Peripheral olfactory structures and maturity-related crypt receptor neuron kinetics in the olfactory epithelium of carp Cyprinus carpio (L.): implications for carnal vulnerability and pest management

Carnal vulnerability is a powerful yet underutilised tool in integrated pest management. The lack of species-specific knowledge of underpinning sexual drivers and mechanisms for their detection has precluded efficient exploitation of the vulnerability. As a step in understanding how mature common carp Cyprinus carpio communicate and attract conspecifics, the present study undertook anatomical and histological examinations of the olfactory system, tracing changes in crypt receptor neurons (CRNs) within the olfactory rosette in relation to gonadal development, as proxy. Quantification of the density and relative position of CRNs in the lamellae revealed that their density increases significantly with sexual maturity in both males and females (P < 0.001). In contrast, the CRNs were concentrated in the basal and surface layers of the epithelium (P < 0.001) in females and males respectively, suggesting a sex-specific deployment and mobilisation of CRNs with the onset of maturity. This suggests that the mature males are likely equipped to detect and respond to pheromones more rapidly than females, triggering courtship behaviours such as mate pursuit that are generally associated with mature males. This maturity-driven CRN proliferation and mobilisation reveals a susceptibility, particularly of male C. carpio, to carnal lure and capture that could be exploited in pest management programs.