48
JounNnr, oF THE AN,rpRrcaN
Mosourro CoNrRol, Assoclltrox
VoL. 7, No. 1
EFFECTS OF AROSURF@
MSF ON A VARIETY OF AQUATIC
NONTARGET ORGANISMSIN THE LABORATORY
P. G. HESTER, M. A. OLSON eNo J. C. DUKES
John A. Mulrennan, Sr. ResearchLaboratory, Florida Department of Health and Rehabilitatiue Seruices,
Panama City, FL 32406-0272
. ARSTRACT' Ninety-six-hour static acutetoxicity tests were conductedin the laboratory to determine
the effects o! a !7 mllm' (50 gal/acre) application of Arosurfo MSF (2 mole ethoxylate
of isostearyl
-Procambarus
alcohol) on Fundulus sitnilus, P^alaemonetes
pugio, Palnemonetespalu.dosus,Uco spp.,
spp.,
GammarusqPP.,Asellus spp.,Streptocephalusseali,Physa spp.,'Laeonereisculueii and an unidentihed
amphipod.Test temperaturesof 20-2?'C were basedon thJambient water temperaturefor the season
ofthe year when the desired.lifestageswere more abundant. No acute toxicity was observedwith any oi
the organismsexposedto this concentrationof Arosurf MSF.
INTRODUCTION
Arosurf' MSF (monomolecularsurfacefilm),
2 moleethoxylateofisostearylalcohol,has been
registeredfor control of immature mosquitoes
in all classesof waterby the U.S.Environmental
Protection Agency (EPA). Before registration, a
number of mosquito control programsin Florida
were using this product under a Florida experimental usepermit. Onestipulationof the permit
requiredresearchstudiesbe conductedto determine the effects of this material on a variety of
aquatic organisms that normallv occur in or
adjacent to the fresh or saltwatlr habitats in
which the larvicide might be used.
Arosurf MSF has been shown to be effective
for control of many mosquito speciesin a variety
of aquatic habitats (Levy et al. 19g0, 19gi,
1982a,1982b;Mulla et al. 1983,Takahashiet al.
1984).Limited laboratorystudieshavebeenconducted on the effects of Arosurf MSF on nontarget organisms.No acuteeffectswere observed
from one 0.68-ml/m' treatment of Arosurf MSF
on a speciesof frog or 2 freshwater fish species
exposed for 6 months or to 4 saltwatei fish
speciesexposedfor 7 days (Webber and Cochran
1984).Webber(1983)conducted96-h acutetoxicity testswith Arosurf MSF at 46.8ml/m2 on 3
speciesof fish without noticeabledetrimental
effects.There were no effects on mayfly naiads,
adult diving beetles and ostracods after field
evaluations at L gal/acre (Mulla et al. 1983).
Field evaluations of Arosurf MSF at I gal/acre
by Takahashiet al. (1984)indicatedthat corixids, notonectids,clam shrimp and a speciesof
adult beetlewere acutely affectedbut all, except
for clam shrimp, had recoveredto pretreatment
population levels by day 3. Their sampling
methodsdid not indicate detectablemortalitv in
copepods,mayfly naiads,chironomid larvae or
4 speciesof beetle larvae.
In this paper we report the results of static
(test solutions and test organisms were placed
in test chambersand kept there for the duration
of the test) laboratory studies to determine the
acute toxic effects of Arosurf MSF on a wide
variety of aquatic organisms,excluding members
of the classInsecta.The criteria for determinine
acute effects in these organismswas lack oi
movement or reaction to gentle prodding. The
rnaximum dosagetested was 47 ml/m2 (b0 gal/
acre), 100 times the maximum Arosurf MSF
label recommended application rate for mosquito control.
MATERIALS
AND METHODS
Static toxicity tests to determine the acute
effects of Arosurf MSF on specific indicator
organismswere conductedin the laboratory utiIizing methods recommendedby the American
Society for Testing and Materials (ASTM
StandardE 729-1980).
The organismsused in conductingtest were
longnosekillifish fFundulus similus(Baird and
Girard)], grass shrimp (Palaemonetespugio
Holthius), freshwater shrimp [Palaernonetes
paludosus (Gibbs)], fiddler crab (Uco spp.),
crayfish (Procambarus spp.), freshwater amphipod (Gammarus spp.), freshwater isopod
(Asellus spp.), fairy shrimp (Streptocephalus
seoll Ryder), snail (Physa spp.), polychaete,
lLaeonereisculueri (Webster)] and an unidentified amphipod.
