BIOLOGICALLY-BASED TECHNOLOGIES FOR MANAGEMENT OF CROP INSECT PESTS IN LOCAL AND AREAWIDE PROGRAMS
Location: Insect Behavior and Biocontrol Research Unit
Title: A transgenic embryonic sexing system for Anastrepha suspensa (Diptera:Tephritidae)
Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 22, 2012
Publication Date: October 1, 2012
Citation: Schetelig, M.A., Handler, A.M. 2012. A transgenic embryonic sexing system for Anastrepha suspensa (Diptera:Tephritidae). Journal of Insect Biochemistry and Molecular Biology. 42:790-795.
Interpretive Summary: Development of effective and safe sexing strains for biological control has been shown to be important for the most successful biological control programs using the Sterile Insect Technique. But thus far, sexing systems were only developed for one insect pest species, the Mediterranean fruit fly. Scientists at the USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology,Gainesville, Florida, created new conditional sexing strains for the Caribbean fruit fly. An antibiotic added to the food can switch off the system during the rearing of the flies, allowing them to survive and reproduce. Under restrictive diet conditions without the antibiotic, all females die during a very early stage in development, which is be important for large-scale production of a male-only population. Female death early in development is important to prevent the costly consumption of larval diet, which can be as much as several tons a day. This is the first report of an early sexing system in general, and the first successful transgenic sexing strategy in an important New World pest.
The Sterile Insect Technique (SIT) is a highly successful biologically-based strategy to control plant and animal insect pest populations, that relies on the large-scale release of sterilized males that renders females in the field non-reproductive. Despite its success, the more widespread use of SIT is limited by the lack of methods, in most species, to eliminate females early in development, resulting in higher costs and lower efficacy. For medfly, a mutant-based sexing system is available as well as a transgenic system where a tetracycline-suppressible (Tet-off) toxic molecule is female-specifically produced. However, the former classical genetic system took many years to refine, and the latter system results in female death primarily in the pupal stage after rearing costs have been incurred. Here we describe a new transgenic Tet-off sexing strategy that is not only highly efficient, but eliminates female insects early in embryogenesis by a well-characterized apoptotic mechanism.