rife. It in - in of l..t J. 1. in .ORGANIZATION HEALTH

WOR.LD HEALTH

ORGANISATION ^MONDII.LE

.ORGANIZATION

^DE

^LA

^SANTE

ONCIIOCERCIASIS CONIROL PROGPATOIE

III

THE VOLTA RIVER BASIN ^AREA

Originalr

^French

Annual review

of

^{research on}

insecticidee in

^oCP

L9-20

ApriL

1985, Bouak6

(Ivory

Coast)

1.

The annual meeting on

insecticidesr

research was

held in

^{Bouak6 on 19 and}

20

April 1985. Dr N. Gratz, Director of the

Vector Biology and

Control Division

(VfC1

of

^{IIHO was}

elected

Chairman and Dr

J.

Mouchet as Rappoteur.

l..t

^VecEor

control situation

^since

A.rril

¹⁹⁸⁴

The

Chief of

^VCU

^{recalled the} vector control tactics

^used

in the

Progranroes

- in ^the

oavanna zones where

only S.

^damnosum and

S.

sirbanutr tr'ere present,

treatEent

has been continued

with

Abate _;

- in ^the

inter:oediate zones

of ^the Ivory

Coast where

S.

soubrense/

S. sanctipauli

were

involved in ^the

transmission, Teknar had been used

in the .lry

_season and chlorphoxim

in the rainy

seasone

it

^{should be}

stressed

that the latEer

^product

did not

cause any

ecological disaster

;

- since the

beginning

of

^1985, EreaErients had been suspended on the reachee wtere only

S.

soubrense/S.

sanctipauli

associated

with forest

onchocerciasis,

i.e.,

Ehe

very mildly blinding fom,

were found _;

- there

had been postDonements and suspensions

of treatment

wherever the

epideaiological

and

entoaological situations

nade

it ^poesible;

the drought had caused nany $ratercourses

to dry up

;

-

^treatment

of the

Lower Bandana had been euspended, since November,

to allow reconstitution of the blackfly

f.auna

in order to carry

out

resistance

^tesEs

to

^make sure

that the

savanna species

in this

^region

lrere normatly

susceptible to

Abate _;

- furthermore,

permethrin had been

tested operationally for

15 weeks on

the

Sas6aadra.

In the

Eeotern

extension,

treatments on

the

Sankarani

basin

^and

the

upner Saesandra had been

limited to

breeding

sites of high-risk in

regard

to

the

reinvasion of the

Prograul're

area ; this

^{had been}

to

avoid having

to treat

the extremely nunerous

strall

streans

in the

region.

The area

of distribution of S.

soubrense/

S. sanctipauli

as

well as that

of

S.squarrroeum

in the

^western extension zonc were nuch more

in the north

than

in

the Programoe

atea.

The

first

two spec

ies

coexisted

with S.

damnosun/S.

sirbanul in very large

areas where severe onchocerciasis was

rife. It

was imposeible as ^yet

No. 421IVCU/AIH/3 .4

to

determine

the

parE each species played

in the

transrnission

of ^the

^severe

forus of the

disease

; the sitrration

^r.rould be

the

same

as

^long as L3 Chchoce;:ca

tarvae

of the

vecEor could

not

be

identified. This ooint

had been considered as

the first

^research

priority of

OCP

since it

was indispensable co know the

real vector role of

each species

in order to direct

Ereatnents

against

^{Ehe most}

epidemiologically

dpngerous species.

Treatments would be

started in tire

western extension

only after

the approval

of the

JPC

in

1985,

i.e, at

besE,

in

the mict-dle

of L987.

No budget had been allocateC as

yet for

such EreatmenEs.

2.

Develooment

of

chemical

insecticides

^(see Annexes

2

^{ar:.d 2.2)}

Of the

29 forrnulaEions received

about 20

in river.

in

Lom6, 27 were tesEed

in

^{trough and}

2"L.

Pyrethroids

Neu formulations

of

permethrin

(9)

were tesEed

in

trough and

in river

⁽⁶⁾

buE none

of

thesr showed any rnarked advantage

over

Ehe

forouLation of

^TalcorC

which

is at

presenc under

operational trial.

A formulaEion

of

alphamethrin

for agriculturat use,

FesEac, proved

to

be

exEremely

satisfactory at

0.002 and even

at

0.001 mg/1/10 mn

in trough'

The

river trial at

0.002 ng,/L/10 mn gave

a carry of 1.2

^km

but it is likely to

be ^{much more}

in the

high-water

period.

