Cadmium-induced visual impairment in a rice field predator Pardosa pseudoannulata may involve inositol phosphate metabolism.

The toxic effects of cadmium (Cd) on rice field spiders have been extensively studied. However, a systematic investigation into the toxicity and underlying mechanisms affecting the visual system of rice field spiders from spiderling to the subadult developmental stages has not yet been reported. This study aimed to investigate the effects of Cd on eye development in the predatory spider Pardosa pseudoannulata. Cd exposure decreased levels of melatonin, dopamine, and acetylcholinesterase in third- and seventh-instar spiderlings, accompanied by a significant elevation of malondialdehyde at the third instar, indicating oxidative stress. Ultrastructural analysis revealed damage to the spider eye, including abnormal heterochromatin in vitreous cell nuclei, photoreceptor nuclear membrane dissolution, and disorganization of Golgi bodies, endoplasmic reticulum, and mitochondria. Predation assays under natural light, white light, and darkness showed Cd-induced impairment of predatory ability with light-dependent behavioral changes. Transcriptomic analysis identified altered expression of cuticular protein and vision-related genes. Proteomic analysis identified 53 differentially expressed proteins localized to Golgi and endoplasmic reticulum. Notably, many differentially expressed genes and proteins were enriched in the inositol phosphate metabolism pathway. These findings provide preliminary insights into Cd-induced molecular and structural responses in arachnids.