Proceedings of the 7th Internatwnal Work-mg Conference on Stored-product Protection. - Volume 1

Study on the application techniques of stored grain protectant

Zhang Guohang' and Li Yuchen2

Abstract

Owmg to their high efficacy and low cost, Ferntrotluon andMalathion both are the most commonly used stored grampro tee tants. Results showed that the mixture ofdeltamethrm With Malathion, ferutrothion or pmmiphos-methly could extend the insecticidal spectrum, and havesynergistic effectiveness. The pmrmphos-methyl anddeltamethrm both showed the stable effectiveness undersubtropic climate conditions By usmg the formulations ofgranule and nee hull used as the carner , the pesticidesdegraded gradually and slowly, and no high peak appeared inthe whole treatment penod. The residue amount of pesticidein wheat flour and its products were higher than these in themilled nee and its products These four protectants showedno harmful acttion to the quality of cereal seeds.

Introduction

Malathion was recommended as the first protectant used mthe control of stored gram pest smce the begmnmg of 80's.Practise in more than ten years demonstrated that theprotectant was welcomed by the national gram depots andfarmers more and more due to its high efficacy, lowtoxicity, long persistence and Wide adaptability toenvironment. Thus it provides an efficient measure for themtegrated management of stored gram pests There are fourpesticides (Malathion, Fenrtrotluon, Pinrmphos-rnethyl andDeltamethrm) Widely applied m Chma It can be predictedthat new protectants and correpondmg applied technologyWill be developed unceasmgly (Zhang, 1997)Every pesticide possesses its own charactenstic m the

control of store gram pests. For the purpose of bnngmg theefficiency into full play, it is necessary to investigate thecorrespondmg applied techmque of this pesticide.

Selection of the regular pesticide

Under the normal applied condrtion, the comprehensivecompanson on the control efficacy and the cost (Ratio ofefficacy and cost) of the followmg five protectants

1 Zhejiang Provmcial Gram Science Research Institute, P R Chma

2 Jl1m Provmclal Gram and OJJ Storage Company, P R Chma

(Malathion, Ferutrothion, Malatlnon-Deltamethrin mixture,Pmrruphos methyl and Deltamethrm) shows the result as 11.1 1 .2 2 6.7 respectively In addition some specialpesticides are selected for the special requirements, such ashigh temperature, high humidity, special pests, resistan tpests etc. Malathion and femtrotlnon are the most Widelyapplied pesticides. In Australia, the controllmg cost ofmalathion and femtrothion is more than one time cheaperthan that of pmrruphos-methyl and chlorpynphos-methyl(Bengston, 1986).Nearly 50 tons of malathion have been apphed annually m

the national grain depot m the major gram producingprovmce Iihng smce 1990 and a satisfactory efficacy wasreported in several years It is recommended to applypesticide at once on the gram when it was put into storage,which is enough to prevent the stored gram from pestdamage m whole year. The applied method m the mtegratedmanagement is as follows. After the harvested grams WIthhigh moisture content are dried, the grams in the upper 30em of layer and the outer wall of gram bm are treated WIthmalathion, m order to prevent the foreign pests mvadmg.Only 1.5 kg of 70% malathion emulsion is needed to apply inevery 150 tons of gram. ThIS measure replaced the ongmalfumigation method and achieved the objective of lesspesticide applied, low cost and good efficacyIn other areas, the control of stored gram pests mostly

used the measure of treatmg the upper layer of gram bmWIth protectant and fumigating the middle and lower layer ofgram bm With alurmmum phosphideThe techmque of treatmg the whole bin With protectant IS

recommended to use m those gram depots With highmechamzmg ability m puttmg grams mto storage. Theapplication of those protectants, such as malathion andfemtrothion m the protection of stored grain and seeds frompest damage was adopted in the peasant households inZhejiang, Huber, Guangxi , Shanxi, SIchuan and Guangdongprovmces, and a satisfactory efficiency was obtamed Itnunmuzes the original 5 - 10% losses caused by the pestdamage and replaces the application of fumigant as well asimproves the safety SItuation and prolongs the persistence ofefficacy

Insecticidal spectrum and mixed formulation

Results showed that those organophosphorus pesticides,such as malathior femtrothlOn and pmmophos-methyl,performed satisfactory efficacy to maize weevil (S1,toph1,lus

