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Proceedings of tlte Ttl: International Worhng Conference on Stored-product Protection - Yolume 1

Evaluation and standardised testing of diatomaceous earth

Zlatko Korumc1 and Peter Ormesher

Abstract from / Epochs DePOSIts range III tluckness from a few mches to several hundred meters. The deposit Diatomaceous earth (DE) deposits are found around the may be fmely lammated or massive (Quarles and Wmn, world We have extensively tested DE samples collected 1996) . from 80 different sources m Australia, Canada, Chile, When mmed , diatomite contams 50% or more moisture. Chma, Denmark, France, Germany, Japan, Macedonia, The solid component contams about 86 to 94% silica, the MeXICO, Spam , and the USA There was a WIde variation III remamder bemg chIefly alumma and alkalies from clay. The the insecticidal activity of DE samples from different only changes to diatomite dunng processing (chrushing, sources. HIgh msecticidal actrvity was positively correlated drymg , nulling) IS the reduction of the moisture content and WIth gram bulk density reduction The most effective DE mean aggregate MOIsture is reduced to 2 - 6% samples had lower tapped densities « 300 gIL), good and nulling reduces particle SIze to 0.5 to over 100 rmcrons, adherence to the gram (> 70%), a SI(h content greater WIth the majorrty of particles measunng from 10 to 50 than 80%, a pH below 8.5, and reduced gram bulk density microns. The result of this process IS diatomaceous earth, a by more than 2.5 kg/hL when applied at a concentration of fme, talc-like powder or considered to be non-toxic to 50 parts per milhon (ppm). Mean particle size (below 15 mammals DE IS extremely stable and does not produce tOXIC microns) and shape were not correlated WIth cherrucal residues or react with other substances in the insecticidal activity. Assessmg these frve physical environment (Quarles, 1992) charactenstics allows for the rapid screenmg of DE sources DIatomaceous earth (DE) IS produced in more than 30 before time consummg bioassays are conducted. countnes World production of DE has been steady at Reduced susceptibility (1 3 - 2.2 fold) of Tribolium approximately 1.4 nulhon tons Major producers are the U. casiameum , Cryptolestes [erruqmeus and Rhyzopertha S. , followed by France and the Republic of Korea These domuuca adults exposed to DE for 5 - 7 generations, as countries accounted for 61 % of the world production. compared With unselected lab strains, suggests that msects Denmark and countries of the former Soviet Union, each may be able to develop physiological or behavioural produces about 7 % of the world production. The prmcipal resistance mechanisms to DE use of diatomaceous earth IS m the of vanous alcoholic beverages, and as a additive in spice and sugar, and pharmaceutical and biotechnological medta The second largest use of DE IS as an absorbent (pet htter and 011 spIl1 Introduction absorbents) DE IS also used as a pestictde carrier, catalyst carrier, roughness and flattmg agent m and polishes, an antiblockmg agent III polyethylene film, a soft m Diatomaceous earth (DE), formed from fossilised , and automotive polishes, a bulk extender and a IS composed of almost pure dIOXIde Diatoms are thermal msula tor (Lemons, 1998) unicellular and probably the most Widespread group of DE IS probably the most efficacious natural dust used as an plants on earth. They are abundant III all aquatic msectIcide The dust particles adhere to the bodies of the ecosystems, but also occur III terrestrIal enVIronments msects as they walk over It. Damage occurs to the msects' There are more than twenty-five thousand species of dIatoms protective wax coat on the , mostly by sorption and to With no two havmg the same morphology (Round et al a lesser degree by abraSIon, or both. The result IS the loss 1992). When the dIatoms dIe, the tmy shells smk and form of water from the Illsect's body through deSIccation resultmg thIck layers over the centurIes. Eventually these deposits m death (EbelIng, 1971) The other mode of action of DE IS became fOSSIlIsed and compressed mto a soft, chalky rock repellence caused by the phYSIcal presence of the dust called diatomIte, the unprocessed (mmeral) form of DE. A (WhIte and al , 1966) There are probably other modes of well-documented record of diatoms extends back to the action of DE that are yet to be dIscovered (Quarles, 1992). mId penod, but the vast majonty of deposits are De has been studIed extenSIvely as a stored-grain

