Treatment of Sassandra tributaries (Guinea): Monthly report, May 1985

W,, From Mr F.C. Hleszak VCU Consu1tanty'r/estex our ref. 525/v qJ /$M/az. 3 MEMORANDUM To Dr B. Philippon Chief VCU Attention Dr D. Baldry Date a .h:ne 1985 Your ref. SUbJCCI TNBAT].IINT OT SASSANDRA TRIBUTARIES (cumra) : MoNTHLY RBPORT, MAY 1985.Originator Successful helicopter treatments have continued through the month of l'lay. fhis combined with a poor (or a very late) rainy,6eason has 1ed to satisfactory entomological results being obtained not only localJy but aleoin the exiating OC? area. Pont Routier on the Leraba rivqr for instance recot- ded its first f\ of the year when a solitary femaLe was caught in week 22. Within the locaL zone the point is clearly demonstrated at !,tassa-dolgg! (River,,Sien) Iis?._l, 4A, ?t Nicolodougou (River Basbe) Fiss. A, 9,and Niamotou (River Boa) Figs 3; Ii where a cIer.r suppreds,Ion is evident fromprevious years. The new\y treated rivers Dion at Tere (Fig. 8) and Gbanhala atGbanhala (fig.13) even in the lack of adequate precontrol data show a markeddecline in DBRts following treatment. Whilst it was hoped that the annual reinvas: orr' into the OCP zone emanated from the Cminean rivers, it is clear that the results presented herein confirms this since, the effective control of these rivers has a vride reaching effect well into the OCP &reao Ttris point is typifie-d-by the results at l,tassadou6ou (Iig. Z) and more northerly at NtGapye (Fig. L0) where the peak reinvasioi period (weeks 18-20 in previous years) appears to have been fassed vrithout a sin61e fly being caught. On a wider scale it is interesting to obserwe the excellent resultsbeing obtained much further north in lG1i, La Faya for inbtance has stiII to record its first f\y of the year. These detaile vril1 be further elaborated uponby D.G. Zerbo in his ana$sis of the eva'tuation. Hotlever, despite the overall good results two rrproblemlr areas havebeen identified' fhese are Badala on the Biver Bagbe and further north and to a lesser extent Lamodou on the River Boa. The Lamodou resulta are in fact only very slight and since tend tomirror those at Badala which is geographically S.tV. alont the path of the ITCZit is tempting to conclude that the increased flies are arriving from the eame6ource- Therefore, for the purpose of this discussion the same iogic wiII sufficein both caSeso From the be6innin6 of l'lay the f\y populations at these two sites( refer to graphs 1A, 5) have in genlral incieasea and ftuctuated aror:nd muchhigher mean dai\y values rvith hi6h proportions of parous flies, f'our posoibleBources were identified, thus , .../.. o -2- 1) Tfre Iiivers Bagbe ;rnd Boa. 2) The tributaries at the upper Ba6be. 3) The untreated River Bafing ana its tributaries,4) Tfre untreated Loffa river system. As the Bagbe and Boa are treated. successfully and the majority atthe flies are parousr the possibility of these as being the source can be nrledout. The tributaries of the upper Bagbe, name\r the l,lb6o and Debe were includedin the weekly treatment cycle from week 21. Foltovrin8 tvro weeks of treatmentthere has been no appreciable improvement. As such tfie River Bafing ( and itstributaries) is progralrmed for treatment starting veek Z), coincidentatly at atime when prospections revea'ted the onset of bretd.ing neces6atating itrstreatment regardless. The Bafing Seographically looks the most likely source since thenatural bamier, i.e. mount Tetini,/Branton and the c?raine de Dahatini has abreak creating a natural corridor to northerly migrating flies 5ult eoutt otBada1a. The final