Pyriproxyfen Disrupts Chitin and Trehalose Metabolism in the Silkworm Bombyx mori

Pyriproxyfen, a juvenile hormone analog insecticide, poses severe risks to non-target silkworms (Bombyx mori), as evidenced by disrupted metamorphosis-a process strictly dependent on chitin synthesis and its precursor trehalose. However, the specific molecular interference of pyriproxyfen in these metabolic pathways remains unclear. This study investigated the transcriptional response of silkworm midguts to pyriproxyfen using RNA-Seq and validated spatiotemporal gene expression via qRT-PCR. By integrating transcriptomic data with long-term spatiotemporal profiling, we revealed novel tissue-specific expression dynamics. RNA-Seq identified 2059 differentially expressed genes, primarily enriched in metabolic pathways. Spatiotemporal analysis revealed that most chitin- and trehalose-related genes generally exhibited a biphasic "suppression-compensation" trend (initial downregulation followed by upregulation). Notably, tissue-specific responses were evident, with ChsA being continuously suppressed in the middle silk gland, which may be associated with impaired sericin secretion, while showing abnormal upregulation in the posterior silk gland. Additionally, trehalose metabolism genes (Treh and Tret) paralleled the fluctuation of chitin genes, indicating systemic metabolic reprogramming. These results suggest that the toxicity of pyriproxyfen is associated with a decoupling of trehalose metabolism from chitin synthesis and the induction of tissue-specific metabolic disorders. The tissue-specific, long-term spatiotemporal profiling of chitin and trehalose genes presented in this study fills a critical knowledge gap. This study characterizes the transcriptional profile associated with pyriproxyfen toxicity and provides a robust molecular reference for assessing its environmental risks to beneficial insects.