Short term impact of pyraclofos in the non-target fauna in tropical environment

ONCHOCERCIASIS CONTROL PROGRAMME PROGRAMME DE LUTTE CONTRE L-ONCIIOCERCOSE IN WEST AFRICA EN AFRIQUE DE L-OUEST ECOLOGICAL GROUP ElevenE.h session Kara, 27 February-2 March 1990 Doc .0547 / vcu( 1989 ) ORIGINAL: FRENCH SI{ORT-IERM IMPACT OF PYMCLOFOS ON THE NON-TARGET FAUNA IN TROPICAL ENVIRONI'{ENT \ L. Yaroeogo, J .M. Tapsoba and M. Bihoum ocP/vcu/HYBr0/ 89 /\ ,{ \ \ L -t \ \ 2- SHORT-TERM IMPACT OF PYMCLOFOS ON THE NON-TARGET FAUNA IN TROPICAL ENVIRONI.IENT L, Yameogo, J.M. Tapsobarand M. Bihoum Int roduct. ion The search for new larvicides and/or new formulations contlnues Eo be one of the main research llnes of the Onchocerciasis Control Programme in WesE Africa. WiEh Ehe appearance of resistance t.o temephos and then chlorphoxim ln certainforest. cyEoEypes of the vector, Si-mulium damnosun s.1., the selection oflarvicides utilizable in a large-scale canpaign, totally effect,ive on t,he vector and relatlvely harmless Eo the non-target fauna became a necesslty. It is in this context thaE Bacillus thuringiensis seroc,ype H-14, carbosulfan and permethrin were s.EEa-ffin[iany candidate larvicides (Yameogo et a1. 1988). This document presents the short-Eerm results obtained wit.h pyraclofos (OI1S 3040) on fish as well as the non-carget benthic fauna. CharacterisEics of the producr Pyraclofos (ISO draft), wiEh che chenlcal name of (RS) - (g-l-(4- chlorophenyl)-pyrazoL-4'yl-o-erhy1 t-nroul phosphorothioate), is an organophosphorus compound whose molecular weight is 360.80. It is soluble in water up Eo 30 ppn at 20oC, and soluble also in alcohol and acet,one. Its densit,yis 1.27I (28oC). The formulation used in the Erials r{as a 50% emulslfiable concent,rate pale yellow ln colour. It is an insecticide/acaricide produced by the company Takeda Chemical Industries Ltd. It acEs by conEact and ingestion. The dose effective against S. damnosufl is beEween 0.05 ppm/10 min. and 0.1 ppm/10 min. Mat,erials and methods The toxlcity study was carried out ln laboratory and in river using the Eechniques now well known in the Programme area: acute toxicity t,est.s in tanksfor fish (Yameogo eE al. in press), gut.ter tesEs, sanpllng of encomic drifE(Dejoux 1975 and 1980, Troubat, 1980 and Yameogo 1984 and 1988)r pre- and posr- Iarviciding qualitative observat,ions. The species used for the Eests are those representative of rhe study area and which adapt themselves well to the working conditlons. Results and dlscussions A. Impact on t,he aquat,lc entomofauna Gut,ter Ees Es The experiment, which was carrled ouE on Ehe Sassandra, ln Cote d-Ivoire, with pyraclofos batch 039, ln comparison wlth temephos and chlorphoxim ln the presence of an untreated gutter, gave the results whose summary is presenEed in Tables I to IV. , The drifr of the Sirnuliidae was che greaEBsE, even in the control gutter. Among the non-Earget organisms, it was the Epheneroptera (mainly Baetidae) which were affected most, by the larvicides, particularly by chlorphoxim which caused a detachment of alnosE 987" of chese organisms (Flg. 2, 3 and 4). The Trichoptera, on the other hand, were not very suscepEible, with a drift. less than 402 at the doses tested. Since E.he tests were carrled ouE on Ehe same day and under the same condiEions, with a faunal composition conparable from one gutter to the ot,her, che nain facEor t,hat could be the cause of the differences recorded in the detachment. is Ehe nature and/or dose of Ehe lnsect.icide. Thls makes it possible Eo comPare Ehe insecticides t.esEed by a direcE comparison of the Eotal drifE of Ehe organisns in the gutters (Fig.I). Thus, pyraclofos presents here aE the operaEional doses a toxlcity which is between Ehat. of t.euephos and rhat of chlorphoxim. IE acts part,icularly on Centropt,ilum * Baet.is and Pseudopannota which detached up to more than 802 while t,he other organisms, with Ehe exceptlon of the Simuliidae which presented a drift above 4O7". Considering Ehe percent,age of detachment., Ehe classificaEion of theprincipal taxa can be made as follows for Ehe three larvicides EesEed: Cen?r. + 8oelr. Pse ud. Amphi. Orlho Chiro. Tonyt Cheum. Trrco Pyroclofos (lor O39) (O, lmg /l/lOfiin, roo % Chlorphorim (O,O5 mgl l/ lOmlnl too % Cantr. + 8oell. A.eh]. Ionyl. Cheum Chiro. Or?ho. remdpnos (O,lmg /l/lOminl lOOTe Centr. tBoc?i. Chiro. Preud. Ortho. Amphl. Tonyt Cheum. Trico. O "/o o% Ilhtle at the operational doses Centroptllum + Baet,ls were t.he organisms affected most by the three organophosphorus compounds, the classifi.catlon of the susceptlbllity of the taxa varles from one larviclde t,o anot.her for the oLher organisms. 