ESSENTIALS OF WHEAT SEED INSECT CONTROL

Losses in wheat seed can occur due to various reasons; these include post-harvest factors such as inadequate storage, pests well as rodent infestation. Therefore, development of proper wheat seed insect control method and technique is an important issue.

Reasons for Deterioration In Wheat Seed

This can be due to -

• physical conditions like humidity and temperature
• biological factors like arthropod, micro-flora, vertebrate
• Technical reasons like poor storage conditions and techniques.
The Main Objectives Of Any Insect Control Method
• Reducing pest incidence to economically acceptable levels
• Ensuring that all the control measures adopted are cost-effective
• Ensuring minimal negative environmental effects.

Importance of Monitoring Insect Infestations

Needless to say, frequent monitoring of storage conditions is essential for wheat seed insect control as it helps to identify problems in a timely manner. On the other hand, rodents are not affected by physical conditions of temperature or humidity, and their only requirement is gaining access to the wheat seed. Therefore, for avoiding of damage to stored wheat seed grains due to rodents the rodent-proof storage buildings should be built.

Using Synthetic Insecticides For Control Of Insects

Chemical treatment of grain and fumigation can be conducted since many sustainable and cost-effective techniques are available. The use of insecticides (e.g. chlorpyrifos-methyl, malathion, or deltamethrin) done through impregnation of prophylactic tarps or jute bags is common in the Asian subcontinent as a means of insect control. Disrupting mating opportunities of insects by use of synthetic sex pheromones has also been found effective. A sound mix of all the techniques can lead to an effective wheat seed insect control.

Use Of Inert Insect Repellents

Use of silica-bearing ash and dust with stored grain can effectively control storage insects. The ash of rice husk contains almost 90 percent silica and has been extensively used as an insecticide by farmers in India and Japan. Besides this, vegetable oils like the peanut oil and palm oil are very effective against certain pests like bruchid beetles. For areas where pesticides are expensive, vegetable oils like groundnut, sunflower and rap-seed mixed in pirimiphos-methyl is very effective especially against S. granarius in the wheat grain.

Botanical Insect Repellents

Certain Plant products are very effective for protecting wheat seed and other stored grain from insect damage. For example, the powdered roots of Derris elliptica, dried fruits of Capsicum, and the seeds and leaves of the neem tree (Azadirachta indica) are very effective insecticides. So are the leaves from Schinese molle, Eucalyptus globulus, Datura stramonium, Lycopersicum esculentum and Phytolacca dodecandra, as they cause high rate of adult weevil mortality.

Certain aromatic plants have also been found effective in eliminating grain storage insects. Extracts of nutmeg (Myristica fragrans) and mace, with their high acetone content are found to be reasonably contact toxic and work as strong repellents to S. oryzae, Similar effects are achieved with oil and seed extracts of Til (Anethum graveolens) and coriander (Coriandrum sativum) and are very effective in wheat seed insect control.

Resistant Crop Cultivars To Storage Insect Damage

Use of resistant cultivar reduces insect fecundity (i.e. effective egg production), thus reducing the rate of their population increase.

Thus, the important principle procedures for effective wheat seed insect control are:
• Prediction and prevention of insect infestation,
• Selection of appropriate insecticides and its dosage,
• Effective application of insecticides,
• Safe method of insecticide application and understanding label information.

It is essential to follow an “Integrated Pest Management” (IPM) regime, which essentially is the coordination between the physical, chemical and biological parameters which play an important role in wheat seed insect control - Therefore, customary pest control techniques for wheat seed insect control include:

 Having a controlled climate of cooling and aeration that reduces insect reproductive rate.
 Airtight storage atmosphere
 Heat treatment to disinfest grain(more than 60°C) ;
 Physical barriers for protection of uninfested grain;
 Fumigation with deep penetrating gases;
 Using contact insecticides for control of flying insects;
 Admixing of insecticides on grain
 Rodent control
 Using resistant crop cultivars.