Physical Method of Pest Control

Definition:

Physical control refers to the modification of environmental physical factors to minimize or prevent pest problems. Insects require a specific range of physical conditions, and any deviation from this range can be lethal to their survival and life activities

Physical Methods in Pest Management

1. Manipulation of Temperature:

Temperature influences insect activity and metabolic rate. Controlling temperature can help eliminate pests.

• Sun drying: Drying seeds in sunlight kills eggs and hidden stages of stored product pests.
• Cotton seed exposure: Exposing cotton seeds in a thin layer to sun heat for 2-3 days (April-May) helps kill pink bollworm larvae.
• Heat treatment of sugarcane setts: Using hot water or hot air treatment to kill scale insects carried through setts.
• Hot water treatment:
  • Paddy seeds at 50-55°C for 15 minutes to control rice white tip nematodes.
• Use of flame throwers and torches:
  • Flame throwers against locusts.
  • Burning torches against hairy caterpillars.
• Cold storage:
  • Fruits and vegetables at 1-2°C for 10-12 days to kill fruit flies.
  • Storage of potatoes to control potato tuber moth.

2. Manipulation of Moisture:

Altering moisture levels can control pest populations.

• Alternate drying and wetting of rice fields to manage Brown Plant Hopper.
• Drying seeds below 10% moisture content to inhibit development of insects such as rice weevil and pulse beetle.

3. Manipulation of Light:

Light influences insect behavior and can be used for pest control.

• Mating frequency reduction: (e.g., Bihar hairy caterpillar)
• Reduced fertility: (e.g., Indian meal moth)
• Disruption of diapause: Affects all diapausing insects.
• Light traps: Used to attract positively phototropic insects.

4. Manipulation of Air: Increasing carbon dioxide concentration in stored grains causes asphyxiation of stored product pests.

5. Use of Irradiation:

• Gamma irradiation (from Co-60): Used to sterilize insects in laboratories.
• Example: Cattle screw worm (Cochliomyia hominivorax) was successfully controlled using this technique in Curacao Island by E.F. Knipling.

6. Use of Abrasive Dust:

• Activated clay: Causes injury to the insect’s wax layer, leading to moisture loss and death. Used against stored product pests.
• Dri-die: A porous, finely divided silica gel used to control stored insect pests.

7. Use of Radiant Energies:

Different forms of radiant energy have been tested for insect control, particularly in stored grain pests.

Visible Light Control Methods:

1. Photo taxis: Attracting or repelling insects using light.
2. Altering photoperiod: Floodlighting fields to prevent diapause and disrupt insect development.
3. Behavioral modification: Artificial lighting in apple orchards interferes with codling moth egg-laying.

8. Use of Sound Energy:

• Acoustical devices: Bird scarers (acetylene exploders) produce sudden loud sounds to frighten birds.
• Firecrackers: Used to scare away animals like squirrels, foxes, rats, mice, and deer.