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Proceedings of the 7th Internaiional Worhng Conference on Stored-product Protection - Yoiume 1

zearnais Motschulsky) and not to Lesser gram borer(Rhiaopertha dominica Fabricius ) (ZheJlang GrainSCience Research Institute, 1986) On the contrary, thedeltamethnn, as the representative of pyrethroid pesticide,showed drversified effectiveness to these stored gram pests.These two groups of pesticide constitute differentinsecticidal spectrum For the purpose of controllmgdifferent species of pests and broaden the msecticidalspectrum of certam pesticide, a nuxed formulation ofpyrethroid and organophosphorus pesticides was put forwardin the early stage (Bengston et al. , 1980). For the purposeof further understandmg of the synergistic property of thesetwo groups of pesticide on the efficacy, the expenment wasconducted These results are showed m FIgure 1 As can beseen from this figure, the mixture of deltamethrm and

lor;

malathion, ferutrothion or pmrruphos-methyl showed acertam degree of synergistic activity m the control ofSitophslus zearnais weevil. The mixed formulation candecrease the apphed dosage (Zhang et al ,1990a) Duguetet al. (1990) pubhshed a simihar expenmental result.

A comparison on the environmental stability ofpesticide

There IS a significant difference in the efficient protectmgpenod to pests and the degradatrve rate of pesticide residuem the stored gram among vanous pesticies. Under thenormal productive condition, the stability of pesticideresidue m grain depot was decreased as the followmg order:pmrruphos-methyl > ferntrotluon > malathion (Zhang etal , 1993).

/00:0 O:IOQ50:50

0-0 -------00 Deltamethnn + Malathion

+- - +Deltamethnn + Fenrtrothron

X-- --- X Deltamethnn + pmrnphos-methyl

Ratio of Deltamethrm and organophosphorus

Fig.l. Combmed action of the mixed preparation of action of Deltamrthnn and three organophosrus insecticides on com weevil

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Proceedinqe of the 7th International Working Conference an Stored-product Protection - Volume 1

In the summer (August - October) of Zhejiang andGuangdong provinces, the average temperature of storedgram was 29. 5°C and 36. 2°C respectively The efficacy ofpmrruphos-methyl to S. zeamais weevil showed a higheffectiveness under the high temperature and high humiditycondinon of Guangdong province (FIgure 2). However theefficacy of femtrotluon in Guangdong was lower than that inZhejiang (Zhang et aI., 1990b) The expenments onvanous protectants conducted by Guangdong Gram ScienceResearch Institute also demonstrated this result (Hua et al. ,1986). Desmarcheher and Bengston (1979) conducted aninvestigation on the degradative rate of 17 protectants. Theresults also confirmed the above mentioned results.Deltamethnn showed a satisfactory efficacy m the control

of R. dominuxi weevil and the degradative rate of residuein stored grain also showed a stable pattern The half-life

(~ t ) of deltamethrin m the gram depot condition was

around three times longer than that of malathion (Zhang etal. 1993). So, It IS suitable to be used m the control of R.dommica weevil in the southern Chma with high

~ 12c::o-5'"0o.~~Q)0-

eoc::.~+JUQ)+Jo~0..

8

5 10 15Fenltrothion

10 15Pirlmiphos-Methyl

Guangdong

temperature and high hunudrty

Influence of formulation on the pesticide residue

Regularly, the dust formulation mixed with the storedgram often causes a high resrdue level m gram at the earlystage after treatment, and the umt weight of wheat ISdecreased accordingly, thus mfluencmg the quality of storedgram (Yu, 1985) Besides, the powder induces the harmfulinfluence on environment dunng the apphcation penod. Twonew formulations were developed. One IS the use of nce hullas the earner which could be prepared for immediateapplication (Zhang et al. , 1980) and the other IS the granuleformulation manufactured by the mdustnal process (Ge etal. ,1996). The property of these two formulations IS similarto the controlled release formulation. It resulted m a lowresidue of pesticide for stored gram. Especially the granuleformulation, whose residual performence showed that gramafter treatment WIth pesticide by the peasants whenever Ifthe gram IS necessary for use, and need not be wornedabout whether the pesticide residue in gram IS higher thanthe MRL.

