Evaluation in a river trial of Carbosulfan 20% ME on S.damnosum s.l. larvae

EVALUATION IN A RIVER TRIAL OFON s. DATINOSUH S. L. GARBOSULFAT.I 2OZ MELARVAE Technical Report OCP/IRU 90.02 Insecticide Research Unit Onchocerciasis Control Programme Programme de Lutte Contre l'Onchocer@se World Health Organization Organisation Mondiale de la Sant6 Bouak6 - March 199O a Lc,.lc iiealth Or'!-1ni:ation - Oni,rcae|clasis 3oi^,trol FroG.aflie Insecticide Resear,-:'Unit ccP,r I RU,r 90 . oePage 2 ABSTRACT EVALUATION IN A RIVER TRIAL OF CARBOSULFAN 20% ME ON S. DAMNOSUM S.L. LARVAE+ Authors: M. Ocran, C. Back A 20% Vl/W micro-emulsion formulation of carbosulfan was tested in a srnall river of southern COte d'Ivoire. The Mpedo River had a very low discharge (0.103 m3ls at the time of the trial and was colonized by larvae of Simulium yahense and S. sanctipauli. The dosage rate was 0.05 m9 a.i./Lx10 min (=15.5 ml of formulation), which corresponds to the operational dosage for carbosulfan in the OCP area. A first treatment showed no effect on a breeding site located 2.8 km downstream which was heavily colonized by Simulium spp. larvae. A second treatment gave 99% and more than 99% at two heavily colonised breeding sites located respectively 100 m ano 400 m dowrrstream. It is concluded that the carry was between 400 m arrd 2.8 km. This is at least equal to the carry of the operational 25% EC carbosulfarr in similar conditions. There was a visible impact on small fish, freshwater prawns and surface-dwellinE insects, which supports the restriction of carbosulfart to rivers with high discharge. RESUME EVALUATION EN RIVIERE D,UNE FORMULATION EN MICRO-EMULSION DE CARBOSULFAN A 20% SUR LES LARVES DE S. DAMNOSUM S.L. Auteurs: M. Ocran, C. Back On a test6 dans une petite rividre du sud de la C6te d'Ivoire une nouvelle formulation de carbosulfan. en micro-6mulsion d 20% M.A. Le d6bit de la rividre Mpedo 6tait faible (0,103 m3ls), et les gites 6taient colonis6s par des larves de Simulium yahense et S. sanctipauli, Le dosage 6tait de 0,05 mg m.a./Lx10 min(=15,5 mL de formulation), ce qui correspond d la dose opdrationnelle pour le carbosulfan dans la zone OCP. Un premier traitement n'a eu aucun effet sur les larves de Simulium d'un gite situ6 e 2,8 km en aval. Un deuxidme traitement a donn6 99% et plus de 99% de r6duction dans deux gites situ6s respectivement it lO0 m et 400 m du poirrt d'6pandage. La port6e efficace est donc comprise entre O,4 et 2,8 km; ce qui est a.J moins 6quivalent a celle du carbosulfan op6rationnel(CE d 25%). On a constat6 un impact visible sur les poissons, sur les crevettes d'eau douce et sur les insectes vivant A la surface de l'eau, ce qui supporte la restriction de l'usage du carbosulfan aux riviEres d fort ddbit. tThi. do.r.6nt do6s not constitute a fcrmal publication. It should not be revieHed, abstracted, quoted or translatecl Hithout the agreement of tJorld Health organization. Authors alone are responsible for views e^pressecl in signed articles. .Norld H6alth organization - onclroc€rciasis cont?