rivers of

WORLD HEALTH ORGANZATION

ORGANISATION MONDIALE DE LA ^SANTE

ocP/vcu/HYBro/84.5 ORIGINAL: ^FRENCH

ANNUAL UEETINC OF THE HYDROBIOLOGTSTS rN CHARGE OF THE AQUATIC MONTTORTNG OF RIVERS IN THE ONCIIOCERCIASIS CONTROL PROGRAI,IUE AREA

Ouagadougou, 20-23 Febuarv 1984 REPORT

A.

INTRODUCTION

1.

The hydrobiologista reaponsible

for

the aquatic monitoring

of

the

rivers of

the OCP area

held

their

meeting

at

the Progratrq"e headquarters

in

Ouagadougou, Upper Volta, on

20'23 February 1.984.

2.

The meet.ing rres chaired by l{r W. Guenda (Upper

Volta).

Mr

c.

}lensatr (Benin) and

Mr

L.

A. K. Antni (Gtrana) were appointed as rapporteurs.

3.

fhe adminietrative head nelconed the participants on behalf

of

the Programqe Director,

in

the

latterrs

absence. He informed the participants

of

the Directorre satisfaction with the good work carried out by the national teams aod stressed the importance

of

their

collaboration

for

the present and future developments

of

the Programe.

this

was

all

the Eore Bo because external cooperation and financing would not

last

forever and becauee each

state would one day have

to

ao8uue reeponeibility

for

the operations previously carried out

by the OCP.

B.

^{ADOPTION OF THE AGENDA}

4.

The hydrobiologists adopted the folloning agenda:

Opening

of

the meeting.

General presentation

of

^VCU

activities.

Report on the fourth meeting

of

the Ecological Group (Bouak6, 2L-23 Septeuber 1983).

Report on the

activities of

the national teans.

Report

of

research on the enticholinesteraae

activity of

the

fish

brain.

New larvicides tested on the non-target fauna.

(a)

Reeults obtained using the

traditional

protocol.

(b)

Proposed new

protocoll

technique and results.

Plan

of activities for

1984-1985.

Any other bueiness.

Recomendations.

1.

2.

3.

4.

5.

6.

7.

8.

9.

The issue of thir document doec not constitute

formal publtrcation. lt rtroild not be rwiewed, abstract€d or guotd without the agrcement of

the World Healfi Organization. Authors alone

are responsible for vicwr cxpressed in ^signed

arthles.

Ce dooment ne comtituo pas une publication.

ll ne doit faire lbbjet d'aucun compte rendu qr rtlsumd ni ^d'aucune citation sans l'autoriration de l'Organisation mondiale de la Sant6. Les opinioru exprimdes dans les articles rign& n'engagent euc leurs auteurs.

ocP/vcu/BYBrol 84.5 page ²

C.

GENERAL PRXSENTATION OF VCU ACTIVITIES

5.

^The situation since the

last

^meeting

in April

^{1983 was reported uPon.}

6.

On the entomological

Ievel,

the situation rras the best since the

start of

operations in L975. Transmiseion coul-d be regarded as interrupted

or

as brought down

to

a tolerable leve1

over 902

of

the

initial

area.

7.

The excellent entomological situation

in

1983 had been oade possible by the benefit derived from a better knowLedge both

of

the bio-ecology

of

the vector aod

of

^methode

for

the application

of

insecticides, taken

in

coojunction

with

the shortage of rrater.

8.

Confirmation

of

these good tesuLts was provided by the medical evaluation. Thus, the incidence

of

the disease waa zero over 902

of

the Programe

area; all

^{children below the age}

of five

rrere free

of

onchocerciasis, and the overall prevalence

of

the disease had also declined over the ^same

area.

Reversible eye lesions were regressing

in

the _Protected zone.

9.

^Good reeettlement

of

the valleys ttfreed"

of

the vector ^and an increase

in

the aoount of

Land cultivated along the

river

baoks are to be noted

in

^some zones. Neverthele8o, as the Ecological Group has streesed,

it will

be necessary

to

follow

this

recolonization attentively insofar as landscape damage could cauae serious ecological disturbancee

in

the

localities

concerned.

10.

Of the 22 ^OOO km

of rivers in

^{the OCP area, 600 km were treatgd}

at

the time when the

rrater level was lowest, 13 000 km wtren the spate was

at its height.