Fendona,

a

preparation

of ^the

^{same proCucE}

for

^public

healch usee gave

less satisfactory resulEs.

The

first

^{product wa6}

tested in

^the

Ivory

CoasE

in

a watercourse

with a

discharge

of

^.50 m3/sec,

while the

second was

tested in

Togo

in ^a river

whose <iischarge r,ras 10 times

less.

Furthermore,

it

should be

recalled that the blackflies in the lvory

Coast are much more susceptibLe

to pyrethroids

than those

in

^Togo and

Benin.

These turo products should therefore be

tested

under

similar conditions. In

^any case,

decision in

regard

to their

deveLopnoent would be

largely conditional

upon

cheir toxicity for the

non

target

fauna.

Cyhalothrin

(102 EC) proved

to

be

very

promising

at

^0.025

in river

but

Eoo

toxic for the

crustaceans.

-3-

OMS 2012 and OMS 2013 gave,

in trough, the

same

results as the

preceding product

but

were noc

river tested.

They

are

nrobably

too toxic for

the

inverEebrate6.

The performance

of tiarrrik

was

not

as good

as the

otrher pyrethroids.

Esfenvaterate (0MS 3023)

did not give

good

results,

even

in

^trough.

2.2

Carbamates

Por Ehe

first ^time,

carbamates having

a high acti.rity against blackfly

lanrae have been obtained.

CarLosulfan

(tdarshall (R)

from FMC), OMS 3022,

in a

482

or

252 EC,

is active in trough

⁽¹⁰⁰²

mortality

ac 0,A25 ,rlrelLllO

mn). In river trials at

O,2 dg/L/10 mn

it

had an

effective carry of 2I

kla

in a

low-discharge watercourse

but

was

toxic for the

non

target fauna, including fish ; at ^0.05 it

^was

no

longer

active but for 6 kn

(discharge

of

4

n3/sec)

and

its toxicity for the

non target fauna was

of the

same

order as that of

chlorphoxim

; at ^0.02 it

no longer

killed the blackflies. It

should be

tested

under

ooerational

conditions,

l'tethiocarb, Mesurol (F') Bayer, ^Or,lS 93

yiel,ted

an LD 100

of 1.5

nE,lLllC nn

for

che 5OZ flowables and

0.5 for the

102

ECs.

Only

the

flowables were

river

tested ; ^they

^{should be reviened}

in

regard

to their effect

on

the

non

target

feuna,

2.3

Organophosohorus comnounds

The

four

new

formulations or

azamethiohos were

not better, either in

trough

or river,

than

the previously tested

formulations.

The two tenephos, from Phytagri and Cheminova, were

river tested at

0.1

during the

low-trater

period. _Their

performance \ras

not 6uperior

Eo

that of

Abate

which

is utilized in

^OCP.

In

conclusion, many permethrin formulations were

tested

sone

of

^{which uere}

slightly superior to

Talcord which had been

tested

on

a large

scale.

Alphaaethrin

is

an extreDrely

active product.

The

results of the trials

^on

the

non

target

fauna

are

awaiced

in order to

decide on

the continuation of its developent.

Carbosulfan

is a very pronising

carbamate wtrich should be

tested

on an orrerationa- scale.

2.4 Action

on

the

non

target

fauna

The

action

on

the

non

target

^fauna

is

evaluated

in

troughs comParativellT

to

temephoa and

chlorohoxim.

While

the tests

can be

carried out guickly,

the

analysis of the resuLts is

always

very long in

view

of the

necessity

of identi- fying

a

very great

number

of

organisms.

A11

the

products

tested

so

far

have proved

to

be more

toxic

than temephos

and even than chlorphoxim.

Ttre group pointed

out that while this evaluation

^was

of very great

i:uportance

it

should nervertheless be cross-checked

by field

observations which atone would rnake

it possible to

evatuate

the reconstitution of the

non

target

fauna

after

^the

cessation

of

^{treatment and hence}

^the long-'terrl inpact of the

^products.

2.5

Operational

trials

Permethrin

(Talcord)

was

tested

on

the

SassanCra

basin in

che

Ivory

Coast,

over

235 lcn,

for

15 weeks, from 14 Augusc

to

^{20 November}

1984.

