Thiacloprid affects trophic interaction between gammarids and mayflies.

Area of Science:

• Environmental toxicology
• Ecotoxicology
• Aquatic ecology

Background:

• Neonicotinoid insecticides, such as thiacloprid, contaminate surface waters.
• Predator-prey interactions are crucial for ecosystem functions.
• Understanding the impact of thiacloprid on these interactions is vital.

Purpose of the Study:

• To assess the effects of thiacloprid on the feeding behavior and predatory activity of Gammarus fossarum.
• To investigate the consequences of altered predator-prey dynamics on G. fossarum's biomass.
• To evaluate the potential impact of thiacloprid on ecosystem functions like leaf litter decomposition.

Main Methods:

• Field-relevant concentrations of thiacloprid were used.
• The study assessed leaf consumption and predation rates of Gammarus fossarum on Baetis rhodani nymphs over 96 hours.
• Changes in Gammarus fossarum dry weight were measured.

Main Results:

• Thiacloprid exposure increased Gammarus fossarum predation on Baetis rhodani nymphs at concentrations of 0.50-1.00 μg/L.
• Leaf consumption by Gammarus fossarum decreased with increasing thiacloprid concentrations.
• At 1.00 μg/L thiacloprid, Gammarus fossarum dry weight increased by 15%, while at 4.00 μg/L, it decreased by 20% due to reduced feeding.

Conclusions:

• Thiacloprid adversely affects trophic interactions in aquatic ecosystems.
• Altered predator-prey dynamics can lead to significant changes in ecosystem functions, including leaf litter breakdown and nutrient cycling.
• The findings highlight the ecological risks posed by neonicotinoid contamination in surface waters.