DTIC ADA592127: Temporal and Storage Effects on Ultra-Low Volume Droplets of Insecticides Collected on Teflon-Coated Slides

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by  Defense Technical Information Center

JournaloftheAmericanMosquitoControlAssociation,29(4):389–392,2013
CopyrightE2013byTheAmericanMosquitoControlAssociation,Inc.
OPERATIONAL NOTE
TEMPORAL AND STORAGE EFFECTS ON ULTRA-LOW VOLUME
DROPLETS OF INSECTICIDES COLLECTED ON
TEFLONH-COATED SLIDES1
MUHAMMADFAROOQ,AARONM.LLOYD,ALDENS.ESTEP,TODDW.WALKER
ANDTONYHUGHES
USNavy,NavyEntomologyCenterofExcellence,Jacksonville,FL32212
ABSTRACT. Use of microscope slides is the most commonly used method to field-assess the droplet
spectrum of ultra-low volume (ULV) sprays. Due to absence of analysis facilities during military
deployments, slides must be stored and shipped, and the impact of delays in processing and storage
conditionsondropletsisunknown.Thisstudywasdesignedtoevaluatetheeffectofstoragetemperatures
anddurationondropletsonTeflonH-coatedslides.TreatmentsincludedBVA-13mineraloil,Kontrol30-30
(30% permethrin), and FyfanonH (96.5% malathion), 2 slide wrapping techniques (proper and improper),
and 2 storagetemperatures (23 and45uC), replicated 6 times.The same areasofa slidewere measuredat
different times for 56–58 days using the DropVisionH droplet measurement system. Regardless of the
wrapping technique, droplets of BVA-13, Fyfanon, and Kontrol 30-30 on slides stored at 45uC reduced
significantlyafter1,2,and1day,respectively,butdropletsonslidesstoredat23uCwerenotsignificantly
affected.Theresultsofthisstudymayassistvectorcontrolprofessionalstoaccuratelyinterpretthedroplet
sizeandhelpintheeffectivedispersalofULV-appliedinsecticides.
KEYWORDS Dropletdurability,evaporation,shrinkage,volumemediandiameter,reduction
The efficiency of ultra-low volume (ULV) is still the preferred field method (Carroll and
applications depends on airborne insecticidal Bourg 1979, Dennett et al. 2006). The Depart-
droplets impacting on flying insects (Sutherland ment of Defense (DoD) personnel must under-
1983). Droplet size is one of the most important stand and comply with accurate droplet size and
physical factors influencing the efficacy of ULV dispersalforeffectiveULVapplications.Military
sprays (Mount et al. 1968, Mount 1970, Suther- personnel are often deployed to areas where
land 1983, Curtis and Beidler 1996). Haile et al. facilities to analyze the slides for droplet size are
(1982) found only slight change in efficiency of not available; still the readiness has to be
ground ULV application of malathion for a maintained as a DoD principle. Therefore, slides
dropletsizerangeof5–25mm.Tsudaetal.(1987) are often shipped for off-site analysis in condi-
foundhouseflyknockdownandmortalitydepen- tions not ideal for droplet preservation. The
dentupondropletsize,with30mmastheoptimal potential forerrorsdue tocollection, transporta-
diameter. Furthermore, they speculated depen- tion, and storage always exists, but the extent of
dence of droplet movement on interaction of theseerrorshasnotbeenmeasuredorinvestigat-
ed. Current practices of covering slides with a
inertial force and velocity, the droplet size–
blank, sealing the edges with a tape, and
dependent factors. Suitable ULV droplet sizes
measuringthedropletswithin4days(Davenport
forpesticidesarecommonlyspecifiedonproduct
1976) were not found to be based on scientific
labels, withemphasisontestingofspraydelivery
evidence. Anderson and Schulte (1971) observed
systems for droplet size.
no changes on malathion droplets left undis-
Despite automated droplet measurement sys-
turbed for 4 days in an air-conditioned room.
tems such as the hot wire probes and lasers
Moreover, the current practices are time and
gainingpopularity,useofglassmicroscopeslides
labor intensive, requiring personnel to facilitate
quick reading.
