Proceedmqs of the 7th Iniernaiional Workzng Conference on Stored-product Protection - Volume 1

Efficacy of Cyfluthrin as a Residual Surface Treatment onConcrete Against Tribolium castaneum and T. confusum 1

Frank H. Arthur/

Abstract

The pyrethroid msecncide cyfluthnn (Tempo) is labeled mthe Umted States as a residual surface treatment on concretefloonng surfaces. It is available as an emulsifiableconcentrate (EC) or wettable powder (WP), and can beapphed at 2 label rates; 8 or 16 ml of 23% [AI] EC or 9 5and 19 0 g of 20% [AI] WP per 95 m2 The WPformulation IS more effective than the EC on concreteStudies with Triboluun confusum , the confused flourbeetle, and T castaneurn , the red flour beetle, twocommon pests of flour mills and food warehouses, show thatT. confusurn. ISmore susceptible to cyfluthrm WP than Tcastaneum The application rate of cyfluthnn, the timemterval m which T casiameum is exposed on treatedconcrete, and the age of the residues are all Importantfactors that should be considered when conductmg residualevaluations of cyfluthrm on treated concrete As thecyfluthrm residues age on concrete, longer exposuremtervals Will be required to k111T castaneum

Introduction

Tribolium. casiameum (Herbst), the red flour beetle, andT confusumi (duVal), the confused flour beetle, arecommon msect pests of flour nulls and food storage facrhtiesm the Umted States Infestations can result m thecontammation of fimshed products and the reduction ofproduct quahty, which could have senous economicconsequences. When retailers or consumers reject mfestedproducts, the cost of replacmg the product WIll have animmediate econorruc Impact, and customers may choose adifferent suppher the next time they make a purchaseResidual insecticides are often used to control Tribolium

species and other msect pests within the storageenvironment, and the efficacy of these msecncides is

I This paper reports the results of research only Mention of apropnetary product does not constItute a recommendation orendorsement by the U S Department of Agnculture

2 Gram MarketIng and Production Research Center, 1515 CollegeAvenue, Manhattan, KS, 66502, USA

dependent upon a vanety of factors, mcludmg the surfacesubstrate, the specific msecticide and formulation, and thetime msects are actually exposed on the treated surface.Organophosphate insecticides are generally less effective onconcrete compared to non-porous surfaces (Cogburn 1972,Watters 1976, White, 1982, Wilhams et al. 1983, Roperand Wright, 1985; Jam and Yadav 1989, Arthur 1997).Pyrethroids are usually more effective on concrete and otherporous surfaces compared to organophosphates (Williams etal. , 1983; Jam and Yadav, 1989), but thetr activity may bedependent on formulation Wettable powder (WP)formulations of organophosphates and pyrethroids arecomparatively more effective than emulsifiable concentrates(EC) apphed on concrete (Watters 1976, White 1982,Williams et al 1983, Jam and Yadav 1989, Arthur 1994a)The pyrethroid msecticide cyfluthnn (Tempo) is

registered m the Umted States as a general surfacetreatment for mtenor surfaces It IS available as anemulsifiable concentrate or a wettable powder. Applicationsof the 23% [AI] emusifiable concentrate can be made ateither 8 or 16 ml of concentrate m 3 8 hters of water tocover 94 m2, while the 20% [AI] wettable powder can beapphed at either 9.5 or 19 grams in 3.8 hters of water tocover 94 m2• Labels for both formulations specify applicationat the high label rate when the msect infestation IS severe.In this paper several of the physical and biological factors

that affect the residual efficacy of cyfluthrm as it affects Tcastaneuni and T. confusum are reviewed and discussedthrough presentation of recent results These factors shouldbe considered when planmng research projects with residualmsecncides or developmg msect management plans for flourmills, processmg plants, and food warehouses. Some may beunique to cyfluthnn , but all are apphcable for practicalmsect pest management m storage facilities.

Efficacy of Cyfluthrin Wettable PowderVersus Emulsifiable Concentrate

In this test ready-mix concrete was treated With themaximum label rates of the emulsifiable concentrate (16 mlper 94 m2) and wettable powder (19.0 g per 94 m2)formulations of cyfluthrm (Arthur 1994a). Bioassays wereconducted by confmmg T castaneurn and T confusumon the treated concrete at regular post-treatment mtervals.

