru.rfi/,1S. "orrU=u"." (partlcularly the Beffa fo:m, Mered'ith g!9l', ctor of 0. volvulus in the south of Togo and Benin. The vectorial capacities seem to te slmilar to those found jn the pre-forest zone in Ivory Coast (qrifferrgr6 g at., L9-77). The results also ind.icate that sinilar high capacities are naintained. when the speciespair invades northeln areas Curing the rainy season. Results of the However, the numbers of fl-ies caught in the llorth wexe always therefore the species pair may not play an inportant role in and" trans- same areas as Populations of in the 16wer Mono and 0u6n6 1ow the is,mission of 0. volvulus in northern Togrr arld Benin. More d.ata needed to draw further conclusions. In Togo populations of S. damrosl:m/S. sirbarrum are found further south than in Ivory Coast occr:rrlag jn tbe S. sanctip-au1i/S. soubrense, particularly rivers. Although jnfection rates have always been found higher in S. d'annosun/ sanctipauli/S. soubrerlqe, the parasitic load wasS. sirbanum than in S. The vectorial capacity of S, squa,rnosu.rn is sti1I not very c1ear. Garrns et aI. (f9gO-gZ) found. infection ia{es to be lower in S. pgr}a.nosumS 1980 82 i rat tl p n tiran in Slaar,rrosun/S! slqbg4um but higher than in S. sanctipauli/ up to six tjmes higher in the latter species pair. The find.ings j:r southern Togo are of particular interest si-nce both types of transmission, transmission by savanna species artd forest species are founa together. The findings might suggest that the d.ifferences in transmission are duo to the physiolory of the flies rather than clue to d.ifferent strains of 9.g}41}gg. It is 1m1ikely that in the case of two existing fo:ms of the .parasitejn the hi::aan poprlation in these aleasr the microfilariae of the forest form should be ingested and developed only by {orest flies and the savanna fo:m only by savaina flies (Ca:ms g[ "1. , l9e2). * j, . 4** ""r/ . "f=U*rl* Q. F?nctip?ul-i/S. soubrense. Re ltSrfirrnd nearly the sa,me infection rates in Elffifr7S. sirUarur, *rd ll $. sgua,nosum. Th". parasi.tic load 3fS. squanosum and S. da.mto but lower than in S. sancti was of about the sa.me value 6ALI species ox species pairs showed. a zoophilic tend.ency as tJrey all were fourd. to ear:ry. oncbgggrgg Ia:rrae en4matically sepa.rable from 0. volrn:-lus (Omar, 1982). However, nothing is &:rown about the host preference behaviour of these species. Stud.ies are continui::g in ord.er to obtain more d.ata and to get more info:nnation on the vectorial role of the varj-ous S. dannosuE couplexln Ivory Coast, [ogo and. Beni.::. References BARBIXRO Y.K. ( 1982). Stud.ies on the vectorial capacity of roembers of the Si-qg]-iun dagnoqrq conplex in Southern ?ogg. Report OCPACU, utito @tober-1,{ necember 19s2). IAI'IG P.