1 Hedley Technologles Inc , 2600 Skymark Avenue, SUite 101- protectant (Quarles, 1992; Banks and Fields, 1994; BUlldmg 4. Mlsslssauga, Ontano, L4W SB2, Canada Korumc, 1994, in press; McLaughhn, 1994; Subramanyam 738 Proceedings of the 7th Internatwnal Workmg Conference on Stored-product Protectwn - Volume 1 et. al , 1994; Quarles and Wmn , 1996; Korumc et al. , 1997 ) Differences m the efficacy of various DE The Difference Among DE's from formulations agamst the same msect species have been Different Geological Locations reported. The efficacy of diatomaceous earth (DE) agamst msects Numerous expenments were conducted With 36 different depends greatly on several physical properties of the diatom natural manne and fresh water diatomaceous earth samples particles (Ebelmg, 1971 ; Quarles and Wmn, 1996 ; collected in 1994 and 1995 from vanous deposits from the Subramanyam, 1995; Korumc, 1997) The analysis of USA, MeXiCO, Canada, Australia, Japan, Chma , and physical and chemical properties of DE is time consummg Macedoma (Koruruc, 1997), and With approximately 40 and expensive, and can be conducted only by experts at additional samples collected dunng 1996 and 1997 from specially equtpped laboratones Therefore, bioassays were Canada, the USA, Chile, France, Germany, Denmark and considered the most important cntenon for the assessment Spam A great difference m efficacy agamst msects was of the efficacy of DE agamst msects. However, this method observed between samples (Korumc, 1997, m press). For is relatively expensive and time consummg, smce it requires example, the L~ (lethal concentration for 90 % of msects expertise and a well-equipped entomological laboratory exposed) in mg of DE per kg of wheat (ppm) for nee By studying different physical properties of DE's, we weevil, Sitopluiu» oryzae (1. ) was 270 ppm for Cehte 209 attempted to discover the correlation between selected (USA), 438 ppm for DE from Austraha, 603 ppm for J 3 properties of DE samples and their efficacy agamst msects (Japan), 829 ppm for DIaFl1 610 (USA), and 1137 ppm for Accordmg to the results we developed a rapid, simple and Melocide DE 100 (USA) For all species tested, there was low-cost procedure for the prediction and the assessment of no mortahty With 1700 ppm of C 16 (Chma ) In many the msecticidal value of DE, Without conductmg bioassays or cases, samples of DE from different locations in the same tnne-consummg and expensive physical and chemical country exhibited a great difference in efficacy (Table 1; analyses Korumc, 1997)

Table 1. The efficacy of different diatomaceous earths on Canadian Western Hard Red Spnng wheat agamst nee weevil (RW) and red flour beetle (RFB) (Korumc, 1997).

% LC50 (95 CI) - ppm Diatomaceous earth RW after 5 days RFB after 14 days

Cehte 209 (USA) 270(213 - 340) 417(328 - 529)

J 2 (Japan) 333(263 - 423) 631(506 -787)

DE Aus (Australia) 438(346 - 553) 494(383 - 637)

Dicalite (USA) 496(393 - 626) 569(438 -738)

C 7 (China) 546( 430 - 393) 609( 456 - 812)

J 3 (Japan) 603(480-758) 562( 430 -737)

Mx 2 (Mexico) 634( 493 - 815) 648(497-847)

Perma Guard (USA) 680(555 - 832) 1211 (728 - 2014)

DIaFil 610 (USA) 829(561-1223) 1477(447 - 4883)

Melocide DE 100 (USA) 1137(546 - 3734) 2047 ( 1178 - 3556)

