activities ' - - IN

ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRAMME DE LUTTE CONTRE L'ONCHOCERCOSE EN AFRTQUE DE

L'OUEST

ANNUAL MEETING OF HYDROBIOLOGISTS Kara,

23-24

February

1990

Openine

of

the meetine

At

9 a.m.,

Dr

Quillevere,

Chief, VCU,

welcomed

all

the participants on behalf

of

the Programme Director and wished them every success

in

their

work.

The

following officers

were then elected

for

the meeting:

-

Chairman:

Dr

C. Back, while waiting

for

the arrival

of Dr

C. Leveque, member

of

the Ecological Group and Chairman

for

the meeting.

-

Raooorteurs: Moussa Elimane Diop, ichthyologist, and Fanfode Konde, invertebrate biologist (Guinea team).

The

following

agenda was ^proposed:

l.

Presentation

of

VCU

activities '

2. Presentation

of

reports

of

national teams (Cote

d'tvoire,

Ghana. Guinea, Mali) 3. Geographical and biological distribution

of

certain species

in

the Programme area 4. Other matters

5. Discussions between the Hydrobiologists and the members

of

the Ecological Group (26/2/90).

Dr

C. Back, Interim Chairman, asked each participant to introduce himself and then gave the

floor

to

Dr

Quillevere to present the activities

of

VCU.

I.

1988-1989

ACTIVITIES

OF VCU

The Chief

of

VCU dealt

with

the

following

points

in

his presentation:

(a)

Larvicidine in

1989

It

was characterized particularly by the stoppage

of

treatment

in

the

initial

area, the complete coverage

of

the southern extension, the coverage

of

Guinea and Sierra Leone, and the start

of

treatment in Senegal.

(b)

Insecticides used

Five insecticides were used

in

the Programme area: Abate, Chlorphoxim, Carbosulfan, Permethrin and B.t.H.l4.

The production

of

chlorphoxim had been

interrupted.

The search

for

a replacement insecticide was

in

progress. Pyraclofos, an organophosphorus compound, had demonstrated an excellent efficacy during the trials carried out

in

1989 and therefore appeared to be a potential candidate.

(c) Insecticide rotation

The

different

larvicides were rotated according to the hydrological conditions

of

the watercourses treated

with

larviciding suspensions at high

water.

This technique allowed the greatest ^possible

insecticide and

flight-hour

savings to be made.

(d) Reinvasion

This problem was solved by the extension

of

larviciding

in

Guinea and Sierra Leone. The effect

of

the

larviciding

was

felt

up to north-western Cote d'tvoire.

(e) Transmission

The points where

it

had not been completely eliminated were

in

the east

of

the border with Nigeria: but this transmission remained moderate.

In conclusion, the results obtained were good and supported by the excellent entomological results

in

the whole Programme area.

2) Insecticide research (a) New larvicides

A

new pyrethroid,

beta-cyfluthrin

(Bayer, OMS 3051) had been very effective on the blackfly larvae and would be tested

further in

1990.

A

new organophosphorus compound (OMS 3052, Bayer) proved to be ineffective and was discarded.

(b) New formulations

New formulations

of

carbosulfan (FMC

Int.) in

micro-capsules and micro-emulsions were tested in

gutter.

The micro-emulsions would be tested

in river

and on the non-target fauna

in

1990 as well as a

new formulation

of

bioresmethrin

(Roussel-Uclaf).

_New formulations

of

B.t.

H-14 from

the company Solvay were also being analysed.

(c) Research related to aerial ooerations

Diagrams on the carry

of

the operational insecticides had been produced. _{As part}

of

the optimization

of

aerial operations, a discharge forecasting programme had been developed by ORSTOM (IIRSDA Adiopodoume).

A

programme

for

the optimization

of

dosages and

flight

plans had also been produced by the University

of

_Quebec 6 Trois

Riviires

^(Canada).

(d) Susceotibilitv monitorine

The monitoring

of

susceptibility to the operational insecticides was continued

in

the OCP area.

The relative susceptibility to pyraclofos and the other insecticides was particularty _studied in order to assess the risks

of

resistance to this new

product. The

1987-1990 data were reanalysed and stored so as ro

better evaluate the thresholds

of

susceptibility

of

the btackfty populations.

