JounNal oF THEArr,tnnrcaNr
Mosqurro CoNrRor,Assocrlrrorl
VoL.8,No. 1
COMPARISONOF THE SYNTHETIC PYRETHROIDS ESBIOTHRIN@
AND BIORESMETHRIN@WITH SCOURGE@
AND CYTHION@
AGAINST ADULT MOSQUITOESIN A LABORATORY WIND
TUNNEL
T. G. FLOORE, C. B. RATHBURN, JR., A. H. BOIKE, JR., J. S. COUGHLIN rnn M. J. GREER
John A. Mulrennan, Sr. ResearchLaboratory, 4000Frankford Aoenue,PanarnaCity, FL 32405
ABSTRACT. Both candidateadulticides,Esbiothrin@and Bioresmethrin@,exhibited quick knockdown
1-h posttreatment. Esbiothrin elicited the fastest knockdown, but Bioresmethrin was more effective at
both 1- and 24-h posttreatment than either Esbiothrin or Scourge@
against both Aed.estazniorhyruhus
and Cul,exquinquefasciatw. Mosquitoes treated with Scourge required more time and a higher dosageto
respondin a physiologicalmanner similar to those treated with either of the candidateadulticides.More
than twice the dosagerate of Cythion@was required than either candidate adulticide to causea similar
physiologicalresponsein treated mosquitoes.
INTRODUCTION
and serial dilutions were preparedthe day ofthe
test with reagent grade acetone (ACS). TreatSynthetic pyrethroid adulticides exhibit ment consistedof exposing 2 cagesof 25 mos9
highly selective insecticidal activity, rapid quitoes of each speciesto 0.5 ml of each dilution
knockdown and low mammalian toxicity, and for 10 seconds.The treatment regime started
are promising environmentally acceptablemos- with the control cages (treated with acetone
quito adulticides. Esbiothrin@,one ofthe allethonly) followed by the lowest dilution and prorin series of synthetic pyrethroids, exhibited gressedto the highest dilution last.
Between
quick knockdown against many flying insects
eachserial dilution, a "blank" ofthe next higher
(Anonymous).
including mosquitoes
Biores- dilution was sprayedthrough the chamber prior
methrin@combined rapid knockdown and high to actual treatment
of the mosquitoes.This propotency with very low mammalian toxicity (Elcedureprevented dilution of the next treatment
liott et al. 1978). Carter (1989) found Biores- by the previous lower concentration.
methrin effective as a thermal fog or ULV spray
Twenty minutes after treatment, the caged
in controlling mosquitoes.
mosquitoes were anesthetized with COz and
The John A. Mulrennan, Sr. ResearchLabo- transferred to clean
cylindrical cardboard holdratory (JAMSRL) conducts laboratory wind ing
cages (Floore 1985). This procedure was
tunnel tests to screen promising new mosquito replicated
once each week for 4 weeks to comadulticides for use in the state of Florida. We pensate for
slight variations in the testing concompared the effectivenessof 2 synthetic pyrditions. The temperatures ranged from 23 to
ethroid candidate mosquito adulticides (2% Es26'C (mean : 24'C) during the 4 weeksand the
biothrin and 2% Bioresmethrin) against susceprelative humidity was 60-75% (mean : 67.5%).
tible, laboratory reared adult Aedes taeniorhynThe term "knockdown" describesthe mosquichus (Wied.) and,Culcx quin4uefascintius
Say.
toes'condition approximately t h after exposure
to distinguish between reversible paralysis and
death. Some recovery of mosquito activity was
MATERIALS AND METHODS
expected24-h posttreatment (Beard 1960).MorTbo candidate adulticides, 2% Esbiothrin tality counts were made 24 h after treatment.
(L280-103-1)and 2% Bioresmethrin(L280-103- Abbott's formula (Abbott 1925) was
used to
2) were comparedwith 2 commercially available correct control mortality, and the LCso, LCgo,
adulticides Scourge@(18% resmethrin/14% pi- corresponding 95% confrdencelimits and standperonyl butoxide (PB)) and Cythion@(91% mal- ard error were determinecl by an EPA probit
athion) in a laboratory wind tunnel againstAe. analysis program. The toxicity ratio (TR) for
taeniarhynchusand Cx. quinquefasciatusadults. LCsoand LCgowas found by using the formula:
ZoeconCorporation, Dallas, TX, provided the 2
candidate adulticides.
Toxicity ratio (TR-)
A laboratory wind tunnel chamber adapted
LCso or LCgo standard insecticide
for ULV aerosolswas usedfor testing (Rathburn
1969, Rathburn et al. 1982) a wide range of
LCsoor LCsocandidate insecticide'
dilutions (5-8) ofeach formulation against each
Ifthe toxicity ratio was lessthan 1, the standmosquito speciesto determine the LCsoand LCgo
values at 1- and 24-h posttreatment. The stock ard insecticidewas more elTectivethan the can-
WrNo TuNNsr,Tpsrs
MARCH 1992
didate. If the TR was more than 1. the candidate
insecticidewas more effectivethan the standard.
The wire-screenedcagesusedin the tests were
decontaminatedby washing in 2 acetonebaths
and baked in a laboratory oven at 146"C for 1215 h and reused. The cardboard holding containers and organdy screenswere discarded.
ment, Bioresmethrin was 226x more effective
than Cythion at the LCgolevel against Ae. taeninrhynchus and 678x more effective than Cythion against Cx. quirquefasciatus (Table 2).
Against Ae. taeniorhynchizsat the LCgoIevel 24h posttreatment, Bioresmethrin was 5X more
effective than Cythion and against Cx. quinquefasciatuswas 6x more effective than C1'thion.