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Proceedmqe of the 7th Iniernatumal Worhng Conference on Stored-product Protection - Volume 1

As the residuee aged, survtvsl of both T castaneuni andT confusurn. steadily mcreased on concrete treated withthe emulsifiable concrete, m contrast to survival on concretetreated with the wettable powder (Table 1) Survival of Tcastaneum. and T. confusum was 75.0 and 57.5 %,respectively for bioassays conducted 6 weeks after theconcrete was treated with the EC In contrast, less than 3%

survived when they were exposed on concrete that had beentreated 6 weeks earlier WIth the WP By the conclusion ofthe test, survival was 100% for both species exposed on theEC, while survival on the concrete treated with the WP was25% for T castaneurn and 20% for T confusum . Theresults clearly mdicate that the residual efficacy of the WPformulation ISsupenor to that of the EC formulation.

Table 1. Percentage survival (mean ± SEM) for T caetaneuni and T confusuni exposed at selected post-treatmentmtervals for 6 hours on concrete treated with 16 ml of 23% [AI] cyfluthnn emulsifiable concentrate (EC) versus19.0 g of 20% [AI] wettable powder (WP) per 94 m2(data from Arthur 1994a) a

Formulation Week 0 Week 3 Week 6 Week 9 Week 12

T castaneum

EC 0.0 ± 0.0 47.5 ± 27.5 75.0 ± 18 5 100.0 ± 0.0 100.0 ± 0.0

WP 0.0 ± 0.0 0.0 ± 0 0 0.0 ± 0.0 27.5 ± 21.4 25.0 ± 25.0

T. confusurn

EC 0.0 ± 0.0 40.0 ± 23.0 57.5 ± 25.3 95.0 ± 5.0 100.0 ± 0.0

WP 0.0 ± 0.0 0.0 ± 0.0 2 5 ± 2.5 20.0 ± 20.0 20.0 ± 20.0a Survival was significantly greater for both species (P < 0 05) exposed on concrete treated WIth the EC versus the WP formulation, exceptfor month 0

Species Variability betweenT. confusum and T. castaneum

In this test concrete was treated with cyfluthnn WP at 9.5 gper 94 m2, and T. castaneum and T confueiun wereexposed for 1 and 2 hours at regular post-treatmentintervals. Survival of T castaneum was greater thansurvival of T. confusum at both the 1 and 2-hour exposuremtervals for all residual bioassays except at 6 weeks,indicatmg that T. confusum. was more susceptible than Tcastaneum to cyfluthnn WP (Table 2) If both species arepresent m the same environment, residual applications

should be directed to control T. castaneurn , the leastsusceptible of the two species. However, It IS Important tonote that these results showmg the relative susceptibilitiesof T castaneum and T. confusum to cyfluthrm WP maynot be applicable for other msecticides. Some researchreports state that T casianeurn was more susceptible to aparticular insecticide (Ardley 1976, LaHue 1977, Bengstonet al 1980, Arthur 1997), while mother tnals either thereverse was stated (Arthur and GIllenwater 1990, Arthurand Zettler 1991, 1992) or there was no difference msusceptibihty (Arthur 1994a, b) T confusicm. and T.castaneurn apparently vary m their susceptibilrty to residualinsecticides

Table 2. Percentage survival (mean ± SEM) for T casianeum and T. confusum exposed for 1 and 2 hours at selectedpost-treatment mtervals on concrete treated WIth 9.5 g of 20% [AI] cyfluthnn wettable powder (WP) per 94 m2

(data from Arthur 1998 a, b). a

Week 6

T castaneuni 12.5 ± 9 5

T confusum 30.0 ± 21.1

T cas taneurn 2.5 ± 2.5

T ccnfusurn. 22.5 ± 19.3

Week 12 Week 18 Week 24

1 hour exposure

52.5 ±27.5 90.0 ± 70.1 90.0 ± 7.1

40.0 ± 23.1 27.5 ± 17.0 32.5 ± 17.0

2 hour exposure

57.5 ± 25.3 77.5 ± 13.1 85.0 ± 5.0

15.0 ± 15.0 17.0 ± 17.0 30.0 ± 20.4

a Survival was significantly greater (P < 0 05) for T castaneum at weeks 18 and 24 for the l-hour exposure and weeks 12, 18, and 24 forthe 2-hour exposure

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Proceedings of the 7th lnternaiumal Working Conference on Stored-product Protecium - Volume 1

Application of Cyfluthrin at theLow Versus the High Label Rate

As residues from a contact msecticide age on a treatedsurface they break down and become less effective One ofthe Important considerations in evaluatmg the residualcontrol of a contact insecticide is the application rate,because mcreasing the application rate will normally mcreasethe residual effectiveness of that insecticide This 1Sdemonstrated by companng survival when T castaneurn

was exposed for 1 and 2 hours on concrete treated with 9.5and 19.0 g per m2 of cyfluthnn WP (low versus lugh labelrate) (Table 3) Survival of T castaneum exposed for 1hour at 18 weeks post-treatment was 90 and 10%,respectively on concrete treated with 9.5 and 19.0 g perm2 No beetles survived when exposed for 2 hours at 18weeks post-treatment on concrete treated With 19.0g perm2• These results indicate that when cyfluthnn WP is usedto control T castaneurn, several apphcations of the lowlabel rate will be necessary to achieve the same degree ofresidual control as one application of the high label rate.