The dosaP,e

eoployed was 0.015 me/1/10

rm, i.e,

0.045

litre of

207. EC per m3/sec

of

discharge,^

The discharge

varied

from 60

to

600 m3/sec.

The

applications

were uade on

a

number

of ^points varying froa

27

to

35.

The

results

on

the vector

were

excellent;

no breeding

site

^was

^positive

^{and the}

number

of blackflies

caught on man decreased, from 86

to 2 after the rhird

^week.

The

carry of the

product was 15

km..

No

fish or

macrocrustacean

mortality

^was

observed

but the

invertebraEe fauna was

seriously affected (reduction of

the

order of 302). Its reconstitution started

one month

after the interruPtion of

permethrin treatment and was

getting to its inicial level at

^{Ehe end}

of

two

months, which

is very

encouraging.

It is

envisaged Eo

test carbosulfrn in the

near

future. This

^product has an average

oral toxicity for

mamals (LD 50

=

^42O

^mg/rat)

^{and a}

^very

^lotr

percuraneous

toxicity ⁽²

000 mg/kg

rat). Its

disadvantage

is its instabilit-'r

above sOoC.

IE

can

rurn into

carbofuran wtrich

is ^very roxic

^(SlL4

mg/kg/rat).

Under

the

Programmets

conditions, there is little risk of alteration. ^In

view

cf the delivery times, the trials could start in

rnid-August and

last

12 weeks.

-5- 3. ^Bacillus

thuringiensrs

f{:!1

3.1

^New

formulations of Bacillus thuri

ⁿ⁹l.ensLs _"

r.

^{H-.14) (see Annex}

ⁱ⁾ In line with

the wish exoressed

by the

Expert A.dvisory Conrmitte ^(EAC)"

OCP has prepared

a plan for the

developnent

of B.t.

H-L4

preparations.

^An

LC 100

of

1.6 ng/1/10 mn and LC 90

of

O.S

nlgll-ll0

ran have been

retained

^as thresholds

of activicy for the takinq of a

_rrroduct

into consideration

^(Annex

j).

Abbott

sent

3 new

forrulations of B.t.

H-14 which

are oily

flotra.btes.

None

of

^them causes 1002

mortaltty at 1.6 nql]-/lo

ma

but

one

of

Ehen ^(ABG 51 77)

will

be

river tested

when

the nanufacturers's

formulacion chemisE

cmes to visit the

Prograume so

that

he can see

the

oerformance

of this

^{producE on}

^the

^sDot.

Vectobac ABC 61 45 which had been selected

last ^year,

^was

^tested in river

^where

its

perforuance and

constraints

^were

similar to

^those

of

Teknar.

Sandoz withdrew one

of its

^proCucts, SC

60,

which was considereC pronising.

On

the other

hand,

it

continues

to

^{produce SC}

93, derived

from an

asporogenous

strain,

which proved

to

^be

very

^promising

at 0.8

mg/1/10 nn without

addition of water.

The

trials

which had given

very

good

results

on

the

Bagbe gave

disapoointing results

on

the

Cornoe.

This

uas

not

due

to

resisEance

by the

insect

but

seened

to

have

resulted

from

the hydrological conditions of

che

river

^and

from

the

physiology

of the larvac. It

^was

^also

^thought

that the

oroduct could

alter during

storage

but the loss of activity

^{proved Eo be}

^sLighE.

^{OCP has ordered}

20 000

litres of

SC 93

for large-scale field trials.

SC

99,

an

equally very

promising

product,

seerned

to

have been withdraqm and replaced

by

^SC 98

a

sample

of

^{which has}

just _arrived in

^Bouak6.

Solvay proposed 32 ne'a

forslulations

none

of

which was

superior to

^Ehe one

tested laet

^year.

Tate and Lyle proposcd

a

product whose

results are close to

those

of

the products used

at

^present.

Galil

^{Advanced Techno 1es roduced}

only

non-formulated ^powders.

Knoll

Bioproducts senE

a highly

concentrated aqueous suspension

of viable

spores, which however, does

not

cause any

mortatity of blaekfly

^larvae.

To surn

up, there is only

one promising

fotmulation,

Sandoz SC

93,

which

will

be tesEed on

a large scate.

SC 98 which has replaced SC 99

is

awaited.

It

does

not

seen

too utopian to think

^Ehat

tn the

near

future

prcpar'rticns

permitting treatnents at

O.4 ^g1gl1.ll0 nn and even

less

could be had,

but

^Etre

disappoint6enEs

of the past

^{few years} should keep

in

check any

too

hasty opEirii ^snt

3"2

Operational

rrials of B"t.