1Mention of a trademark, vendor, or proprietary The objective of this study was to evaluate
productdoesnotconstituteaguaranteeorwarrantyof temporal and ambient temperature effects on
the product by the US Navy and does not imply its ULVdropletsafterdepositiononTeflonH-coated
approval to the exclusion of other products that may
slides. The specific objective was to determine
alsobesuitable.Theviewsexpressedinthismanuscript
potential droplet size reductions over time on
are those of the author and do not reflect the official
Teflon-coated slides under different wrapping
policyorpositionoftheNavyandMarineCorpsPublic
HealthCenter,NavyBureauofMedicineandSurgery, and storage conditions.
Department of the Navy, Department of Defense, or The experiment was conducted at the Navy
theUSGovernment. Entomology Center of Excellence, Naval Air
389
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1. REPORT DATE 3. DATES COVERED
2013 2. REPORT TYPE 00-00-2013 to 00-00-2013
4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER
Temporal and Storage Effects on Ultra-Low Volume Droplets of
5b. GRANT NUMBER
Insecticides Collected on teflon-Coated Slides
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
US Navy, Navy Entomology Center of Excellence,Jacksonville,FL,32212 REPORT NUMBER
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)
11. SPONSOR/MONITOR’S REPORT
NUMBER(S)
12. DISTRIBUTION/AVAILABILITY STATEMENT
Approved for public release; distribution unlimited
13. SUPPLEMENTARY NOTES
14. ABSTRACT
Use of microscope slides is the most commonly used method to field-assess the droplet spectrum of
ultra-low volume (ULV) sprays. Due to absence of analysis facilities during military deployments, slides
must be stored and shipped, and the impact of delays in processing and storage conditions on droplets is
unknown. This study was designed to evaluate the effect of storage temperatures and duration on droplets
on TeflonH-coated slides. Treatments included BVA-13 mineral oil, Kontrol 30-30 (30% permethrin), and
FyfanonH (96.5% malathion), 2 slide wrapping techniques (proper and improper) and 2 storage
temperatures (23 and 45uC), replicated 6 times. The same areas of a slide were measured at different times
for 56?58 days using the DropVisionH droplet measurement system. Regardless of the wrapping technique,
droplets of BVA-13, Fyfanon, and Kontrol 30-30 on slides stored at 45uC reduced significantly after 1, 2,
and 1 day, respectively, but droplets on slides stored at 23uC were not significantly affected. The results of
this study may assist vector control professionals to accurately interpret the droplet size and help in the
effective dispersal of ULV-applied insecticides.
15. SUBJECT TERMS
16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a. NAME OF
ABSTRACT OF PAGES RESPONSIBLE PERSON
a. REPORT b. ABSTRACT c. THIS PAGE Same as 4
unclassified unclassified unclassified Report (SAR)
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std Z39-18
390 JOURNALOFTHEAMERICANMOSQUITOCONTROLASSOCIATION VOL.29,NO.4
Table1. Meandropletcharacteristicsof3sprayliquids,BVA-13mineraloil,FyfanonH,andKontrol30-30,at
time0hand4daysaftersprayundervariousstorageandwrappingconditions.
Dv0.516SD(mm)
BVA-13 Fyfanon Kontrol30-30
Storage
Wrapping (uC) 0h 42days 0h 4days 0h 4days
Proper 23 17.760.7a3 17.060.7a 14.560.7a 15.261.1a 14.560.6a 14.860.5a
45 17.661.2a 9.862.4b 13.860.8a 8.561.2b 15.361.1a 9.262.0b
Improper 23 17.660.4a 17.960.3a 14.260.9a 15.061.5a 14.760.5a 14.160.5a
45 17.460.7a 10.361.7b 14.860.9a 7.560.8b 15.260.6a 10.361.8b
Open 23 NA4 NA 13.660.4a 14.060.3a NA NA
1StatisticalcomparisonsforDv0.1andDv0.9wereidenticaltothoseforDv0.5andthusarenotreportedhere.
