Biotechnology-enhanced SIT: Challenges & opportunities

The SIT was used to eradicate Cochliomyia hominivorax (Coquerel; Diptera: Calliphoridae), from the U.S.A, Mexico and Central America. Cochliomyia hominivorax is an obligate parasite of warm-blooded animals and remains a major pest of livestock in most of South America. As genetic suppression is significantly more efficient if only sterile males are released, our main objective has been to produce engineered strains that produce only males on diet that lacks doxycycline. Ideally females would die at the embryo stage to save larval diet costs and sterilized males would be competitive in the field.  While several male-only strains have most of the desired characteristics, males from the embryo-lethal lines showed reduced mating competitiveness. To address the latter, both components of the genetic system were engineered to be female-specific. Our results with the new male-only strains will be presented and potential further development of male-only strains will be discussed.

Genetic suppression should be more efficient if fertile males are released in the field as the dominant female killing gene is passed on to the next generation. We have developed male-only (fsRIDL) lines for Drosophila suzukii (Matsumura, Diptera: Drosophilidae), a global pest of soft-skinned fruits.  Repeated releases of fsRIDL males successfully eradicated lab cage populations.  As coupling fsRIDL to a gene drive could be more effective, we developed and evaluated the ability of gene drive strains to suppress lab cage populations.  fsRIDL strains alone, or coupled with a gene drive, appear promising for genetic biocontrol D. suzukii with potential application to C. hominivorax.