C 2 (China) 1501 (542 - 4154) low mortahty at 1700 ppm

Mx 1 (MeXiCO) 1648(515 - 5101) low mortahty at 1700ppm

Can 1 (Canada) 2044( 464 - 9007) low mortality at 1700 ppm

C 16 (Chma) no mortahty at 1700 ppm no mortality at 1700 ppm

Other differences m the vanous DE formulations tested content (Table 2; Korumc, 1997; Table 3; Korumc, m were: diatom species, origin (rnanne or freshwater), pH press) value, particle shape, particle Size distribution, and Si(h

739 Proceedmqs of the 7th Internatwnal Working Conference on Stored-product Proieciuni - Volume 1

Table 2. Some DE's properties * that may influence the efficacy against msects. 50 ppm DE DE Adherence Wheat bulk tapped pH to wheat SIOz Particle SIze distnbution DE density reduction density kernels Mean Below 12 (kg/hl) (gil) (%) (%) m microns microns (%) Cehte 209 (USA) 3.2 222 5.7 84.0 87 82 65 0 J 2 (Japan) 2.9 230 4.5 75.0 80 13.1 46.3 J 3 (Japan) 2.5 230 5.2 73.0 80 7.5 75.7 Mx 2 (Mexico) 2.2 328 8.5 72.0 80 N/A N/A Aus (Australia) 2.6 220 6.5 71.0 85 11.1 57.8 Dlcah te (USA) 2.4 218 7.0 74.0 85 10.4 57.4 Perma Guard (USA) 2.2 286 8.0 70.0 93.0 10.7 62.7 DiaFl1 610 (USA) 2.0 244 8 0 70.0 87.0 7 80 Melocide DE 100 (USA) 1.8 500 7.2 62.0 83.6 11.1 54.8 DlaFl1 620 (USA) 2.0 390 8.0 70.0 87.0 8 80 C 2 (China) 2.0 322 6.2 70.0 83.0 N/A N/A C7 (China) 2.2 234 6.0 70 85 16.4 34.7 DE Can (Canada) 1.9 442 5.9 70.0 70.0 N/A N/A * Methods according to Korumc (1997)

Table 3. Diatom species m vanous formulations of diatomaceous earths collected from different Rapid and Rough Prediction of geological locations 1 • Potential Insecticidal Value of DE Formulation and source DIatom speces Based on the results of research conducted by Maceljski and NaVICUlalyra (Ehrenberg) Karajeva Korumc (1972) and Korumc (1997, m press), it was A~hrwu1es oranius ObVIOUSthat one cannot predict insecticidal value rehably on Buiulphm tumne1fl J.E. Smith (Boyer) the baSIS of only one property of the DE tested. Thalasswtnx frauenfeldt Cleve & Grunov The results of our research WIth numerous DE samples, DE Aus (Austraha) AnamoeonetS senans from various geological locations, proved that the efficacy of Can 1 (Canada) Aulacosetra (Melostra) amlngua (?) DE depended on different properties of the diatom particles. Aulacosetra (Melostra) Thsxute« Properties included the ability of the DE particles to reduce Aulacosetra (Melostra) tSlandl.Ca(?) gram bulk density ( weight}, the tapped and loose StephanodlSCUS Ehrenberg density of the DE, the tendency of the DE particles to FragtlaruL Lyngbye adhere to the grain surface, the particle size distribution, Tet~yclus Ralfs the diatom shape, and the pH value It IS possible to Melocide DE lOO(USA) Aulacosetra (Melostra) tSlandun evaluate and to predict the msecticidal value of diatomaceous Perma Guard (USA) Aulacosetra (Meloszra) tSlandun Aulacosetra (Melostra) dtStans earth by very SImple and low cost analysis of these properties of DE, without conducting bioassays or extensive DE SD, USA Aulacosezra (Meloszra) ltrata arconadtntS (?) Mx 2(MeXlco) StephanodtScus Ehrenberg physical and chemical analyses (Koruruc, 1997). Cyclostepharws Round The most Important properties are: J 1 (Japan) Cycwtella bcdanu» (complex) • the effect of DE on bulk density (test weight reduction) J 3 (Japan) Fragilarn Lyngbye • the tapped denSIty of DE DE from Macedoma Plux:aenteus undulatus • the adherence of DE particles to the kernel, and C 15 (Chma) Plux:aenteus undulatus • the SIlicon dIOXIdecontent (of moderate Importance) C 20 (Chma) Aulacosetra (Meloszra) Thuxutes · the pH value of DE slurry (suspensIOn). C 21 (Chma) Aulacosetra (Melostra) amlngua Korumc (1997) developed two methods for the rapId I speCIes determmed by ReIdy Klmg of Freshwater Institute, assessment of potential insectiCidal value of DE The first Wmmpeg, Mb., Canada method is based on the predIction of the potential lethal dose 2 data from Cehte CorporatlOn, Lompoc, Ca, USA needed to kill 50 % of the msects tested (LDso)· Data for