^H-14

Sandoz SC 93

will be

Eested

oPerationally.

The selecred basin

will

^be

^trcated

^ac

^0.8

^{ng/1/10 mn}

in order to

evaluate

the effect of

^{Ehis 4osage on}

^the blackfliqs.

Furthermore,

the carry of

the producE

will

be

studie.l at

dosages

of 1.f:, 1.2

and

0.8

mg/1/10 mn.

The

possibility of applying the

^producE

by aircraft is envisaged'

^{The use}

of the

Turbo-Thrush would be

a great

advantage

for the rainy

season treatments.

4. Insect

^{Growth Re}

lators

^IGRs

The meEhodology develo.ped

in

^Bouak6

for

Ehe screening

of

these _ProducEs had been presented

to

^{Ehe 1984 rneeting}

in

Lon6 r.rhich considered

it

acceptable'

IC

conbines Ehe use

of

troughs which make

it ^possible to subject the t''rvae

to a

well

deternnined ^Cose

of a product, during a

^{known lapse}

of time,

^and

^the

^use

of mini-gutters,

where they are painEained

in river h'ater,

up

to

pupatjon"

A

plan for the

develonment

of

^{ICRs has been prepared}

for the

EAC (Annex 5) ' AE Ip.TO,

a preliminary

screening

is carried out at firsE, maintaining

che product

in

contact

with the IGI for

60 minutes

in order to elirninate

for:nulations

vithout

prospccts

of success.

Products urhich have passed

this test ^are

then subjected ^to

a

secondary screening covering

the sixth

^{and seventh}

instar ^larvae ; ^the

^contact

is

10 minutes and

the

observation

perio.l lasts up

^co

pupation. Finally,

^under

the

sasre

conditions, a tertiary

^screening

of the third, fourth

^and

fifth ^instar larvae is ^carried

^out.

Trials ^are

^co be

carried out

on small

rivers'

Avermectin, from Merck, Sharp & Dohm,

llas ccrtainly

^one

of the

^xnost Pronising producrs

since ir

caused almost 1002 reducEion

at

haEchings

at ^0.0I

^{mg/l/10 mn'}

But the trials

^{have been}

temporarily

^{suspended because}

of the toxicity of

^the

product which

is sinilar to ^that of rrarathion.

^{However, 5OO}

g of the

fornnulation

will

be

sent to

^IB.TO

in order to rest

^the meEhodology proposed

for the river

trials of

^IGP.s.

-7-

OHS 2C15 (Bayer) _and Ol,{S 2016 (Shering) srere elirainated

during

^the prelfuninary screen ing.

Diailin

and OMS 2016 (Sherine) were

rejected

^drrring

the.prinary

screening.

OltS 3010 (ttaag) was

not retained

because

of its

lor,r concentration ^which would

require the

spraying

of 2 litres of it

^per m3/sec

of

discharge.

Ol,lS 3009,

a

product, r'rhich

is very active

on

nosquito larvae,

has ^noE reached ^I:1TO.

An

IKI preparation is

being evaluaEed"

OMS 3007 and OHS 3019 (gumitono), both

equivalent to ^juvenile

horrnone, are Ehe

only

two products

still

^under

consideration. At 0.t

ng/1/10 mn,

they

cause 1007 reducEion

of

emergence

of latc instar tarvae.

The secondary screening

is in

progress and

the results r+ill

be known

very

soon.

In brief, it is

noted

that

the ^means

for the evaluation of the efficacy

^of

the

IGRS

is

^now

available;

however, a methodology

for evaluating their Eoxicity for the

non

target

fauna should be

developed.

^Two proCucts have reached ^secondary screening.

The group

hiehly

reconunended

the exploration of thc diflubenzurcn class

of producEs qrhich

are active

on

the larval

st,ag,es. A

special effort

should be nade

to obtain

forsrulaEions

of

these proclucts from

the

manufacturers.

5. Larvicide

evaluation Eethods

OCP has arlopted

the hybrid evaluation

^systen

uhich

cornbines

the

^use

of

the

closed-circuit

trough

for the contact of

10 minutes

t'ith the

producE

to

be Eested

and

the

use

of the open-circuit mini-gutters during the

observation

of

24 hours

or up

Eo

pupation.

