A self-limiting sterile insect technique alternative for Ceratitis capitata

Background

Genetic biocontrol systems have broad applications in population control of insects implicated in both disease spread and food security. Ceratitis capitata (the Mediterranean fruit fly), a major agricultural pest with a global distribution, is one of the appealing targets for such genetic control.

Results

In this study, we establish and characterise a novel split-CRISPR/Cas9 system we term Sex Conversion Induced by CRISPR (SCIC) in C. capitata. Using the white eye gene for toolkit selection we achieved up to 100% CRISPR/ Cas9 efficiency, displaying the feasibility of C. capitata split-CRISPR/Cas9 systems using constitutive promoters. We then induce sex conversion by targeting the transformer gene in a SCIC approach aimed for SIT-mediated releases upon radiation-based sterilisation. Knock-out of transformer induced partial to full female-to-male sex conversion, with the remaining individuals all being intersex and sterile. SCIC population modelling shows a strong potential to outcompete traditional SIT, allowing for faster population elimination with fewer released sterile males. 

Conclusion

Overall, we construct an appropriate CRISPR/Cas9 toolkit for the use in C capitata. Our results build the foundation for further genetic pest control methods in the species and related tephritid agricultural pests.