Table 3. Percentage survival (mean ± SEM) for T. castaneum exposed for 1 and 2 hours at selected post-treatmentmtervals on concrete treated WIth9.5 g or 19.0 g of 20% [AI] cyfluthnn wettable powder (WP) per 94 m2(datafrom Arthur 1998b). a

Week 6 Week 12 Week 18 Week 24

1 hour exposure9.5 g 12.5 ± 9.5 52.5 ±27.5 90.0 ± 70.1 90.0 ± 7.1

19.0 g 0.0 ± 0.0 0.0 ± 0.0 10.0 ± 7.1 33.3 ± 20.2

2 hour exposure

9.5 g 2.5 ± 2.5 57.5 ± 25.3 77.5 ± 13.1 85.0 ± 5.0

19.0 g 0.0 ± 0.0 0.0 ± 0.0 0.0 ± o 0 17.5 ± 11.1

a All compansons between the two apphcation rates were sigmficantly different (P < 0.05) for both the 1 and 2-hour exposures, except formonth 0

Exposure Interval as a Dosage Factor

It ISoften difficult to eradicate infestations inside mills andstorage facilities because the msects spend much of theirtime in protected refugia , and will have hrruted contact Withinsecticides apphed as residual surface treatments (Pmruger1974, Barson 1991). ThIS IS especially Important wheninsecticides are specifically targeted to selected sites withmthe facility instead of bemg broadcast over a large area.Insects such as T. castaneum may encounter a treatedsurface, then leave that surface before It ISknocked down by

the residues. The actual time that T. castaneurn isexposed on a treated surface before it can be knocked downISan Important mortahty factor that should be considered inaddition to the apphcation rate. The concept of exposureinterval as a dosage factor IS illustrated usmg data fromArthur (1998c). T. cosianeuni were exposed for differenttime penods at selected post-treatment mtervals on concretetreated with 9.5 g per m2 cyfluthnn WP, removed from thetreated surface, and held for one week. Survival decreasedas exposure interval mcreased, and as the residues aged,survival mcreased for a given exposure interval (Table 4) .

Table 4. Percentage survival (mean ± SEM) for T castaneum exposed at selected post-treatment intervals for 15 to 90mmutes on concrete treated With 9.5 g of 20% [AI] cyfluthnn wettable powder (WP) per 94 m2(data from Arthur1998c). a

Exposure (nun) week 2 week 6 week 10 week 14

15 0.0 ±O.O 28.0 ± 7.3 78.0 ± 5.8 92 ± 4.9

30 2.0 ± 0.0 6.0 ± 6.0 48.0 ± 15.9 90.0 ± 5.7

45 0.0 ± 0.0 6.0 ± 2 5 44.0 ± 16.9 88.0 ± 3.7

60 0.0 ± 0.0 6.0 ± 4 0 18.0 ± 8.6 54.0 ± 9.3

75 0.0 ± o 0 2.0 ± 2.0 14.0 ± 6.0 52.0 ± 17.4

90 0.0 ± 0.0 2.0 ± 2.0 2.0 ± 2.0 12.0 ± 9.7

a Regressions for exposure mterval (m ) on percentage survival (y) significant (P < 0.05) for each week

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Proceedinqs of the 7th International Workvng Conference on Stored-product Protectwn - Volume 1

Summary

The results of these studies show that the residual efficacyof cyfluthrm apphed as a residual surface treatment onconcrete will depend on the formulation, the target species,the apphcation rate, the age of the residues, and theexposure interval. While these specific results for cyfluthnnmay not be apphcable to other insecticides, these samefactors should be considered when evaluatmg msecticides forresidual control on treated surfaces The concept ofexposure mterval as a dosage factor should be given specialconsideration, because m actual field SItuations msects mayhave the opportunity to escape treated surfaces Moststored-product beetles are mobile insects, and Willrarely becontmuously exposed to insecticidal surface treatments

Acknowledgement

I thank J. E. 0 Bryan, H. C. GIllock, J E. Whitlock, andC. A. Trotter for technical assistance WIth the researchprojects discussed m this paper Gustafson, Inc supphedthe cyfluthrm used m the vanous projects. I also thank TW Philhps and J. L. Zettler for reviewmg the manuscnpt