The work must be

carried out

along

the river

^{which feeds the}

rini-gutEers. This

system makes

it possible to cest

both conventional-insecticides and IGRs

by the addition of

hatching cages

for the latter.

IP.TO has constructed an apparatus which makes

it ^possible to transport

ti.rre

Larvae,

fixed

on

oalettes,

from one

site to

another

in

^case

^the

^{trough and the}

nini-gutter are

noE aE

the

same

Dlace.

^The

tarvae

can

easily survive for

^rnorc

than 24 hours

without

any notable

mortality.

The IGR evatuation methods shoutd be published so

that

these conpounds

could be

tested in other countries, especially in

che United States vrhe:e thc

industry

produces many IGRs every ^year.

6. Adulticides

In order to neutralize the

effecEs

of reinvasion

an

adulticidc

^treatment

trial

had been

carried

ouE, from

the

ground, on

the

Faya

sttc in llali in

^1933"

The

results

proved

disappointing

^and

the operation

seeue<i

coscly

^($900

^per

^krn

of river).

Io

May t9A4, an

adulticide

treatment

trial

by

helicopter

^rras

carried

out on

the lto in

^{Togo; 21} lm o€

gallery forest of

the main

river

and 12 km

of its tributaries

were

treated vrith

permethrin

in only

one

application.

^The

^results

were

not encouraging"

^The

blackfly density

wtrich became

nil after the

spraying

rose to its initial le'rel within

5

days. Fish

and macrccr.ustaceans were se\rerely

affected.

The low

residual activity of the

treatment was

attributed

^Co

the

rairr which

fell the

day

after the spraying.

But

rain is a

normal ohenomenon

of

the

reinvasion

^periods.

The

cost of the operation is only

$50

per

km

of river,

^{r,rhich secrns low but}

since reinvasion is

^almost

daily,

treaEnents r,rould have

to

be repeaEed several Eimes

per

week and

the cost

would then become

prohibiti.re in

view

of thc

^aretrs

to

be treateC.

The group considered

that this strategy

was

not appropriate to

OCP|s needs.

7,

Improvemen

t of inseeticide application

techniques

Most

of the

problems

related to insecticide

spraying by

aircraft

^{have been}

solved

ar present,

Each

helicoptcr

can be

utilized for all

^{Ehe products cmployed}

in

^OCP.

A

modification of the

Ereatment

cycle will

be

tested in the

^western exEensi',-'i:

eone according

to

an appli-cation

cycle of 9

and 12

days. This cycle will

^be

applieC

in the first ^placc in the dry

season

I ^the pilots will

be supervised ^an'.i

the

entomological monitoring

r.rill

be stePped uP.

It is only

when these

modifications of

cyctes have oroved

their

^worth

^that

they

could be introduced

into

^OCPrs

operational

sysEem'

-9-

Bupharie was

alao laid

^{on VCU|}

^s

^pre6ent

^policy of

poetponetrent ^and

internrptlon of

treatmente wtrich could poeeibly be developed

furthcr

^{when the}

exteaaions

8re

i.oplenented.

ttre officere in

charge

of

^VCU

^are well

^awere

thst

^8ny

nodification of

Greatpent

cycte

represents

a risk

^uhich

^mrst

^be

linited

^by

^{a reliable}

^entono-

logical oonitoring.

Furthetuore,

^OCP hae

juet successfully tested e

systcn

for the tetetraas- nireion of hydrological

data

collected

and coded by Argoe beacons and

tranaoitted by eetellite to a tele-receiving Btation in the

^Programe

aree.

^{Ttria syaten}

nakec

it

^poeelble

to knor the

ecect

quantity of insccticide

^which

oust

be releaeed

at

each apraying

point of ^the rlver,

^{even t*ren}

its

banke

are inacceseible.

^Beaides,

the rpatc

aurge can be

follolrcd in order to

avoid ueeleee

treatneats, after

^Bpates

rhich

hsve warhed

the

breediog

eites.

On

the

banke

of

srnall

rivers

^{wtrich do}

^not

^have

^either

^gauge

etaffe or

beacons

it is

^ptanned

to copstruct

coloured slabe ^which

witl

nake

it ^poseible to

^evaluaEe

the

diacharge

at a

glance.

. Ttrere

are in fact

^two

alter:nativeer either continuing the

^{heavy treatnents}

or

reductng then

in order to cut

down

the

Prograruoe'E

cost.

