The Effect of X-ray Irradiation on the Fitness and Field Adaptability of the Codling Moth: An Orchard Study in Northeast China

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.

Loss-of-function in testis-specific serine/threonine protein kinase triggers male infertility in an invasive moth

Genetic biocontrol technologies present promising and eco-friendly strategies for the management of pest and insect-transmitted diseases. Although considerable advancements achieve in gene drive applications targeting mosquitoes, endeavors to combat agricultural pests have been somewhat restricted. Here, we identify that the testis-specific serine/threonine kinases (TSSKs) family is uniquely expressed in the testes of Cydia pomonella, a prominent global invasive species. We further generated male moths with disrupted the expression of TSSKs and those with TSSKs disrupted using RNA interference and CRISPR/Cas9 genetic editing techniques, resulting in significant disruptions in spermiogenesis, decreased sperm motility, and hindered development of eggs. Further explorations into the underlying post-transcriptional regulatory mechanisms reveales the involvement of lnc117962 as a competing endogenous RNA (ceRNA) for miR-3960, thereby regulating TSSKs. Notably, orchard trials demonstrates that the release of male strains can effectively suppress population growth. Our findings indicate that targeting TSSKs could serve as a feasible avenue for managing C. pomonella populations, offering significant insights and potential strategies for controlling invasive pests through genetic sterile insect technique (gSIT) technology.

Side effects of X-ray irradiation on flight ability of Cydia pomonella moth

BACKGROUND

The sterile insect technique (SIT) has proven to be an effective approach in managing the population of major invasive pests. Our previous studies showed that irradiation of Cydia pomonella males at a dosage of 366 Gy X-rays resulted in complete sterility. However, the mating competitiveness of sterilized males is significantly compromised, which can be attributed to a decline in their ability to fly.

RESULTS

In this study, we examined the flight patterns of both male and female adults of C. pomonella. The results revealed significant variations in the average flight speed of both genders at different stages of maturity, with females displaying longer flight duration and covering greater distances. Effect of irradiation on the flight performance of 3-day-old male moths was further evaluated, as they demonstrated the longest flight distance. The findings indicated a significant decrease in flight distance, duration, and average speed, due to wing deformities caused by irradiation, which also limited the dispersal distance of moths in orchards, as indicated by the mark-and-recapture assay. Reverse-transcription quantitative polymerase chain reaction analysis revealed a down-regulation of flight-related genes such as Flightin, myosin heavy chain, and Distal-less following radiation exposure.

CONCLUSION

These findings demonstrate that X-ray irradiation at a radiation dose of 366 Gy has a detrimental effect on the flight ability of male C. pomonella adults. These insights not only contribute to a better understanding of how radiation sterilization diminishes the mating competitiveness of male moths, but also aid in the development and improvement of SIT practices for the effective control of C. pomonella. © 2023 Society of Chemical Industry.