OF 2 FORMULATIONS: OMS 3051 AND OMS 3052

t

EVALUATION IN ^{TROUGHS ON} S. ^{DAMNOSUM S.} L. ^LARVAE

OF 2 FORMULATIONS: OMS 3051 AND OMS 3052

Technlcal Report OCP,/IRU 89.Os

Insectlclde Research Unlt

Onchocerclasls Control Programme Programme

de Luttte

Contre !'Onchocer@6e

World Health Organlzatlon Organlsatlon Mondlale

de la

Sante

Bouak6

-

^{December 1989}

t{orld Harlth or€anizrtlon

-

onchoc.rcl.siB control Pro€rrrunc

-

InEcctlcldc Rasa$ch unlt ocP/rRU/60.05 Prgo 2.

ABSTRACT

EVALUATIO.I ON SINULIUM DAMNOSUM

S.t.

^LARVAE OF

2

NEW FORMULATIONS:

oMS 3051 2-5

GlL

(B-CYFLUTHRIN) (PYR), AND OMS 3052 (OP) FROM BAYER*

Author:

^{M. H. Ocran}

Trough tests on S.

damnosum

larvae were performed at the IRU

field

station at

Soubrd

(RCI) with one pyrethroid formulation

OMS 3051 (B-Cyfluthrin, 2.5

g/L) and

an organophosphate OMS 3052 (500

g/1) to

evaluate

their

efficacy on

larvae. ^{The OCP}

standard

protocol was used

in testing. The results are

compared

wlth

data

from

recent

tests with

permethrin (PounceR, 2OO

e/L)

^{and temephos (200}

g/L)

formulations

currently in

operational

use in

OCP.

The results indicate

that OMS 3051

is a very ^potent formulation, with

1003

mortality at a

dosage

of

0.195

UglLxl0 mln and a

^{LCSO (0.0094}

UglLxl0 min) which is 24X lower than ^for

permethrin.

It

^was

very lrrltating to the

larvae, which

glves the

lmpresslon that

It ls ^{acting more by contact. The emulslon} was unstable after 3h, wlth

^a

preclpltate

of ^{white powdery}

^substance

at the

bottom

formlng within

48

hours

of preparatlon. The OMS 3052 formed

a

^{good emulsion}

that

^remained

stable for

^4€!h,

but

^gave

a whlte

deposit

after

72h.

It

^was

less

actlve

than

temephos:

a

mortallty

of

^{l0OS was obtained}

at 0.4

mg,/Lxl0

min, whlle

^temephos

gave

10OX

mortality

at

0.1 to

^0.15

mg/LxlO mln. The

LC50 (0.120 mg/LxlO

min)

was

4X higher than for

temephos.

RESUME

EVALUATION SUR LARVES DE SII,IULIUM DAMNOSUI'I S.L. DE

2

NOUVELLES FORMULATIONS:OMS 3051(B-CYFLUTHRIN, 2.5 G/L)ET OMS 3052

A.rteur: ^{M.H. ocran}

Des

essais en trough

^(systdme

de circuit ferm6) sur des larves de

^S.

damnosum

s./. ont 6t6

effectu6s

au

Laboratoire

de I'IRU A

Soubr6 (RCI), selon le

protocole

de test dtabli par

^OCP,

avec de

nouvelles formulations:

un

pyr6throTde

f 'OMS 3051

(B-Cyfluthrin, 2.5 g/L), et un

organophosphor6 I'OMS 3052

(500 9/L) de ta firme Bayer. Les r6sultats sont

compar6s avec

ceux

d'essais

r6cents

^avec des formulations op6rationnelles

de

perm6thrine (Pounce, 2@

g/L) _et de

t6m6phos (2OO

g/L). Les rdsultats indlquent

premidrement

que

I'OMS 3051

a ^une

^activit6

trds

^6lev6e

^{avec une}

^CL10O

de I'ordre de

0.195 UglLxlO

min et une

CL50 ^(0.0094

Ug,/Lx1O

min)

ZIX

plus faible que

celle

de la

perm6thrine.