^The

^nain

^features

of the ttro typcs of

treatment

are

^;

Minintro dose

for r

¹⁰⁰²

urortality or

even

a bit

lese

Oaly the

nain*

breeding

eites are

treated

7

daye

tiore

than 7 daYe (according

to the duration of lanral life) for

^{ercanPle 9-12 daYs}

Voluntery iaterruPtion during high'tater

Periods

or

whea

the blackflY population is nil

Heavy treatoents

I

Reduced treatnente

Ilose

of

insectide

Serreral

tines the

uininun doae which

givee

1007

nortality

Coverage

All ^{the lanral}

^breeding

eitee

treated

Cycle

Continuity

52 weeke

per

year or throughout

the

^period

the river

^lows

*

_An underdoaage could

easily lead to the selection of

resistance.

8. Insecticide

resistance

It

was noted

with satisfacEion tlrat the

Abate-resistance

of the

savanna

species, SS. damnosun/S. sirbanum, which ^appeared on Ehe lower Bandama ^qTas no

longer observed

after the

treatment

of the

bree<iing

sites with n"t. H-l/r

and

even

after ics incerruption at the

beginning

of

1985.

It

was however noEed

that

^{t.here was}

quite a lov susceptibility

^of

S.

damrosrrm/S. sirbanum

in the

^fambia near

to the

border between

this

^country

and

Senegal. It

cannoE be

ruled out that this

^{was due}

to the utilization

^of

agricultural inseccicides in ^the

"new

lands". Further information is

necessary.

Temephos

resistance in the

untreaEed

rivers in

southern Ghana has decreased.

In the

southern and

restern

extension zones,

susceptibility of

S.soubrense/

S. sanctipuali

has decreased

in

conDarison

with that of the

savanna

species. It is highly

^probable

that

temephos resistance would develop

in

case

of utiliaaEion of this

^product.

l.toreover,

in the

eastern

part of the

Prograrme (Togo, Benin) Ehe various

sPec

ies of the S.

damnosunr conplex show

a fall in susceotibility to all

the

insecticides, especiatly to the

Dyrethroids and

to

^{DTT, probably a6}

^a result of the intensive

use

of

these products

in cotton

fanns.

The negative

correlati.on

between

resistance to

^{temephos and}

susceDtibilitv

Eo

pyrethroids

has been

confirmed.

Org,enophospha

te-resistanr S.

soubrense/

S. sanctipallli

populations

are

abouc

ten

times

nore susceptible to

pyrethroids

than populations

of the

sane species

in

^Togo and Benin which

are not

organophospiratc-

resistent.

9.

Ooerational

implication of

resistance

The contingency

plan to

be used

in

case

the

savanna species develop

resietance

to

organophosphates has been updated ^(Annex

6)

and

will

^{be presented}

to the

1985

ueeting of the EAC. It is

^based on

the

us.3

of peroethrin

about r"-hich

the Ecological

Group

will

be consulted.

9.1

^Plan

of

oper

ation

envisaged

in

¹⁹⁸⁵

OCPis present

strategies in the

savanna zone have

not

been no<tified snd

wiLl

be applied on

the

Sankarani

in

^Guinea.

-

^11.*

As

in

^1964,

^the alternation of

^Teknar

in the dry

season

with

chlorohoxim

in the

high-water ^perioC

will

^{be continued}

in the

intermediate ^zones

of

^the

Ivory

Coast.

9.2

^{Meditnr and long-term}

^strategies

(1)

A proposal made

in the

long-Eerm stragegy

consists in ignoring

the

spec

ies of the S.

soubrense/S. santipauLi groun

by

treaEing onlY

the

savanna

species which

are non-.resistant, since they

^alone

are

responsible

for

^severc

onchocerciaeis. This simolifying

^{soluti.on qrorrtd} undoubtedly

solve all

^OCPrs

probtema

related to

resistance-

The group

raieed

^two

objections. In ^the first ptace, there is

^{no proof}

aB

yet that S.

soubrense/S.

sanctipauli

^do

not parEicipate in ^the

transmission

of

^severe onchocerciasis

in the interoediate

^zones

; this

^Proof can onLy be ^h"qC when

the identity of the oarasites

has been known and

it

^{has been}

^possible

^to

idencify the

L3 Onchocerca

larvae of the

^vectors.