(?) a great probabIhty of the accuracy DE tapped densIty, bulk denSIty reduction and percentage of 740 Proceedmgs of the 7th Internauonal Workwg Conference on Storeti-proiuct Protecuon - Volume 1 adherence to wheat kernels were used for regression and IS also predicted If two or all three of the Important correlation procedures to descnbe the relationship between properties are marked with a mmus (-), then the them. The equations are used to predict the DE potential prediction IS that the DE IS not effectrve enough to be used insecticidal value expressed as LC50 The second very for insect control (Korunic, 1997) SImple, rapid method IS based on the effect of DE on the reduction of the bulk density (kg/hl.) of Canadian Hard Red The Possible Development of Spring wheat (14% m c), above or below a pre- in determined level, the tapped density (g/L) of DE, above or Diatomaceous Earth Tolerance Adults below a pre-determmed value, adherence of DE to the of Several Stored-product Insects Canadian Hard Red Spnng wheat kernels (14% m c ), above or below a pre-determined value, SIOz content m DE There are numerous reports from around the world on the (%) and pH value. Using this cnterra , DE samples were WIdespread resistance of several stored-products insects to classified as good DE, or as not prormsmg DE (low tOXICIty the gram protectants from the , , against msects ) (Table 4). The second method can be carbamate, chlorinated hydrocarbon, Bacillus thunngiensis performed easily in different laboratones and at very low (B t) and botanical groups and to fumigants The cost resistance status of stored products insects have been recently summanzed by Subramanyam and Hagstrum Table 4. The cntena for the predrcuon of potential (1995). As insects developed resistance to an msecticidal value of diatomaceous earth. making It ineffective, newer msecticides or insecticide The predicted activity of DE + alternatives must be used The use of newer may offer excellent imtial control, but repeated use of It in The reduction of wheat bulk >2.5 kg/hl <2 5 kg/hl the same storage area increases the chance of developing densi ty usmg 50 ppm resistance to the newer insecticide The development of DE tapped density <300 gil >300 gil resistance can be slowed by using lower application rates, pH <8.5 >8.5 fewer apphcations, and less persistent pesticides Adherence to wheat kernel (%) <70 >70 (Subramanyam and Hagstrum, 1995), or using methods SIOz content ( % ) >80 <80 such as use of alternatrves to protectants, assiduous hygiene Particle SIze and coohng protectant-treated gram (Collms et al. , 1993) a) mean (mIcron) <15 >15 The development of reSIstance in stored-gram insects to b) below 12 mIcrons (%) >65 <65 commonly used gram protectants and fumIgants, coupled WIth the consumers concern for pestICIde reSIdues m The most effIcaCIOUSDE's have the greatest mfluence on processed cereal gram (NatIonal Research Counctl; USA, bulk denSIty (reductIon of weIght mass above 2.5 kglhl) , 1993), has prompted the exploration of new dIatomaceous the lowest tapped densIty (300 g or less m one 1lter earth based msectIcides as alternatIves to commonly used volume), the hIghest adherence to the wheat kernels (70% gram protectants. To date, reSIstance m stored-gram or hIgher), a pH value below 8.5 and a SIOz content of 80% msects to diatomaceous earth has not been documented or hIgher. In the DE samples tested, partIcle SIze (Subramanyam and Hagstrum, 1995). Smce only a phYSIcal dIstnbutIon and the shape of the diatoms were not correlated mechamsm IS mvolved, genetIc reSIstance IS unllkely WIth effIcacy agamst RW and RFB (Korumc, 1997). (Ebelmg, 1971) The SIlIcon dIOXIdeand trace metal OXIdes Subramanyam (1995) studIed fIve commerClal DE m DE, unlIke the actIve compounds m chemIcally actIve formulatIOns and also found out that effIcacy was not msecticides, do not mterfere WIth metabolIc or enzymatIc correlated WIth partIcle SIze functIOns. However, we observed, while conductmg Usmg the cntena