[. antl. PHIER.S0N B.V. (fgeo). Pi.ctorial keys to the rnain speoies ancL specj.es groups within the @ [heobaltl oonplex occu-:ring in west Africa (lipt@ Troper:ned. Parasit. , 11, 1U-120. eaat{s n. ( rgTo). Sinu].ium Parasit., 29, 481-49L. GAfiMS R?, CHE(E R.A., IffiNm U" (f929), A stu y of the reinvasion in the Southeastern areas of the OCP. IJEO/OCP Working Grorp on Reinvasion. Ouagadougour ]-1-1, November 1979t 64 pp. GARMS R., CHW(E R.A.1 IGRNffi. U. (f9eO). Investigations in 1980 on the reinvasion bnr Simuliy4 4ggnosun s.l. into the Easteln areas of the 0CP, includ.ing experimental treatnent of potential sorrces. Repor! OCe/VCu, \tHO Consultancy (B uay-9 August 1980). GAIMS R,, ICmNEn M., CHEKE R.A. (1981)" Sttrd.ies i.n 1981 of the reirrrasion by Sj:ur:Lilg_@ggg s.1, into tbe Eastern area.s of the OCP and. the resrrlts of erqperi-mentaL treatments of potential ssurces. Report wPfVCv, MIO Consultancy (rO ttay-fJ Deoember 1gB1). GARMS R., CIIEKE R.Aor xERNm. u. (f9e:-). Contribution to the transnission of onchocerca vo1.r*.Lus by different species of the -EIIE4S tlamrosu4 complex irr. Togo and Benin. 1980, 1981. Supplenent to Reports of L979t Use of norphological charaoters damrosum s.1. populations in West in the stu(y ofMrica, Troperuned. 7GAIMS n., CHHG R.A., YAJITIE CnG.r SOIJA S. (DAZ). ILre occur":eence and movements of different members of the S@ complex in Togo arrd. Benin. Zn Angew. Zool., W GUrII;ET P., ESCAtrTRE H.e 0UEDnAOGO M,, qUIHjETJ:ERE O. (r9eO). Itlse en 6rriclence dture r6sistance au t6m6phos dans Ie complexe Si4!4iu4 dapqrosum, (S, sanctipauli/S. soubrlnss) en C6te O'ivo:-re-(Effiu ffie se d.ans 1a R6g'ion du Bassin de Ia Volta). Cah, ORSTO{., s6r. &:.t. m6d.. et Pa,re,sito1., ].,B? 29t-299, KIIRTAK n., CIIEDRAOGO Mo, OCAAI{ M,, IEIE 3", Q}ILLE:'I f. (f9Oe)o PreliminaAf note on the appearance in Ivory Coast of resistance to chlorphoxin 5n Sinr:-l-ir:n soubrense/.sarlctipauli lanrae already resistant to temephos (Abate(R)) wEo/vBc / B2.B5o. MEBEDITH s.Eno,, cEurE R.Aor caxMs a. (f9el). Yariation and dlstrihrtion of foms of Sfum4hgq_Eorr!trgnEg ancl S. sanctipaull in West Africa. ann. trop.Mmss)l- CIIIAR M.S. (fggZ). Reporf on studies on the histochem:ical tllfferentiation of filarial larvae in Srur4iUs_damosun s.]. and. on the vectorial capacity of the main species of the conplex ln Togo and 3min. Report -OCr/vCO, \llEO Conzultancy (t5 nugust-I5 Decernber 1!82). O,IAR M.S., GARI,IS n. (f9ef). Histochemical cltfferentiatisr of filarial larrae for.urd in Slm:lium d.a,urrosrrm s.1. jJt West Africa. tropeermed..Parasit., 12, 25 - PHIIIPP0N y. (t977). Etude de la transnission dt@(r,e"cturi r' l98r) (ireroaiooa, 0nchocef.iar"@ Theobald, 1905 (Diptera, Siuuliidae) en Afrique tropicale. Travan:x et Documents de ltORSTOvI, 63, lOB pp. IA.OITHON J., HEBnAHD G", IRlTD'HCli J.I{o, COUREI O, (].?Al). Etud.e de ]a. capacit6 vectrice erperiaentale de Siqf.lir:n soubtq1se-Eigr1iUq s+Ictipaqli en zone de savane humid;@r-Edt"-d]@L luo !7'rRTo/Rap " 83, qIIILEVERE D., SECBAN Y,, PmIIIR]'EZ B, (tglt). Etude du comploce Sj-utrlir:n da.mro-gu* en Afrique de lt0uest Y. Id.entification rnorphologique d.e fenelles en C6te dtlvoire. Tropenmed. Parasit., 28, 2M-251. BQUIffiEVERE l. (t97il. Contributim b lr6tnrd.e d.es caract6ristiques taronoroiques, bio6colog:iques