Pest Surveillance

Definition Pest surveillance is the systematic monitoring of biotic and abiotic factors in the crop ecosystem to assess pest populations and predict potential outbreaks. It helps in understanding the population dynamics of pests and their natural enemies, enabling strategic pest management decisions.

Purpose of Pest Surveillance

• To determine pest population levels and their potential damage.
• To forecast pest outbreaks and take preventive measures.
• To evaluate the effectiveness of pest control measures.
• To identify natural enemies for biological control strategies.
• To maintain environmental balance by minimizing unnecessary pesticide use.

Importance of Pest Surveillance

1. Timely Pest Control: Helps in initiating pest management before the population reaches damaging levels.
2. Cost-Effective Management: Reduces the cost of pest control by minimizing pesticide applications.
3. Environmental Protection: Lowers environmental pollution by avoiding indiscriminate pesticide use.
4. Pest Forecasting: Provides essential data for predicting pest outbreaks.
5. Stability of Agro-Ecosystem: Maintains ecological balance by preserving beneficial organisms.
6. Decision-Making Aid: Assists in strategic decision-making regarding pest control measures.

Objectives of Pest Surveillance

• Identify Existing and New Pest Species: Determine the types of pests affecting crops.
• Assess Pest Population and Damage: Monitor pest density at various crop growth stages.
• Study Weather Impact: Analyze the influence of climatic factors on pest populations.
• Changing Pest Status: Track shifts in pest status (e.g., from minor to major pests).
• Evaluate Natural Enemies: Observe populations of beneficial insects like predators and parasitoids.
• Impact of Cropping Patterns: Examine the effect of different crop patterns and varieties on pest dynamics.

Components of Pest Surveillance

1. Pest Identification: Accurate identification of pest species is crucial for targeted control measures.
2. Distribution and Prevalence: Mapping pest distribution and assessing its severity in different regions.
3. Incidence and Damage Levels: Determining the extent of crop damage and yield loss.
4. Population Dynamics: Studying pest life cycles, population fluctuations, and dispersal patterns.
5. Weather Assessment: Evaluating climatic conditions influencing pest development and survival.
6. Natural Enemies Assessment: Monitoring populations of natural predators and parasitoids.

Survey and Sampling Techniques

Survey:  A systematic collection of insect population data in a specific area and time.

• Types of Surveys:
  • Qualitative Survey: Focuses on pest detection, especially for newly introduced species.
  • Quantitative Survey: Measures pest abundance numerically to predict population trends and assess damage potential.

Sampling: The process of selecting a representative portion of the total population to estimate pest density and distribution. To evaluate pest density, monitor pest spread, and assess damage potential.

Sampling Techniques

1. In Situ Counts: Visual Observation of insects on plant canopies. Advantage: Quick and straightforward. Example: Counting aphids or caterpillars on leaves.
2. Knock Down: Dislodging insects from plants by jarring or shaking. Collected insects are then counted. Example: Collecting hoppers from paddy plants.
3. Netting: Using sweep nets to capture flying or jumping insects. Example: Grasshoppers, hoppers, or odonates.
4. Narcotized Collection: Anaesthetizing fast-moving insects to count them accurately. Example: Using ethyl acetate for immobilization.
5. Trapping:
   • Light Trap: Attracts phototropic insects like moths.
   • Pheromone Trap: Uses species-specific attractants for monitoring.
   • Sticky Trap: Captures small sucking insects like aphids.
   • Bait Trap: Attracts pests using food baits (e.g., for sorghum shoot fly).
   • Emergence Trap: Captures soil-borne insects emerging from the ground.

• Crop Samples:
  • Collecting plant parts and counting pest populations.
  • Example: Collecting cotton bolls to check for bollworms.

Scientific Surveillance Methodologies

Fixed Plot Survey

• Method: In a one-acre plot, five micro-plots of 1 sq.m. are marked: four in the corners and one in the center. Periodical assessment of pest incidence is conducted in these micro-plots. No chemical sprays are applied until the pest population reaches the Economic Threshold Level (ETL). Example:
• In rice fields, counting the total tillers and tillers affected by stem borers in 10 randomly selected plants per micro-plot. Observing leaf damage by leaf folders and expressing it as a percentage of damaged leaves.

Roving Survey

• Method: Conducted weekly in randomly selected fields along a prescribed route. Observations are recorded from the west corner by diagonal walking to 100 meters. Large areas are covered in a short time, providing a comprehensive view of pest distribution.
• Purpose: To assess pest population and damage from randomly selected spots representing larger areas. To identify endemic areas with high pest prevalence.

Decision-Making in Pest Management

• Purpose: To decide when to take control measures based on pest population data.
• Process:
  1. Population or Damage Assessment: Estimating pest density or damage level.
  2. Comparison with ETL and EIL: Checking if the pest population exceeds Economic Threshold Level (ETL) and Economic Injury Level (EIL).
  3. Action Decision: If the pest density crosses ETL, initiate control measures to prevent reaching EIL.

Economic Threshold Level (ETL) and Economic Injury Level (EIL)

Economic Injury Level (EIL)

• Definition: The lowest pest population density that causes economic damage.
• Purpose: To justify the cost of control measures.
• Calculation:

EIL=C/V×I×D×K

Where:

• C = Cost of control measures per unit area (Rs./ha)
• V = Market value per unit yield (Rs./tonne)
• I = Crop injury per insect (e.g., % defoliation)
• D = Yield loss per unit injury (e.g., tonne loss/% defoliation)
• K = Proportionate reduction in injury from control measures

Economic Threshold Level (ETL)

• Definition: The pest population level at which control measures should be taken to prevent reaching EIL.
• Purpose:
  • To prevent economic losses by timely pest control.
  • To minimize pesticide usage and environmental pollution.
  • To maintain pest populations at manageable levels, supporting sustainable pest management.