References

Ardley, J. H, 1976 Synergized bioresmethnn as apotential gram protectant. Journal of Stored ProductsResearch 12, 253B259.Arthur, F H., 1994a. Residual efficacy of cyfluthrmemulsifiable concentrate and wettable powder formulationson porous concrete and on concrete sealed WIthcommercialproducts pnor to msecticide application. Journal of StoredProducts Research. 30, 79 - 86.Arthur, F. H., 1994b. Degradation of cyfluthnn EC andWP residues on pamted steel: effects of commercialsealants on residual persistence. Journal of Stored ProductsResearch 30, 163 - 170.Arthur, F. H, 1997 DIfferential effectiveness ofdeltamethrm dust on wood, concrete, and tile surfacesagamst three stored-product beetles. Journal of StoredProducts Research 33, 167- 173.Arthur, F H., 1998a. ReSidual tOXICityof cyfluthrmwettable powder agamst Tnbolium confusum exposed forshort time intervals on treated concrete. Journal of StoredProducts Research 34, 19 - 25.Arthur, F. H., 1998b ReSidual studIes With cyfluthrmwettable powder: tOXIcity towards red flour beetles(Coleoptera: Tenebriomdae) exposed for short timemtervals on treated concrete. Journal of EconomICEntomology 91, 309 - 319

Arthur, F H., 1998c Effects of a Food Source on RedFlour Beetle (Coleoptera: Tenebnomdae ) Survival AfterExposure on Concrete Treated With Cyfluthrm Journal ofEconomic Entomology 91, 773 -778.Arthur, F. H., and H B Gillenwater , 1990 Evaluationof esfenvalerate aerosol for control of stored product msectpests. Journal of Entomological Science 25, 261B267.Arthur, F H, and J L. Zettler, 1991. Malathionresistance m Triboliurn. castaneum (Coleoptera:Tenebnorndae ): DIfferences between discnmmatmgconcentrations by topical apphcation and residual mortalityon treated surfaces. Journal of Economic Entomology 84,721B726Arthur, F H. and J L Zettler; , 1992 Malathionresistance m Tribolium confusum Duv. (Coleoptera:Tenebnomdae ): Correlatmg results from topicalapplications With residual mortality on treated surfaces.Journal of Stored Products Research 28, 55B58.Barson, G , 1991. Laboratory assessment of the residualtoxicity of commercial formulations of msecticides to adultOryzaephilus surinaanensis (Coleoptera: Silvarndae )exposed for short time mtervals. Journal of StoredProducts Research 27, 205 - 211.Bengston, M , M. Connell, R. A. H. Davies, J M.Desmarcheher, M P. Philhps, J. T. Snelson, and R.Sticka, 1980 Femtrothion plus (IR )-phenothrm, andpirirmphos-methyl plus carbaryl, as grain protectantcombmations for wheat. Pesticide Science 11, 471B482Cogburn, R R., 1972. Natural surfaces m a gulf portwarehouse: mfluence on the toxicity of malathion andgardona to confused flour beetles Journal of EconomicEntomology 65, 1706 - 1709.Jam, S., and T D Yadav., 1989. Persistence ofdeltamethnn, etnmfos and malathion on different storagesurfaces Pesticides 23, 21 - 24.laHue, D W, 1977. Chlorpynfos-methyl: doses thatprotect hard Winter wheat agamst attack by stored graminsects. Journal of Economic Entomology 70, 734B736.Pmmger, D. P , 1974. A laboratory SImulatIOnof reSIdualpopulations of stored product pests and an assessment oftheIr susceptibIlIty to a contact msectIcIde. Journal ofStored Products Research. 10, 217 - 223.Roper, E M and Wnght C G., 1985 German cockroach(Orthoptera: Blatelhdae) mortalIty on vanous surfacesfollowmg applIcatIOn of diazmon Journal of EconomicEntomology 78, 733 - 737Watters, F. L., 1976 PerSIstence and uptake m wheat ofmalathIOn and bromophos on concrete floors Journal ofEconomiCEntomology 69, 353 - 356.White N. D. G., 1982 Effectiveness of malathIon andpmffilphos-methyl applIed to plywood and concrete tocontrol Prostephanus truncatus (Coleoptera:

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Bostricludae). Proceedings of the Entomological Society ofOntario 113, 65 - 69.Williams, P., R. 1. Semple, and T. G. Amos. 1983.

Relative tOXICItyof three pyrethroid insecticides onconcrete, wood, and Iron surfaces for the control of graminsects. General and Applied Entomology 15, 7 - 10.

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