The second

objection resulted

from observatione made on

the

Bandaoa'

Is thc

continuacion

of

^temephos

applications to

nixed S.,laurosum/S. sirbanun and

S.

soubrenae

S.

sancti

li not

capable

of

leaSing

to

develop'uent

of

organo- phosnhace-resistance

in the first pair ?

^The events which occurred on

thc

^lor'rer

Bandama

give rise ^to

^much

^caution

^before expressinB an opinion'

(2)

The second

strategy consists in trying to control S.

^soubrense

s sane!Ur4g!! where these soecies

are

associate,l

with blinding

onchocercinsis'

This is the

case

esneciallv in the

southern extension ^areas

of

^{Togo and Benin}

and

in

Guinea where

ia addition

these two species

are

found ouch more

to

the

north

than

in the initial

^{Programne area.}

In

view

of the

hete-rogeneity

of

^{ehe Pro2ramne area}

^both in

regard

to

^thc

distribution

^and

susceptibility of ^{the vector}

species and

in

regard

to tlte

polymor- phisrc

of

the.disease anrl

the ecology, it

anpears necessary

to adjust the

technicues

to the conditions in

each

region. But

these techniques lrould be base4 on

insecticide rotation while

^hoping

the

^number

of

availq.ble ^{producEs r'rould} increase

during the

^coming Years

B.t.

H-14 srculC

reoain the basic

^{product Curi.ng Ehe} lor.r-water season ^an<i

it is of particular

importance

to obtain very quickly formulations

^{which ruould} be

easier to

handle than

the

^{present Teknar (SC 93}

in rrarticular) '

Dtrring _th.e high-$rater season tenephos/chlorphoxim

vould

be

alternrteri with pyrethroide initialy,

_{and then} carbanates

with

rGRs shourd compounds

of

these grouDs becoae

available.

The

hartful _effects of

sone

of

these

products, like ocunethrin, fcr

the

non-target

_fauna

muld

_{thee be}

_{limited both} in

space and

in

tinre an<!

the fr:sir.

water fauna woulc heve Ehe

time to reconstitute itself during the 1erio6 of

treatment

with B't'

H-14

as

scemed

to

show

the

operacional

trials of ttris

product

carried out ia

19S4.

rn

Togo and Benin

for

example,

a B.t.

E-14

fornulatioa

would be usec

fcr

9

uonthe' Next, there

woul,l be 2 months

of

spates and subsidences _:Ln flow

during

which

the blackfly pooulation is low, rmaining

_{one month}

_during

_ruhich

either a

cht'nicaL

insecticide or

an

interruption of

treaEment cour,l _{be envisa-}

Bed' rn

^the western extension

zonc, the

treaunent

cycle

and

insccticide rotation

shouldbe stuCied accorrling

to the

basins.

since ocPrs

eize

does

not

oake

it possible

_{any ronger}

to

_{,Be onry one}

insecticide'

treatments shoulrl be programed accordinc

to

cach

region.

The

restriction

_imncsed

_by the Ecological

croup on any extension

as

rong

as

crro

insecticides equivalent to

Abate

are not available therefore no ron'er

arises

in the

6IrEe terms eince no procluct

will either

be used perElanently

or

orrer the wtrole ^prograume area.

l'breover" it is illusory to think thet

two oroducts having

the

same

perfrr_

Bance as Abate and

not

prorluciag aore

effects

on

the non-target

_fauna

uill

be

fouod.

ldhat ehould be looked

for is a

group

of

prorlucts which would

*ake rorati.a*

possible

throughout

the year in

each

region, the toxicity of

some

of thco for

the

non-tergct

_{fauna being} comrtensated

for by the possibilit3, of reeonstitution

_of

this

fauna

during _the

periods

of

treafinent

with B.t.

lI_14.

Furthennore, _these

alternations

_{would make}

it possible to

increase the

nuonber

of

products

utilizable _{during a short}

_period.

Finally, _the

al'ternati-ons _shouLd decrease

the risks of

resistance development.

rn return, this strategy

uourd

reguire a

continuous

eontror of

the

susceptibility of the various

_soecies

to the insecticices

_{used and}

it

vrould

certainly

be necessary

to retrein

sooe

of

ocprs

staff

accordingly.

-13- 10.

