Insecticides and cadmium impair programmed appendage regeneration in Pardosa pseudoannulata: Mechanisms and...

Biological control by natural enemies is critical for sustainable pest management, yet chemical pesticides threaten the efficacy from natural enemies by diminishing their populations and reduce control effectiveness. The spider Pardosa pseudoannulata, a key natural enemy of insect pests, relies on precise appendage regeneration for survival and predation on insects. Early-stage regeneration is governed by the PKA/CREB-mediated melanization pathway, influencing development and initial melanization of regenerated appendages. Here, we reveal that subsequent melanization stages are regulated sequentially by MAPK (mitogen-activated protein kinase) and Wnt (wingless-related integration site) signaling in turn. Low concentrations of insecticides (chlorpyrifos, buprofezin) and heavy metal cadmium caused no direct mortality but severely disrupted regeneration. These chemical stressors dysregulated genes across PKA/CREB, MAPK, and Wnt pathways, impairing development and melanization of regenerated appendages. Our findings highlight how sublethal chemical exposure compromises spider fitness, undermining biological control. This study exposes hidden risks of agrochemicals and heavy metals to arthropod regeneration. It also advances understanding of conserved melanogenesis disruption mechanisms shared across taxa.