et vectrices des membes du oomplexe Siurrlir:n d.a.mrgsr:ra pr6sent en C0te dtlvofue. franarr:c et d.ocr.rments de lrOBSTCIvI, 109, 1O4 p, REIIZ R. (L98il. Stud.ies cnr the rej.nvasion W @ s.1. S. da.mrosum cmBlex in Togo and Berin'1982. -,- eonffict (zg ;uly-Jl october 1982). Report ocP/VcU, tEO tRAOnE S., EffiBAB.D G., ntIVAtr J., FAYE O" (fgee). Etucle d.e 1a blo6ootrogte. et d.es caract6ristiques veotrices naturelles des femel-les clu ginrpe Sirr.r1j.r:n soubrense-sanctipauli en zone d.e savane.tlo.tZffi i:eto tbe eastern a.reas of the and. cn the vectoriaS. capacity Onchocerciasis Cortrol Programe of &ifferent'species of the Egoo!El{ro BTlap{ . -\_ ${o +t \*-.-.-._v If, ,2*\r. :rffif .fv7, "l bo 5 U ,i atl tA B I <ag c: 4J = c} u(}(.) x,u(,o -(J H Ek -oo uFF3J Uo f, G(:,oE& 6g = 6 Eu =E 5o a tx e(,or J(:, et-26O v't nt =oc:u() 6 (Jz6 Co # / EEoJI {t+t Fa bg!e ,'l $fl Elxl ,d$l il tr -i Id ^ (e i. ili TabLe 1 STECIffi COYIPOSITION CF BITll{G FtY POPUI,ATION AT VAN.IOUS C.qTCHING SITES N'[ TOGO AND BMTnI (GAXMS et al. L7BZ, RENZr Wel) YEAiT MOI'ImI ]r0. 0F rE4Al,ffi D(A].IT\ID % oF TorAr PozuLATroN D/ vrt da/si sq sa/so Gbass6 Garms (a) et al. Land.a Pozanda(F) Garins et gI. Renz Barbiero B6t6rou (H) Garms et aI. Renz Iand.a Mono (G) Ga:ms et al. Kaboua Garms Renz (r) et aL. Diod ii Rerrz Barbiero T6t6tou Garms (.i ) et al. Renz Barblero 1981 1980 Lge2 I982 L979 1981 1982 1980 1981 j.982 1982 t9B2 1981 L9B2 L982 i,{ay Jrrne JuIy August Sept. May Jr:rre July July-Aug. Oct.-Dec. June July I'1ay Jrrne August Sept. July-Aug. May June July July Sept. July-Aug. JuIy-Aug. 0ct.-Dec. I,lay Jr:ne July August July-Aug. 0ct. -Dec. 1o 51 t6 52 51 50 r91 ].55 550 107 27 5, 12 L45 1t 11 52t 477 181 100 5t 150 502 444 421 623 lBB 124 2tg 55l- ,18 too 100 100 100 100 B4 54 5o 5L Q.tul 51 77 100 92 97 60 44 64 4L 2B t5 5 11 4 oU BO 41 E) 2 0.5 U 0 0 o 0 t6 46 50 15 46 7 3 o B 0 t7 40 1' 52 65 0 0 t1 7B 72 0 0 n 0 2 t9 o 0 0 U U o 0.5 0.5 1 o 1o 20 U o 12' 15 1 I 7 e4 95 75 1B 20 20 ,7 95 97 95 BO Table 2 SPECI$ C0FrrrcSfTIOli 0F BITIIIG FOPULATIONS AT r\,,/0 cATCIiniG srTrs 1l.I ivoRY 0OAST ([R{ORE et al. 79e2) SITE I'l0itj[tl No. oF f'm,lALIS ffiA}IINAM 75 OF TOTAT POPUI,ATION dafsi saf so Massadcugou Nr golodougou Latokaha 1981 t982 1-982 tg81 l-9E2 September October May Jrrne Aug.-Sept. July October November Janua:ryr llarch I{arch 1M 664 t 000 t16 61L 684 566 74 l45 4L3 57 25 57 /b 59 7 5 t9 2) 25 22 91 75 41 24 1t 91 95 B1 97 75 7B 7 Table z niFEoTrolis (nlr.'gcrIw STAGES) rouro BY GArllS et a1.(1980-1g82) AlrD RSTZ (t982) rN S. SANCTTPAULI/S. SOUBRA{SE (golsa), S. DA}NOSU},|S. SIP-BANUi{ (dalsi) AidD S. SQUAI'IOSII{ (sq) Di T0G0 AITD Bn{D{ G}fi4S et al. tgBz, RINZ 198' No. of parous flies d.issected. 9/o of parous flies with L1 ],Iean No. of L) per fIy Estimated No. of LJ 1000 parous flies so/sa d.a/ s1 sq Investigator 505 481 4.8 1.9 7.4 8.2 152 ,24 274 250 17.5 5.o t.9 1.4 519 B4 r107 291 7.7 5.l- 2.4 L.4 182 72 Ga.rms et aI Renz Ga:ms et a1 Renz Garms et a1 Renz Gar"ns et aI Renz