^Temephos

ie stil1

^used

for

three-guarters

of

the

zone. In

the south-east, ^v*rere straiuq resistant

to this

larvicide have appeaied, Teknar

is

used

at river

discharges

of

up

to

200

#/".".

Above

that

level, chlorphoxim

is

substituted inso

far

as the resistance

that it

^inducee

is

less stabl.e than

resistance

to

^temephos.

11.

Reinvasion problems

still exist in

the west and south-east. This problem could ^be

partly

resolved

if

Ereatment rrere to be extended

to

the Southern and Western extensions.

This

will not,

hotever, be possible

until

the Progrme ^{has two} effective replacement

insecticides

for

temephos

at ite disposal.

Experimentation rsith an adulticide wae already

carried out

in

Mali

last year.

Further experimentation

will

be conducted

in

Togo

in

the forthcoming months.

L2.

^A

pilot

study

of

remote t,ransruission using Argos buoys as an ansver

to

the use

of

too

litt1e or

too much larvicide because

of

the time between the reading

of

the water level

gauges and treatoent,

vill

enable

this

latent period

to

^be reduced as much as

possible. If

successful,

this

technology could be applied throughout the ^Prograu e.

D.

^{REPORT ON THE FOURTH MEETING OF THE} ECOLOCICAL GROUP

13.

Items discussed by the Ecological Group

of direct

concern

to

the hydrobiologists rrere

read out ^(Anoex

1).

fhe hydrobiologists took careful note

of

the remsrks -ede.

E.

^{REPORT ON THE ACTIVITY} OF THE NATIONAL TEAI,TS

14.

Ivory Coast

(a) Fish:

The results appear

to

indicate a continuous decline

in

catch per

unit

of

effort. In

general, the fishing

is

^poor even

for

the professional fishermen

at

^some

stations.

^{Ttrere also appears}

to

be a probleo over

recruitment.

^{Ae regards} the fecundity of the main species, the laboratory work

is still

not complete.

(b)

Invertebrates: Even although

all

results are not

yet to

hand, reference has been made

to

the

relatively

harmlessness

of B.t.

E-14 with regard

to

the non-target fauna.

15.

^Ghana

(a) Fish: Activities

^were

caried

The data obtained

in

1983 do not indicate NevertheLeos, there would

at

^{times aPPear}

(b)

Invertebratest Although

non-target fauna, ^some taxa such as

affected,

particularly in

the Oti.

appreciable influence on the

drift 16.

^Benin

decline

in

aeetylcholinesteraee

activity

temephos

for

eight years.

ocP/vcu/HYBrol 84.5 Page ³

out

in

accordance with the protocol as

laid

^down.

a

fall-off in

^{the numbers}

of

certain ^species.

to

be replacemeot

of

^{some epecies by others.}

temephos does not aPPear to ^{have any} drastic

effect

^{on the}

Leptophlebiidae (Ephemeroptera) and Odonata geeu

to

^be Abiotic factors, especially water

level,

^{have an}

index.

Fish and invertebratee3 The collection

of

pre-treatnent datar which

is

continuing, shows the coneiderable influence

of

hydrology on

fish

cetcheo and invertebrate populations.

L7.

^Togo

(a) Fish:,

^A prelininary

list

^hae been produced

of

the fishee

of

the Volta and l'lono

basins.

This

List

^{remains very} incomplete becauee baeed solely on

gill

net eanples.

(b)

Invertebrates: Ae monitoring was not begun

until April

1983 the

results

^{are very} Limited, but they should subeequently provide good knowledge

of

the invertebrate comt"unities

inhabiting

rivers

thet ^have not yet been treated.

L8.

Upper Vo1ta

Invertebrategs As processing

is

not yet complete the results cannot be regarded ae

definitive.

Neverthelessl there ^nould not appear to have been any faunietic changee by comparison with previous year8.

19.

Overall the results show that population structure

or

^sampling

is directly

influeoced by

the bad hydrological conditions that have been a feature

of

recent

years.

The nearly identical results obtained

in

treated and untreated

rivers

Leave us

to

^asalrrtre

that

the

larvicides ^{employed had}

little effect.

As regards fishee, there

is

^some inforrnatioo

to

^shou

that

a considerable

fall-off in

catches has been recorded

in

Senegal and Mali

in

^areas

outside the OCP

area.

Thie poor general situation therefore emerges aa a

direct

conaequence

of

the drought that has exiated

for

^aome years

in

West Africa.

F.

