Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest

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N. P. Kandul, J. Liu, A. Buchman, I. C. Shriner, R. M. Corder, N. Warsinger-Pepe, T. Yang, A. K. Yadav, M. J. Scott, J. M. Marshall and O. S. Akbari,  GEN Biotechnology,  1:372-385. 2022.

The Drosophila suzukii invasion of western countries has created an immense agricultural and economic threat to crop production. Despite many attempts to suppress its population, D. suzukii continues to destroy soft-flesh fruits. Precision guided sterile insect technique (pgSIT) utilizes the accuracy of programmable CRISPR gene targeting to generate sterilized males that can be deployed to suppress populations. Here, we generate pgSIT in D. suzukii and empirically and mathematically demonstrate that sterilized males are fit, competitive, and can eliminate populations of D. suzukii. Altogether, we describe an efficient way to generate sterile D. suzukii for release and safe effective population suppression.

Comparison of SIT and pgSIT.
(A) Classical SIT relies on ionizing radiation to sterilize pupae or adult flies, then females are discarded and adult males are deployed. As a result, every male released in the environment is reared, sterilized, and sex-sorted at a 1 · production scale. (B) In pgSIT, a genetic cross between parental strains harboring Cas9 and gRNAs targeting genes essential for female viability and male fertility results in Cas9/gRNA-mediated disruption of the targeted genes leading to female lethality (aka. sex-sorting) and male sterility in the F1 progeny. Each sex sorted parental female can produce up to 300 progeny and 50% of those will be sterilized males, resulting in 150 sterile males produced for each sorted female. This results in a potential scaling benefit of 150 · . In addition, traditional SIT requires the handling and release of adult males, resulting in reduced fitness costs due to manual manipulations. With pgSIT, eggs can be directly deployed and hatched in the environment, thereby eliminating the need to manually manipulate the sterilized males, resulting in preservation of their fitness. gRNA, guide RNA; SIT, Sterile Insect Technique; pgSIT, precision-guided Sterile Insect Technique.

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