m Table 4, DE formulatIOns WIth the numerous bIOassays WIth vanous DE's, that msects may be hIghest effIcacy agamst nce weeVIl and red flour beetle have able to develop phYSIOlogIcal or behavioural reSIstance to all fIve propertIes marked With a plus (+) As more DE Therefore, we began to evaluate the potentIal for adults propertIes are marked With a mmus ( - ), 2CtIVIty agamst red flour beetle, lesser gram borer and rusty gram beetle msects IS decreased The most Important propertIes are ( Cryptolestes ferrugineus Stephens) to develop tolerance gram bulk denSIty reductIon, DE tapped denSIty and or reSIstance to dIatomaceous earth after several generatIons adherence of DE partIcles to wheat kernels If these DE of selectIon m the laboratory. Laboratory strains of test propertIes are all deSIgnated +,It IS predIcted that thIS DE msects were reared contmuously m the laboratory WIthout WIll have good actIVIty agamst msects. WIth two + marks msectIcide exposure for the fore-mentIoned propertIes, and + marks for another The procedures descnbed by Brown and Payne (1988) two propertIes (SIOz and pH), good actIVIty agamst msects was followed for conductmg laboratory selectIon 741 Proceedinqs of the 7th Iniernatumal Worhng Conference on Stored-product Protecium. - Volume 1 experiments. Adults of each generation were exposed for 10 selection with synthetic gram protectants, after only a few days to Hard Red Spnng wheat (14% m c ) treated with generations, were much higher than the tolerance/ 500 ppm of DE Protect-It1M, then transferred to untreated resistance levels that we produced With DE treatment m the wheat. The adult progeny of surviving insects were treated laboratory after 5 to 7 generations of selection. again with DE as descnbed. Bioassays were held at 30°C and Tolerance usually mdicates an induced response that IS not 70% r. h genetically transmitted. Based on results obtained, we While srgmficant for all three insect species tested, the cannot make a conclusion about the nature of the observed resistance levels (up to 1.5x in red flour beetle, 2. Ox m decrease m efficacy against insects, after the selection lesser gram borer and 2. 3x m rusty gram beetle) achieved pressure in the laboratory, Without knowing If the resistance after 5 to 7 generations of very stnct laboratory selection IS stable m successive generations after the selection pressure, are very low. This phenomenon may be more pressure IS dropped. It IS also unknown If resistance may be correctly descnbed as increased tolerance to DE Golob et increased by further selection. al. (1991) have shown that the Mexico, Tanzama and Togo In the practice, where the selection pressure IS much less strains of larger gram beetle Prostephanus truncatus pronounced, msect tolerance to DE will probably develop (Horn) can survive the recommended dosages of permethnn much more slowly. However, the results achieved are (3.3 ppm) and pmrmphos-methyl (16.6 ppm) after three or sigmficant because they indicate the possible need to four and SIX generations of selection, respectively. The mcrease apphcation rates to mamtain an acceptable level of three insect strains exhibrted 3.5, 10 . 5 and 1.5- fold control as tolerance, or resistance, to DE develops. The resistance to permethnn, and 3.3, 3 . 1 and 11 1-fold doses of DE currently used in practice have adverse effects resistance to pmrmphos- methyl. respectively. Armstrong on gram properties ThIS hrmts the Wider use of DE for and Soderstrom (1975) found that continuous gram protection (Koruruc, m press). The use of even pressure produced llO-fold resistance within four higher doses WIll mcrease the seventy of these adverse generations in a malathion susceptible (Fresno) stram of effects Reduced susceptibih ty (1. 3 - 2 .2- fold) of Plodia mterpunctella El-Lakwah et at. (1992) found an Tribotium. castaneum , Cryptolestes [erruqineus and increase in the time needed to kill 50% of the adult red flour Rhyzopertha dominica adults after 5 - 7 generations of

