Risk Assessment for Tomato Fruitworm in Processing Tomato Crop-Egg Location and Sequential Sampling.

Area of Science:

• Agricultural Entomology
• Crop Protection
• Pest Management

Background:

• Helicoverpa armigera is a significant pest impacting processing tomatoes and other crops.
• Understanding oviposition behavior is crucial for developing effective pest management strategies.

Purpose of the Study:

• To investigate the oviposition preferences of Helicoverpa armigera on determinate tomato plants.
• To describe the spatial distribution pattern of Helicoverpa armigera eggs in the field.
• To develop a sequential sampling plan for Helicoverpa armigera in processing tomatoes.

Main Methods:

• A three-year field study was conducted on determinate tomato plants.
• Oviposition site preferences (stratum, leaf, leaflet, leaf side) were analyzed.
• Spatial distribution patterns were assessed using Taylor's power law.
• A sequential sampling plan was developed based on Iwao's method.

Main Results:

• Eggs were predominantly found on upper canopy leaves (strata a and b) across all growth stages.
• A significantly lower egg count was observed on lower canopy leaves (stratum c).
• The spatial distribution of eggs was aggregated, tending towards random at lower densities.

Conclusions:

• Helicoverpa armigera exhibits distinct vertical stratification in oviposition on tomato plants.
• The developed sequential sampling plan offers improved efficiency and precision over fixed plans.
• Further refinements to the sampling plan are recommended for enhanced pest management.