Screwworm Male-Only Lines: Past, Present and Future w/ Dr. Maxwell Scott

In this webinar, Dr. Maxwell Scott presents the development and application of male-only lines for the New World screwworm, a major livestock pest. He begins by explaining the sterile insect technique (SIT) and its historical success in eradicating screwworm from North and Central America. The central challenge is to improve SIT efficiency by releasing only sterile males, which requires genetic sexing systems. Dr. Scott details his research journey, starting with work on the Australian sheep blowfly in New Zealand, where he developed a tetracycline-repressible female lethal system using the tTA transcription factor and the pro-apoptotic gene hid. He then describes the transfer of this technology to screwworm at NC State, including the development of transgenic strains with female-specific promoters and introns. The presentation covers the construction of single-component and two-component systems, the use of the transformer gene for sex-specific splicing, and the challenges encountered with ovary expression and mating competitiveness. Recent work has focused on improving sex specificity and early lethality, with promising results in laboratory and field trials. Dr. Scott concludes by discussing the potential for integrating these strains into future genetic biocontrol programs, emphasizing the need for continued research and regulatory approval.