Micro/nanoplastics as emerging pesticide carriers: Toxicological implications and mechanistic perspectives in the model insect, silkworm Bombyx mori

Micro and nanoplastics (MNPs) are increasingly recognized as emerging contaminants capable of interacting with co-existing agrochemicals, including pesticides, thereby altering their environmental fate and biological effects. In sericulture, silkworms are particularly vulnerable to combined exposure through contaminated mulberry leaves, which may receive pesticide inputs via direct application, atmospheric drift, and/or environmental deposition. This review synthesizes current knowledge on the role of MNPs as carriers of pesticides and their implications for toxicity and mechanistic responses in silkworms. We summarize major classes of pesticides relevant to sericulture, including organochlorines, organophosphates, neonicotinoids, pyrethroids, anthranilic diamides, guadipyr, plant-derived pesticides, nanopesticides, and insect growth regulators, and discuss their known effects on silkworm development, physiology, and survival. Particular attention is given to the formation of MNPs-pesticide complexes, which may modify pesticide bioavailability, uptake pathways, and toxicity through vector-mediated transport and gut-level interactions. Potential mechanisms underlying combined toxicity, such as oxidative stress, metabolic disruption, intestinal damage, and interference with detoxification systems, are discussed. Research indicates that MNPs typically increase pesticide bioaccumulation and toxicity rather than reduce them. However, the effect’s direction depends on the interplay between particle-facilitated transport and sorption-limited availability, rather than just plastic concentration. MPs and NPs operate through distinct mechanisms, such as luminal retention and epithelial translocation, and therefore should not be grouped into a single exposure category. Finally, critical knowledge gaps are identified, including the lack of environmentally realistic co-exposure studies, limited mechanistic evidence in silkworms, and insufficient understanding of MNPs-pesticide interactions under field-relevant conditions. This review highlights the need for integrated risk assessment frameworks to better evaluate the ecological and sericultural risks posed by MNP-associated pesticide exposure.