Persistent, Bioaccumulative, and Toxic Chemicals in Wild Alpine Insects: A Methodological Case Study

Area of Science:

• Environmental toxicology
• Ecotoxicology
• Insect ecology

Background:

• Persistent, bioaccumulative, and toxic chemicals (PBTs) pose a global threat to insect populations due to their environmental persistence and long-range transport.
• Laboratory studies on PBT effects on insects are common, but field studies on wild populations are scarce due to methodological challenges.
• Quantifying fitness proxies like fecundity in wild insects is difficult, and PBT concentrations in the environment are often minuscule.

Purpose of the Study:

• To investigate the effects of PBTs on wild insect populations in their natural environment.
• To test the feasibility of using pooled body burden data for detecting PBTs in insects.
• To evaluate fluctuating asymmetry as a sensitive indicator of PBT exposure and effects in insects.

Main Methods:

• Field study conducted on bumblebees (Bombus spp.) and ants (Formica spp.) in the Austrian and German Alps.
• Analysis of minuscule PBT concentrations (polychlorinated biphenyls and Hg) in pooled insect samples.
• Assessment of fluctuating asymmetry in insect wings and heads as a proxy for stress.
• Estimation of inbreeding levels using population-genetic markers to rule out genetic stressors.

Main Results:

• Pooled samples proved practical for quantifying PBTs in wild insects.
• Significant correlations were found between PBT levels and fluctuating asymmetry in both bumblebees and ants.
• Inbreeding levels did not confound the relationship between PBTs and fluctuating asymmetry.

Conclusions:

• Fluctuating asymmetry is a viable indicator of PBT effects in wild insects.
• The study provides a methodological framework for assessing the impact of persistent environmental chemicals on insect populations.
• Findings highlight the importance of considering PBTs as a significant anthropogenic threat to global insect health.