Reporting on a collaboration of the The University of Adelaide, The University of Melbourne, South Australian Research and Development Institute (SARDI), Western Sydney University, and Applied BioSciences at Macquarie University, a recently published study investigated an innovative marking method for Queensland fruit fly Sterile Insect Technique (SIT). By use of CRISPR/Cas9 gene editing, a non-GMO
phenotypically distinct Queensland fruit fly (Q-fly) yellow strain was developed to differentiate released sterile flies with their wild counterparts, providing an alternative marking method to the use of fluorescent dyes which can have negative impacts on fly quality.
We would like to congratulate Thu N. M. Nguyen and her coauthors for recent publication of this innovative study in the Journal of Pest Science!
"Disruption of duplicated yellow genes in Bactrocera tryoni modifies pigmentation colouration and impacts behaviour"
Thu N. M. Nguyen, Vivian Mendez, Christopher Ward, Peter Crisp, Alexie Papanicolaou, Amanda Choo, Phillip W. Taylor & Simon W. Baxter
Irradiated Queensland fruit flies (Bactrocera tryoni) used in Sterile Insect Technique (SIT) programmes are marked with fluorescent dyes to distinguish them from wild flies when recaptured in monitoring traps. However, coating sterile pupae with powdered dyes can reduce emergence rates and fly quality and can sometimes produce insufficiently certain discrimination through inadequate coating or because the dye is transferred to wild flies through contact. Here we created a phenotypically distinct B. tryoni strain that lacks typical melanisation patterns through CRISPR/Cas9-mediated mutagenesis of tandemly duplicated yellow-y genes and then assessed effects of this visible trait on fly performance. Recessive mutations are only required in one of these copies to restrict melanisation and generate a phenotype clearly distinguished from wild type. The yellow strain showed significant declines in eclosion rates and in the percentage of fliers directly after emergence. Locomotor activity was greater in the yellow strain, and these mutations did not generally affect mating probability, copula latency, or copula duration. The longevity of yellow flies was approximately 10 days shorter than wild-type flies in both sexes. Overall, replacing dyes with yellow body marker for SIT can simplify production, eliminate a step that is known to reduce fly quality, remove potentially hazardous dyes from production, enable accurate discrimination from wild flies, and improve cost-effectiveness; however, direct comparisons of the decrements in performance associated with dyes on mass-reared wild-type flies and disruption of yellow-y genes are now required to determine the relative suitability of these marking methods for B. tryoni SIT.
Photo: Queensland fruit fly pupae (Maurizio Benelli).