Fixed precision sequential sampling plans for the greenbug and bird cherry-oat aphid (Homoptera: Aphididae) in winter...

Area of Science:

• Agricultural Entomology
• Pest Management
• Quantitative Ecology

Background:

• Accurate pest population estimation is crucial for effective crop management.
• Aphids, including greenbugs (Schizaphis graminum) and bird cherry-oat aphids (Rhopalosiphum padi), are significant pests of winter wheat (Triticum aestivum L.).
• Existing sampling methods may not be efficient or precise across diverse field conditions.

Purpose of the Study:

• To develop and evaluate fixed precision sequential sampling schemes for greenbugs and bird cherry-oat aphids in Oklahoma winter wheat.
• To assess the accuracy and reliability of these sampling schemes under varying field conditions.
• To provide a tool for efficient pest monitoring in wheat production.

Main Methods:

• Estimation of aphid numbers per wheat tiller in 189 Oklahoma winter wheat fields.
• Calculation of Taylor's power law regressions for population density estimation.
• Construction and evaluation of fixed precision sequential sampling schemes using a dataset of 240 samples across three growing seasons and four locations.
• Recording of wheat cultivar and growth stage for each sampled field.

Main Results:

• Taylor's power law parameters varied significantly among growing seasons, locations, and plant growth stages for both aphid species.
• The developed sampling schemes achieved median precision within 20% of expected precision across a range of population intensities.
• Observed precision often exceeded expected precision, particularly in samples with high aphid populations, indicating the schemes' robustness.
• The greenbug sampling scheme tended to over-predict precision due to a positively skewed deviation distribution, while the bird cherry-oat aphid scheme showed a more symmetric distribution.

Conclusions:

• Fixed precision sequential sampling schemes based on Taylor's power law are effective for monitoring greenbugs and bird cherry-oat aphids in winter wheat.
• These schemes provide reliable aphid population estimates despite significant variations in environmental factors and crop growth stages.
• The developed methods offer a practical approach for optimizing pest management decisions in wheat production systems.