possibility is the Loffa river system, from which pros-pections during April and Mqy revealed heayy infestations of Sirufi", uo*andYahenssl.Initia1workonthef1iescomingtobitemanat@ metric an{ysis (ttrora</antenna ratio) init:.If1y revealed S. damnosum s.I. and, @r but further vrork arso revealed. ugr.rolrn, .rra yor,EiilE5!ffi-t;;Loffa system cannot be rured. out as o po"EfEffioce rffipoor resurts atBadala. With the treatment of the Bafing in the coming vreeks the problemshould be a little dearer, unfortunately the Loffa systei if it should requiretreating regardless of being in a particularly difficult area to treat is alsooutside of the present OCp area. The treatment failures of B.t. on the Sassa:rdra at the beginning ofMay clear\y manifest themselves on thlmost easterly catching points of theGuinea rivers. Refer to r,rassadougou (Fig. 4), t'lrcorlaougJ"-lFii. zl) *ra-wiurnoto,,I *. - \\'t'l$o )).'lhe most like\r cause of the failure tras degredation of the B.t.(Tehrar) due to.a-ae_and proron6ed exposure without use in the or" ;;;#;"r-peratures. The labe1 on each drum clearly states that rractivity may be impairedby prolonged storage qt above )2'ctt. Unftrtunately, some of thl cheminal hasbeen stored for over 5 months, in ambient temperatures in excess of 3r;; i;-black drums where it is reasonable to assur" it'l" insice temperatures reach lo'cor more. -It is difficult to know what to do to alleviate this problem butclearly something is needed to be done to avoid a sirailar occorance. A list of aerial prospections as carried out in IIq1, is included(Annex 1). with the addition of i'ir Fiasorgbo" una his tean at oclienne to givethe larvaI cytotaxonomic identification "rra tt" ,liIso? ur.& u;iII undertake adultidentification by morphometric analysis ( tr,orax/ant"n',ol.dr,ti;i ; consise pic-ture is being compiled for the Er€ao Refer to I'ie . L2 r.rhere t' e resuLts areshown on a map of the area. Positive.p.rospections this month have lcd to the inclusion of therivers Gbanhara, Gboroni, Gbe, Gben, Dgpur^Mboo,.suessou, Bafin6, Gouan, Bogho,and Koue into the treatment rycIe for the first time" 3eiause tf,e majority of aaa -3- the e>rperimental area is now treated an operational circuit has been proposed(see memo at Z9/5/85) to help helicopter lo6istics. As indicated in the April report helicopter operations have continued smoothly vtith no operational problems having been encountered or envisaged. The use of the dribbler/B.t. system has 6iven much better'd.istribution at Abatein the water than so1e1y using a Bx nozzle. Although there are a few rrtric}grrlgitesr in the main the whole area is easily accessa.ble tq airborne treatmenttactics. Applications have in general tended tol,,ards tl;re "Iightrr treatmenttactics as described by Dr Kurtak. This regime being cor,giclered as more appro-priate for a new treatment, as it gives a scientific b?'tF i-ine from which iub- sequent treatment strategies car be based on. At the moment the whole area is treated at intervals at one week.However, obsenrations by Dr Agoua (oe/nac 4.11 - ocp/B3.tz) on the lengths oflanrar life (damnosum 6.1.; sirbanumr. s?nctipauri, soublense) on the riverBagbe in l'tay fffi=""ared tfET the mi;l;ilil-j;va1 life vlq6- Ir-u* day; i; ambient water temperatures of a?'