Hermetic storage
In hermetic storagethe grain or othercommoditiesare placed in an airtight
enclosure. The natural respiratory activities of the grainand the associated
insects and fungi reduce the concentration of oxygen and increase the
concentrationof carbondioxideto a lethallevelto insects and fungi.
Controlledatmospheres
Thistypeof storageinvolves the use of externally generated gas to displace the
intergranulargases. The aim is to reducethe concentrationof O 2 to about1% or
to raisethe carbondioxide to about80%.By doingso, insectsand fungi
infestation are retarded or controlled.
Inertdusts
Inertdustsare made fromsilicaaerogels,various clays,diatomaceousearthand
othersilicates.The dusts functionas insect killer by injuringthe cuticleof the
insects and causingthemto bleedwhichresult in losingwaterand deathby
desiccation.Highprice, cleaningand health hazardto the workers limitthe use
of this controlmethod.
26.7 Futuretrends
Methyl bromide and phosphine are the most widely used fumigants for
controlling pestinfestationin graincereal,dry foodproductsand quarantine
insects. Nowwe are facingthe problemthat methylbromide will be phasedout in
developed countries in the near future and certain stored product insects
developedresistanceagainstphosphine.Methyl bromide is known to havewide
spectrum effectivenessand it is assumedthat onlya different combination of
alternative fumigantscan replaceits use. Thissituation will haveseriousimpacts
on industries and consumers, who rely on this fumigant for structural fumigation
and post-harvest commodityuntilsuitablealternativeswill be developed.
Thissituation has led to the emergenceof otherfumigants.Amongthemare
sulfuryl fluoride,for spacefumigationand for the control of dry woodtermites
and otherpest structures. Also,carbonyl sulfide was rediscoveredas an alter-
native to methylbromide. Thecombination of heat, carbon dioxide and
phosphine, whichhas beenintroduced recently,was foundto be very effective.
The futuretrend is to reduce the use of toxicchemicalswhichare hazardous
to people and the environment:
∑ The use of integrated pest management (IPM). In this approach emphasison
routineinspectionand cleaning to detect the problemsbefore an outbreak
occurs.The use of varioustraps(pheromone, light,glue board) is veryuseful.
∑ Theuse of phytochemicals: substantial workis underwayto evaluatethe
potentialof essentialoils fromaromaticplantsfor the control of stored
product insects.
Improvingthe control of insects in foodprocessing 423