L'effet irritant

observ6 suggEre

que le ^produit agit

essentiellement

par contact. Par ailleurs

l'6mulsion

pr6par6e n'6tait plus stable aprBs 3h, et aprds ,t8h un ^pr6clpit6 blanc a

6t6 observ6.

La

deuxidme

formulation,

I'OMS 3052,

a par contre produit _une

6mulsion

stable ^pendant 48

h,

^{mais aprds 72h}

un ^pr6cipit6

^blanc

^a

6t6 observ6. L'OMS 3052

est moins actif ^que le

t6m6phos:

une mortallt6 de

^1OOx

a 6t6 obtenue a

^0.4

mg,/LxlQ

min tandis qu'avec le

^t6m6phos

on obtient

^100X

de mortalitd

larvaire

entre 0.1 ^et 0.15

mglUxlO min;

la

CL50 (0.120 mg,/Lxl0

min) 6tait

4X sup6rieure A celle

du

t6m6phos.

r Thig d@uo€nt do6s not con8titute a formal publication. It ahould not be revieHed, abstracted, quoted or translated without the ^agreement of t{or'ld Health organization. ^Authors alone ^are

reEponsiblc for Yiews €xprcaa€d in'aign€d articlee.

I

llorld H.tlth Org|rnlzttlon

-

Onchoc.rclesis Contro'l Programc

-

Ins.ctictd. Rcse$ch Unlt

EVALUATION

IN

TROUGHS ON

S.

DAI'INOSUI,I

S.t.

LARVAE OF

2

NEW FORMULATIONS:

OMS 3051 (PYR) _{AND OMS} 3052 (OP) (BAYER),t

1. INTRODUCTION

Pyrethroids (permethrin)

^and organophosphates (temephos

and

chlorphoxim)

are

among

the larvicides currently applied in the

OCP operational zone

on

^a

rotational basis according to

season

and to level of susceptibility of the

larvae.

Permethrin

is applied at a rate of

^0.015

mglL for

10

min

^(O.O45L

p". r3/" ^river

discharge). The

organophosphates

are

^applied

at the dosage rate of ^0.05

^to

0.1mg/L

for

^{1O min (0.15L}

to 0.3L per msls river discharge).

New formulatlons of

both ^classes of lnsectlcides are constantly being tested and

compared wlth operational

formulatlons In order to select

improved

verslons that are

effective

against S.

damnosum

s./. at

acceptable dosage

rates and which will not

cause

greater than necessary environmental

damage

as compared wlth

operational

formulatloni*o

formulations supplied by Bayerl ^were thus ^tested with

these

objectives in mind. This is mainly to ensure that

OCP

uses larvicides

that preserve as much

as

^possible

other non-target

organisms

in the rivers which

are

under

^weekly treatments

(Wahle

1978), especially

with pyrethroid

formulations.

2.

MATERIALS & METHODS

The experimental

products provided by

Bayer were:

-

^{OMS 3051 FCR 4545 025}

^Ec

^{116 (2.5}

s/L)

^50g

-

^{oMS 3052 MAT 9460 500 EC 009 (500}

s/l-)

^19st

(Recelved Bouak6 26/10/89)

The

prellminary

evaluation

of

these

two formulations using the trough

test

method (closed-circuit system) were ^performed at Soubr6 (06 -

^O9/11/89),

according

to the standard

^{OCP protocol}

(refer to

Annex

for

^method). Larvae used were collected

from the

Sassandra

River at the site of

^Koperagui and

they

conslst mostly

of the S.

sanctipauli cyto-species,

of the S.

damnosum complex.

