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An Ecological Risk Assessment for Insecticides Used in
Adult Mosquito Management
Ryan S. Davis, Robert K.D. Peterson, and Paula A. Macedo
ABSTRACT
West Nile virus (WNV) has been a
concern for people across the United States since the disease was
initially observed in the summer of 1999. Since 1999, WNV has caused the
largest arboviral encephalitis epidemic in US history. Vector control
management programs have been intensively implemented to control
mosquitoes that carry WNV. Our deterministic ecological risk assessment
focused on 6 common mosquito adulticides used in vector control,
including 3 pyrethroids (d-phenothrin, resmethrin, and permethrin),
pyrethrins, and 2 organophosphates (malathion and naled). Piperonyl
butoxide, a synergist for the pyrethroids, was also assessed. Both
aquatic and terrestrial nontarget organisms were considered for acute
and chronic exposures to the adulticides. Tier I exposure estimates were
derived from ISCST3 and AERMOD for deposition and air concentrations
affecting terrestrial organisms and PRZM-EXAMS for standard pond
concentrations affecting aquatic organisms. Nontargets exposed to
adulticides included small mammals, birds, as well as aquatic
vertebrates and invertebrates in a pond subject to receiving the
chemical via drift and runoff. Risk quotients were obtained by comparing
exposures to toxic endpoints. All risk quotients were low indicating
that risks to ecological receptors most likely were small.
Davis, R.S., R.K.D. Peterson, and P.A. Macedo. 2007. An ecological risk
assessment for insecticides used in adult mosquito management.
Integrated Environmental Assessment and Management 3: 373-382. (PDF)
Equine Risk Assessment
for Insecticides Used in Adult Mosquito Management
Jerome J. Schleier III, Ryan S. Davis, Leslie M. Shama, Paula
A. Macedo, and Robert K. D. Peterson
ABSTRACT
Since West Nile virus (WNV) was introduced to New York
City in 1999, it has subsequently spread through the Americas, creating
human and animal health risks. Our equine risk assessment focused on
three pyrethroid insecticides (phenothrin, resmethrin, and permethrin),
pyrethrins, and two organophosphate insecticides (malathion and naled).
Piperonyl butoxide, a synergist commonly used in pyrethroids, was also
assessed. The objective was to use deterministic and probabilistic risk
assessment methodologies to evaluate health risks to horses from vector
management tactics used for control of adult mosquitoes. Our exposure
estimates were derived from the Kenaga nomogram for food deposition,
AgDRIFT® for deposition onto soil and hair, AERMOD for
ambient air concentrations, and PRZM-EXAMS for water concentrations. We
used the risk quotient (RQ) method for our assessment with the RQ level
of concern (LOC) set at 1.0. RQs were determined by comparing the
exposure to no-observable-effect-levels. Acute deterministic RQs ranged
from 0.0004 for phenothrin to 0.2 for naled. Subchronic deterministic
RQs ranged from 0.001 for phenothrin to 0.6 for naled. The probabilistic
assessment revealed estimates of deterministic acute and subchronic RQs
were highly conservative. Our assessment revealed that risks to horses
from adult mosquito insecticides are low and not likely to exceed the
LOC.
Schleier III, J. J., R. S. Davis, L. M. Shama, P. A.
Macedo, and R. K. D. Peterson. 2008. Equine risk assessment for
insecticides used in adult mosquito management. Human and Ecological
Risk Assessment. in press.
Regional ecological risk assessment for the introduction
of Gambusia affinis
(western mosquitofish) into Montana watersheds
Jerome J. Schleier III,
Sharlene E. Sing, and Robert K. D. Peterson
ABSTRACT
Qualitative risk assessment methodologies were used to
assess the risk of establishment and consequent impacts on native
minnows and species of concern (SOC) associated with the intentional or
unintentional introduction of the mosquito biological control agent,
Gambusia affinis, to various Montana watersheds. Gambusia
affinis introductions for mosquito control have been made throughout
the world; some introductions have resulted in deleterious effects on
native species. We used average January water temperatures, the
presence of dams, and the presence of native minnows and SOC to define
endpoints for our assessment. Our results suggest that a section of the
Missouri River running between Wolf Creek and Landusky had the highest
overall risk score, which corresponds to the highest likelihood of
establishment and effects on native minnows and SOC. We also
demonstrate how rivers with the highest temperatures are not necessarily
at the highest risk of having deleterious effects on minnows and SOC;
conversely, these rivers were found to be at highest risk of a
population of G. affinis establishing.
Schleier III, J. J., S. E. Sing, and R. K. D. Peterson.
2008. Regional ecological risk assessment for the introduction of
Gambusia affinis (western mosquitofish) into Montana watersheds.
Biological Invasions. DOI 10.1007/s10530-007-9202-1. (PDF)
Effects of single and
multiple applications of mosquito insecticides on non-target arthropods
Ryan S. Davis and Robert K. D. Peterson
ABSTRACT
Mosquito management plans have been implemented in the
U.S. and globally to manage mosquito vectors of West Nile Virus (WNV)
and many other diseases. However, there is public concern about
ecological risks from using insecticides to manage mosquitoes. Two
studies were conducted during the late summers of 2004 through 2006 at
Benton Lake National Wildlife Refuge near Great Falls, Montana.
The first experiment was conducted in 2004 and 2005 to assess acute
impacts of mosquito adulticides (permethrin and d-phenothrin) and
larvicides (Bacillus thuringiensis israelensis and methoprene) on
non-target aquatic and terrestrial arthropods after a single
application. The second experiment was conducted in 2005 and 2006
to assess longer term impacts of permethrin on non-target terrestrial
arthropods after multiple repeated applications. For aquatic samples, in
the first study, no overall treatment effects were observed despite a
potentially deleterious effect on amphipods on sample date 1 in 2004.
During the same study, 1 of 54 responses had a significant overall
treatment effect for sticky card samples. Many of the responses
for sticky card samples suggested significant time effects and
time-by-treatment effects. Three response variables were associated with
fewer individuals present in the insecticide treated plots in a
multivariate analysis. For the multiple spray study conducted in
2005 and 2006, 6 of the response variables collected via sticky cards
exhibited significant overall treatment effects, but none was associated
with fewer individuals in the insecticide treated plots. None of
the responses collected using sweep net sampling suggested overall
treatment effects. Time and time-by-treatment effects were prevalent in
2005, but no discernable pattern was evident. In general, nearly all of
the responses evaluated for either study indicated few, if any,
deleterious effects from insecticide application.
Davis, R.S., and R.K.D. Peterson. 2008. Effects of
single and multiple applications of mosquito insecticides on non-target
arthropods. Journal of the American Mosquito Control Association, in
press.
Other Ecological Risk Assessments:
Maine Board of Pesticides Control -
http://www.state.me.us/agriculture/pesticides/wnv/results3.htm
New
York City Department of Health Adult Mosquito Control Programs -
http://www.nyc.gov/html/doh/html/wnv/feis.shtml |
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