Genetically Tweaking Flies to Save Livestock

A Clever Approach to Pest Control

Scientists are working on an innovative method to control the New World screwworm, a destructive fly that once plagued North and Central America. Traditionally, the pest was managed by releasing sterile flies, but a new approach using only male flies could enhance this technique.

Genetic Modification for Gender-Specific Control

Researchers have engineered special genetically modified flies using a system that deactivates a gene with a substance called tetracycline. The aim is to ensure only male flies survive. Two different gene promoters were used to control gene deactivation: one from a related fly species and the other from the screwworm itself.

Challenges and Discoveries

The goal was to deactivate the gene in early embryos, killing female flies before they develop. However, the gene was unexpectedly active in pupae. To ensure female flies died, researchers tested various methods of administering doxycycline, a form of tetracycline. They found that timely administration could save female flies by maternal transfer, but reducing doxycycline resulted in all surviving flies being male.

Breeding and Survival Rates

All modified fly strains met the criteria for colony breeding. However, the modified males did not survive as well as regular flies after doxycycline removal. In mating tests, modified flies performed poorly compared to regular flies, especially in competitive scenarios. One strain performed well in non-competitive tests but struggled in competitive settings.

Conclusion

This study underscores the importance of precise gene activity control and careful antibiotic timing. It represents a significant step toward developing more effective genetic control methods for pests.