Mechanistic Model for Simulating Pesticide Uptake into Maize Pollen

Area of Science:

• Agricultural Science
• Environmental Chemistry
• Ecotoxicology

Background:

• Seed coatings protect crops but can lead to pollinator exposure to pesticide residues.
• Understanding pesticide translocation into plant reproductive parts is vital for pollinator safety assessments.

Purpose of the Study:

• To extend a dynamic pesticide uptake model to include flower compartments (nectar and pollen).
• To simulate and assess pesticide exposure risks to pollinators from seed coating and spray applications.

Main Methods:

• Extended a dynamic pesticide uptake model to incorporate maize flower compartments.
• Simulated field experiments involving seed/soil and spray pesticide applications.
• Fitted dissipation half-lives for imidacloprid in pollen, comparing model predictions with observations.

Main Results:

• The model successfully simulated field experiments for both seed/soil and spray applications.
• Simulated dissipation rates (growth dilution, degradation) were often lower than empirical loss rates due to continuous soil delivery.
• Fitted imidacloprid half-lives in pollen ranged from 0.2 to 0.9 days, aligning with spray application observations.

Conclusions:

• The model predicts that mobile, persistent, and nonvolatile soil chemicals can translocate to pollen.
• This finding is significant for assessing risks from Persistent, Mobile, and Toxic (PMT) chemicals.
• The model can be integrated into broader frameworks for estimating pollinator exposure to pesticides.