2Majorchangeindropletsoccurredwithin4daysanddatafor0hand4daysarecompared.
3Meansat0and96h foreachcombinationoffactorscomparedwithStudent’st-test(a5 0.05)having differentlettersare
significantlydifferent.
4NA,notapplicable.
Station, Jacksonville, FL (30u139N, 81u419W), andspreadfactorfrom0.60to0.72asappropriate
from May to August 2011. Spray materials were for each spray material. At 0 h, the droplets were
BVA-13mineraloil(hereafterBVA;AdapcoInc., measured from 5–25 spots on the slide or until
Sanford,FL),FyfanonHULV(malathion96.5%; a minimum of 200 droplets was recorded. The
Cheminova Inc., Wayne, NJ), and MasterlineH locationofeachspotonallslideswasnotedusing
Kontrol 30-30 (permethrin 30.0%; Univar USA scalesontheDropVisionmicroscopetableinorder
Inc., Austin, TX). These materials were sprayed to ensure that all subsequent measurements were
through a truck-mounted Clarke GrizzlyH ULV takenatthesamespots.Thedropletsizestatistics,
sprayer (Clarke Mosquito Control, Roselle, IL) suchasDv ,Dv ,andDv ,andtotalnumberof
0.5 0.1 0.9
at a flow rate of 120 ml/min. droplets were determined. The Dv , Dv , and
0.1 0.5
Teflon-coated 7.5 3 2.5-cm slides (John W. Dv arethedropletdiametersatwhich10%,50%,
0.9
Hock Company, Gainesville, FL) were waved and90%ofthesprayvolume,respectively,consists
twice through the spray cloud at 3 m from the ofdropletssmallerthanthesesizes.Whenthetotal
nozzlefromtoptobottomandthenfrombottom numberofdropletsrecordedonaslidewasbelow
to top in order to collect enough droplets for 50,thesubsequentmeasurementsonthatslidewere
measurement. A total of 24 slides were waved for terminated.
each spray material, with 12 slides wrapped both Analysis of variance was performed with
properly and improperly. Proper slide wrapping JMPTMstatisticalsoftwareversion5(JMP,Cary,
involvedplacingarectangularpapergasketonthe NC)fortheeffectofwrapping,temperature,and
sprayed slide, covering it with a clean glass slide, the delay in reading after collection on droplets.
andsealingalltheedgeswithaclearadhesivetape. For droplets’ longevity under various wrapping
For improper wrapping of slides, only the longer and storage temperature combinations, means of
sideoftheslidewastaped.Slidesweregroupedinto the Dv , Dv , and Dv at any reading time
0.1 0.5 0.9
sets of 6, each properly and improperly wrapped werecomparedwithrespective0-hdata,usingthe
foreachsprayliquid(n536)andwerestoredinan t-testat95%levelofconfidence.Thereadingtime
oven(modelAF30;QuincyLabInc.,Chicago,IL) priortothetimewhentheDv ,Dv ,andDv
0.1 0.5 0.9
at 45uC, whereas the remaining slides (n 5 36) differed significantly from the 0-h measurement
were stored at 23uC. An additional 6 slides were was defined as the stability period for that size.
