Insects belong to Phyllum : ARTHROPODA
Class : INSECTA
Having 3 pairs of legs and outer skin called cuticle,body divided into 3 parts head,thorax and abdomen.The head bears 1 pair of antennae,the thorax carries 3 pairs of legs,1 or 2 pairs of wings.The exo skeleton is chitinous.
As per the pause committee report,the storage losses due to insect pests of stored grains are 2.55%.In addtion they are also responsible for the qualitative losses of food grains.
The classification of primary and secondary insect pests is given below:
Commodities attacked :
Wheat,Rice ,Maize ,Jowar and Paddy etc.,
Life history and habits :
Class : INSECTA
Having 3 pairs of legs and outer skin called cuticle,body divided into 3 parts head,thorax and abdomen.The head bears 1 pair of antennae,the thorax carries 3 pairs of legs,1 or 2 pairs of wings.The exo skeleton is chitinous.
As per the pause committee report,the storage losses due to insect pests of stored grains are 2.55%.In addtion they are also responsible for the qualitative losses of food grains.
The classification of primary and secondary insect pests is given below:
RICE WEEVIL :
Scientific name : Sitophilus oryzae
Nature of Damage :
Damage is done by adults and larvae.Grains are hallowed out.Kernals are reduced to mere powder ,Sitophilus oryzae ans S.zeamais are known to attack in fields too.Adults cut circular holes.Heating takes place during heavy infestation.which is known as dry heating.Identification :
- Size 3 m.m
- Weevils are beetles having characteristic beak or snout.
- Antennae elbowed and slightly clubbed.hind wings present except in S.granarius.
- colour ranges from reddish brown chocolate to almost black.
- S.zeamais -largest among three species.
Commodities attacked :
Wheat,Rice ,Maize ,Jowar and Paddy etc.,
Life history and habits :
Female makes a cavity and lays translucent white eggs and then plugs the hole with gelatinous secretion.Eggs are laid singly.
Single female lays 150 to 250 eggs.The leg less,fleshly and curved larva remains in the grain and pupates also inside the grain.larval stage lasts for about 20 days.Pupal period is for 3-6 days.When development is complete the adult comes out having a circular hole.Adult lives for 3-5 months.Grain having moisture less than 10 % is not attacked.The life cycle takes 26days at 30 degrees centigrade and 75% R.H.The optimum climatic conditions for developments range from 26 to 36 degrees centigrade.
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