The

^larvae from

this site are regularly

used

for tests and have a

normal

susceptibility

to

all

operational insectlcides.

a Thi6 document do€6 not conBtitute a formal publication. It should not be revi€w€d, abstracted, quot.d or translrted Hithout the ^lgreeoent of t!,orld Health organization. Authors alon€ ere rcBponBible for views expresEed in sign€ct articles.

tBlyer ^AG, Oivision Phytosanitaire, 0509O Leverkunsen Bayerrrerk, ^FRG.

oerrnuree .tiCik prs. _{8 .i,}

A

a

Horld Hcslth Orgnnlzetion - O.rchoc.rclrais Control Progran[c - In..cticldc Rcserrch Unit ocP/rRu/lg.03 pego 1...

3.

RESULTS

3.1. ^OMS 3051

(B-Cvfluthrin)

_{O25 EC} (FCR ₄₅₄₅₎

B-Cyfluthrln was supplled as a pale yellow, rather fluld

emulslfiable concentrate. ^When

pipetted into ^water, it

^showed

a clear tendency to

remaln at

the ^surface for over a minute, before sinking slowly to the bottom of

^the

container.

After

shaking,

an off-white

coloured emulsion was formed.

Three

hours

after preparation there

was

a

notlceable separation

of clear solution

above and

emulsion

below, which later completely

deposlted

as fine white ^powder at

^the

bottom.

The results of 2 tests

^{(Table -}

1) ^showlng percentages of mortallty

at

different

doses

are

presented. Results

of ^probit

analysls

are

also

given ln Flg

^1.

The average ^LC50

for thls formulatlon

was 0.0094 UglLxlO

mln.

The extremely low dosages caused

strong larval reaction and

detachment

of young larvae at 6

^mln

exposure and

of

mature larvae

at 9

mln exposure.

&2.

^{OMS 3O52 5OO}

q/L

₉₄₅₀

This

organophosphate

also provlded by Bayer is a pale yellow

emulsifiable concentrate,

but slightly denser than the

above

pyrethrold formulation. It

^mixed

and

dispersed

easily in water forming a white unlform

emulsifion

after

^shaklng,

and

foaming moderately

at the top. It

^remained

stable 24 h after mixing, but

a

whlte

deposit was observed 72

h

later.

a

The exposed

tarvae

reacted more slowly

to thls formulation, the majorlty of larvae

remained

apparently unaffected at the lower concentrations. At

^higher

concentrations

both young and mature larvae

^became

agitated and

^detachment

occured

at 8

min exposure.

The average LC50

for the three tests

was 0.120 mg/LxlO

mln as

shown by

the results of ^probit

^analysis

in

^{(Table 1}

and Fig

^3).

4.

DISCUSSION

oMs ³⁰⁵¹

The

trough tests

showed

that the

OMS 3051 was

a very ^potent

formulation

whlch caused larval

detachment

at all the

concentrations

tested, but dld

^not

actually kill the larvae. It

was observed

that 7 h after

detachment,

larvae

^were

still ^alive in the collecting nets.

However,

in a

^separate

test

when

larvae

were

treated at

^{dosages 10}

X higher,

100%

mortality

was

obtained, with all the

^larvae

actually being

^killed.

llorld Hoalth Orgrnlzrtlon - qrchocorclrBis Control Progrenrc - Ineactlc{dc Rclcrrch Unlt

This

^shows

that at

lower dosages

the

formulatlon probably acted

by

contact and

larvae

^detached

as a result of strong irrltatlon. It ls

^posslble

that the

effect

of the solvent on the larvae is ^qulte

conslderable

causing

detachment before ^the

actual

active lngredlent could

^have

effect, lf the low

LC50

is

consldered.

When compared

wlth operatlonal

permethrin (Table 1

and

Flg.2) whlch had a LCSO

of

^2.243

ttg/L,

^{OMS 3051}

is

24 X more potent.

oMs 3052

The organophosphate ^OMS 3052

is 4 X less (potent) than

temephos (Table 1

and Fig. 4). This

OP formulation forms

a

stable emulsion

for

^48h

and its

^physical

characteristics

are as

good as those

of

temephos, except

that it

sediments heavlly

after

22

hours. It ls

less

actlve than

temephos, whlch gave 1003

mortallty at

^0.10

mg/LxlQ

mln,

whlle OMS 3052 gave _1@S

mortality only at

0.4

mg/Lxlo

min.