^{REPORT OF} RESEARCIT ON THE ANTICHOLINESTERASE ACTIVITY OF THE FISH BRAIN

20.

Fieh taken

in

the Wtrite Volta

(tita

and T. galilaea) have not exhibited any

thie river has now been treated with

eignificant reduction rraa noted

in

any fish

release. It

^{should be noted}

that in

no caae

against the insecticide lrave.

wtratever

its

location

relative to

the point of were the

fish

^able

to

take avoiding action

2t. In

the Black Volta,

fish (T. zillii)

^{were placed}

in

cages

0, 0.5, L,

2 and 5 km from the temephos application

point. gnry-aGactivity

lras measured 24 and 48 hours

later.

No

22. Brief

information nas given on experiments carried out

in

an aquarium

in

the

laboratory.l

Chlorphoxi., chl.o.pyriphos-methyl ^and piriniphos-methyl bring about greater acetylcholinegterase

inhibition

than doea temephos. Likewise, the time taken

to

return

to

^a

normal vaLue

is greater.

Ilowever, no

fish

mortality was noted although the cerebral enzSmatic activi.ty

of

individual

firh

was no more than 44-552

of

normal

for

the three larvicideE coupared with temephos.

1

Pellissier, C.,

^Leung Tack, D. & Gras, G (1983) Action du t6n6phos sur

lractivitd

ac6tylcholinest6rasique du cerveau de

Tilapia

guineensis. 3Ene

partie:

action conpar6e du t6n6phos

et

de

trois

insecticides de rbmplacement. Toxicol. Europ., Vol. V,

No.2:

^53-69.

ocP/vcu/HYBro/ 84 .5 Page ⁴

G.

^NEW I,ARVICIDES TESTED OUT ON THE NON.TARGET FAUNA

23.

A

brief

account was given

of

the various phases passed through by any new

larvicide

that looks promising with respect

to

the

vector. It

was recalled

that

the OCP laboratory

in

^Lom6

t as engaged

in

testing new chemical cornpounds

whilst

the IRTO team

in

Bouakd was evaluating

B.t.

H-14 formulatioos. From among

all

the larvicides tested,

five

formuLations had been the

t6'ject of tests in

the

river r"g"iding

the non-target

fauna:

^two permethrin formulations (Talcord _and Coopex), two azamethifos formulations (53 B and A 5809

B),

and one

B.t.

^H-14 formulation (Bactinos) _.

24.

The two permethrin formuLations tested

in

the

river at

a concentration of

0.015 pprn/tO min exhibited

a fairly

considerable impact on the non-target invertebrate

fauna.

Detachment

of

Ephemeroptera, which reached 90-95%, was

of

the same order as that noted

for

Sinuliidae, the

figure for

Trichoptera was

of

the order

of

60%, and

that

for

Chironomidae 5-2OX.

It

should, however, be noted

that in

the llydropsychidae (Trichoptera) detachment was

practically

^100%

in

the

earlier (lst

and 2nd)

instars. Similarly,

the

Chironooini and the Tanypodiinae, alone among the Chironomidae, rrere

little

affected, whereas

the

drift of

the Orthocladiinae exceeded 70%.

Lastly,

no mortality was noted among fishes and large crustaceans.

25.

A campaign

lasting

eeveral months

will

be undertaken with the Talcord formulation on the Saesandra

in

the Ivory

Coast.

The hydrobiologists

will

follow up the impact,

of

the

first

treatnent and

will

attempt

to

estimate the range

of

action

of

the

larvicide

against the

non-target

fauna.

Subsequentl.y, great attention

will

be paid

to

the aquatic monitoring of

this river

insofar as wtren

this

insecticide

is

used

in

a dose effective against simuliids

it

appears

to

be egually

toxic

as regards the non-target

fauna. It will

not be

until

^several

larviciding

cycles embracing the rainy seaaon have been carried out

that

the hydrobiologists

will

be able

to

take an objective decision on rrhether or not

to

use

this

larvicide which cannot

at

present be regarded as operational.

26.

The short-term impact

of

two azamethifos formulations reveals effects cooparable to thoee

of

temephos. No taxonoxnic group apart from the Simuliidae and the Baetidae

is

reall.y

affected. Similarly,

no mortality lras noted among fishes and large crustaceans. But

for

the

fact that this larvicide is

^an organophoephates compound,

it

could be a serious candidate for S. ^damnoeum

controL.

Unfortunately, given that we are almost cerEain

to

see resistance

eev;iffiE-in

some vector

strains, this

insecticide ^{cannot be regarded as a} candidate to repl.ace teuephos.