^ol Programme - Insecticide Research unit oc? I LRUI !,tt.ttz ?Page 3 EVALUATIoNINARIVERTRIALoFCARBoSULFAN20%ME ON S. DAMNOSUM S.L. LARVAE+ carbosulfan is one of the operational insecticides used by ocP; its use is restricted to a few weekly cycles of treatments in the rainy season' and mostly inareaswhereSimuliumdamnosums./.populationsareresistantto organophosphate insecticides. out of five experimental carbosulfan formulations supplied by FMC1 which were tested in troughs (cf' reports OCP/IRU 89'04 and ocP/IRU 89.06), one was selected for further evaluation in a small scale river trial. The purpose of the experiment described below was to assess the carry and impact on non-target fauna of this new 20% W/W micro-emulsion formulation' The results of impact studies will be treated irt a separate report by the Hydrobiological Surveillance Unit of OCP' The trial was carried out on the Mpedo River, a small river of the forested areaofsouthernC6ted,Ivoire.Thisriveriscolonizedmainlybytwocytospecies of the simulium damnosum s./. complex, s' yahense and s' sanctipauli' Two treatment points were selected (see map in Antrex)' the first one being. 2'8 km upstream of the first breeding site, arrd the second 100 m and 400 m upstream of the first two breeding sites. r Forthefirsttreatmentpointtherewasonlyone.breedingsite2.Skm downstream, and for the second two breeding sites respectively at 100 m and 400 mdownstream.At3oomdownstreamofthesecondtreatmentpoint,agutterwas praced in the river 49 h before treatment and manuaily coronized with rocal lotic insects. supports to which simutium larvae were attached were marked and their density evaluated 24 h before treatment' on the day of treatment (9/2/90) discharge,measuredwithanott(modelc2)currentmeter'wasestimatedat0'103 m3ls.The dosage rate fcr both applications was equivalent to 0'05 mg a'i'/L for l0min,oratotalls.45mLoffOrmulation,whichistheoperationaldosageused byoCPforcarbosulfart.TheformulationwasmixedwithSLofriverwaterand appried with a Hudson sprayer fitted with a fine spray nozzre. Apprication was done in 3 min ro s and 3 min zz s for treatments 1 and 2 respectivery. water *Thi" do"raent ooes not constitute a formal pub'lication' q".i"o - ". trans'lated without the agreement of t{or'ld iesponsiote for views expressed in signect articles' It should not be reviewed' abgtracted' Health Organization. Authors alone are 1 Frlc Int".national Amouroussion, GR-1 AG,AgriculturalChemicalGroup'AgoraCenter'lO-l2KifissiasAvenue'Paradissos' INTRODUCTION MATERIALS & METHODS 51 25, Athens, Greec€ V^JDrld Health Organization - Onchoce.c'i aSis C'iirL' ul er'ogramffle - InsecticiCle Research Unit ocP,/IRU,/90. O2Page 4 quality data and treatment details larvae on marked supports were was monitored bY surber sampling, in the gutter. are shown in Table 1. The density of Simulium re-evaluated 24 h post-treatment. The impact drift sampling and measurement of detachment RESU LTS There was no detectable detachment or mortality of Simulium larvae at the breeding site located 2.8 km downstream of the first treatment point (Table 2). At 1OO m and 4OO m downstream of the second treatment point there was respectively 99% and more than 99% detachment/mortality. Immediately after application a spotty film of formulation showed at the surface, from which surface-dwelling insects like gerrids (Hemiptera) tried to escape. Small fish and freshwater prawns were visibly affected for a period of 3 h after treatment. DISCUSSION The experiment on the Mpedo River has shown that the carry of the 20% W/W micro-emulsion ranged between 400 m and 2.8 km at a very low discharge. This carry is at least equal to that of the operational 25% EC operational formulation in similar conditions (Table 2). The visible impact on non-target fauna supports the restrietions put by OCp on the use of carbosulfan; which is limited to river with a discharge greater than 70 m3/s. ! CONCLUSIONS AND