Assessing potential collateral effects on amphibians from insecticide applications for flea control and plague...

Area of Science:

• Wildlife toxicology and conservation biology
• Ecotoxicology of insecticides in terrestrial ecosystems

Background:

• Disease mitigation in wildlife requires assessing collateral effects on non-target species.
• Insecticides (deltamethrin, fipronil) control plague vectors (fleas) for prairie dogs and black-footed ferrets.
• Burrow-dwelling species may be exposed to these insecticides through treated dust or contaminated fecal pellets.

Purpose of the Study:

• To evaluate the potential effects of deltamethrin and fipronil residues on western tiger salamanders (Ambystoma mavortium).
• To assess impacts on salamander survival, body mass, and activity in simulated burrow environments.

Main Methods:

• Western tiger salamanders were exposed to realistic concentrations of deltamethrin dust or fipronil-laced fecal pellets in mesocosms.
• Treatments mimicked natural burrow conditions, with control groups receiving untreated fecal pellets.
• Salamander survival, body mass, activity, and tissue residues of insecticides were monitored.

Main Results:

• All salamanders survived the experimental period; no acute lethal effects were observed.
• Deltamethrin and fipronil sulfone (a metabolite) were detected in salamander tissues, indicating uptake.
• Salamanders exhibited increased activity outside burrows post-treatment, with deltamethrin levels correlating with burrow use.

Conclusions:

• While acute toxicity was not observed, insecticide uptake suggests potential for sublethal or long-term effects in western tiger salamanders.
• This study highlights the importance of evaluating unintended consequences of wildlife disease mitigation strategies.
• Further research is needed to understand the chronic impacts of deltamethrin and fipronil on non-target burrow inhabitants.