5.

@I{CLUSIO}.IS AND RE@MMENDATIfiS

5-1. OMS ³⁰⁵¹

OMS 3051

ls

extremely

active but on the other

hand,

lts irritant effect

may

be a dlsadvantage as lt may indlscrlmlnately affect most other

^non-target

organlsms.

Thls

^however

needs to be ^proved by testlng on non-target fauna

|nother

dlsadvantage

ls lts lnstablllty

as

an

emulsion.

These

results lndlcate a

^poor

formulatlon and

OCP/IRU has reservations ^as

to lts

^possible

^{use ln the}

^Programme

in lts present form. Thls

formulation has to be lmproved before

further ^testing is

^performed

by

OCP.

ocP/IRU/rg.03 pegr ₅

5.2- ^{OMS 3052}

The low

LCSO

of ^{thls product}

^shows

^that lt ls not actlve enough to

^be

considered as

a

Simulium

larvlclde. If lts activlty can

be improved, OCP/IRU could

carry out further trough tests

and

eventually tests on non-target fauna

6.

LITERATURE CITED

Wahle,

8.,

^1987.

Short-Term Effects and

Comparlson

of Permethrin EC

2O%, 25I

and ^sOX Formulations on Non-Target Aquatic Invertebrates.

OCP/IRU

Internal

^{RePort 15/87.}

Table 1 - ^{RESULTS OF} TESTS IMTH OMS 3051 Al.lD OMS 3052

wTH PERMETHRTN (OMS 1821) Al,tD TEMEPHOS OMS 786

Control mortalaty 1.9 - ^3.1%

Repoil lRUr89.05

' Conlirlencc llmitc st 9506 too wlde Tcmperaturc : - 25o - ^30oC

TuDidiU :-l0-30JTU

Condr.rctivlty: - 98 - 104 rr€

FORMUI.ATION Teet No

(16 ITORTAI.JTY FOR IIATURE LNryAE

LC50

,€rt-xl0' (t}5%r.t.)

LC95

r€f[-xl0'

(*,w.t.)

LC99

/grlr10' (p5qdr-u

ldl*lO ^mftoQoqre

o.oo24.0.ooE? o,ote6 o,o3E q.I03

.!;26

^2.6

6-0

^10.0

Nbr of Teetc

oMs ³⁰⁵¹

(2.5 CL) FCR 4545

(BAYER}

oMs l@l

(2s0cL) POUNCE PERMETHRIN

(FMC)

I@-3zl 189-30

r89-08

tL2

(575t

38.2

89.G ^glLg

(8t _{odn, (ffit}

^roQ.o

(ffit

t5.0 (taot

70.0 (2t0)

Tf .2

(t8q m.3

(2761

0.000,1

(0.@*

0.0t4e)

2.245

0.008

7.276

o.o7t2

r t.849 2

1

.

^{l.:,'; ; :, .: , ..:. : '}

'

_..9{Irt.O ^{arln olporure}

0.oi25 :{:02ti'0.06'0.075'', 0;1''; :o;ts ^'0.2

,'ii

0;t

mg/l-xl0'

(*;qu.u

mg/lrl0'

(959,E^t.)

mClrl0'

(e,ft9,€.t.)

oMs 3052 5o0s/L

oult

_gelo

(BAYERt

oMS 786

2@CL

TEMEPHOS (oP) (PROCIOAI

r89-35 r89-37

r89-r0 2,7 (3!ro)

4,7 (327)

{e @.8

^75,1

(fitr)

(255, (12s)

s.l

(1111

s.9

(13t)

,,2.2

27.9

(36t

O5)

7t.3

^84.0

(@t

^pgt

0.r20 (0.076-

0.t02)