- l.l-'c. rt is therefore,tempting to suggestthat future treatments (particularly during the attack ptia"") "o.rla ue ilacedfurther apart. Not only would this be as eificient biollgical)y but it would also have a reduction in costs. An 8-8-12 day treatment cycl" io" instance wouldgive a reduction in costs of 25?6 (natary, pers. comm.)o However, further information on other species and other rivers inthe area and for different times of the year is cllarly required before a:ry firmfecommendations are made. A further consideration to increase operational efficienry in the area would be the installation of add.itional fuel/insecticide depots ( to reduceferry flights). T\*o main sites identified. are at'Baranama (n:.ver'Dion) rrra -- -Diassadou8o.u (River Kourai). This subject is dealt with in more detail in rry memo at 29/5. ft is unlike\y that there will be a problem of resistance to abatein the foreseeable future, therefore there is no requirernent or potential forthe use of alternative insecticides. Hor.rever, it vrould be intereit:.ng from anoperational standpoint to know if there is any reduced carry or efficacy in thecooler mountain rivers, particularly in the rainy seaaon as this would have considerable importance vrhen determining future aerial strategies" Insecticide quantities at the moment are determined by observing therivers for'any visible cue that would give an indication as to the rate of f1ow.This method is probably accurate in shaltow areas up to about Z mj/st-;";-"1--'''higher discharge rates there is a considerabre ,argin for error. Currently N rGolodougou (Bagbe) distance upstream. the on\r calibrated water gauges are at Niamotou (Boa), , and Biankouma ( Bafing') which are on\r usefur for a smaLl New gauges at Badala (Ba8be)r Gbeleba- (cuantrala), sanankoro (sankarani), and Diamarodou and Bara:rama (Dion) r.main uncalibrated and are of 1ittle use. Simp1e co}our coded vlater gauges such as tle concrete embankments asdescribed by Dr Subra vrould be very useful-. Perhaps another alternative mightbe a simple colour banded metal pole standing in the river having a float to ...r/... 4- lndicate to the pilot the vrater IeveI (see sketch page 7). \'Jhilst this vrouldgive a clear inCication of the river leve1 it is interesting to speculate how such a device vrould stand up to the onslaught and ravag;es of the elements and a 1ocal population. Enclosure Figs. 1A, 2A, 3, 4, 4A, 5, 6, 6 A ?, B, g, 10, rL, L2, 13.t cc Chief VCU Dr Baldry Dr l,/a].sh Dr Baker Mr Colussa ,/Mr Zerbo ,/ Dr Agoua Mr Wilson A*.s- I Rceccrrrrr- G. e- gutuEY s MADE Dur'^rcr M r9gr 2|5--- Src.n, Kour-.crn, L0l.n , Cr\oZ, Kourari r-<iL.a glr lls l(ou* L^', Gr Z-a-r1oo) e 7 i .-b'o-) -- -qlS Ban. ,. Moosorf o , - B-x'., k,::ororo, -frora r-Koltcrnt-SourSarr-(,.'r!l^ Rt-a-,.a,) tra.l5 Bo€ [ noo- -r-r-l( at 4. :o \o$r-bonrhbg- rro{Jld . __ ta+ [tor:a Sgn+he+ic. p\os*ie . dutctlc Re{e..ab\c hngtil- cptror-rr CteF |o orde in pos'#ianeffiruttg- eosg vicrl Fa rlot, I r primo3.,aolaur- <r- -doodsi:d- -- RQA r^rhilc(t?&a -JAt;ini leve-\^ $ crc{ uer I b t orulge r^) ) 7 o 2,, o l.( I,L l,o .ilhcrtfsor Abatr.. --[ i\nrllon c-hqrl'ldea tn M e oNLY bh,k r,thihr e,{fl!ah e.eA 7z ,D I I Hallrd 1 L.t (- s'a blur +'o E,S 3'O L.S t lgur ,i FO C9 I -11 1 o\ -1' o os N -a d"J C runr.)^ GNJ .E l * I o e 2L €+ I b o3 2 <- t-.. 'f :1.- r.8 <_ IF+ i I 'Ir'y' ^:--, 1oG - (9 @fi I ?1) lD , ::::II -2:=i- +++:i.H:ii -r-.+-- +--++::-:.,'_z: -'.1 .l-1.i..# +-t+ 1 o '{r ;Li !', 'f o. -*- - I _- -- ---- t- Il- -ll I - '---t -- r-. =:r::: -+!+-r - -il:::: :=*-tt -+r- rj++i+;L-- E.## ----t-*::=;---l €_t: _+ -{a _--'l ::;=:::i--' :_-_::r I(, F) .o J ..-- l : L'-::l ir '; --) - -. I I ,- a- bft \ h c H b* \a., \ { $ oC i tr ,o (.s ,u-! 6\ C e5,), '1o.c't r*''< /,) !, /.t: | -)/., --:c ...t l rf ( \ t I +, ltr :-_l -j-:._- -,I - :rl (^, qjo Z-Dxt MEex DtrRs (1 ts l,o tq + 'n m*tDr u -+ 1 f.