r--

-- -

-I---

5 10 15Fenitrothlon

5 10 15Pirimlphos-Methy1

ZheJiang

Dosaget mg/kg)

Fig. 2. Comapanson on the protectmg pencxl of Ferutrothio and pmrruphos-Methyl on com weevil (Sztophzlus zeamais ) mZhejiang and Guangdong province

Pesticide residue in the processing of rice and wheat

The reSIdue of malathiOn, femtrothion and pmmiphos-Methyl m the mIlled nce and cooked nce was much lowerthan that m the processmg products of wheat-wheat flourand steamed bread (Table 1). It can be attnbuted to thefollowmg reasons. The processmg of nce undergoes theprocess of nce hull and rice bran, and the hull wereseparated from the nce, then the nce was sorted from the

bran, thus the pesticide which existed mamly m the hullbran portion of rice can be removed thoroughly, WIth only aless amount remamed m the mner mIlled nce gram Mterwashed and cooked with water, the pestiCIde reSIdue waswashed and degraded almost completely On the other hand,the processmg of wheat IS that the whole wheat grams weregrounded mto flour and the bran Then the bran wasseparated from the flour Owmg to the pesticIde reSIduebemg mamly sItuated m the bran portion, so the pestiCIde

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Proceedinqe of the 7 th Internatwnal Worhng Conference on Stored-product Protection - Volume 1

residue comes to the wheat flour With the bran. Althoughseveral times of separation process of wheat flour from branare carried out, It IS difficult to remove the pesticide residuefrom the flour completely Thus, the residue of pesticide is

/0

5

higher in wheat flour than that m the milled rice. Althoughthe fermentation and steam process are carried out III thepreparation of steamed bread, however, no washmg processis conducted, so more pesticide residue are remamed.

•

-.X ·

----~__\-x--~

6 /2Timetmonth)

A ••----..... Dust formulation

B 0--- - ---0 Hull earner

C *- - - -lC. Granule formulation

Fig.3. Degradative dynamics of vanous forrnulanons of Malatluonl Stl mglkg) m wheat

The influence of protectant on the quality of cerealseeds

According to the expenment of treatmg the nce , wheat,barley, corn and sorghum With the regular dosage and theone to two times higher dosage of malathion (Zhejiang Seedcompany et aI., 1981), fenitrothion, pmrmphos-rnethyl

(Zhang et aI., 1986) as well as the mixed formulation ofdeltamethnn and malathion (Zhejiang Gram SCIenceResearch Institute, 1990c), the tested pesticides showed noharmful effects on the seed quality. However, If the dosageof malathion IS too high (for example, 100 times higher) Itmay cause the phytotoxicity to seeds (Zhejiang GramSCIence Research Institute, 1982).

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Proceedmqs of the 7th Internatwnal Workmg Conference on Stored-product Protecuon - Yolume 1

Table 1. companson on the residue of Malathion and Ferntrothion m nee and wheat grams and their processing product (rng/'kg).