0.032

0.33

0.132

0.51

0.23 3

I

a

' ^.':,:

;. '': O.4

Fig.1

RESULTS OF PROBIT AilALYSIS

6 ltorrtlon. ^ctII-2 CRITERIO0I : O. I

HETEROCENq'II OATA

loa - LO99 _LO99 = -1.147a5 -t.a8a ( ( 0.181

= O.O7l2l2 ^O.O33 < < 1.518

loc - LO95 _LO95 = -l.tlo5t6 -1.6C2 ( ( _-0.492

= O.O393.O O.O22 < < 0.322

loe ^LOSO ₌ -2.O2118 -2.393 ( ( _-1.815 - _{LO5O = O.0O9393 0.004} ( ( 0.015

10.361 2.611

lntercept I : alopc ^b :

OEGF ₌ G1{I-2 ₌

Prdrbt ^I ltY =

HETER ₌ T-VALUE=

GFAC ₌ TITLE SUBTITLE

3.8.b = ^0.Og't

:CEgltOgA B-CYFLUTHRIN ()l{S 3O5l ^(BAYER) 2.5 G./L EC FCR 't5,t5 :KOPERAGUI R. sAS9AI{ORA 09.tl.89

31{.4376 o. oo0 52. aO6

2.150 o. 39{

8G3 283 66C 364 389t9a

tt8t39 863 263 549 3aatt9

loaa7

2l

Oor.

unit6:uglL :

DATA TRANgFoRtlg

Controt:-3.1I

_i

! r Loc

^{coRR. @RR.}

oATA

^{txBE TEgTEO OEAD}

!

^{O8Si. OGIE OEAD PROsrr} PROEIT OOITRIB.^{PREO. CHI-SQ.}

OORR.

PERC.

,

o.

o.t95

039 too.o -0.7r0 862.5

c8,t1lm 8{yfr,rmntn ^q|S 30tr ^(BAva) 2,, clL E fER {r4, rPtmcut R. 8e86eroRe e9.il.89

-2

LoC H}sE ( in ^pglL )

E G

5 6 a 5 a 2

249a5t 0totEa 053aza 523 038

99.992.?

8t

9a 28

3t52 2

93 3I

7o 483

G35 a39E30 037 03?433 tt33 8

G

5 5 5 5 3 3

o.382.78 1.56 47. tG c3.22 tG8. o.03t7 Il.aG

oo oo oo

ot9or9 oo9oo9 oo2oo2 5 5 7 7 a 4

92.9

-t.tog

^2c2.1

82.4

-r.7r0

^5a5.2

0'1.5 -l .7tO ^3'13.4 30.c -2.or3 ^1r0.3

53.C -2.0t3 tor.r

33.8

-2.620

^ar.O

5.O

-2.620

^A.2

t

I

?

6

,

,l

3

t

E

;

9 E

I

a

,

2 2

{

^{0 2}

o I

23 a 3

C

7

I

.i

a .',{

.r.:.

Ftq.2 5

lt rrtlo.r3

CtlI-2 CRIfEBIQ{-i,.- HETEROGENOT'3 OATA-- -0.!

t'e

_tBEt

=

rl:8IEBI

l:88t

I I

^a306tr2

RESULT3 OF PROEIT ^ENALYSIS

o.8Gr92

7. 276398 0.522

(

<

3.328

(

⁽ -1025^.608

5= o.

5=

l=b=

log L09

LO9 ^a

lnt

rc.pt rlopo

loo - LD5O _LOSO = O.3508,1 ^ERR

= 2.213012 ^ERR

3.87r 3.218

OATA ^{OGIE TESTEO DEAD}

t 27C

2tot8t

rco

S.E.b = ^0.203

LOO OG}E

r.(x)o o. G99

0.398 o.o9?

(p&rsrlGril) (nrc) R. S&6SORA 2t.6.89

coRR. conn. PREO. Cflt-sQ.

OEAD PROEIT PROEIT OOITRIB.

