Protection practices: Insect - pest of wheat
Aphids- Sitobion avenae, Rhopalosiphum padi and various other species
Distribution: All wheat growing areas, especially in NWPZ and Peninsular India.
Development: The aphids exist in different stages, viz., winged (alates), wingless (apterous) sexual and asexual forms. The rapid spread takes place through asexual reproduction where females give rise directly to nymphs rather than eggs. Infestation usually occurs during second fortnight of January till crop maturity.
Management: When feeding in sufficient numbers, they can cause considerable damage, but under normal conditions, losses are not much. Chemical pesticides are recommended for this pest in wheat if the level of aphids per tiller crosses 10 during vegetative phase and 5 during reproductive phase. However, there is need to keep watch on this pest. The spray of imidacloprid @ 20 g a.i. per ha initially on border rows and if infestation is severe then in entire field will give good protection against this pest. Generally, natural enemies present in the field help in controlling the population of this pest.
Brown Wheat Mite- Petrobia lateens
Distribution: In most of the wheat growing areas, under rainfed conditions, especially in the states of Rajasthan, Haryana and M.P. Sometimes, it is a pest in humid and warm conditions of irrigated areas also.
Development: They Brown wheat cause damage through mite infestation
sucking mouth parts. When present in large numbers, mites cause a silvery flecking on leaves. Individual mites are too small to be visible with naked eye without 'effort. These can be seen by shaking the infested leaves on a white paper.
Management: Most of the times, mites do not cause any production constraint in wheat so no management practices are required. However, there is a need to keep vigil on this pest so that it may not become important in changing cropping sequence of future.
Army Worm- Mythimna separate
Distribution: Mostly in the warmer climates of central India and to some extent in northern plains.
Development & Management: The larvae are found in the cracks of soil and hide during the day but feed during night or early morning. In wet and humid weather, they may feed during day time also. They survive during summer on the subsequent crops like rice and also continue to exist in rice stubbles before wheat crop comes in the field. Recently, this pest is catching attention in the northern India under Rice-Wheat rotation and where rice stubbles / straw remain in the fields.
Legume Pod-borer- Helicoverpa armigera (= Heliothis armigera)
Importance: This is a polyphagous insect that attacks various legumes as a pod border. It is seen damaging wheat ear heads at grain development stage when major hosts are not available. However, the damage is below economic threshold level.
Distribution: It is found mostly in northern and central parts of India. Wheat can serve as a bridge host for carry over of this polyphagous pest.
Termites- Odontotermis obesus, Microtermis obesi
Distribution: Mainly in the northern and central India, but also in some pockets of peninsular India.
Early Symptoms of Damage: Termites attack the crop at various growth stages,
from seedlings to maturity. The severely damaged plants can be easily uprooted and look wilted and dried. In case roots are partially damaged, the plants show yellowing.
Management: For effective management, chemicals like endosulfan, chlorpyriphos and carbosulfan can be used both for seed treatme
Submitted by krishnadubey on Tue, 17/04/2012 - 16:35