0n t.he other hand, a regrouping of the organisms inEo EphemeropEera, Trlchoptera, Diptera-Chironomldae, Diptera-Simuliidae and other organisms gives the same classiflcati.on, i.e.: Irichoptera (I Chironomidae ( EphemeropE.era ( Simulidaae Flnally, the diagrams on the classlficatl,on of the principal taxa according t.o their suscepEibility reveal two distlnct groups of organisms for pyraclofos and temephos: - CentroPEilun * BaeEis, on the one hand, which are very susceptible and could be affected mosE in the long term by the weekly spraying of these larvicides; the Chironomidae, Cheumatopsyche, TricoryEhus and Amphipsyche, on the other hand, whlch do not appear to be very susceptible to Lhe effects of pyraclofos and temephos and should Eherefore be able t.o withstand the impact of the larvicidlngif ot.her phenomena were not Eo come into play. 0n Ehe other hand, for chlorphoxim, TricoryEhus with Centroptilum * BaeEis and Pseudopannota bertrandi, constituted Ehe nosE susceptible taxa. The Cheumatopsyche and Orthocladiinae reraained at the bottom of the susceptibility scale whlle the Amphipsyche, Chironomini and Tanyt.arsini were moderately affectedin the short term by this organophosphorus compound. It. emerges therefore froro this experlment that all Ehe organisms do nog completely presenE the same reacEion to insecticides belonging t,o t.he same chemical family. Furthermore, generally speakitrg, a marked impact. of rhelarvicides should be expecEed on Ehe Ephemeropt.era in the long Eerm. However, che roonitoring, which has been going on for some twenty years now in the watercourses treated in Ehe Programme area (Yameogo et aI, 1988, Elouard et' al,in press), shows only a rarefication of the Tricorythidae and certain Baetidae species in the worsr cases. Contrary to all expectations, a marked presence of PseudopannoEa berE,randi has been observed in cerLain hydrobiological monltoring stations (OCP Annual Hydrobiology Reporr, i989). River tests The resulEs discussed here are t.hose recorded during the operational trial of pyraclofos batch 082 on Ehe White Bandama during the high-water period. DrifE sampllng with double nets and qualitat.ive observati,ons were the only techniques which could be employed because of Ehe parElcular hydrologlcal condiEions under which the experirnent was conducted. .) ( I )less susceptible . drif c 5- (a) Study of the impact of an operaElonal treatment ' Before EreaEtrent, the appearance of the drtft lnt,ensity,curve was of the classie type; 1ow durlng the day, the drift /ncreased at night to reach 33 lndivlduals per nJ of filtered water, and thenr decreased regularly (rig. 5) After Ereatment, the drift collected for almost, 4 hours is comparable to that of the eve at the same Eime. The drift lndex lncreased only a shorE time before sunset, then fel1 Lo merge with the eve2s biological-activity drift. This increase which occurred only more than four hours after the application of theproduct was not due to a delayed effect nor does iE correspond to the nightdrift. It could be due to Ehe larviciding made at 13.4 kn upsEream, ten mi.nutes before that made at 300 metres fron the sampling point. Twice greaEer than the Pre-treat.EenE night drift, the peak oecurred two hours earller and was lnfluenced by the Chirononidae while t.he Ephemeroptera made up the greaEer part, of Ehe pre- rrearmenr drifr (rig. 6). On t.he whole, the drifE remained 1ow at Ehis station, marked by Ehe abundance of early larval sEages and the almost conplete absence of surface IlemipEera ln the collections. 