?.otg

OEGF 3

ctII-2 ₌ ProbebllltY ₌

HETER ₌ T.VALUE=

GFAC ₌

38.ata2 o. oo0

I 9. 207 4.300 1.413

TITLE:POII|CE (PERIIEIHRIII) (Frc}

SI,BTITLE: TOPERAGUI, R. SASSANORA 2I.OG.t9 Dolc ullt.!ug./L

Contrll : ^1.3 t ^{DATA TRANSFOM€}

oB3

t

^OORR.PERC.

2I

3 a

lo

5 5 25 2.

27G 99.3

112

77.2

ra7

^?o.o

21

^t5.O

27C.t4t.

taG.22.

92 7522 53

o? a5 25 23

aa?

?34 3 a

5l0r

c. t20 t. t52

3 0c

I

99.?6.

e9.

13.

tc.t.

t5.tl.

I ^{.f . tEa}

PlqrfE KMIRfiCUI,

I

?

6

,

{

,

a

3

2 2

{

^{.? 0 2}

LoC DGSE ( ln ^pg/L )

o

o

/

lntcrcept rloga Probrb

T

i Flg.t

RESULT9 OF PROBIT ^ENALYSIS

t tt mtlont

^CtlI-2 oRITERIoII _=NoUs

Olil

"t

^IBEB

^:

a?i6B38B 6913'r'.','.9i38'

rao - LD95 _LO95 = ₌ -0.17677 _O.3330O3 -0.651 _0.223 ( ( ( _< 1.2620.10t roo --- LO5O _Loso = -O.32tO7 -t.117 ( ^{< -0.791}

= o.tt993o 0.076 < ( _0.t62

GFAC ₌

OATA

^{OGIE TESTED}

tt3l 'l4l₁₂₅

255 3?3?38 330327

{

TITLE!C89ll06A ^llAT

ST,BTITLE : I(OPERAGUI R.

oo.. untt.:tlo/L Co,rtrol : ^2.1 I

S.E.b = ^{O. l3a}

o -o.398 l=b=

OEGF ₌

ctII-2 ₌ ,lllty ₌

HETER ₌ -vALUE=

8. _'110 3.702 263.7176 o. oo0 a3.958 2.450 o.346

967a ol,rs 3052 (8AYER) O.P. 50: ^EC

SA:}SANORA 06.11.89

! ^{OATA TRANSFORMS}

a

!

! r Loo

coRR. ooRR. ^PREo. otr-Eo.

! oss.

^{DosE oEAD} PRoBrr PRoBrr oolrRrB.

.354.orG .50t.608 .534

. co3 .329.525

OORR.

PERC.

t

^OEAT)

431 a37 312r78 2a7 t 3'a 22

I I

^O.,a

2

^0.3

E

^o.2

a 5

^{o. 0.115}

c 7

^0.o2so.1

E ^O.Ol25

-t-1 -l

-t

I

a 8

I5 7 7

ro0.99.

?3.

G9.33.

35.6.

2.

a30 -o.523 a36 -o.699 -O.82't ooo oo0

309.

I 7G.

236.128.

t5.2.

I

t

t

2 cI

7 7 09.90.

G9.72.

3a.42.

o.a.

8 7 5 5 a a 3 2

6.93?

^rO.G?

6.a?a

^25.O1 5.C22 rr.3G

5.3GO 2.9r

a.708

^12.93

a.708

^2.aC

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RESULTS OF PROBIT ANALYSIS

5

lt mtlon

^dtr-z cRrreRl()rl

:

o.l

HETEROOENOT'II OATA

loc ' - LO99 _LOeg = -0.G2919 -t.O21 < ( 5.588

= O.231859 ^O.O95 ( ( 38?Ga0.l{8 loo - LO95 _LO95 = ₌ -O.8?916 -t.t?l ( ( o.t32061 ^o.oG7 ( ( 2036.27E^3.309

loE LOSO = -t.lE2rl7 -2.51a ( ( _-1.212 - _LO5O

= o.o32925 ^o.OO3 ( ( 0.061 9.Oa2

2.724 5.4172 0.0G5 2.708 t.300 o.794

(? Flg. a

lnt

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TITLE:

EUBTITLE Ooto unlt.

