Pest control of Storage for Maize.docx

Pest control of Storage for Maize.docx

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PestcontrolofStorageforMaize

PestcontrolofStorageforMaize:

Insects

Rodents

4.1.CharacteristicsofStorageInsectPests

Beetlesandmothsarethemostpredominantpestsinthetropiccausinggreatlossanddeteriorationtofoodgrain.Thesepeststypicallyhaveafourstagelifecycle:

egg,larva,pupaandfinallyadultasshowninthefollowingfigure40:

Fig.40.Cycleoflifeofatypicalstorageinsectpest.

Adaptedfrom（AGROTEC/UNDP/OPS,1991）

Theeggsarelaideitheronthesurfaceofgrainkernel（normallyonphysicallydamagedpartofthegrainorinsideatinyholepartlyboredonthekernelbytheparent.Theeggshatchintolarvaewhichvoraciouslyeattheirwaywithinthegrain,andareresponsibleformostofthedamageoncrop.Thelarvaegraduallytransformintopupae,adormantnon-feedingstage.Theselaterhatchintoadultswhicheattheirwayoutofthegrainkerneland（ifbeetles）immediatelystartaggressivefeedingonandfurtherdestructionofthegrain.TheProstephanustruncatusorlargergrainborer（LGB）lossesintherangeof10-35percentin5-6monthsinhouseholdstorageandup60percentlossesovera9monthstorageperiod.Adultmothsareshort-livedanddonotfeed,buttheirlarvaevoraciouslyfeedandcauseheavycontaminationtothestoredproductthroughwebbingandfrass.

Insectpestdamagetograinmayfoldintooneofthefollowingcategories:

·Boredholesinthegrainanddisappearanceofalargeportionoftheendosperm.

·Injurytothegermreducingthenutritivevalueandlossofliabilityofthegrain.

·Heatingandcondensationandmouldingofthegraincausingreductioninnutritivevalueandrisktoformationoftoxicsubstancesasaflatoxin.

·Contaminationofstoredgrainwithexcrementandfrass.

·Infestedgrain,speciallybySitotrogacerealellafigure41A-3,mayhaveasickeningsmellandtastethatmakesthegrainun-palatable.

·Maininsectcausingsignificantlydamagetocereal,includingmaize,asshowninthefollowingfigure41Aand41B.

Fig.41A.Commoninsectpestsofmaize.

1）.Triboliumcasteanum,2）.Sitophilusgranaries,3）.

Sitophilusoryzaeorzeamais,4）.Cryptolestesferrugineus.

 （Source:

casaBernardoLtda）

Fig.41B.Commoninsectpestsofmaize.

1.Orizaephilussurinamensis,2）.Prostephanustruncatus（LGB）,3）.Sitotrogacerealella,4）.Ephestiacautela.

（Source:

casaBernardoLtda）

ThislistincludethelargergrainborerLGBintroducedinAfricain1981（figure41B-2）.ItcausesseverelossesonmaizegrainandevendrycassavainTanzania,KenyaandTogoandthreateningallneighbouringcountries.Moreover,thetable24presentsomepropertiesofimportantgraininfestinginsectswithemphasisformaize.

Table22:

Somepropertiesofmostimportantgraininfestinginsects

ScientificName

CommonName

Productsinfested/Damaged

TypeofDamage

Temp.forpopulationcontrol（°C）

Optimumtemp.forreproduction.（°C）

Sitophilusgranarius

Sitophiluszeamais

Sitophilusoryzae

Granaryweevil

Maizeweevil

Riceweevil

Maize,sorghum,wheat,rice,paddy.

Larvaedevelopinsidekernelandfeedonstarchyinterior.Adultshatchandeattheirwayoutofthegrainandcontinuetofeedvoraciouslyonthegrain

17

18

18

28-3（）

29-31

29-31

RhizoperthaDominica

Prostephanustruncatus

Lessergrainborer

Largergrainborer

Paddy,rice,wheat,maizedriedcassava/potatocs

Maize,anddrycassavatubersorchips.

Larvaeentergrainandfeedonstarchyinterior.Adultsboregrainfreelyandvoraciouslyeatandmaydestroyentiregrainkernels

21

18

3（）-35

32

Oryzaephilussurinamensis

TrogodermagranariumEv.

Saw-grainbeetle

Khaprabeetle

Maize,wheat,sorghum,rice,pulses,oilseeds

Larvaeandadultsfeedonbrokenanddamagedgrain.

Thelarvaisaveryseriousstoredproductpest,thebeetleitselfdoesnodamage.

19

22

34

33-37

TriboliumConfusum

TriboliumConstaneum

Cryptolestesspecies

Confusedflourbeetle

Rust-redflourbeetle

Flatgrainbeetle

Maize,wheat,sorghum,

flour,groundnuts,milledcerealproducts,driedfruit,legumes,tapioca.

Larvaeandadultsfeedonbrokenanddamagedgrain.

Larvaefree-livingonbrokenanddamagedgrain.Adultswillattackthegermofsound

21

22

20

30-33

36

33-35

Sitotrogacerealella（Oilv）

Ephestia

cautellaWalk

Corcyra

cepalonicaStaint

Angoumoisgrainmoth

Tropicalwarehousemoth

Ricemoth

Maize,wheat,rice,paddy,sorghum

Groundnuts,rice,maize,wheat,sorghum

Maize,wheat,rice,millet,sorghum,groundnuts,cocoa

Primarypest,attacksgraininfield.Mostdamageoccursinstorageonlythroughlarvae.Adultsdonotfeed.