RECOMMENDATIONS The new 20% W/W micro-emulsion formulation of carbosulfan was shown to be at least as effective as the current operational formulation; but further river tests are needed to determine if its carry is superior. River trials by Lahr and Everts (19g9) showed that with the 25% EC carbosulfan at 75% the operational dose (O.OS mg/Lxl0 min) caused no serious impact on the prawns Caridina africana Wahle (1986) on the other hand found a rapid and acute drift of aquatic invetebrates 45 min after application of carbosulfan 25% EC in gutter. Further analysis of the data from the Mpedo trial will provide a better assessment of the product and its selectivitY. s|orldHealthorganization-onchocerciasiscontrolProgramme-lnSecclcloeR€E€.. ocran, M.H. & c. BaCk. 1989. Evaluation in troughs on s' damnosum s'/' larvae of 3 new formulations of carbosulfan (carbamate)' Report OCP/IRU 89'04' 6 pp' ocran, M.H. & c. Back. 1989. EvaluatiOn in trcughs on s' damnosum s'l' larvae of 2 new formulations of carbosulfan (carbamate)' Report OCP/IRU 39'06' 5 pp' LahrandEverts(1989).Evaluationofshort-andmedium-termeffectsofweekly permethrinandcarbosulfartlarvicidingonCaridinaAfricana(Atyidae)in the Kan River, Ivory Coast. Unpublished doc. University wageningen.33 pp' wahle, B. (1986). carbosulfan on non-target aquatic organisms' Unpublished OCP/IRU doc. 9 PP' Page 5 LITERATURE CITED a TABLEI-TECHNICALDATAoFRIVERcoNDITIoNSANoAPPLICATIoNTECHNIQUEoFRIVERTESTS Wff H CARBOSULFAN 20016 MICRO-EM U LSIO N ( 1 8-OGl ) TEST NO FORMULATK'N RTVER RIVER CONO]TiONS APPUCATION METHOO 2 3 4 5 -t6 tie :slo R90 01 (19/01/eOi i R9o-02 ( I 9/01 /90) Carbosulfan 209'o M.E 1 8-061 Carboeullan 200.,b M.E. in 5L 68 4 rtver : water Mpedo 25030 26 f63co :, Hudson i Sprayer 1 3 min on foot : l0 6ecs 300 m 24h 267 rn 5L iver Hudson Sprayer on foot 3 mrn 2.5 km 22 secs : 24h Mpedol 0.103 Uo 36. water( I 8-061 l. Diocharge (m3/s) 4. Turbidrty (JTU) 7 ApPlicatron Method 10. Time tletween APPlicatton and Observatton TABLE 2 - (Datel R9o-01 1 9/01/90) R86-07 (03/03/86) Q5ohEC Lot 001 9) 2. Ternp6rature oC 5 ConductrvitY gS L Duratron of APPltcatton 004 3pH 6. Oilutron befote applicatlon 9. Distance f rom APPlicatton Point to f rrst breeding stte RESULTS OF RIVER TESTS WITH CARBOSULFAN 200'6 MICRO-EMULSION (18-061) COMPARED WITH OPERATIONAL zfo.hEC NoTEST 10006 at 300 m mtnimum Ellcctive carrY (Obtarrce wlth t0otl6 or marly 100|16 300m+370 t_..___---.-- I -_1._--- River Obctatgp (mUa) Ef(ectq on S. damnoaum 6.1. at YariuJt distarres bebw treatment Point No effect at 2.8 km0.05 Doe o')(mgful 0.r03 400m+990.6 at 100 m; 99 + o6 at 400 m0.1 03 005R90-02 19/01 I I -t ff) a, + t-9 o ct Y a 9t ul .t o d -5d1 ._ a '_tttttl aa aao O zd I r{ a, 1, t9 o ,oo r'Fr al r,I+;\919G €dt .c e:.tlr I I d t oz e to $-s $$ o o, \ r, .! h .lr o9ld.!1,l<rt+{, Pd3'sa .6 t,l- 'I 3'r' ) ,[i i: I 'ie'i; tE16orlnr^ F-, krict t.' rc € o e t rF t6 aa{rl o : o t, d v U) Ea bo cl €clroJl t{- :.lo(9L9 o o o- E : oo+++!O*I o o o, f x c{ ooA t- Vf < o U :D- a( o tsf d IJ Hd oo trlq- '{, / t *nli * + G3 o '4 (9 .r' \ qo cd ..