27.

The

first

treatment

of

the Sassandra with Bactimos wouLd not appear to have affected the

non-target benthic

invertebrates.

Effects are

of

^{the same} order as those noted with Teknar.

For the moment the search

for

better

B.t.

^H-14 formulations would appear

to

be the approach

to

follow

in

order

to find

an

insectiffie

as a

real

replacement

for

^temePhos.

28.

An account was given

of

a new procedure

for

testing ner, larvicides against the

non-target

fauna.

The

tests,

carried out

in

multiple gutEers, are based on eight hours of experioentation. This eeems a more precise duration ttran

four

^{and 24}

hours.

The research is

initially

based on the use

of

three gutters, one

for

the

control,

^one

for

Ehe new larvicide being tested

at its

concentration effective against simuLiids, and one

for

^{temePhos at} 0.1 ppr/10

nin. It

^has also been proposed

that a

fourth gutter be used

in

^which chlorphoxim

will-Le

tested

at

the same concentration as

that

used

in

the control campaign. ^The impact

nill

be assessed on 4th

instar

Ch".r.top"y"h". larvae

or

on 6th and 7th

instar

S. damnosum

larvae as

well

aa on

all instarilfrffi[ortant

^species eocountered.

H.

^{PI"AN OF} ACTIVITIES TOR 1984.1985

29.

Generally speaking, the experimental protocol

hitherto

employed has been maintained.

Ilowever, each team

is

free

to

^{use other}

auxiliary

techniques provided

that

the required

minimum hae already been

fulfilled.

Furthermore, each team was asked

to

_Present

its

report

ocPlvcu/HYBIo/ 84.5 Page ⁵

in

a more detailed form, noting

in particular

the actual numbers

of

the main taxa so that

everyone

will

be

in

a position

to

understand the conclusions drawn.

30.

The only changes envisaged reLate

to

the choice

of

some stations

in

the Southern

extension

zone.

Thus,

in

Benin, the Lanta

site

on the Kouffo (invertebrates)

will

have

to

^be

replaced by another, as yet unspecified, and

in

Togo the Atchinedji

site

on the Mono (fishes)

will

^have

to

substitute

for

the Kpessi

site

on the same

river.

These changes are a

consequence

of

the prolonged nature

of

the annual drying out

at

these trro

stations.

Lastly, ^. the siEes abandoned

in

Ghana during recent years because

of

roadworks

will

be revisited

because the roadworks are now finished (invertebrates).

31.

The teams working on invertebrates

in

Togo and Benin have asked

that

the teams

of

the

OCP subsectors should continue

to

send them Surber sampLes from

rivers

currently being

treated.

The principle was admitted provided

that

the monitoring

of

untreated

rivers

is carried out and remains the

priority.

32.

Each team working on invertebrates was asked,

in

as

far

as possible, to measure current

velocity at

the

level of

each Surber sample taken and

to

cease giving a blanket

velocity

for aLl samples.

It

was further recormended that when the rocks vrere covered with Tristicha

t1ifariathethicknessofthematformedbythep1antsshou1dberough1y,eas.,rffi

T6iET-T each sample.

I.

RECOMMENDATIONS

33.

The hydrobiologists formulated a number

of

recomendations

that

they would

like to

see

carried out by the ^OCP:

(a)

_They recomended

that

the testing

of

new candidate larvicides on the non-target fauna should not be carried out

until

these larvicides had reached the

river trial.

stage;

(b)

_{Ttrey expressed the wish}

that

the OCP should inform the national teams regularly of fluctuations

in

water level

at

the various stations;

(c)

_They recomended

that

the OCP should

distribute all

documents produced

in

the context

of

aquatic monitoring;

(d)

_They expressed the wish

that

the ^OCP should enter

into

contact

with

toxicol.ogists

to

learn ntrat standard tests could be carried out

to

assess the

toxicity of

^compounds other than organophosphates compounds

for

fishes;

(e)

They expressed the wish that larvicide rres tested

in

the

river J.

^{APPROVAL OF THE RXPORT}

nat.ional teams should be irmediateLy informed when a

trial

^stage.

34.

