Applied entomology lecture 2

Insect Control

Definition of Insect Control

• Insect Control: Defined as everything that makes life hard for insects, prevents their increase or spread, and/or tends to kill them.

Limitations of Insect Control

• Complete eradication of insects is not possible due to several limitations:

  1. Rapid Growth: Short life cycles allow for quick population increases.

  2. High Reproduction: Insects possess a high fecundity.

  3. Adaptability: Insects adapt efficiently to environmental changes.

  4. Chitinous Structure: Their exoskeleton provides protection.

  5. Resistance Development: Some insects develop resistance to insecticides.

  6. Cost Issues: Control costs need to be lower than the damage imposed by insects.

Transition of Insects to Crop Pests

• Insects have become agricultural pests due to:

  1. Interference with Natural Vegetation: Agricultural practices disturb natural balance.

  2. Monoculture Practices: Favorable conditions for pest multiplication.

  3. Introduced Plant Species: New infested plants introduce new pests to areas.

  4. Trade: Movement of goods can distribute pests.

  5. Scientific Zeal: Some scientific activities unintentionally introduce pests.

  6. Reduction of Predators: Decrease in insectivorous animal populations.

Interference with Natural Vegetation

• Transformation of natural landscapes for agriculture leads to pest migration:

  • Armyworm, Spodoptera litura: First appeared on cotton in Pakistan.

  • Rice pests: Early 1980s attacks in the rice tract of Pakistan.

  • Potato Tuber Moth, Gnorimoschema operculella: Shifted from wild grass to potato.

  • Grasshoppers: Shifted to crops post-colonization.

Encouragement of Pest Multiplication through Monoculture

• Monoculture (planting same crops widely) creates favorable conditions for pests:

  • Cotton in Pakistan: Supports rapid multiplication of cotton whitefly, Bemisia tabaci.

  • Rice Cultivation: Leads to several insect pest generations in cultivated fields.

Introduction of New Plants

• New plants may carry pests that can thrive in the absence of natural enemies:

  • Examples include the Pink Bollworm and other pests introduced through trade.

Distribution through Trade

• Pests have spread into Pakistan via trade:

  • Examples include Sugarcane Stem Borer, Chilo spp. and others introduced from Japan and the USA.

Scientific Zeal

• Scientific transfers may inadvertently spread pests:

  • Gypsy moth: Brought to America to crossbreed but became a pest.

Reduction of Insectivorous Animals

• Hunting of animals that control insect populations can exacerbate pest problems.

Principles of Insect Control

• Based on several important factors:

  1. Biotic Potential: Inherent ability to reproduce and survive.

  • Divided into Reproductive Potential and Survival Potential.

  2. Environmental Resistance: Factors that limit insect population growth.

  • Consists of Physical (light, temperature, humidity) and Biological Factors (predators, diseases).

  3. Biological Equilibrium: Balance between biotic potential and environmental resistance leads to stable insect populations.

Coefficient of Destruction

• The percentage of progeny that must be eliminated by environmental resistance to maintain equilibrium.

Foundation of Insect Control

• Based on:

  1. External Morphology: Structure and characteristics of insects.

  2. Internal Anatomy: Understanding the internal systems aiding in pest management.

  3. Metamorphosis: Different life stages of insects aid in timing control efforts.

  4. Life History: Detailed information on insect life cycles supports effective control measures.

Study of External Morphology

1. Head Region: Includes mouthparts, eyes, and antennae, influencing insecticide choice and traps.

2. Thorax: Region of locomotion; legs and wings are crucial for movement.

3. Abdomen: Houses reproductive structures which impact control strategies based on ovipositor types.

Importance of Internal Anatomy

• Body cavity hosts parasites; tracheae and spiracles are entry points for insecticides.

Importance of Metamorphosis

• Different life stages indicate when insects are most damaging; larvae/adult stages need targeting for control.

Types of Methods of Insect Control

1. Natural Control: Involves climatic, topographical, and biological factors.

2. Applied Control: Human-influenced measures categorized into: - Mechanical Control: Hand picking, trapping. - Physical Control: Temperature manipulation, light traps. - Cultural Control: Practices like crop rotation, breaking soil for pest reduction. - Biological Control: Use of natural predators and pathogens. - Legislative Control: Laws regulating practices to control pests. - Reproductive Control: Inducing sterility in pests. - Chemical Control: Use of insecticides. - Miscellaneous Control: Includes IGRs and other attractants. - Integrated Pest Management (IPM): A holistic approach that combines various control methods to minimize pest populations sustainably.