Unrevealing the impact of multiple stressors on the life history of insects
Road infrastructure, which spans millions of kilometers globally, contributes significantly to environmental pollution through contaminants such as tire-derived particles and road salt. While most studies focus on the lethal and sub-lethal effects of single pollutants, organisms are often exposed to multiple contaminants that may interact and amplify toxic effects on life-history traits.
In this study, we experimentally tested an ecotoxicological scenario common in nature, where non-target organism is exposed to both salt and tire particle during their larval stage. Using the black soldier fly (Hermetia illucens), as model organisms, we assessed the independent and combined effects of varying concentrations of salt and tire particle on juvenile and adult life-history traits.
We hypothesized that larval exposure to tire particle would prolong development time and reduce egg-to-adult survival, body size, and the magnitude of male-biased sexual size dimorphism. Furthermore, we predicted that joint exposure to salt and tire particle would result in greater fitness costs than either contaminant alone or exceed the additive effects of the two stressors.
Our results showed that both contaminants reduced larval growth and adult body size, with synergistic effects intensifying these impacts. However, adult lifespan was not significantly affected, suggesting some resilience in males. These findings emphasize the need to consider multiple stressors in ecotoxicology to better assess real-world pollution impacts on insect populations.