wavedforthe Fyfanon applicationthat were not Assomeoftheslidesonlylastedfor4daysand
covered at all (open), were placed in the original mostofthechangeindropletsizeforotherslides
containerwithlidclosed,andwerestoredat23uC. stored at 45uC was observed within 4 days, only
Eachslideinthestudywasconsideredareplicate. the comparison of various sizes under different
Slides with BVA, Kontrol 30-30, and Fyfanon conditionsbetweentime0hand4dayswasdone
weresprayedonMondaysof3consecutiveweeks. (Table 1). For all spray liquids, the reduction in
Droplets on the slides were measured at 0 and Dv ,Dv ,andDv overtimeforslidesstored
0.1 0.5 0.9
4 h and at 1, 2, 3, 4, 7, 14, 21, 28, and 56 days, at45uCwasmuchmoreabruptcomparedtothat
except the last reading of Fyfanon, which was of slides stored at 23uC. By day 21, the droplets
takenat58days.Dropletdiameterwasmeasured on all slides from BVA spray stored at 45uC
with DropVisionH System (version 2.2; Leading dropped below 50 and further measurements on
Edge Associates, Waynesville, NC) and the these slides were curtailed. The change in Dv ,
0.1
relevantstatisticswererecorded.TheDropVision Dv0.5, and Dv0.9 for BVA slides stored at 23uC
system parameters used to score an individual with time was not significant for 21 days.
dropletwereanimagesize.6pixels,roundness1.0, Furthermore,thedifferenceindropletparameters
DECEMBER2013 OPERATIONALNOTE 391
ForFyfanon,thenumberofdropletsonslides
Table2. DayselapsedbeforeD 1significantlychanged
v0.5
from0hwhencomparedwithStudent’st-test(a50.05) stored at 45uC decreased to ,50 by day 4 and
for3sprayliquids(BVA-13mineraloil,FyfanonH,and further measurements were stopped. Overall, the
Kontrol30-30),wrappings,andstorageconditions. Dv , Dv , and Dv for slides stored at 23uC
0.1 0.5 0.9
were not significantly affected by time (Table 1).
Sprayliquid
The difference in droplet parameters of properly
Storage Kontrol and improperly wrapped slides under both
Wrapping (uC) BVA-13 Fyfanon 30-30 storage conditions throughout the measurement
Proper 23 21 .58 .56 times was not significant. The droplets of open
45 1 1 1 slides became significantly smaller than those of
Improper 23 21 .58 .56 wrapped slides at 23uC after 28 days. The Dv0.1,
45 1 2 1 Dv , and Dv for slides stored at 45uC
0.5 0.9
Open 23 NA2 58 NA significantly decreased from the diameter at 0 h
1StatisticalcomparisonsforDv0.1andDv0.9wereidenticalto in 1–2 days (Table 2). Among slides stored at
thoseforDv0.5andthusarenotreportedhere. 23uC, these parameters did not significantly
2NA,notapplicable. change over the study period of 58 days for
properlyandimproperlywrappedslides,whereas
of properly and improperly wrapped BVA slides itchangedsignificantlyin58daysforopenslides
underbothstorageconditionswasnotsignificant (Table 2).
for .4 days (Table 1). For BVA slides, compar- ThenumberofdropletsonslidesfromKontrol
ison of Dv0.1, Dv0.5, and Dv0.9 at any time with 30-30 stored at 45uC decreased to ,50 by day
the diameter at 0 h (original size) indicated that 21andfurthermeasurementsdiscontinued.There
these parameters significantly decreased from were some significant yet sporadic differences
original size by day 1 for slides at 45uC and by in droplet parameters from properly and impro-
21 days for slides stored at 23uC (Table 2). perly wrapped slides at 45uC, possibly due to
Fig. 1. Correction factor forDv0.1, Dv0.5, and Dv0.9 of slidesfor3 sprayliquids stored at45uC for different
hoursofdelayinreading.
392 JOURNALOFTHEAMERICANMOSQUITOCONTROLASSOCIATION VOL.29,NO.4
measurementerrors.Thesedifferencesforslidesat Research Program of the US Department of
23uC were not significant throughout the study Defense through the Armed Forces Pest Man-
period. The Dv , Dv , and Dv for slides agement Board. We thank RayPlatt for his help
0.1 0.5 0.9
stored at 23uC were not significantly affected by during droplet collection, and Peter Obenauer,
time.ComparisonofDv ,Dv ,andDv atany Carl Doud, and Jennifer Wright for their review
0.1 0.5 0.9
time to the diameter at 0 h indicated that these of the manuscript.
valuessignificantlydecreasedin1dayforslidesat
45uC and did not significantly change during the
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