* l, --- 3 F I TTIl DS cooq+ H b- / \ ' --'P /I FI n / --l I -- t I '; I i -t- -lII d- IJ---- I ri f: -- - ,,--lr' -:'--F -u n 3 o - -. r- - --t- -, --L+.. =:E: -+- -- - t-_-. +*rL-!i*-.#i+F.-t-_.+# *: -- r-- -j -:, ,-:--- i:t---:L I I I I i I I t \ t .; ',9r,', T) (' + 0 -l -: A up n / J-: :t4 I -l I /\ F t* '9- + C t B. 11 la N Ne I oI 3 i) +' o :c I f.-.I/ti-ftt2 I f L\I + $ J 4i4.-lJ-J++u++u* - l-4r---_+!+r--_ _-t--- --l ii-' --i---. r-+-= ---+--- ::--lj::: ,-+-_ ' |--..l- -- - - ..-{-.--r.r- ,i--1,,,r-., L---- -,-,,-+ l;lr: l-tl i-.- -:----- -:-T- -i -\- - 5+ E B ?+:,-_:,i.,,..1,J1 .Jr--rerl ,1. tr'i tr ----+ -- !4; -'i (.'r ,bi"--l/ l, c/l NJ lo , I I I I I i 1 i i : I I 'l I ,j I I I t/r 1, ry nt n (r) rn z a + 'Cr I I I i .r'.l*r-l -.J---i- -.f,+--..(-+*--i-i -*F.!i+r_ -+'*: i+- --.-+ --- ----_--i__- Tl d +P -4 + - -- I,--a - l:- I i l I I --_+++-++_: -l--+--+-r.- I -*t-,--,:---_1-+ +_! , =a-i L- I -- -.i---:-:-:-: i .= -"1;- -. L, I trf \ .J r ,Jl t0 LJ -J : r.. ls{' G .l o H n a I lo," . : ari.F.. t-3d )t J I If-- I I I -rl oh -.+i + . :1--,: ,- . l .N TtI !T .f|J(r a ...-+l+ rI- # 'J--I-J .:=L-: -----+--r =dL-:ir=-=:t:--: =::h:: etr,'" tsl-:-:--:].- -- --l=l: ,t.,-T 1-.-l:_-::.:, i __+_ =_+__ 1-l- ol -a- r.F.g E s $ zzscI3OaflmhI on: aOf, ,.-oI' .Dr ./i nt I n o o tI cr_ lr' f- --'i- --':- -1 '--- ---.tl- -,- I ..-i-- -- -t-- - t,I I I I I I I I -t rF2. , tdIo _sE :U4 -ra f 51trl --t- I I r^i ;l Dt' ---J_ -'l:'. --:- -*-- - ---.- - -- I I I I, + i'o lt )a il Zq 2b Gouon. to 5 S to l7 l+ ,r, 13 Lo 2e_ I -1 d o -os \el i : Tl 6 o 3o zo f, rLr ii 'r1 ..7r{'* -.++*++lgL -*l---li-f r+-:++*+ :=:I1:t --irF-L+ +j4 -;'!:-: Ij.i--:": i-- ,i' I --_-_, +___.J ' :-j --: ,--- -1 -- I :,-- ' '-- r lTr .' lo LE, 2 3A- 3V - . -- -'- -:-_- .1.- -. - .1 ' .--l Kouna i =-EhC --_-+__ --1- :t::-:_'- 5h, ..] 'rl C) -.J *- .H i**=I:--E + --+-- J-ts-- -..1i( EJ++ J--_ =--:l:--= l-_t. _ -- [i -f-_:_: # .l t, + I i I I' I I t I '',- | I t f, F a + af ae tt o n rJ I 1 - -: l.- I : 6 ut .J Ut oZ \CD ITI ?N! -$tfl fr a ,r _.--+-- t -_ _-;i_-t_::_; . ! I l-a-t--- ---l -. -- l --* --- --, _:.! . : -_1 .t t_ -l - --t-_--- -_ t-- _ --' I t \-, -{- J. J rI:t:,' (ro .,\...., -- LANbeovEta u I {vt';IrI .3 T .t o ,o o- N r 6' sO N) o \N (n1 0h )E fn tnx # n rrt ! or* N P AI N |.) o N m t^) o (^l t, ur F (^t[- (,{ A I N r. a 11 ,] tu =(nr f n o r'! r , ...i n 0 o a:*, ..:, -. qr o o I\r -G G- a- \!o r) lr) N) -t h)s }Ss 8 lrr h) (, + tA o td { o t $.. *t F c. t a il q b rn F 7( 76d@ EUt(o (D C9t' @ T @f ---1 ) 'lz Co-lp -D Llc If' I -r ----L o(rt -T) _C t D _{: o J-- L Lcl 0 1 P l^ t { a + I .a --.11\J \- t3 rts + ,( \ \ ,ri .r'- ., l -' !- ,il ceq(no(9 o $ @t @ .€ a 6r o N o FrAa 7:"q c-"b FZIC,Z fir) ,g( li*L,* 5 ll. o Nr o NN N * \) c H 6 Lltl t!f \r) C w \ { .t f I ./ *->r Co 't oTt tz > o oC (, Ln I ']D o! ;+ o J 0- Lc) 0 ) o 1,1 h o 0 .+ L '(' L .F , N ( 2 rr1 FN n a o i -ii---+-: 3prctrt CotvtPcStrtoN i'ra.,- Fe t #; d 5.-deeaeg.!l:-r d 5. oirbqnorn t+e"'*r- 5.qo l,rgnse 5l . SOubre h5€ lOoruA S. soncl rmoli 'J d , aat r.! I o I tr +. J tJ 6 oJ \- IA ll, 1 w:r iJ Jda z 9a + .fo a/ , o v N+ I Bor tr Jt Loe,o I I I I I , I u(ll oJ) B ^q8E /t { lo ? I Blphlq a ---+--.Otx- r l. l: t- ll ii I eo|,icar Lr iv I e*;1* 3oelle * i: -.ff,.*q6h t a I --'r,--i - --- +- - . *xp,.qft;r . - ,/ Cr .-.MEAN o oanfoEEK r, L, o o t 'fr 3 l* i.) l---'F f v '1' Fraer Usc,K oF t7.cer 4cdr -''-_ !---- -t_,---_____ i_ t- . -i --.--_ -.-_-___-_,:-_--.- 'i I I I -- - ----.1 i j _- T -,--:---- _ I _l_-_____ - ___ _l .- - r-:; al==: .- l. - i--.-. -.-!. . - r. +--- ,BgJ Ir.dt,t , i. ) -'. r.l i I I I I I I IL- I I I I