All but 4 organisms were tested in 600-ml
Pyrex@beakers containing 400 ml of water.
When testing polychaetes,100 ml of sterilized
beach sand was added to the water to provide a
substrate for burrowing. Three organisms were
tested in 6-liter rectangular glassaquarium jars:
longrrosekillifish, grassshrimp and fiddler crabs
were tested with 4, 2 and 1 liters of water,
respectively.The fiddler crab jars contained 600
ml of sand at one end to provide a beach above
the water level. Containers were suspendedin a
water bath that utilized a Haake@(Haake Inc.
SaddleBrook, NY) open bath immersion circu-
MARCH 1991
Errnc'r oF ARosuRFor Aquerrc ORcANrsMs
lator for heating or a Ladau@(Brinkmann Instruments Inc. Westbury, NY) cooling coil to
regulate and maintain the water temperatures
(+0.5'C)duringtests.
Waters used for a diluent in preparing test
solutions came from a deepwell (alkalinity and
hardnessofca. 150ppm) for freshwatertests or
from the Gulf of Mexico for saltwater tests. Sea
water was filtered through a 10-pm sieve and
the salinity loweredto 15-17ppt with deionized
water. The pH values for both fresh and saltwater tests ranged from 7.7 to 8.3. All water was
aerated and treated with ultraviolet irradiation
for 24h before testing. Water quality was monitored during all tests for dissolvedoxygen and
pH; salinity was also monitored in saltwater
tests, and hardnessand alkalinity in freshwater
tests.
Equal numbers of treatment and control containers were used in all tests. Arosurf MSF was
pipetted directly onto the water surfaceof treatment containersat an application rate of 47 ml/
m2 basedon the surfacearea of the water in the
test containers. A 12L:12D photoperiod was
maintained using fluorescent lighting during all
tests. Test water temperatureswere selectedfor
each organism basedon conditions during their
peak natural abundance.Most organisms were
collectedduring the summer months when water
temperatures were relatively high and were
tested at 27'C. Amphipods and isopods only
occurred in abundance during the winter
months; therefore, the water temperature for
these tests was maintained between 20-22"C.
All organisms were held for 96 h posttreatment, The number of organismsand replications
varied amongorganisms(Table 1). The number
of organismsutilized per replication was based
on loading (organism numbers that would not
result in stress or unacceptablelevels of dissolved oxygen) and/or cannibalism. Mortality
counts were conducted at 24 h intervals with
dead organismsremovedat each count. Control
mortality exceeding57o rendercd a test invalid
and results were discarded.The treatment mortality was adjusted by use of Abbott's formula
(Abbott 1925)when control mortality occurred
and was exceededby treatment mortality.
Some organismswere field-collectedat the
desired size or stage of development (Tables 1
and 2) for conducting the toxicity tests, whereas
others (grass shrimp, saltwater amphipods,
snails and fairy shrimp) required specificrearing
techniquesto obtain the desired developmental
stage.
Special handling requirements (such as fednonfed, diet, number/container and techniques
of transfer to minimize mortality) for each of
the organismswere determined by preliminary
/o
nonchemicaltests (Table 1). Grassshrimp and
amphipods were fed during the toxicity test,
whereasall other organismswere fed only during
the pretest acclimation period.
RESULTS AND DISCUSSION
Water quality parameters measured during
each test were within the standardsprescribed
for conducting static acute toxicity tests (Environmental Protection Agency 1975, ASTM
Standard E 729-1980).Dissolved oxygen contents were above 60% saturation at 48 h posttreatment and above 407o satvation at 96 h.
Change in both the fresh and saltwater pH
values were within 0.2 units for any given test.
Salinities during saltwater tests normally increasedby 1 ppt at 96 h posttreatment due to
evaporation.
Ninety-six-hour static acute toxicity tests of
Arosurf MSF (47 ml/m') did not acutely affect
any of the life stagesat which organisms were
tested (Table 2). The highest treatment mortality observedwas 3.3% in fiddler crabs. Eight
percentof the crabsusedin this test escapedto
the water bath with equal numbers escaping
from both treatment and control containers,
indicating that treatment had no affect on their
ability to climb the glasssides of the container.
Grassshrimp and fiddler crab were observedon
occasionsto be physically caught in the globule
of excessArosurf MSF. Arosurf is a monomolecular film and afberthe film has coveredthe water
surface, the excess(as in this extremely heavy
dosage)forms a globule that collects in some
area of the container. Upon probing, it was
evident that the organisms were alive, and by
the next observation period they had escaped
from the globule.