3.

ectivities of

the OCP Hydrobioloev Section

in

Cote

d'Ivoire.

Ghana and Toeo

The OCP Hydrobiology Section continued

in

1989/1990

with

the monitoring

of

the entomofauna

of

the rivers

of

Cote

d'lvoire,

Ghana,

Mali

and

Togo. It

also organized and participated

in

the evaluation

of

the medium-term impact

of

pyraclofos on the non-target fauna

of

the White Bandama. Furthermore,

it

conducted comparative gutter tests

of

new carbosulfan formulations and, as recommended by the ^last meeting

of

the Ecological Group,

pre-larviciding

data were collected on a number

of

watercourses in Sierra Leone.

The entry

of

the routine monitoring data was continued

in

the OCP headquarters in Ouagadougou and, as recommended by the tenth meeting

of

the Ecological Group, a year-book and historical data ^on certain stations were produced and distributed to the national teams.

The monitoring

of

River Amou in Togo had not revealed any harmful effect

of B.t.

H- 14 on the principal _taxonomic groups. The abundance

of

most

of

these taxonomic groups had not changed over the years though there had been seasonal

fluctuations.

The fauna was dominated by the Chironomidae, which could be explained by the use

of

agricultural pesticides

in

the coffee and cocoa plantations

lining

River Amou.

Despite the carbosulfan tarviciding, the faunistic situation

of

the Marahoue had remained ^good.

However,

it

^was observed that among the Ephemeroptera, the Caenidae were now dominant, while in previous years the Baetidae had been predominant. Moreover, a gradual increase was observed

in

the relative frequency

of

the Hydropsychidae on the rocks (after the high water) as well as a decrease

of

the Chironomidae. On the whole, the fauna seemed not to ^present major disruptions.

The faunistic situation

of

the White Bandama

in

1989 was not fundamentally

different from

that

of

1988

The

drift

increased

form

December 1988 to

April

1989,

with

a rock-fauna density which becanre considerable

in

February 1989.

On the Comoe, the use

of

permethrin led to an increase

in

the

drift

index,

with

an increase in young Mockokidae (mainly Synodontis)

in

the

drift.

At

Bamboi on the Volta

in

Ghana, some effects

of

permethrin on the

drift

were observed. As in 1988, a decrease

of

the Tricorythidae and Heptageniidae ^was noted again.

II.

PRESENTATION OF REPORTS OF NATIONAL TEAMS

A.

ICHTHYOLOGY

(l)

Ghana

Three rivers were monitored: the

Oti,

the Pru and the Black

Volta.

The monitoring protocol used was the one established by

ocP.

The catches per

unit effort

(CPUEs) were

in

general low compared to those

of

the previous ^year.

The condition

of

the

fish in

1989 remained in general at the same level as

in

1988. As regards length structures,

for

most

of

the species, they recalled those

of

the previous

year.

The results obtained

in

¹⁹⁸⁹

were therefore, broadly speaking, comparable to those

of

^1988.

(2) Cote

d'Ivoire

4ArsE€

Six series

of

sampling were carried out at Niaka, Cbfue and at the Road Bridge on the Leraba The data analysis showed that:

-

the most representative species

of

the stations were

still

^present

in

the catches;

-

the numerical and weighted CPUEs were not very

different significintly from

those

of

^the

previous years' monitoring;

-

the coefficients

of

condition remained dependent on seasonal variations and hydrological conditions;

-

the study

of

the gonadosomatic ratios (GSRs) indicated that many species reproduced in the rainy season;

Despite the possible harmful effects

of

the larvicides, they had therefore not shown any drastic and irreversible effect on the

fish

fauna.

(3) Guinea

Three stations were

monitored. [t

was mainly

in

the evolution

of

catches that changes were recorded. The CPUEs showed some decrease compared to the previous year although they were relatively

high.

The species-richness showed some stability as well as the mean coefficients

of

condition

of

the principal _species. As regards reproduction, the results obtained corroborated ^those

of

1988. The action

of

the larvicides was not evident and remained to be verified.

(a) Mali

Eight missions were carried out on the Baoule at

Missira.

The results obtained showed a normal CPUE

trend.

The coefficients

of

^condition

of all

the species remained stable.

