Synergistic Pesticide Effects on Complex Arthropod Trophic Interactions in Arable Systems.

Area of Science:

• Agricultural Ecology
• Environmental Toxicology
• Soil Science

Background:

• Arable systems rely on biodiversity for essential ecosystem services like pest control and nutrient cycling.
• Current pesticide risk assessments often overlook complex trophic interactions and synergistic effects.
• Pesticide mixtures can pose underestimated risks due to synergistic interactions.

Purpose of the Study:

• To assess the impacts of synergistic interactions between a pyrethroid insecticide and fungicides on model arable communities.
• To evaluate effects on biological control, invertebrate biomass, soil processes, and food web structure.
• To highlight the need for considering community-level endpoints in pesticide risk assessment.

Main Methods:

• Utilized model arable communities including pests (aphids, weevils), predators (beetles, spiders, mites), and soil biota (mites, earthworms).
• Investigated synergistic interactions between cypermethrin (pyrethroid insecticide) and Azoxystrobin/Prochloraz (fungicides).
• Analyzed impacts on biological control, biomass of trophic groups, soil ecosystem processes, and predatory arthropod food web architecture.

Main Results:

• Pesticide mixture impacts on biological control, biomass, and soil processes were additive.
• Synergistic interactions simplified the architecture of predatory arthropod food webs.
• Potential mechanisms include direct toxicity, altered pyrethroid detoxification, and indirect effects via fungal food resources.

Conclusions:

• Synergistic pesticide interactions can significantly alter agri-ecosystem food web structure.
• Current regulatory approaches may underestimate risks by not considering community complexity.
• A holistic approach incorporating community structure is crucial for safeguarding agricultural ecosystems.