Joint cadmium and polypropylene microparticle action in cadmium tolerant model insect

Microplastic enlisted as a contaminant of emerging concerns in polluted environments interact with traditional contaminants such as metals, causing, among others, their increased accumulation in the body. Harmful effects depend on the exposed animals' possible preadaptation and/or cross-tolerance. The project aimed to assess the role of this phenomenon in the limited toxicity of polypropylene fibers (PPf) in 0%, 0.02%, 0.06, 0.18%, 0.54%, and 1.6% of Cd-supplemented food of larvae of Spodoptera exigua multigenerationally selected to cadmium tolerance. The activity of 20 digestive enzymes (API-ZYM test), defensins, and heat shock proteins, HSP70 levels in the exposed groups were used as biomarkers. PPfs caused the increase of Cd accumulation in the body, while intake of polypropylene microfibers did not change the biomarker levels. Moreover, multigenerational Cd pre -exposure, due to increased tolerance of Cd and, possibly, cross-tolerance, prepares the insects for an addi-tional stressor (PPf) alone and in interaction with cadmium.

Automated summary

Microplastics, a contaminant of emerging concern in polluted environments, interact with traditional contaminants such as metals and cause increased accumulation of these contaminants in animal bodies. The harmful effects are dependent on the animals' preadaptation and/or cross-tolerance. This study aimed to assess the role of this phenomenon in the limited toxicity of polypropylene fibers (PPf) in larvae of Spodoptera exigua, which were multigenerationally selected for cadmium tolerance. The biomarkers used were digestive enzymes, defensins, and heat shock proteins (HSP70) activity levels. The study found that PPfs increased the accumulation of cadmium in the body, while intake of polypropylene microfibers did not affect the biomarker levels. Furthermore, multigenerational pre-exposure to cadmium prepared the insects for additional stress from PPf, possibly due to increased tolerance and cross-tolerance.