Control

o.025 o.or25

TEI{EPtIG KOPERAGUI

3.8.b

=

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CtlI-2 ₌ ProbrbtlltY ₌

HETER ₌ T.VALUE=

GFAC ₌

OATA

OG}E TESTEO ^OEAI) :llG/L

: 1.7 t

55 3C

7A 5Ct4

7

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301602 903 o8s

:

84.7t.

27.22.

5 8

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OEAO PROEIT PROBIT OCITRIB.

OORR.

PERC.

aI

23 a

0.075 03

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o.o5 80

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8 ^6:025 6 ^5.54G 3 ^a.357

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3.853 oo 2 2

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[email protected] Coritrol Prcgrerno

-

fnsrctlcldo Ronrch Unlt

ANNEX

OCP PROTO@L FOR CLOSED-CIRCUIT TROUGH TESTS

BRIEF DESCRIPTION.

Thla rthod, rlrlch ree dcvolopcd for ^OCP by 0r. H. J..nbrck, lr berad on r .y.tco that ho rnd llr. ^R.

Oruglor u3.d oxtansiv.ly ln ^Ncr York Statc. It ^{hrs bocn} furth.r nodificd by the ^(rcP Inr.cticld. Rc-

ac$ch Teaf ln Lolc, Togo. Larvae collect€d in the fi€ld are alloH€d to attach on a rcnovablc plata

lylng ln ^{tho bottom} of . trough uhere xater i€ rccirculated by e ^{pump. Thc} plrtc iB tmnsfcm.d to I

ricor,A trough rh.r. th€ ^inB ctlclde haB .lrcedy bccn nlxcd lnto the rcclrculrtlng xater. Aftor ^lO rlntfia3 tha plato l. ^tmnrfamod to a third trough xlth clcrn xrt.r. lbrt.llty tr coqntcd r?t.r ^2a

lpur3.

TECHNICAL DETAILS.

Tlf, tnought utod aro constrrEtad of alrrlnlll rnd prlntocl rhlt.. Th. trouEha rra 80 ca long, 15 cr rt<lr rnd ! cr rteop. Thoy rrc clorad rt th. uppor .nd. At tho lor.r .nd, r con.trlctlon or llp,

13 c. long, !.! cr rl<lr ^end 2 c. d.op l! rttrchod. A rcloveblo ..tll Plrt r.3t3 tn thc botto ^of thlt llp. llrt r ^{13 plrpod} lnto th. clord .nd of tho trouEh rnd flor. ov.r tho plrto tn ^tho llP lnto I r.t.rvolr, to b. ^{r3plrrtod by thc punp} rg.ln. 8i.ll .loctrlc c.ntrlfuS[l Plrps rlth r dl.chrgo o?

rbout 22 L./rln rra u..d, md thc vcloclty of nat.r ^ovcr th. rttrcm.nt Plrto ¹³ rbout ⁷⁰ ctl3. ^For thc rttrc?Dnt .nd oba.rvrtlon 3y3tcri, th. r.ffvolr ia r pllltlc r.rt.-buckct holdlng 60 L of t.ltar. ^{For tho} axpoiuro ay3too, r lO L onelolrarc pot ts uacd r! r rasarvolr to roduco tha amunt of ln actlcldo ^nac(bd. Rlyor rret.r la u..d rt rll 3trge. for routltr to.t8. It3 chlrrct.rl3tica (t.ip.rtturo, ^pl{, turbldlty ^end conductiv{ty) rr. r.laurcd rnd not.d.

