Effects of polyamide microplastics with different particle sizes on the development of silkworm <i>Bombyx mori</i> (Lepidoptera: Bombycidae) and its progeny: A study based on the age-stage, two-sex life table

Influenced by human activities, microplastics (MPs) are widely distributed in terrestrial ecosystems. However, their ecotoxicity remains unclear. Therefore, we assessed the ecotoxicity of polyamide microplastics (PA-MPs) by investigating their toxic effects on the model insect, the silkworms <i>Bombyx mori</i> (Lepidoptera: Bombycidae). In this study, fifth-instar silkworm larvae were fed mulberry leaves treated with PA-MPs for 120 hours, but no changes in mortality rates were observed. However, the body weight, pupal weight, cocoon weight, egg laying amount, and cocoon shell weight in F₀ generation silkworms were significantly reduced. This indicates that PA-MPs have sublethal effects on silkworms. To further investigate the effects of PA-MPs on the offspring of silkworms, we applied the age-stage, two-sex life table analysis. We found that in the PA-MPs treatment group, the duration of the larval and pupal stages of F₁ generation silkworms was significantly prolonged, while the lifespan of the adults and total longevity were shortened. Meanwhile, the life history parameters (<i>s_xj, e_xj, l_x, f_xj, l_xm_x</i>, and <i>v_xj</i> values) and population parameters (<i>R</i>₀<i>, λ, r</i>, and <i>T</i>) of F₁ generation silkworms in the PA-MPs treatment group were also lower than control. This indicates that PA-MPs have transgenerational effects, affecting the growth, development, and reproduction of F₁ generation silkworms. Our research findings demonstrate the sublethal and transgenerational effects of PA-MPs on silkworms, providing evidence for their ecotoxicity.