->P Hd +- v'l ba I \ \ OCP PROTOCOL FOR CLOSED-CIRCUIT TROUGH TESTS ANNEX BRIEF DESCRIPTION. Thi6method,whichlrasclevelopedforocPbyor'H'Jamnback'igbasedonasystemthatheanclMr'R' caugler used extenstulrv in Ner york state. rt has b€en furth€r modifi€d by the ocp rnsecticide Re- a€archTeaminUot",-iogo'Larvaecollectedinthefieldar€allowedtoattachonaremovableplate .lying in th6 botcom of a trough Hh6re water is recirculatod by a Pump' The plate iS transferred to a EecondtroughHheretheinsecticidehasalreadybeenmixedintotherecirculatingwater.Afterlo minutee th€ plate iB transferred to a third trougtr Hith cr€an iater. Mortarity is counted after 2'f hourB. TECHNICAL DETAILS. The troughs usod are constructed of aluoinium and painted white' The troughE are 80 cm long' 15 cm r{ide and 6 cm deep. They are closed at the upper end. At th€ lower end, a constriction or lip' 15cmlonE,E.scmwideand2cmdeepisattached.Aremovabl€metalplateregt6inth€bottomof this llp. water iB pump€d into the cloaed end of the trough and flot{6 over the plate in he lip into a resorvolr, to b6 aspirated by the pump again. small etectric cantrifuga'l Pumps Hith a ctischarg€ of about 22 L/min are LJ.o, .no ihe velocity of water over the attachment plate iB about 70 cmls' For the attachn6nt and obs€rvation systems, the reservoir is a plastic naste-buck€t holding 60 L of Hat€r. For the exPo5ure 5y3t6m, a 1o L enamelwar€ pot ie ueed as a reservoir to reduce the amount of insecticid€needed.RiverUateriausedatallatagesforroutin€tests.Itscharacteristics it.ip.."tr"€, PH, turoioity and conductivity) ar€ mcasurect and noted'Larva€arecollectedbyremovingtheirnaturalsupportafromtheriver.Theyaretransported in ptastic uaEs pracio in an icebox. care i3 taken to Beparat€ the larvae from the ice by a 'lay r of fresh 1€ave9 Or grasa. Although the equipment can b6 us€d at the riv€rgide using a portable g€nera- tor, thie typ6 of test i6 ugually aone in a laboratory ihich may be at Eotl€ distance from the col- lectins f,l"t1rt"'r....ion Hith th€ attached larva€ is e1a::1 ::..:":-::::ty"l:-t:::::'.]n:^:ti;:: ffi::- ra.l.ly leav6 tne vegeiation to s€ok a "t.on!." current and-thus attach to thc plate of th€ lip' |'hich ha3 th6 higheBt velocity in the trough. Tn! '1".r". ar€ left lor 24 h to ensure firn attachment' Lar- va€whichpupat€Cturingthisperlodareeliminatedjustbeforeexposure.Theplat€usuallycontain6 .lori roo t.irr" larvai and aeveral hundred young larvae' The.larviclde formulationa are "pp.op.i"1"1y diluted with distill.d Hater immodiat€ly prior to the tc5t. Th€ quantity necessary for the iowest concentration i6 add€d by pipott€ to th€ reservoir of the exposure trough Hith the pr.p "'nning' The insecticid€ i€ allowod to run for 5 min to obtain a uniforn diEp€real. eiiiiion.l insecticide ii added to th€ Bao€ aygtom to obt'in the higher concentra- tions ina Ti?"il"it;n" atrachm€nt troush ie now carefullv'tift€d out and plac€d ln tho €xpoaure ffoush t?;."T.'ffilfJti,l;,["il]'"lt.H[ period ar6 cousht in a net attach€d to the rip or th€ trough. Afterth€€xpoBurePeriodth€plateandth€n6tar€tranBferredtoaholdingtrough.Atthe end of a 24 h oba€rvation period, tn" o.iiat"d larvae in th€ net, as Hell aB any d€ad one. 6till at- tach€dtotheplatcarepreBervedinatcotrorforcounting.Afir6tcollectionisgonerallymade2h after expoBr". "in"t iost larva€ d€tach in trri. period and th€ larvae nay d€coopose if left dead too long. Th€ living r""raa aro killed witrt'hoi *.i"" and also preBerved in alcohol for counting' The ::*:",:t.?:?mi"ri'*il'i":r""::i"::;:: iij:ii:lr":l*;i:'*.m^r'.*'f.ttL's:"::l"u: ,wrrJ \ except for thc."nt"ii-*n.re tney ar€ included in the numb€r surviving. Thc u.ual conformation of a te6tB iB a range of 5 concentrationB and an untreated control rith 2 repricat€s at eacn concentration. percent mortality iB carculeted at €ach concentration and th€ concantration/rnortitiiV "ef"tion is €stablished by probit analysis'