48-hr drift cycle at 5 kn fron the spraying poinr Just as at Ehe previ.ous station, the pre-treat,ment drift was of the classlc tyPe. It was however more diversified here, lndicatlng dlfferent nesologlcal conditions. Since the nearest spraying point upstream was located at 5 kn fron the sanpling area, the drifr intensity" increase occurred t hr 30 min. after EreaEment, lnfluenced malnly by the Diptera-Orthocladiinae. Of greater magnitude than that recorded aE 300 metres from Ehe spraylng point, the drift inrensity then decreased but anoEher peak occurred ln the night with the acrophase being around 22h00 (fig. Z). The Orthocladiinae, Simulidae, Baetidae (Centroptiluo + Baetls), and Hydropsychidae (Aethaloptera) present drift curves hE@Tffi-6rGE-the same appearance. The Caenldae and Leptophlebiidae do not seem Eo have been part.icularly affected by uhe treaEment. After Ereatment, t.he relative composltlon of the communities underwent an evolution slmilar to that of the previ.ous sEat.lon; the Chironomidae became the most represenEed, followed by the Epheneroptera, the TrichopEera and rhe Slmulildae (Fig. 8). The drlft here was greater Ehan at,300 metres from Ehe spraying point and t.he second peak recorded around 21h00 could be due Eo a combinatlon of several factors lncludlng t.he natural nlght drifE, probably intensified by a weakening of the organisnso and-the effect,s of a second pyraclofos wave fron the r.reatment point located some 20 km upstream., The tesEs concerned mainly Chrysichcys nigrodlgit.atuss Pollimyrus lsldorl (Valenclennes 1846), rwo species quiEe co@ protocol, inspired by Ward-rand Pairish (lperlodlc solutlon-renewal tests. 6 B. Impact on Ehe flsh fauna (a) Acute laboracory toxicity Collections were made erith drift. neEs bot.h sprayings. The resulEs do noE show an increase slight change in the relarive conposirion of the cepede 1803) and n ln the studv), is that of' before and before the pyraclofos in the drlft intensity buE a (La nllo 983 The results (table V) show that pyraclofos presents an acceptable short-term toxlcity on the specles E.ested, compared to permethrln and carbosulfan. However the slopes of the morEaliEy lines show morEality lncreases Ln 24 hours for low dose increases (Fig. 9). Besides, here exposure Eine plays a particularly important, role in the producE-s EoxiciEy level. The longer it is, Ehe great.er the toxlclEy of pyraclofos even aE relatively low speeds. (b) Immgdisg. river toxiciEy Dlrect observaiions made during the larviciding of pyraclofos in river at Ehe dose of 0.L Wl1/10 rnin. did not reveal "n, fish mortality even though Ehe dose at. the spraylng point was almosE Een time-s the operational one. mystus (Schilbeidae) donlnated 1n the night driftUliEffiidae increased ln the post-treaEroent nlght communities (Fig. 10). Schilbebut the proportion of drift. 0n the other hand, the day drifE, solely composed of Characidae, was not lnfluenced by the pyraclofos application. This product does not seem therefore Eo have a direct lmpact on fish in river. The post-treatment decrease in thedrift int,ensity and che lncrease in the proport,ion of Characldae are the main facEs which should be menrioned. While in laboraEory pyraclofos therefore present,s a relatively high toxiclty whlch increases wiEh exposure time, this has not been confirmed by the results of the river tesEs. No fish mortalicy was recorded and the slight behavloural change observed ln the characidae (parrlcularly fragile fish) was very Eransient. Concluslon The results of the short-tern test.s as presented above show that, t.hepyraclofos form,rlatlon used does not have a particularly marked catasErophic iupacE on the non-t,argeE aquatlc fauna. e-The dlsruptlons recorded ln the biological rhythms of certaLn organisms are Eranslent and of a 1ow magnitude. The short-term gutter t.oxlclty for the Lnsectsls between Ehat of cemephos and that of chlorphoxlo whlle fish are less affected by thls larvicide than by permethrin and