Neoclassical development of genetic sexing strains for insect pest and disease vector control

The sterile insect technique, which consists of the mass production and release of sterile insects to control populations of pests and disease vectors, has been effectively used for decades. An important component of sterile insect technique field applications is the availability of sex separation systems that reliably and economically eliminate females from mass-reared sterile insect populations destined for field release. Genetic sexing strains are important for the effectiveness and cost-efficiency of insect population control programs, including sterile insect technique. Classical approaches to generate genetic sexing strains, such as irradiation-induced chromosomal translocations, have yielded stable strains for species like the Mediterranean fruit fly, Ceratitis capitata. However, significant efforts are needed to establish genetic sexing strains using classical genetic methods, as large-scale random mutagenesis and screening are needed. We introduce here a neoclassical genetic approach, leveraging CRISPR-based gene-editing to target known genes to develop selectable genetic markers, followed by genetic rescue in a male-specific manner to speed up the development of genetic sexing strains and enhance their precision, stability, and adaptability. The integration of molecular tools, genetic markers like the white pupae and temperature-sensitive lethal, and strategies for maintaining genetic stability are discussed. We also review the challenges and opportunities in applying classical, transgenic, and neoclassical genetic approaches to improve genetic sexing strains for pest management.