Linalool fumigation improves mating competitiveness of males for population suppression of the global fruit pest Cydia pomonella.

Background: The implementation of sterile insect technique (SIT) has proven effective in the area-wide suppression of several significant agricultural and sanitary pests by using traditional cobalt-60 (⁶⁰Co-γ) as a radiation source. Recently, X-ray has been validated as a feasible alternative to ⁶⁰Co-γ radiation sources. Nonetheless, higher doses of X-ray irradiation led to insect sterility but diminish mating competitiveness, thereby impacting the effectiveness of SIT applications.

Results: In this study, we assessed the impact of various X-ray irradiation doses (ranging from 0 to 366 Gy) on the fecundity, fertility, and mating competitiveness of Cydia pomonella, a globally invasive fruit pest. Results demonstrated that the sterility rate of irradiated males increased with dose up to 200 Gy, then stabilized. Exposure to 200 Gy reduced male mating competitiveness, with competitiveness index (CI) values of 0.17 in the laboratory and 0.096 in the orchard. This decline is likely linked to the decreased expression of genes associated with sex pheromones recognition, such as CpomOR3a, CpomOR3b, and CpomOR5, post-irradiation. Fumigation of linalool at varying concentrations (70, 83, and 96 μL/m³) enhanced mating competitiveness of males, particularly at moderate levels, possibly by restoring pheromones recognition. Implementation of repeated releases of sterilized males on a pilot scale led to a notable reduction in the population of C. pomonella in the field.

Conclusion: These findings indicate that fumigation with plant volatiles has the potential to mitigate male sterility induced by X-ray irradiation, offering a promising approach to enhance the efficacy of SIT applications for the control of C. pomonella. © 2024 Society of Chemical Industry.