beetle progeny of the F2, F4 and F6 generations exposed to a selection, as compared WIth unselected lab strains, suggests fixed phosphine dose. The resistance ratio was 1. 52, 3.81 that insects may be able to develop physiological or and 4.54- fold, respectively. Subramanuam and Hagstrum behavioral resistance to DE. Therefore, potential tolerance ( 1995) cited numerous recorded cases of different field development should be considered when using DE as a strams of stored gram msect pests exhibitmg very hIgh component of Integrated Pest Management m the fIeld of resIstance ratIos agamst gram protectants and fumIgants. gram protection Also, the tolerance levels produced under laboratory

Table 5. DIatomaceous earth tolerance m adults of the red flour beetle, Tribolium castaneum, as mdicated by an mcrease m the lethal concentratIOn (LC) , after 5 generations of selectlOn m the laboratory. LC50 LC90 Tolerance Ratio * Generation (95% Conf lImIts) (95% Conf lImIts) LC50 LC90 Laboratory stram 601.4(535 - 676) 1000.3(765 -1534) F6 758(598 - 961) 1556(922 - 3535) 1.26 1.55

* Mean martahty af lab stram - mean mortalIty of F6

Adults of F6 were exposed to 200,300,400, 500 and 600 ppm on treated HRSW wlth 14 6% m c Exposure penod: 10 days; temperature: 30°C; r h : 70%; replIcatIons: 5 Wlth25 adults; mlXedsex: age 14 to 36 days

Table 6. DIatomaceous earth tolerance m adults of lesser gram borer Rhyzopertha dO'nnnLca, as mdlcated by an mcrease m the lethal concentration (LC) m mglkg, after 6 generatIOns of selection m the laboratory. LC50 LC90 Tolerance ratio * GeneratIOn (95% ConL LImIts) (95% ConL LimIts) LC50 LC90 Laboratory stram 379(360 - 399) 573(529 - 650)

F7 638(567 -718) 1154(880 - 1766) 1.9 2.0

* Mean mortahty of F7 stram- mean mortalIty of lab stram Adults of F7 were exposed to 200 ,300 ,400 ,500 and 600 ppm on treated HRSW Wlth 14.6 % m c Exposure penod: 10 days, temperature: 30"( ; r h : 70%; replIcatlOns: 5 Wlth25 adults; mlXedsex. age 14 to 36 days

742 Proceedings of the 7th International Worhng Conference on Stored-product Protection - Volume 1

Table 7. DIatomaceous earth tolerance m adults of the rusty grain beetle, Cryptolestes fertugnwus, as indicated by an mcrease in the lethal concentration (LC) m mg/kg , after 4 generations of selection m the laboratory

LC50 LC90 Resistance ratio * Generation (95% Conf. Lmuts) (95% Conf. Lurnts) LD50 LD90

Laboratory stram 59(53 - 65) 105(93 -127)

Fs 132(122 -142) 243(216 - 293) 2.2 2.3

* Mean mortahty of Fs stram - mean mortahty lab stram Adults of F, were exposed to 200, 300, 400, 500 and 600 ppm on treated HRSWwith 14 6% m c Exposure penod: 3 days; temperature: 30"( ; r h : 70%, replications: 5 WIth25 adults; mixed sex: age 14 to 36 days

Table 8. The efficacy of vanous diatomaceous earths agamst the F6 generation of the red flour beetle, Tribolium. castaneum , selected m the laboratory WIth diatomaceous earth Protect-Itl'".

