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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » Livestock Arthropod Pest Research Unit » Research » Publications at this Location » Publication #427403
Research Project: Improved Methods for the Management of Dipteran Pests of Livestock

Location: Livestock Arthropod Pest Research Unit

Title: Improving the sex-specificity of a conditional female lethal system for genetic biocontrol of the New World screwworm, Cochliomyia hominivorax

Author
item VARGAS LOWMAN, AIDAMALIA - Universidad De Panama
item Arp, Alex
item SAGEL, AGUSTIN - US Department Of State
item PATIL, ANANDRAO - North Carolina State University
item QUINTERO, GLADYS - US Department Of State
item VASQUEZ, MARIO - US Department Of State
item ARIAS, ADYANIS - Universidad De Panama
item MARTINEZ, ANDREA - Latin University Of Panama
item SCOTT, MAXWELL - North Carolina State University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2025
Publication Date: 11/18/2025
Citation: Lowman, A.V., Arp, A.P., Sagel, A., Patil, A.A., Quintero, G., Vasquez, M., Arias, A.D., Martinez, A., Scott, M.J., 2025. Improving the sex-specificity of a conditional female lethal system for genetic biocontrol of the New World screwworm, Cochliomyia hominivorax. Sci Rep 15, 40516.
DOI: https://doi.org/10.1038/s41598-025-24434-5

Interpretive Summary: The New World screwworm is a parasitic fly that poses a significant threat to livestock in the Americas. Although it has been eradicated from the USA using the Sterile Insect Technique (SIT), improving SIT efficiency remains crucial. One promising method involves creating genetic strains that produce only males by eliminating females early in development, which would reduce costs. However, while some strains can match wild-type production levels, they often suffer from reduced male fitness, hindering their use. This study aimed to enhance strain performance by focusing on female-specific expression of the lethality system. Researchers tested four transgenic strains using early embryo-specific promoters from the Chhalo and g6541 genes. Strains with the Chhalo promoter showed early-stage female lethality but had reduced male fitness. Conversely, a strain with the g6541 promoter produced males with excellent fitness, though female lethality occurred later in development. Despite the timing issue, this strain's overall fitness makes it a strong candidate for future genetic control programs.

Technical Abstract: The New World screwworm is an obligate parasitic fly and a significant economic pest of livestock in the Americas. Although eradicated from the USA using the Sterile Insect Technique (SIT), enhancing SIT efficiency remains a priority. A promising approach involves conditional female-lethal genetic strains that produce only males in the absence of tetracycline, ideally eliminating females early in development to reduce larval diet costs. However, while some strains match wild-type production levels, reduced male fitness has prevented their implementation. This study aimed to improve strain performance through female-specific expression of both the driver and effector components of the lethality system. We tested four transgenic strains using early embryo-specific promoters from the Chhalo and g6541 genes. Strains with the Chhalo promoter driving tTA expression exhibited early-stage female lethality under a modified doxycycline regimen but suffered from reduced male fitness. In contrast, one strain with the g6541 promoter produced males with excellent fitness but female lethality occurred at the late pupal stage. Despite imperfect female lethality timing, the overall fitness characteristics of this strain makes it a good candidate for future sterile or fertile male release genetic control programs.