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  Stored Grain Pests

Introduction > Source of Infestation > Management > Stored Pests >

Ikisan - Stored grain pests of maize


  • Ever since the advent of stabilized Agriculture, storage of produce has remained an issue of utmost concern.
  • Unless the problem of storage is solved satisfactorily the problem of hungry millions may continue even with substantial increase in production.
  • There are a number of estimates of post harvest losses. Most conservative estimates for the post harvest losses in food grains in India even put at about 10%, a quantity good enough to feed at least 60 million people.
  • Out of the total production, about 70% is retained and stored by farmers for consumption, as seed, feed and payment of wages and only about 30% is marketable surplus.
  • Insects are responsible for enormous spoilage in storage they feed on grain, bore the kernel, destroy the germ portion, cause heating and deterioration in stored produce.
  • As per the Pause committee report, the storage losses due to insect pests of stored grain are 2.55%. In addition they are also responsible for the qualitative losses in food grains.


Ikisan - Sources of infection for stored grain pests in Maize

Sources Of Infection

  • Field infestation, insects fly from stores to fields and lay eggs upon the maturing grains.
  • These eggs hatch out to larvae in favourable conditions when grains reach the stores. They can crawl/fly to fresh stocks and infest them is called cross infestation.
  • It has been a general practices, specially with farmers, that they keep without cleaning the empty food grain bags for use in the next season only.
  • Eggs and larvae of insects remain hidden and feed on the grain fragments in the off season. Whenever the grains are filled up in such bags, infestation reappears.
  • The insects, which may be present in the joints or corners of the carriers, migrate to the food grain lots and cause infestation.


Ikisan - Management of stored grain pests in maize


  • The scientific storage of grains help in minimising the damage by insects, and microorganisms.

The following methods can help in safe storage of grains.

  • Preventive measures
  • Curative measures

Preventive measures

  • Cleaning the storage structures, sealing of cracks, crevices and holes present in the floors. Cleaning of the Sheller before their use.
  • Storage structures/godowns/gunny bags should be disinfected with approved residual insecticides preferably with Malathion 50% EC, with dilution 1 : 100.
  • Proper stacking of the filled bags for proper hygiene and sanitation prevents insect damage in the godowns.

Curative measures

The infestation of stored grain insect pests can be minimized by different methods

Physical control measures

  • Heat treatment of stored grain at 55-60°C
  • Mixing of inert dusts with grain makes entry of insects a difficult task. However here grain has to be washed before consumption.

Mechanical measures

  • These measures are practicable and include sieving of grains.

Ecological measures

  • Temperature, moisture content of grain and availability of oxygen have to be suitably manipulated by designing and constructing the storage structures which create unfavourable ecological conditions for insect attack.
  • Food grains kept in airtight sealed structure remain insect free. Eg. Pusa bin.
  • Grains with moisture content less than 10% are not suitable for multiplication and survival of most of the insects (except Khapra beetle which can survive but it is susceptible to reduced oxygen content.)

Chemical control measures

  • These measures are more popular and effective. They may be used as prophylactic and curative treatment.

Prophylactic treatment

  • These insecticide treatments are to prevent the insect infestation and cross infestation. However insecticide should not be sprayed on food grain directly.
  • The insecticides and their concentrations recommended for prophylactic treatment of stored grain are Malathion 50 E C at 0.5%, Pxrimiphos methyl 50% EC at 0.5%

Curative treatment

  • Mixing of chemicals with food grains meant for human consumption is not recommended. However they can be mixed with grains meant for seed purpose only. Normally pyrethrum dust is used as seed protectant.
  • Fumigation is the best method for controlling stored insects. However, the fumigation of grains should be carried out under expert supervision and proper caution.
  • In our country, EDB and EDCT have been recommended for fumigation of food grains. These fumigants should be handled with great care and by trained staff only.


Ikisan - Stored Grain Pests of maize

Stored Grain Pests

Common Name

Scientific Name

Rice weevil

Sitophilus oryzae

Maize weevil

Sitophilus zeamays

Granary weevil

Sitophilus granarius

Lesser grain borer

Rhizopertha dominica

Khapra beetle

Trichoderma granarium

Red rust flour beetle

Tribolium castaneum

Confused flour beetle

Tribolium confusum

Saw toothed grain beetle

Oryzaephilus surinamen

Rust red grain beetle

Cryptotests ferrugineus

Flat grain beetle

Cryptotests pusillus

Ware house moth

Cadra contella

Angoumois grain moth

Sitotroga cerealella

Indian meal moth

Plodia interpurutella


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