LlrvL tra ^collactod by rcrovlng th.ir nrtur.l .upport. fra tho rlv.r. Th.y rrc tmnlport.d ln plr.tlc brgs plrcad ln rn ^iccbox. C.r. i3 t.k.n to r.Prmtc th. lrrvra fr{ thc lcc ^by r lry.r of frc.tr lorvor or grr38. ^Altlrough thc .quipocnt crn be u!.d rt tha rlv.rslda u.lnE r port.blc ^gotl.m- tor, thlt ^typa of to3t 13 u.uelly ^done ln r lebomtory nhlch ..y bo rt to0lc dlrtrncc fro[ tho col- l.ctlng Polnt.

Thc ya€Dtrtlon ilth tlr rttechcd larvrc lr ^placcd ln th. rttrchr.nt trough. Thc lrvr. nrtu- rNly larva tho vo8otrtlon to s..k r atrongpr cum.nt rnd thu. rttrch to th. Plrta of thc liP, ^rhlch fic ^tho hlg0rrt v.loclty ln tho trough. Tho l.rv8. ero left lor 21 h to.n3ur. flr. rttscluent. ^Lrr- vr. ^nhlch puprt during thli p.rlod rr. .llrln t.d jutt bcfor. .xPo.ur.. Tlt Plrta ^{ucuelly contrlna} rbost ^lOO mtura llrvae ^{rnd tavcral} hundrod young lervee.

Tho lrrvicldo fomulrtlonr ere appropri.t.ly diluted rlth di.tillcd rrt.r lao.dirtcly ^prlor to ^tho tert. ^Tho qurntlty rxrcr.!€.ry for thc loicat conoentretlon lt rddcd by Pipctto to tho r.larvolr of th. ^oxpo.una trqrgh rlth tho prrp running. Tho inrccticldc l. rlloicd to nm for 5 lin to obtrln I unlfon dlapararl. Addttlonrl lnscctlcide is ^eddcd to thc 3.tre ry.tci to obtdn th. htgh.r corrccntre-

tlons ln r tclt3 ..r1.3.

Thc plrta frot the rttscho.nt trough ie notr crcfully ltftcd out rnd ^plrcod ln thc ^cxpoturo

trougn lor I ^d.flnad p.rlod, u3urlly lO rin-

Lrrvta d.trchlng ^during thc .xpoiure ^pcrlod rrc cought ln r rl.t lttrched to thc llp of ^tho

trough.

Aftar tha oxpocun pcriod th. plet. ^8nd thc lrt r. tr.nsfom.d to r holdlng trough. At tho .nd of r 24 h ob..rvrtlon ^pcriodr th. dctrch€d l.rvr. ln th. n t, 13 rall l. rny d.rd oncs .tlll rt- trchcd to tha plrt. rr. pr.s.ry.d ln .lcohol for countlng. A ftrst collcctlon lc ^{gcncrally aada} 2 ^h rftor ^oxpoour. rlnc. rost l.ry.c d.t.ch in thia ^{pcriod and} th. lrv.. ..y d.cdPor.lf loft dcsd t@

long. Tho llylng lervro tr. killcd rith hot ^{yater end} aleo pr.eerv.d ln elcolrol.hforhcounting. ^Tha ,.,,r.Oc" ol OxpeFod, livlng, ^8nd derd lrvac iB.atabli3hod r.prrrt.ly ?or.rtur. (6err-7-" inttrrs) rnd yotrng (17'E-5En) lervec. Llrvae cxpoead to ineccticldc .nd pupltlng durlng th. t.!tB rre not countad

cxc.pt for thc control lhcre they rr. includect in the nulbcr 3urvlving.

Tha uaurl confometion of a tcat6 le e ^rangc of 5 concentrrtlon3 lnd rn untreatcd control

rlth 2 ropllcrt.. rt .rch conc.ntmtion. Pcrc.nt .ortslity t. crlcqlrt.d et crch conc.ntmtlon .nd

th. cdto.ntrutlon/.oltallty rcl.tlo.l i8 cateb'li.hcd by problt enelyrlo.

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