Generating cisgenic sexing strains in insect pests.

Area of Science:

• Genetics
• Entomology
• Pest Control

Background:

• Sterile insect technique (SIT) requires sex separation for efficient pest control.
• Existing genetic sexing strains (GSSs) often suffer from instability and fitness costs, limiting field application.

Purpose of the Study:

• To engineer a stable and effective cisgenic genetic sexing strain (CGSS) in insects.
• To develop a visually sex-sorted strain for improved sterile insect technique efficacy.

Main Methods:

• Utilized CRISPR/Cas9-mediated homology-directed repair for precise genome editing.
• Translocated a sex-specific intron from the transformer gene into the white pupae gene in Ceratitis capitata.
• Generated a homozygous strain (IMPERIAL) with a dominant phenotypic marker for sex determination.

Main Results:

• Created a genetically and phenotypically stable CGSS (IMPERIAL) in the Mediterranean fruit fly.
• Achieved clear visual sex differentiation: brown female pupae and white male pupae.
• The engineered strain exhibited good overall fitness, indicating minimal negative impact from the genetic modification.

Conclusions:

• The novel CGSS approach offers a stable and visually discernible method for sex separation in insects.
• This technique has the potential to enhance the efficiency and economic viability of the sterile insect technique for pest management.
• The minimally invasive genome editing strategy is adaptable for developing CGSS in other economically important pest species.