Study

of

the gonadosomatic ratio made

it

possible to know approximately, at high water, the reproduction period

of

most

of

the species. The species-richness was higher

in April

and October but the diversity was [ow.

ln

conclusion, the results

of

the monitoring

of

the

fish

fauna by the

different

^{teams had not}

indicated any harmful effect

of

the larvicides used. This was important at a time when new insecticides were being introduced

into

the

antiblackfly

larviciding.

B.

INVERTEBRATE

BIOLOGY

(l)

Guinea national team

The invertebrate biology monitoring covered only one station: Sassambaya on the Niandan. Two types

of

activities were carried out there:

-

routine monitoring,

-

special studies on the

drift of

organisms

in

pools and vertical

distribution of drift

Only the monitoring results

will

be presented here. The protocol used was what ^was

recommended by the Programme, but

it

was supplemented

with

two

right drift

collections (500 micron) one hour after sunset.

It

should be noted that the Baetidae (Centroptilum + Baetis), Caenidae, Orthocladiinae and

Chironomini were the most abundant

in all

the samples. The treatment

of

the Niandan was resumed only

in

March 1989.

It

was therefore not very easy to talk

of

direct

impact.

The

different

results obtained

from

the

drift

indices showed that,

in

the absence

of

larviciding, seasonal variations and hydrological conditions seemed to be responsible

for different

fluctuations

in

these indices.

(2) Ghana national team

Despite the decision

of

the Ecological Group to entrust the monitoring

of

the aquatic entomofauna to the OCP hydrobiology section, the Ghana national team continued, at its own expense, the sampling

of

the fauna at Bamboi/Black Volta, Sabari/Oti and Asubende/Pru.

On the whole, the larviciding seemed to have resulted

in

a reduction

of

the abundance

of

the Leptophlebiidae and Heptageniidae on the

Oti

at Sabari, and the Tricorythidae, Hydracarians and Heptageniidae on the Black Volta at

Bamboi.

High

drift

indices were recorded at Asubende on the Pru, these being certainly related to the suspension

of

larviciding on the watercourse

for five

months.

The tnstitute

of

Aquatic Biology, Accra, carried out prospections also on the Black Volta upstreanl

from

Bamboi (mainly Bui area)

in

search

of

a possible monitoring site to replace Bamboi.

[n

the ^absence

of

any adequate site,

it

^was proposed to maintain Bamboi as a monitoring station.

III.

GEOGRAPHICAL AND

BIOLOGICAL

DISTRIBUTION OF CERTAIN SPECIES

IN THE

PROGRAMME AREA

( I ) Eohemeroptera

The results

of

the

light

trapping undertaken at more than 120 sampling points

in

Guinea, Sierra Leone,

Mali,

Cote

d'lvoire,

Senegal and Togo had made possible the establishment

of

the distribution

of

Adenoohlebiodes s.s. (Ephemeroptera: Leptophlebiidae) and the genera Oohelmatostoma and Pseudooan nota

of

Baetidae).

As regards Adenoohlebiodes, only one species

(A.

massirus) was widely distributed

in

the

Programme area. Other species

(A.

rubeus and A. ornatus) were found

in

the forest areas and

(A.

adrieni, A. callasae) were localized

in

the Fouta Djalon.

With regard to the Baetidae,

it

had been established that Pseudonoannota bertrandi, P. muqaninani and Oohelmatostoma camerounense had a wide distribution

in

the whole Programme area. On the other hand, P. modesta was encountered

in

cold waters.

(2) Trichootera

Mr

F.M. Gibon undertook a consultantship

for

OCP on the geographical distribution

of

Trichoptera

in

the Programme

area.

He prepared a report on

it

which was presented.

It

emerged from that work that most

of

the species were widely distributed

in

the

big as well as samll

rivers.

However, some species had a localized

distribution

(either

in

high altitude, savanna, forest or coastal biotopes).

It

was particularly interesting to note that,

in

general, most

of

the species had the possibility

of

colonizing

different

types

of

watercourse.

