The influence of IR25a on electrophysiology and reproductive behaviour in the oriental fruit fly, Bactrocera dorsalis

Behavioural manipulation techniques, particularly attractants, have been widely adopted as environmentally friendly approaches to manage Bactrocera dorsalis. These approaches primarily target odorant receptors (ORs), key molecular components in the pest's chemotactic pathways, to guide pests towards traps or lethal stimuli, offering a sustainable and effective alternative to chemical pesticides. However, pest behaviour extends beyond chemotaxis. Crucial behaviours such as mating, oviposition and defence also directly influence population dynamics, underscoring the need to investigate molecular targets that regulate diverse behavioural processes. IR25a, a co-receptor of ionotropic receptors (IRs), exhibits functional versatility by detecting diverse signals, including both volatile and non-volatile compounds and environmental cues (e.g., temperature, humidity, acidity). These characteristics make IR25a a promising candidate target that influences various behavioural processes. In this study, CRISPR/Cas9 was employed to generate a BdorIR25a knockout homozygous strain (BdorIR25a^-/-). Its effects on various aspects of pest behaviour were systematically investigated to evaluate its potential as a molecular target for behavioural modification. Results showed that BdorIR25a was highly expressed in pupal and adult stages, particularly in antennae and mouthparts. Knockouts exhibited impaired responsiveness to specific chemicals, especially dimethylamine. Additionally, mutants displayed reduced courtship wing vibration, pheromone responsiveness and mating success. Oviposition rates and egg-laying numbers were significantly reduced in females. Importantly, knockouts had no detectable effects on growth or survival, confirming BdorIR25a's primary role in behavioural modification. In conclusion, our findings identify BdorIR25a as a key molecular target with strong potential for manipulating diverse behavioural processes, providing a new perspective for pest control strategies. Future studies should focus on identifying IR25a-associated IRs and other molecular targets within its linked regions to clarify their respective roles in modulating critical behavioural traits. These studies could provide detailed insights into the molecular mechanisms of behaviour manipulation, advancing the development of innovative and targeted pest control strategies.