Diatomaceous earth Stram Concentration/ ppm) Mean mortalrty ( %) ± SEM ± Protect-It 1M 1000 100.0 0.0 a 1000 99 2 ± 0.9 a Cehte 209 1000 80.8 ± 8.2 a 1000 83.2 ± 5.6 a DE Macedonia 1500 94.8 ± 3.3 a 1500 97.2 ± 1.8 a ± DlaFll® 2000 98 0 19a 2000 83.1 ± 5.2 b ± Dryacidecu 1000 99.2 0.9 a 1000 98.4 ± 1.2 a ± Perma Guard® 2000 93 2 1.8 a 2000 82.0 ± 8.2 a ANOVA, Tukey (HSD) Rejection level - 0 050 Means followed by the same letter m the row for determmed DE are not sigmficantly different Exposure time: 12 days

Table 9. The efficacy of various diatomaceous earths against the F6 generation of the lesser gram borer Rhyzopertha domuuca. selected m the laboratory WIth diatomaceous earth Protect-It '".

DIatomaceous earth Strain Concentra tion (ppm) Mortahty ( % ) ( %) ± SE ± Protect-It 1M Lab 1000 80.2 4.0 a F6 1000 85.6 ± 4.3 a Cehte 209 Lab 1000 84.8 ± 4.3 a F6 1000 69.6 ± 7.0 a DE Macedoma Lab 1500 94.4 ± 3.0 a F6 1500 94.5 ± 3.3 a DlaFIl® Lab 2000 84.8 ± 4.7 a F6 2000 74.4 ± 1.1 a ± Dryacideco Lab 1000 80.8 7.4 a F6 1000 89.7 ± 2.7 a ± Perma Guard® Lab 2000 82.4 7.2 a F6 2000 58 6 ± 8.1 b ANOVA, Tukey (HSD) Rejection level - 0 050 Means followed by the same letter m the row for determmed DE are not significantly different Exposure time: 12 days