(3) Fish

Two main types

of fish

fauna could be distinguished

in

West Africa: a Sahelo-Sudan fauna found

in

most

of

the

river

basins (Senegal, Gambia, Niger, Volta, Oueme, Lake Chad and the Nile) and a

Guinea fauna

limited

to the small coastal basins to the south

of

the Guinea ridge, towards the Fouta Djalon and Mount Nimba

in

Guinea, Sierra Leone and

Liberia.

The Guinea

fish

fauna presented certain

affinities with

those

of

the Cameroon area. Some species had been able to reach River Oueme and River Mono.

IV.

RECOMMENDATIONS

A.

Of

the national teams (Ichthvotoev)

(l)

To OCP

(a)

After

using them

for

three years, the teams would

like their

batteries

of gill

^{nets to be}

replaced;

(b) To solve the problem

of

the Zodiac boat in Guinea by replacing

it, for

example, with an

aluminium boat;

(c) To review the question

of

PH-meters which do not seem to be very precise at ^present;

(d) Introduction

of

research workers

in

the national teams to certain data processing statistical methods (factor analysis, etc.);

(e) To collect

all

the data on species reproduction and send them to

Dr

Paugy to synthesize thenl and see to what extent they could be published;

(f) It

would be desirable to establish ^a sort

of

hydrological year-book in order to make available ^to the teams the whole hydrological information on the monitoring stations.

(2) To the Ecological Group

(a) To maintain the monitoring stations

with

the same monitoring frequency; this would facilitate inter-annual comparison

of

the monitoring results.

B.

Of

the national teams (invertebrate _bioloev)

(l)

To OCP

Exhaustive analvsis

of drift

data

-

To see

if

the

drift

could reveal insecticide impact;

-

To choose the best

drift

method capable

of

revealing impact;

-

To continue

with

the

field

(vertical distribution and contribution

of

reach) and theoretical (index

of

aggregation) research on

drift.

(2) To the Ecoloeical Grouo

(a) To choose stations

in

western Guinea

for

the collection

of pre-larviciding

data, considering the fact that some had already been selected during prospection missions;

(b) To replace carbosulfan

with

pyraclofos on the Marahoue to enable the long-term effects

of

the product to be revealed;

(c) To continue the special studies on

drift;

(d) To maintain Bamboi as an entomofauna monitoring station in Chana.

MOTION ADDRESSED

TO

VCU

The national teams seized the opportunity offered by the meeting to praise the efforts

of

VCU as

regards the processing

of

the aquatic monitoring results and expressed the wish

for

that

initiative

to be

continued in order to enhance the quality

of

the progress reports.

LIST OF PARTICIPANTS Cote d'Ivoire

Dr K.

Traortl

Institut d'Ecologie Tropicale, 08 B.P. t09 Abidjan 08 Ghana

Dr E.K.

Abban and

Dr

J. Samman

Institute

of

Aquatic Biology, P.O. Box 38, Achimota, Accra Guinea

M. E.M. Diop et

M.

F. Konde Equipe nationale Oncho Kankan Mali

M. M.K.

Traorri

Cantonnement forestier de

Kolokani,

R6gion de Koulikoro ORSTOM

Dr J.M. Elouard

2051 avenue du val, Montferrand,34032 Montpellier, France

Dr

D. Paugy

Mustium Nationat d'Histoire Naturelle, Laboratoire d'Ichtyologie, 43 rue Cuvier,

75321, Cedex 05, France Ecoloqical Grouo

Dr C. Leveque (Chairman)

Directeur de recherches, Mus6um national d'histoire naturelle

Laboratoire d'Ichtyologie, 43, rue Cuvier, 75231, Paris Cedex 05, France Secretariat

Dr

D. Quilltivere, VCU/OCP, ^{B.P. 549} Ouagadougou, Burkina Faso

Dr

J.F. Walsh, VCU/OCP, B.P. 36 Kara, Togo

Mr

S. Sowah, VCU/OCP, B.P. 36 Kara, Togo

Dr

C. back, VCU/OCP, B.P. 1474 Bouak6, Cote

d'lvoire

Mr L.

Yam6ogo, VCU/OCP, B.P. 549 Ouagadougou, Burkina Faso

Mr

J.M. Tapsoba, VCU/OCP, B.P. 549 Ouagadougou, Burkina Faso Miss K.C. Nignan, OPD/OCP, B.P. 549 Ouagadougou, Burkina Faso