Year
2025
Abstract
The sterile insect technique (SIT) is an agricultural pest and disease vector management capable of addressing at least three of the 17 United Nations Sustainable Developmental Goals (SDGs), including SDGs 2, 3 and 11. Radioactive sources such as gamma irradiation sterilise insects during SIT application in South Africa. However, the use of isotopic irradiators is becoming less favourable because of their high cost, strict regulatory requirements for transporting radioactive sources and stringent precautions and procedures required to protect personnel and the environment from radioactive exposures. Against this background, the South African SIT programs are exploring alternative, safer, effective, and more environmentally friendly irradiation approaches. The biological response of five different insect species (three dipterans and two lepidopterans) was investigated in a comparative study after irradiation with A Rad Source RS2400Q X-ray and a Gamma cell source at the same nominal doses. Furthermore, operational efficiency, running costs, processing capacity, maintenance, practicality, and reliability were documented. The average absorbed dose in the Rad Source geometry reference position was 19.44Gy/min. This data was used to develop X-ray irradiation setups and protocols for the different insect species. The impact of irradiation on downstream sterile male quality post-irradiation showed that X-ray irradiation is comparable to Gamma irradiation. However, the variable output factor of the X-ray system over time and X-ray tube cooling management compromised the reliability of the RS2400Q in these trials. Further development and optimisation are needed to facilitate an expedited process for X-rays to be fully considered as an alternative replacement for isotopic source-based irradiation in South Africa.