Stored penod (month)Grains Pesticide

0 1 3 6 9 12

RIce Malathion 11.4 10.7 6.3 3.1 1.7

Rice Ferntrotluon 12.5 8.5 12.5 8.6 5.8 1.7

milled RIce Malathion ND ND ND ND ND

milled RIce Fenitrothion ND 2.6 ND ND 1.2

cooked nee Malathion ND ND ND ND ND

cooked nee Femtrotluon ND ND ND ND ND

Wheat Malathion 7.1 5.6 3.5 3.2 3.7 1.8

Wheat Ferutrotluon 6.5 5 8 6.7 5.7 4.5 2.3

Flour Malathion 2.6 0.7 2.5 1.9 1.2

Flour Ferutrothion 1.3 0.8 2.2 1.3 1.1

Steamed bread Malathion 0.86 0.23 o 25 0.22 0.18

Steamed bread Femtrothion 0.4 0.47 o 26 0.39 0.19

References

Bengston, M , Connel , M., Davies, R., Desmarcheher,J. , Edler, B. , Hart, R , Philips, M. , RIdley, E. , RIPP,E , Snelson, ]. And Sticka, R., 1980. Chlorpynphos-methyl plus bioresmethnn, methacnphos, pmrruphos-methyl plus synergised bioresmethnn as gram protectantsfor wheat. Pestic. ScI., 11,61-76.Bengston, M. 1986. Personal commumcation.Desmarcheher .J. M. and Bengston, M. 1978. The residualbehaviour of chemicals m stored gram. Proceedings of the2nd International Workmg Conference on Stored-ProductsProtection, Ibadan, Negena, 10 - 16 Sept., 1978, PP138 -151Duguet, J. S , Fleurat-Lessard, F. and Peruzzi, D. , 1990.The advantage of mixed preparation of deltamethnn andorganophosphorus msceticides for the protection of storedcereals A review of recent trials. Proceedings of the 5thInternational Working Conference on Stored-ProductsProtection Bordeaux, pp. 517 - 521.Ge Zhigang , Zhang Guohang and Zhu yongrnan, 1996Investigation on the apphed techniques of Fang-Chong-Ling(malathion) granule formulatiom m the control of storedgralt pests. Journal of Gram storage, 25 (6),17 - 21. (mChinese)Hua Dejlan, 1986. EffIcacy of some gram protectants mGuangdong, Proceedmgs of the 1st Annual Meetmg ofChma Gram Storage SocIety. (m Chmese)Yu Shunan, 1985. Influence of malathIon filler on the umtweIght of wheat. CommumcatIon of Grain and Oil Storage

Science and Technology, 4,24 - 26. (in Chmese)Zhang Guohang, Li Yanhong, Xu Baozheng, Ye Zhongxiongand Shen Zlucheng , 1982 Investigation on the unumformpesticide application technique by using the nee hullearner, Acta Phyto-phylacica Smica , 9 ( 1), 55 - 60. (inChmese)Zhang Guoliang, LI Yanhong and Xu Baozheng, 1986.Influence of stored gram protectants-femtrotluon andpinrmphos-methyl on the quahty of cereal seeds Seed, 5- 6 :25 - 27,32 (m Chinese)

Zhang Guoliang, LI Yanhong, Fu Baokang, Zheng, Junkuiand Ge Zhigang , 1990a. Investigation on the efficacy of themixed preparation of deltamethnn and organophosphorusprotectants in the control of Lesser gram borer(Rhizopertha dominica Fabriciu» ). Zhejiang Gram andall SCience and Technology, 3 - 4 , 14 - 17. (m Chinese)Zhang Guohang , Li Yanhong, Fu, Baokang, Zheng Iunkuiand Ge Zhigang , 1990b. The apphed investigation on thecontrol of stored grain pests with pmrruphos-rnethyl ,Journal of Gram Storage, 19(1) ,3 -12 (m Chinese)Zhang Guoliang, Yu Guoymg, Lm JIang, Wang Zebmg andZhang Dahong, 1993. Investigation on the residue,degradation and dlstnbutIon of malathlOn, fenitrothlon,pmmlphos-methyl and deltamethnn in stored gram .. ActaChma Grain and all, (m Chmese), 8(1),1- 4.Zhang Guohang, 1997. Some advances of gram protectants mChina. J. Chmese Cereal & Oil Association, (SpecIal): 37- 39. (m Chmese)

Zhejlang Gram ScIence Research Institute, 1980.Expenmental report on the apphcatIon of high quahtyprotectant of stored gram pests - MalathIOn. (Internal

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Proceedinq« of the 7th Iniernatumal Worhng Conference on Stored-product Protectuni - Volume 1

information). (m Chinese)Zhejiang Gram Science Research Instituete, 1986Investigation on the Deltamethnn in the control of storedgram pests. Journal of Gram Storage, (in Chinese) 5,69 -73.Zhehjiang Gram SCIence Research Institute, 1990.Productive expenment on the mixed preparation of

Deltamethnn and Fan-Chong-Ling Cmalatluon ) m thecontrol of stored gram pests (Internal information) (inChinese)Zhejiang Seed Company, 1981 FIeld tnals on the apphcationof Malathion m the protection of seeds of barley, wheat,upland rice and corn, Zhejiang Gram and all SCIenceandTechnology, 2,9 - 13 (m Chinese)

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