In India annual storage losses have been estimated14 -million tones of food grain worth of Rs. 7,000 crore every year in which insects alone account for nearly Rs. 1,300 crores.- According to World Bank Report (1999), post-harvest losses in India amount to 12 to 16 million metric tons of food grains each year, an amount that the World Bank stipulates could feed one-third of India's poor.
- TNAU has been estimated the losses to food grains in the farmers holdings in Tamil Nadu 12.9 per cent in paddy 16.0 per cent in sorghum14.0per cent in bajra12.7 per cent in maize.
- Out of these post-harvest losses storage alone 6.58 per cent, in that -insects alone account for 2.0 to 4.2 per cent followed by rodent’s 2.50per cent, Birds 0.85 per cent and moisture 0.68 per cent.
Types of storage losses
Insects cause different kinds of losses viz.,
- Quantitative loss
- Qualitative loss
- Loss of seed viability
- Damage to storage structures
Quantitative loss
- Direct feeding insects cause loss in weight of the stored grains
- A rice weevil will eat 14 mg out of 20 mg of a rice kernel during its developmental period.
- But commercially the whole grain is lost
- A female weevil, through three generations per year, has the biotic potential to reproduce 1,500,000 offspring which will consume 1,500,000 kernel of rice (amounting 30 kg of rice)
- A gravid female of Sitotroga cerealella can destroy 50 g of rice completely in 3 generations
Qualitative loss
- Direct feeding on the grain
- Chemical changes in grain content
- Contamination of grains with moult skin and body parts
- Spreading the pathogenic micro-organisms
- Loss of seed viability
- Insects were found to cause the loss of viability of seeds to an extent of 3.6 to 41 % in paddy
Damage to storage structures
- Insects like Lesser grain borer has the capability to destroy the wooden storage structures, containers polythene lined bags etc.,
- Food losses -Direct or Indirect losses:
- A direct loss is disappearance of food by spillage, or consumption by organisms including insects.
- An indirect loss is the lowering of quality to the point where people refuse to eat it.
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