The organismstested were not dependent on
the air-water interface during any stageof their
life cycle. However, snails and fiddler crabs did
move through the interface without apparent
deleteriouseffects during the period of time that
tests were conducted. Takahashi et al. (1984)
indicated that, with the exception of clam
shrimp, the organismsaffected by Arosurf MSF
were insects that have a ventral plastron which
may be affected by the reduction in surface
tension. This is supported by observations by
Mulla et al. (1983), who indicated that dead
adu}" mosquitoesand chironomidsoccurredon
the water surfaceof treated ponds.
The data herein list a number of organisms
that were not acutely affected by even excessive
applications of Arosurf MSF. Studiesconducted
to date indicate that this material primarily
affects surface dependent insects including
mosquitoes.
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EFFEcTor ARosuRn oN Aquarrc OnclNrsvs
Table 2. Ninety-six-houracutestatic toxicity test of ArosurfoMSF (47 ml/m2) againstselectednontarget
organrsms.
Organism
Life stage
Salinity
ppt
Temp.
"C
Adjusted %
mortality'
F. sirnilis
P. pugio
P. paludosus
Uca spp.
Procambarw spp.
Amphipod
Gammarusspp.
Asellus spp.
S. seali
Physa spp.
L. culueri
Juvenile
Zoea
Juvenile
Juvenile
Juvenile
Immature
Immature
Immature
Post-nauplius
Immature
Adult
15-16
17-19
0
16-t7
0
15-16
0
0
0
0
15-16
27
27
27
27
27
22
20
21
27
27
27
0.0
0.0
0.0
l Treatment mortality
treatment mortality.
adjusted by Abbott's formula when control mortality
0.0
0.0
1.9
0.5
0.0
0.0
0.0
occurred and was exceeded by
toes: Laboratory and field studies. Mosq. News
42:I-ll.
We wish to thank SherexChemicalCompany Levy, R., J. J. Chizzonite,W. D. Garrett and T. W.
Inc. Dublin, OH, for partial funding of this
Miller, Jr. 1982b.Control of larvae and pupae of
crucinns
Anophclesquadrimoculatusand Anoph.el.es
study.
in natural paludal ponds with the monomolecular
surface film isostearyl alcohol containing two oxyREFERENCES CTTED
ethylenegroups.Mosq. News 42:172-178.
Abbott, W. S. 1925. A method for computing the
Lerry,R., W. D. Garrett, J. J. Chizzoniteand T. W.
effectivenessof an insecticide.J. Econ. Entomol.
Miller, Jr. 1980. Control of Culex spp. mosquitoes
18:265-267.
in sewagetreatment systemsof southwesternFlorASTM Standard E 729-1980.Standard practice for
ida with monomolecular organic surface films.
conductingacutetoxicity tests with fishes,macroinMosq. News 40:27-35.
vertebrates,and amphibians. American Society for
Mulla. M. S.. H. A. Darwazehand L. L. Luna. 1983.
Testing and Materials, Philadelphia, PA.
Monolayer films as mosquito control agents and
Environmental Protection Agency. 1975.Methods for
their effects on nontarget organisms. Mosq. News
toxicity test with fish macroinvertebrates,and am43:489-495.
phibians. (Committee on Methods for Toxicity Test Takahashi,R. M., W. H. Wilder and T. Miura. 1984.
with Aquatic Organisms) EPA-660/3-75-009.
Field evaluations of ISA-20E for mosquito control
Corvallis,OR.
and effects on aquatic nontarget arthropods in experimentalplots. Mosq. News 44:363-367.
Levy, R., J. J. Chizzonite, W. D. Garrett and T. W.
Miller, Jr. 1981.Groundand aerial applicationof a Webber,L. A. 1983.The effectof the monomolecular
monomolecularorganic surfacefilm to control saltsurfacefrlm, isostearyl alcohol containing two oxymarsh mosquitoesin natural habitats of southwestethylene groups (ISA-20E) on nontarget organisms:
ern Florida.Mosq. News41:291-301.
fish studiesJ. Fla. Anti-Mosc. Assoc.54:43-44.
Levy, R., J. J. Chizzonite,W. D. Garrett and T. W.
Webber,L. A. and D. C. Cochian. 1984.Laboratory
MiIIer, Jr. 1982a. Efficacy of the organic surface
observations on some freshwater vertebrates and
film isostearyl alcohol containing two oxyethylene
several fishes exposedto a monomolecular organic
groupsfor control of Culex and Psorophoromosquisurfacefilm (ISA-20E).Mosq. News 44:68-69.
ACKNOWLEDGMENTS