Do insect repellents induce drift behaviour in aquatic non-target organisms?

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Aquatic Ecology

Background:

• Synthetic insect repellents are increasingly detected in surface waters.
• Potential adverse effects on non-target aquatic organisms are a concern.
• Aquatic invertebrates may exhibit downstream drift to avoid adverse conditions.

Purpose of the Study:

• To investigate if common insect repellents (DEET, EBAAP, Icaridin) induce downstream drift behavior in aquatic invertebrates.
• To assess the impact of repellents on Gammarus pulex and Cloeon dipterum.
• To determine if repellents affect non-target organisms at environmentally relevant concentrations.

Main Methods:

• Laboratory-scale drift assay was employed.
• Tested three widely used insect repellents: DEET, EBAAP, and Icaridin.
• Utilized aquatic invertebrates Gammarus pulex and Cloeon dipterum.

Main Results:

• No significant increase in drift behavior was observed for either invertebrate species across a wide concentration gradient.
• Even concentrations exceeding maximum environmental levels did not induce drift.
• No direct drift-inducing activity of the tested insect repellents was detected.

Conclusions:

• The tested insect repellents (DEET, EBAAP, Icaridin) do not appear to directly induce downstream drift in Gammarus pulex or Cloeon dipterum.
• Current evidence suggests these repellents may not significantly impact the drift behavior of these key aquatic invertebrates.
• Further research may explore other potential sublethal effects on aquatic ecosystems.