Earthworms Mitigate Pesticide Effects on Soil Microbial Activities

Area of Science:

• Soil ecology
• Environmental toxicology
• Microbiology

Background:

• Earthworms are crucial ecosystem engineers, influencing soil organic matter and nutrient cycling.
• Soil microbial communities are vital for ecosystem functioning but can be affected by pesticide application.
• Understanding earthworm-microbe interactions is key to assessing soil health under chemical stress.

Purpose of the Study:

• To evaluate the impact of the earthworm *Aporrectodea caliginosa* on soil microbial activity responses to two fungicides.
• To assess the influence of earthworms on potential nitrification activity and soil enzyme activities.
• To determine how earthworms modulate the effects of fungicides on soil biochemical indices like Gmean and SQI.

Main Methods:

• Utilized soil microcosms with and without *Aporrectodea caliginosa*.
• Applied two fungicides: Cuprafor Micro® (copper oxychloride) and Swing® Gold (epoxiconazole and dimoxystrobin).
• Measured potential nitrification activity (PNA) and key soil enzyme activities (glucosidase, phosphatase, arylamidase, urease), alongside earthworm biomass.

Main Results:

• Fungicides, particularly Swing® Gold, increased microbial activities in earthworm-free soils, elevating the GMean index.
• Nitrification was the most sensitive activity to fungicide treatments.
• Earthworm presence enhanced all measured microbial activities and significantly reduced the negative impact of fungicides, as indicated by the SQI.

Conclusions:

• Earthworms play a critical role in maintaining soil microbial functional diversity and stability when exposed to fungicides.
• Biotic interactions, specifically the presence of earthworms, are essential for understanding soil's resilience to pesticide contamination.
• Earthworms can buffer the detrimental effects of pesticides on soil microbial functioning.