Female-specific insect lethality engineered using alternative splicing

Abstract

The Sterile Insect Technique is a species-specific and environmentally friendly method of pest control involving mass release of sterilized insects that reduce the wild population through infertile matings. Insects carrying a female-specific autocidal genetic system offer an attractive alternative to conventional sterilization methods while also eliminating females from the release population. We exploited sex-specific alternative splicing in insects to engineer female-specific autocidal genetic systems in the Mediterranean fruit fly, Ceratitis capitata. These rely on the insertion of cassette exons from the C. capitata transformer gene into a heterologous tetracycline-repressible transactivator such that the transactivator transcript is disrupted in male splice variants but not in the female-specific one. As the key components of these systems function across a broad phylogenetic range, this strategy addresses the paucity of sex-specific expression systems (e.g., early-acting, female-specific promoters) in insects other than Drosophila melanogaster. The approach may have wide applicability for regulating gene expression in other organisms, particularly for combinatorial control with appropriate promoters.

Female-specific flightless phenotype for mosquito control

“…These issues could be mitigated by the use of insects engineered to carry specific novel traits, including conditional genetic sterilization or lethality, that removes the need for irradiation (10,(12)(13)(14). Insects engineered to carry a female-specific lethal (or otherwise incapacitating) gene could be used to remove females prior to release (8,11,(14)(15)(16). A system based on a lethal gene [release of insects carrying a dominant lethal (RIDL); (14)] that acts late in development would prevent mosquitoes from becoming adults, the only harmful life stage, yet enable them to survive and compete at the larval stage, when density-dependent competition occurs (17).…”

“…Modeling this system predicts that fewer male mosquitoes of a late-lethal strain need to be released as compared to those carrying an early-lethal gene or irradiated strain to achieve an equivalent level of control of a target population (12,18). We reported previously the construction of repressible lethal strains of insects using the "tet-off" gene expression system based on a synthetic tetracycline-repressible transactivator (tTA) (12,14,16,19,20). Here we describe the construction of transgenic Ae.…”

Strategy for enhanced transgenic strain development for embryonic conditional lethality in Anastrepha suspensa

“…We believe that lethality caused by pro-apoptotic cell death genes (e.g., hid, rpr, or grim), or other well-studied biological mechanisms (10), is preferable to systems for which the lethality mechanism is unknown, including those dependent on a toxic accumulation of the Tet-transcriptional activator (8,(14)(15)(16)(17). While tTA toxicity may be highly effective, it is not species-specific nor is its precise mode of action known (8).…”

Site-specific recombination for the modification of transgenic strains of the Mediterranean fruit fly Ceratitis capitata

“…1), which will be inherited by their progeny together. For example, a combination of a conditional embryonic lethality (6), a sperm marking (7), and a sexing system (3,25) could be put into effect in medfly with the described strains. Deleting piggyBac ends could then further increase the stability of such strains.…”

“…Moreover, insect transgenesis provides powerful tools that have the potential to improve current pest management strategies (2). For a number of economically or medically important species, transgenesis is nowadays exploited to develop strains with different features which may improve the efficacy of existing biocontrol methods such as the sterile insect technique (SIT) (3)(4)(5)(6)(7). The SIT is a powerful pest control strategy involving mass rearing of the target pest insect, sterilization, and release of males over the target area.…”