Both Esbiothrin and Bioresmethrin caused
RESULTS AND DISCUSSION
rapid paralysis (knockdown), loss of legs and
At both 1- and 24-h posttreatment,Biores- enatic flight in both test mosquitoes. Scourge
methrin was more effective than Esbiothrin produced these same physiological properties,
against Ae. tocniorhynchus (Table 1). At 1-h but at a slower rate than the candidate adultiposttreatment against Ae. taeniorhynchu.s,Bio - cides. Bioresmethrin was similar to Scourgein
resmethrin was 1.9x more effective than its insecticidal activity, but required less insecScourgeand 1.4x more effectivethan Esbiothrin ticide to causethe same response.These physat the LCsolevel (Tables 1 and 2). Bioresmethrin iological events occurred quicker in mosquitoes
was more effective than Esbiothrin or Scourge treated with higher dosagesof Esbiothrin than
againstAe. taeniorhynchus24-h posttreatment. either Bioresmethrinor Scourge.However,some
Against Cx, quinquefasciatusat the LCsolevel, recovery did occur with all the adulticides, esBioresmethrin and Scourgewere similar in ef- pecially with Cr. quinquefasciatlus
at lower dosfectivenessat 1-h posttreatment and both were ages. Cythion had little knockdown effect on
better than Esbiothrin. At the LCso level, Bio- test mosquitoeseven at higher dosages.
resmethrin was l.2x more effective than
Scourge and 1.5x better than Esbiothrin l-h
posttreatment (Table 2). Bioresmethrin was
ACKNOWLEDGMENTS
more effective 24-h posttreatment than either
This study was funded by Zoecon CorporaEsbiothrin or Scourge.At 24-h posttreatment
both candidate adulticides were more effective tion, Dallas,Texas.We thank K. R. Shafferfor
againstAe. taeniorhynchrzsthan Cx. quirqrrcfas- assistanceduring the study and J. Smith, Entomology Services,State Department of Health
ciatus.
At 1- and 24-h posttreatmentboth candidate and Rehabilitative Services,Jacksonville,FL,
adulticides were more effective than Cythion for his comments and constructive review of the
against both mosquito species.At 1-h posttreat- manuscript.
Table 1. Laboratory adulticide tests of 2% Esbiothrin and.2VoBioresmethrin comparedwith Scourgeand
Cr"thion in wind tunnel tests against Aedestaeniorhynchusand Cul.exquinquefasciatus.
Insecticide
Hours posttreatment
Lethal concentration in me AI/ml
LCuo
95V CL
LCro
95% CL
Aed,es taeniorhyrchw
2% Esbiothrin
2% Bioresmethrin
Scourge
Cy'thion
2% Esbiothrin
2% Bioresmethrin
Scourge
Cythion
q/
24
24
24
0.0104
0.0075
0.0143
0.9494
0.0818
0.0318
0.0616
0.7720
0.0074-0.0131
0.0057-0.0092
0.0105-0.0190
0.6535-1.6949
0.0692-0.0964
0.0300-0.0338
0.0585-0.0647
0.1631-0.1813
0.0077
0.0054
0.0053
2.3794
0.0955
0.0443
0.0640
0.2725
0.0048-0.0101
0.0027-0.0078
0.0029-0.0075
2.1342-2.6998
0.0657-0.1219
0.0190-0.0467
0.0604-0.0679
0.2574-0.2882
0.0276
0.0262
0.0624
5.9359
0.1682
0.0805
0.1335
0.4068
0.02t2-0.0447
0.0196-0.0418
0.0417-0.1261
2.8106-31.1403
0.1312-0.2958
0.0734-0.0896
0.1239-0.1460
0.3686-0.4586
Culex quinqwfreciatu
2% Esbiothrin
2% Bioresmethrin
Scourge
Cythion
2% Esbiothrin
2% Bioresmethrin
Scourge
Cythion
qi
24
24
24
0.0235
0.0161
0.0200
10.9238
0.1828
0.1013
0.1648
0.6464
0.0178-0.0385
0.0108-0.0397
0.0145-0.0354
8.5148-15.0025
0.1385-0.4360
0.0937-0.1110
0.1480-0.1878
0.5821-0.7358
V o L . 8 ,N o . 1
JouaNu, oF THEAtratnrclr.rMoseurro CoNrnol AssocIATIoN
Table 2. Standard error (SE) and toxicity ratiol data for 2% Esbiothrin and 2% Bioresmethrin comparedto
Scourgeand Cythion in wind tunnel tests againstAedes taeniorhyrchus and Cul,exquirqtrcfasciatw.
Toxicity ratio
lnsecticide
Hours posttreatment
LCuo
SE
Scourge
0.3591
0.2112
0.5484
0.1455
1.38
1.91
0.75
1.94
0.3310
0.4401
0.853;
0.1802
0.69
0.98
0.67
r.44
CS,thion
LCno
Scourge
Cythion
Aedestwninrhynthus
2% Esbiothrin
2% Bioresmethrin
2% Esbiothrin
2% Bioresmethrin
2% Esbiothrin
2% Bioresmethrin
2% Esbiothrin
2% Bioresmethrin
I
I
OA
ot
1
1
24
q^
2.26
9r.29
t26.59
2.38
2.t0
0.79
r.oo
5.41
Cubxquinqrefuciatus
309.01
0.85
440.63
7.24
2.85
0.90
b.ro
1.63
60.82
226.56
q lu
5.05
464.84
678.50
3.54
6.38
tToxicity ratio (TR) : LCsoor LCm standard insecticide
LCsoor LCsocandidate insecticide'
if TR <1 than standard insecticide more effective;
if TR >1 than candidate insecticide more effective.
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