_Relat

_ions

_wi

th

indu

stry

The

relations with industry _are

excelr.ent,

brrt the

ntnnber

of

new producrs

to

be

teste'i

has decrease'l _much

this year. rt

shoul.d ^-ne envisaged

to

revivr:

the interest of

the

manufacturers. rt

ehoul.l be notcd

that

many

of

them trave

created

a public _health

department.

rt is particularly iurrortant to

see

to it that _the effort is

concentrated on

the

ctasses

of insecticice for

s,hich

there is

no

onerational product, e.g..

the

-.analogues

of

diftubenzuron _a&ong

the

iGRs.

clear

_and

well

documented

reports

_prepared

after

e.ech

triar are

essentie.l.

for

the aaintenrnce

of the interest of

the nanufacturers.

At oresent,

_lDost

of

the produets received _{have been} tested,

B.

r.

H-14 _SC 98

fron

Sandoz., OHS 3024 frorn F{Cr OUS 3013

froa IKI,

rernaining _only, an IGF..

11.

Contrac

t

revierr

The

contract u,ith

_{IEIO has been}

very €ruitful to CCf.

The

relations

between _IRTO and OCp

will

be strengthened and

conpletely

coordinated _{when the} Lqae tean

is transferred to

Bouak6 ..tn _1986.

ocP has signed

a contract uith the

London school

0f Trorical

_lGdicine

and Hygiene

for the

_study

of the

biochernistrr/

of

resisEance.

A

contract is

being _prerrared

with the Universit;r of three

Rirrers

in

Canada

for the

_study

of the

diepersion and behaviour

of B.t. in

running _B'aeer.

A

contract

_on

_the

_behaviour

of insecticides in

running

irater is

equall;., being prepared

nith

_rhe

University of California.

Ihe

group _however pointed

out that the

developnent

of insecticides

_was

still highly enpirical

_and

that river trials

_remained

_{the uain} criterion _for the

assessaent

of the efficacy of a

product.

certain _studies

'^'hich cannot

take inco

account

arl the factors

_invorvecl

in the action of a

product shoulci be avoided so as

not to direct the

suapri.:rs onto _wrong

tracks' rt

had been unavoidably observed

in the past that so'e

forn,-r-.

latious

_having

_very rtifferent activities

_{had no} detectable

cifferences

_{as reg:rds}

their physical or

chemical

nroperties.

That

is

why _OcP enccurages

the interested

manufacturers

to

send

their

foruulation _chenists to the

Prograurme area so

that

they can observe

the

behp.vicur

of their

products on

the

spot.

Conclusions

Ocp

has, at

^presente

three

operaEional

insectici<les ',

_two or3;anophospho::us cmrpounds, Abate and Chlorphoxim, and

a Ii.t.

H-14 preparattlon, Teknar'

A

pyrethroid,

permethrin, yieldedvervgood

results durinq

^{oPeraf ionaL}

.-rials

Another 8.t_.

tl-14 formrlation,

^{Sandoz SC 9.1, and}

^a

carha:tate, carbos-:.!-f.an

are

ready

for operational trials.

itigh

hopes have been

set

on

other pyrethroids

(alphamethrin) anC on Ehe

IGRs. It

should be noted Ehat

a

good nethod

for the evaluation of this

^closs

of

corapounds

is

^now

a'railable.

In order to solve the

^{problems posed by}

resistance'

^{Ehe grouo proposed}

that the insecticides

should be

rotated to

meet

the

^demands

of

each region.

In

view

of the

long way which OCP

still

^has

to go, the

grouP consi'lereL

that the effort for the de'relopent of

new

larvicides

^{should be} continueC ani

that

Banufacturers ^should be aoproached so

that

^new products uould be

tried

under

the

Prograrmtets conditions.

Annex

I

t

t,c !E !4l!igtpe!!-q

AKPOB0UA

K.A., Chief

sectore ^OCP 3ouak6,

Ivory

Ccast GRAJZ

N.

(Chair:uran), ^q.IiO,

Director

^VBC, Geneva

HOUGARD

J.H.,

IRTO, Bouak6

KURTA(

D.,

Vctl/OCP

- Insectieides

exDert

MOUCHET

J.,

(Rapporteur),

consultant

^OCP

CC?,Atl

lf.,

^VCU/OCP

-

^Chief

,

^neq,

insecticides

develofroent centree Lom6, To PHILIPPON

8., Chief,

^VCU

QIIELET{NEC G.

e,

^VBC, l,tHo/Geneva

REI.IAID

P.,

^VCU/OCP

-

^New

insecticides

development

centre,

Lom6, Toqo SUBRA

R., Aesistant Chief,

^VCU/OCP

io

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