This report

of

the 1984 annual meeting

of

the hydrobiologists was approved. The report

is

no more than a surmary

of

r*rat was discussed. Greater

detail is to

be found

in

the

individual reports on each agenda item.

ocP/vcu/HYBro/ 84 .5 page 6

The reporE of the meeting of the examined by the Group, which made t.he

that report:

- the Group recoumended that

l'larahoud should be applied

ANNEX

I

EXTMCTS FROM THE REPORT OF THE FOURTH SESSION OF THE ECOLOGICAL GROUP

(nouAxn, 2t-23 SEPTEMBER 1983)

hydrobiologists hel-d in Ouagadougou in April 1983 was

following comments on some of the recormendations in the index of pollution used in the study relaEing to the throughout the Programme area;

when new larvicides are introduced, the Group would like to receive the ^corunents and suggestions of the hydrobiologists so as to be able to assess r*rhether there is a need to alter the monitoring protocol- and to change the indicator species of non-target organisms in the sampling techniques;

the Group expressed the wish to have cournunicated to it all information that the

hydrobiologists could gather on the incorrect use of pesticides in the ^Prograrmne

area;

the Group suggested that for the fut.ure the hydrobiologists should make more

precise reconunendations when drawing up their report and that they should clearly indicate to ^whom these recorunendations were addressed;

on examining the results of the cholinesterase research, the Group noted rdith

satisfaction that cholinesterase activity ^had been unaltered in two fish species taken at random in the treated rivers, even though a reducEion of as much as ^207. ia this acEivity had been noEed in specimens kept in cagesl

the Group noted with satisfaction thet the study on the refuges of the Nzi river

had been carried out. The report showed that rnost of the invertebrate species found in the principaL watercourses were also to be found in the minor tributaries,

even though there were differences in the fish populations of these two categories of natercourse. This confirmed Ehe view that the criteria laid down by the Group concerning the selecEion of new larvicides shouLd be respectedg

the Group had before it a report listing the candidate larvicides provided by

industry. A wide range of these larvicides ^{had been} the subject of initial- selection, which had shown Ehat the formulations of two product.s, permethrin and

azamethifos, were potentially effective against the target organisms while also having potentially acceptable effects against the non-target organisms.

Furthermore, four Bactimos formulations (formulations of B.t. H-14 prepared by

Solvay) had yielded promising resultsl

the Group recormnended that the criteria ^governing the acceptance or provisional rejection of a new larvicide should be sufficiently flexible to enable an opinion to be expressed on any given compound. As a general rule, should the formulation of a compound prove to be lethal to fishes at a concentration equal to or less than

twice the concentrat,ion needed to obtain acceptable mort.ality in simuliids, trials of that formulation ^should be relegated to the lowest priority;

as noted in the previous reports, the protocol established at the outset for the

monitoring of the non-target fauna should be applied whenever a new insecticide is introduced into a river system;

the Group heard a verbal report from the OCP on the use of agricultural pesticides in the Ivory Coast highlighting the fact that appreciable quantities of pesticides were available locally, and that ^some of ^Ehem were perhaps used incorrectly to poison fishes.

)

)

@PIVCUlt{tBro/84.5 Page ⁷

AI{NEX 2

I.984 MEETING OF HYDROBIOLOGISTS PARTICIPANTS

Benin

1.

Mr G.

Mensah

Direction des p6ches, Cotonou

2.

Mr P.

Tauzes

Direction des p3ches, Cotonou

Ivory Coast

3.

Dr K.

Traor6 Lnstitut

drEcologie TropicaLe, Abidjan

4.

Dr A. Yt6

Wongbe

Centre Technique Forestier Tropical, Bouak6 France

5.

Dr

J.

U.

ELouard

ORSTOM, paris

Ghana

6.

Mr K.

Abban Institute of

Aquatic Biology, A,chinota

7,

Mr

L.

A. K.

Antwi rnstitute of

Aquatic BioLogy, Achinota

8.

Dr

J. Sarrman Institute of

Aguatic Biology, Achinota Upper Volta

9.

Mr W.

Guenda Institut

Sup6rieur polytechnique, _Ouaga Toe

10.

Mr

L. Bouraima

Universit6 du B6nin, Lom6

11.

Mr K.

Etou

Direction des productions Animalee, Lom6

ORSTOI.!, Paris

vcu vcu vcu vcu

VCU Consultant

,1

Ecoloeical Grouo

J

L2.

Dr C. Lev3que WHo/OCP Secretariat

13.

Mr B. Coulibaly

L4.

Dr D. ^Peugy 15. . Dr B. Philippon

16.

Dr R. Subra

L7

.

l.tr

L.

^Yameogo