In the past, emergency eradication programs for the Mediterranean
Fruit fly (Medfly) have involved the aerial application of a malathion-bait
mixture over large regions of farming and residential properties.
A food dye (SureDye) and bait mixture is being evaluated as a
replacement for malathion. Recently, promising results have been
found with applications of the SureDye
mixture in trials performed by the United States Department of
Agriculture (USDA) in Hawaii. During the spring of 1996, the California
Department of Food and Agriculture's
(CDFA) Pest Detection and Emergency Projects branch will be conducting
a trial aerial application of SureDye
and bait to assess its pesticide efficacy. Prior to application,
sterile Medflies will be released in a selected orchard in Orange
County and the fly population will be monitored through trapping.
The SureDye and
bait mixture will be applied by helicopter as an ultra-low volume
spray at weekly (6 to 8 day) intervals and will continue for up
to 8 applications. The dye concentrations in the preliminary test
in Hawaii were much less than the malathion concentrations currently
used in aerial malathion-bait sprays.
SureDye is a mixture
of Red Dye #28 and Yellow Dye #8, both of which are xanthene dyes
registered for use as color additives in drugs and cosmetics by
the U.S. Food and Drug Administration. Scientists speculate that
the red dye reacts with light and is transformed into a substance
that destroys the insect's
digestive tract. The yellow dye is believed to increase the activity
of the red dye. The SureDye
compounds degrade rapidly under sunlight and application of SureDye
is not likely to cause significant impacts on the environment.
The reported half life of the dyes is approximately 1 hour under
sunlight. Neither dye persists for more that a few hours in air
or water due to rapid photodegradation.
This study will be conducted as a two-phase project. The first phase will involve the initial development of the appropriate sampling and analytical methodologies. The second phase will consist of comprehensive sampling during application and analysis of samples.
A. Develop and validate analytical methodologies to measure residues
of SureDye product.
B. Measure the amount of SureDye
reaching the ground from the trial aerial application conducted
by CDFA under an experimental use permit.
This study will be conducted by the EHAP, under the general direction of Roger Sava.
Key personnel are:
Project Leader: Pam Wofford
Statistical Consultation: Rosie Gallavan
Senior Staff Scientist: John Troiano
Field Operations: Adrian Bradley, Pam Wofford
Lab Liaison/Quality Assurance: Nancy Miller
Chemical Analysis: Paul Lee
Contact Person: Madeline Brattesani
Question concerning this monitoring should be directed to Madeline
Brattesani at (916) 324-4100; fax, (916) 324-4088; e-mail, firstname.lastname@example.org.
SAMPLING AND ANALYTICAL METHODS DEVELOPMENT
Develop Analytical Methods -
The primary analytical laboratory for this study will be the California
Department of Food and Agriculture's
Center for Analytical Chemistry. Analytical methods will be developed
for residue analysis of SureDye
on deposition sampling media, such as steel sheets and deposition
sheets (Kimbies). The method detection limit, reporting limit
and storage statistics will be determined for all media tested.
The method detection limits will be determined using U.S. EPA
procedures. In addition to providing an estimate of the detection
limits and storage stability, these analyses will give preliminary
information on the precision, accuracy, interferences and costs
that will be associated with each method.
Determine Media of Interest - A survey of deposition sampling
media, such as deposition sheets (Kimbies) and steel sheets, to
quantify deposition will be conducted to determine the best possible
media for chemical extraction and analytical quantification.
Following methods development, sampling will be conducted during
the trial aerial application conducted by CDFA. SureDye
concentrations on the selected media will be measured. The results
will be used to determine amount of SureDye
reaching the ground.
Mass Deposition - 30 sites within the treatment area will be sampled
during application to determine the amount of pesticide reaching
the ground. Site selection will be random; however, sites selected
will be reviewed so that covered areas and locations on the edges
of the treatment area will be avoided. Samples will be collected
immediately after spraying, when spray droplets are sufficiently
dry. Because of the rapid photodegradation of SureDye ,
all samples will be covered and protected from exposure to sunlight.
Depending on results from methodology development, other media may be sampled to determine SureDye concentrations in air, water, soil or vegetation. Sampling to establish dissipation rates may also be conducted if warranted.
QUALITY ASSURANCE/QUALITY CONTROL
All samples will be analyzed for SureDye
by the California Department of Food and Agriculture's
Center for Analytical Chemistry.
Mass deposition will be presented as mean micrograms per square
foot for the treatment area. The number of significant figures
reported in final results will be determined by examining both
analytical and measurement variability. No other formal statistics
will be done. Concentrations measured on other media will be presented
as raw data.
Methods Development: April 1996
Sampling and Analysis: May 1996
Report Preparation: June - August 1996