carbosulfan. However, consldering the solubllity of ln its toxiclty wlth expoeure time, lt rr111 effects well and avold as nuch as posslble operatlonal larvicidlng. AcknowledgemenEs the producE in water and t.he tncrease be necessary to monlt.or Ehe long-term the overlap of pyraclofos waves during Many persona contributed Eo the reallzatlon of this work. We would like to Ehank, ln partlcular, Mr J. WulLlot of therunlversit,y of Lyon, Mr Frank Konde of the Unlversity of Kankan, and Mr B. Coulibaly, Mr B. Dolbezanga and Mr S. Bakayoko of OCP who participated in the data collecElon durtng Ehe operaElonal trial of pyraclofos. The fish specimens were fished by Mr Sinpore who gave us ahighly appreciated help ln Ehe laborarory too. Finally' we are grateful to all E,hose (drivers and Eechnlclans) who, i.n one eray or the other also contributed to Ehe carrylng ouE of these tests. 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Fig.9: Acute toxicity in tonks with P isidori Pyroclofos (OMS 3O4O) OUAGA 05 /88 -2r2 -tr8 - t,4 LOG DOSE(in mc/ t) -016 LEGEND : o-72hr b--- --48hr c....-....?4hr 99,8 99 70 50o/o 30 rO 5 -n -) ro oc(D f o (D ro o,9- ^r E-; > :<J S uio ^z; =1O,;=$ ';'*@a: ioirr : Pox m ip. 5 dr^2 !i; "of N ;tn oft no,ru _oJ N- tot @ o @* @- -gm:-) t- i(D -n -) rD .a C (D r) rD rD ioJqfr 6/ > ofD c > z^ :all oU) -n9rro > x:;':+:. ^ ; @'L; , - d, &-o. oe I r* -a : oo ,, o- m j< lo I ot a o 5o a3) :v o 3393^ a-- al3F Fo L,: .3 yi oJ 1 q Jo a3 l I a a o x ln t; t:l; lH ; $ o J o @ oJ a o P Io>qn ;! /U1 oH; !d rnz .-J N I ru n) o @ @ @ {r I @x (1 rD f l- cl'.1 -l(o l't-Io I r o 3 n nta cn i> m 9fi aZ x ::t o =toU o 6\ .G u(o: ; ! :f I @ 3 F ui. l4 li l; s td ist, t: t: lE la F ! t: lF t: t; r ONCHOCERCIASIS CONTROL PROGRAMME PROGRAMME .DE LUTTE CONTRE L-ONCHOCERCOSE IN I,IEST AFRICA EN AFRIQUE DE L'OUEST ECOLOGICAL GROUP Elevent.h sesslon Kara, 27 February-2 March 1990 OCP/VCU/HYBIO/90 . ] I ORIGINAL: FRENC}I ANNUAL REPORT OF THE MALI ICHTHYOLOGY TEAM ( Summa ry ) llamadou Kossa Traore In all, we undertook elght missions, fron February to October, including four for monltorlng and four for special sEudies. This year we caught 984individuals as agalnst 978 ln 1988. The catches evolved normally fron February to October with a predominance of the Charactdae particularly ln February andApril (Tables I to VIII). Figures,3 and 5 also bear wlEness to the normal evolut.lon of the catches per unit effort on the Baoule. There \{as noirregularlty Eo be reporEed excepL the stlght decrease in the catches of t.he nets with big-slzed meshes in September and October (Figure 3). Specles like A. baremoze, S. schall and S. mystus (Figure 7) evolved para11eL1y, in terms-6f caEch per unit effort (average weight), wich a few except.ions for S. mystus. As regards the coefficient of condition, referring Eo che resulEs of I987 and 1988, it is evoiving favourably for all the species in Table rx. with regard co Ehe gonadosomatic raEio (GSR), its study has made to determine approximately the fecundity period of Ehe greater part of species which is from I'lay to July with the excepEion of t.he Hydrocynus(Tab1e X and Figure 8). it possible the flsh f orskalii As for specles ricfrness, it was hlgher ln Aprll and October (Eig. 9). Thediversity, on t.he oEher hand, was Iow for all the catches since no species repre- senLed 502 of. t.he individuals caughr. Finally, the study of length sEructures or, more preclsely growth, was made wlt.h samples the maximum of which was less chan 30 lndividuals. But, for such studiesr'the ideal thing would have Nevertheless, our studles showed t.he been to have a qulte represenEat.ive number. another; the value of this growth vaperiods (Figures l0 to l5). growEh of many flshes from one month ro rying according Eo the species and the In conclusion flshes consEitute It (the fauna) has The figures in the , we will say that part of Ehe non-Earget fauna which thehas noE been affected by Ehe differenE lnsecE.icide treatments. maintained irs characteristlcs of the ttpre-treatmenE, period. Annex give furEher details.