743 Proceedings of the 7th International Workmg Conference on Stored-product Protection - Volume 1

Journal of Stored Product Research 3. 219 - 229 Acknowledgements Korumc Z , Cenkovski and FIelds P G ,1997 Gram bulk density as affected by diatomaceous earth and application The authors are grateful to Roy Jenkins. Blame Tunlick and method Postharvest Biology and Technology 13, 81- 89 Andrew Mackay for techmcal assistance. Special thanks to Korumc Z • In press Dia tomaceous earths, a group of Mrs Heidy Kling of the Fresh Water Institute. Wmmpeg , natural msecticides Journal of Stored Product Research. for diatom identiftcation and to Dr Paul FIelds of the Cereal Lemons J F , 1998 Diatomite U. S Geological Survey, Research Center. Agnculture and Agn-Food Canada. Mmeral Commodity Summanes, January 1998 Wmmpeg , for cntically reviewing the manuscnpt. Maceljski M. and Korumc Z., 1972. The Effectiveness Agamst Stored-Product Insects of Inert . Insect References Pathogens, Temperature and Hurmdrty Project No E30- MQ-l Grant USDAIYU No FG-YU-130 Fmal Report of Armstrong J Wand Soderstrom E. L.. 1975. Malathion Institute for Plant Protection, Zagreb, p151 resistance in some populations of the Indianmeal moths McLaughlm A • 1994 Laboratory tnals on desiccant dust mfestmg dried fruits and tree nuts m Cahforrua Journal of msecticrdes. In Proceedmgs of the nth International Economic Entomology 68,505 - 507 Conference on Stored- Product Protection, Canberra, Brown T M. and Payne G T, 1988 Expenmental Australia, 650 Ed E HIghley, E J Wnght. H J selection for insecticideresistance Journal of Economic Banks and B R. Champ Vol 2, 638 - 645. University Emtomology, 81, 49 - 56 Press, Cambridge, U. K Banks J. and FIelds P., 1995 Physical Methods for Insect Quarles W 1992 DIatomaceous earth for IPM Control in stored-Gram Ecosystems In Stored Gram Practitioner 14 (5/6): 1- 11 Ecosystems Ed By Jayas D. S, WhIte N. D G and MUlr Quarles W. and Wmn P., 1996. DIatomaceous Earth and W. E.. Marcel Dekker, Inc ,New York 353 - 409 Stored Product Pests IPM Practitioner 18 (5/6): 1-10 Collins P J • Lambkm T M • Bndgeman B Wand Round FE, Crawford R M and Mann D G ,1992 The Pulvirenti C. 1993 Resistence to gram-protectant Diatoms. Biology & Morfology of the genera Cambndge insecticides m coleopterus pests of stored cereals in University Press, New York, USA Queensland, Australia Journal of Economic Entomology, Subramanyam Bh • Swanson C. L , Madamanchi Nand 86 :230 - 245. Norwood S , (1994) Effectiveness Of Insectoec , A New Ebeling W., 1971 Sorptrve dust for pest control. Annals DIatomaceous Earth Formulation, In Suppressmg Several Review Entomology. 16: 123 -158. Stored-Gram Insect Species In Proceedmgs of the 6th EI-Lakwah S M , Ahmed S.M , Khaltab M M. and Abdel- International Conference on Stored-Product Protection, Latief A M., 1992. Selection of the red flour beetle Canberra, Australia, 650 Ed. E. HIghley, E J. Wnght, (Tnbolwm castomeum. Herbst) for resistance to H. J. Banks and B R Champ, Vol 2, 650 - 659 phosphme in the laboratory and biological observations on Uruversity Press, Cambridge, U K. the resistant stram In Insecticides: Mechammsm of Subramanyam Bh, 1995 Comparative efficacy of Action and Resistance. Ed. By Otto D , Webber D. diatomaceous earth dusts on stored-product insects. ESA Andover, UK, pp 409 - 426. Presentation, as Vegas, NV. Contact: Dep Entomology, Golob P. and Broadhead P, Wnght M, 1991 U. Mmnesota, St Paul MN 55108 Development of resistance to insecticides by populations of Subramanyam Bh and Hagstrum D. W., 1995 Resistance Prostephanus truncatus (horn) (Coleoptera): Measurement and Management In Integrated Management Bostnchidae. In Proceedmgs of 5th Workmg Conference of of Insects m Stored Products ed Bh Subramanyam and Stored Product Protection, INRAISDPV, Bordeaux, D. W Hagstrum pp 231 - 398 Marcel Dekker Inc .• France, 999 - 1007 New York Korumc Z. ,1994 Dijatomejska zemlja pnrodm msekticid - WhIte G. D , Berndt W L., Schesser J H. and WIlson J DIatomaceous Earth as Natural Insecticide In Proceedmgs L , 1966. Evaluation of four mert dusts for the protection of ZUPP'94 Ed. by Korumc Z. ,136 -148. of stored wheat m Kansas from msect attack USDA/ARS Korumc Z , FIelds P. G., Kovacs M I P • Noll J. S. , Report No 51- 8, 22 pp. Lukow O. M. , DemIanyk C J. and ShIbley K J., 1996. WhIte G D., Berndt W L. and Wilson J L , 1975. The Effect of DIatomaceous Earth on Gram QualIty Evaluatmg dIatomaceous earth, SIlica- dusts, and Postharvest BIOlogy and Technology, 9, 373 - 387 malathIon to protect stored wheat from msects USDAI Korumc Z , 1997. RapId assessment of the msectICldal ARS Marketmg Research Report No 1038 18 pp. value of dIatomaceous earths WIthout conductmg bioassays

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