Characicrisedbyheavywebbingandfrassonproduce.Damageonlybylarvae.Adultmothsareshort-livedanddonotfeed.

16

16

18

28-30

28-32

30-32

SOURCE:

AGROTEC/UNDP/OPS,1991

4.2.NatureofInsectPestInfestations

Someofthemaizepestshaveflightabilityandoftenstarttheinfestationinthefieldseveralweeksbeforethecropisharvestedorwhenthemaizeisbeingfilleddryinstalksorinshocks.Theabilityoftheinsectstoflylongdistancesbetweenfieldsandtoandfrommaizestoresasshownbelowcanquicklyspreadtheinfestation.

Theproblemisaggravatedbybadpracticesuchas:

·Poorlymanagedstoragestructuretomaizefield

·Carelessdisposalofallcroporofcropresiduesweptfrominfestedstore

·Leavingfitsandpiecesofinfestedcobmaizeinunpluggedfields,orlyingallaroundthefarmyard.

Theinfestationinitiallyinthefieldoftencontinueanintensifiesinstorage,reachinghighproportionwithin2to3monthsofstorageunlesseffortsaremadetocontrolthepest.

4.3.LossMagnitudebyInsectsPestsinTraditionallystorage

Grainmustbeguardedagainstinsectinfestationinthefieldbytimelyharvesting.Protectionmustalsobeavailedduringdrying,soastominimizedryingandstoragelosses.

Weightlossonmaizegrainvariesfromregiontoregion,dependingoncropvariety,storageconditionandduration,andonpestcombinationinstorage.StudiesconductedonZambiagaveweightlossesfrominsectspestsatasmallholderstoragefordifferentmaizevarietiestobeinthefollowingranges:

·Localvarietiesweightlossranged:

1-3percent

·Improvedvarietiesweightloosranges:

5-6percent

·Hybridvarietiesweightloss:

8-9percent

Thesecaseswereobtainedintraditionallystoragefor6to9months,withsimilarworkdoneinKenya,TanzaniaandUganda.Thelowleveloflossinlocalvarietiesisattributedtotheirresistancetoinsectattackbecauseofhardkernelandtothecompleteandbettercoveragebythesheathswhichprotectconsiderablythegraininthefield,duringdryingandinstorageifinsheaths.Inspiteoftheirsusceptibilityshort-coming,improvedandhybridvarietiesarenormallyhighyieldinginfastmaturingcomparedtolocalvarieties.Thesejustifyingtheirproduction.

4.4.Insectpestscontrolstrategy.

Thecontrolofinsectsformaizemuststartbeforetheharvestandnotonlywhentheyaredetectedinstorage.Forabettercontrolthefollowingpointshouldbetakeninconsiderations:

·Thebeststrategyinvolvetimelyharvestingandthenproperdryingandcleaningofthemaizepriortostorage.

·Isimportantalsotoprepareinadvanceallstoragestructureandcontainerstobeused,makingthemreadyandsafetorecievethenewcrop.Somerecommendationsdependuponthetypeofcontainersofstructures,suchas:

-metal,earthware,plasticcontainersmustbewashed,desinfectedwithhotwaterandwelldriedbeforeusing.

-Sacksofjute,sisalandnylonshouldbewashedandboiledinhotwatertokilloffinsectspestsortheirseggsandlarvaeanddriedpriortouse

-Reed-wovenindoorgranaryandout-doorbasket,mud-wallbinsorbrick-wallsilosmustbere-plasteredusinglocalmaterials（cowdung,mud,sand,wood,ash,etc）tosealoffcracks,holesandcreviceswhichcouldhideinsectspestsandtheireggs

-Granaries,cribs,silosandwarehousesmustbecleanlyswept,repairedwherepossible,desinfectedusingpestscontrolchemicals,seetable23.

Table23:

Residualsprayrecommendedforstorefabricsandtheirdossagerates

（wettableanddispersiblepowdered）

Product

Concentration

Malathion

1-2gm/sqmeter

Pyrethrin/piperonylbutoxide

0.1-1.0gm/sqmeter

Phoxim

0.25gm/sqmeter

Pytethrins

0.25-0.5gm/sqmeter

Etrimfos

0.25-0.5gm/sqmeter

Mechacrifos

0.25-0.5gm/sqmeter

Pirimiphosmethyl

0.25-0.5gm/sqmeter

Bromophos

0.5gm/sqmeter

Fentirothion

0.5gm/sqmeter

Dichloryos

50-70gm/sqmeter

4.5.Traditionalinsectpestcontrolmethods.

Traditionalmethodsusedforfarmerstoreduceinfestationofthecropmayfallintothreegroups:

1）.Specialpractices2）.Useofmaterialsuchasashes（foritsabrasiveandletaleffectontheinsectscuticle）,mineralandoilinwhichphysicalbarriereffectsareresponsibleforthecontrolofinsectsand3）.Theuseofwholeorpartsoftheplantswheretheremaybesomenaturalinsecticidal,fungicidalorrepellenteffect（mainlyalcohols,alkaloidsandterpenes）.Thesemethodsincludeasfollows:

·Storingverywelldriedcroporre-dryingwheninfestationisdetected

·Storageofmaizeinsheathsforprotectionbythehusk

·Useofrepulsivelocalherbsandplantstoscareoffthepests（Nimgroundseed,leavesofacanthaceae,acardiaceas,annonaceae,myrtaceae,otherplantsextract,etc,

·Useofdriedinertmaterialsuchas,sand,crushedlimestone,woodashat1-5percentw/wfillingupingranularspaceandhinderinginsectactivity,diatomaceousearth,etc

·Useofabrasiveashfrompaddyh