Genetic Modification-Based Sterile Insect Technique (SIT)

  • A pairs of marked disruption alleles is generated by inserting selectable markers into identical sites in fertility genes, inducing recessive sterile mutations
  • Mutant alleles are propagated through populations containing both fertile heterozygous and sterile homozygous animals; the latter are readily collected by screening for both markers
  • A high-throughput sorting of insects using existing automated fluorescence sorting machines or chemical selection provides high-yield of fit but sterile insects as well as fertile heterozygous

Abstract

Sterile Insect Technology” (SIT) is a powerful and environmentally friendly strategy for controlling and even eradicating insect pests and vectors of disease. In SIT, sterile male insects of a given species are released into the environment to compete with their wild male counterparts for mating to wild females. Mating to sterile males leads to species-specific reductions in the levels of reproduction followed by declines in population size, in some cases driving the population to zero. The sterile insect technique (SIT) has been applied against plant and animal pests and vectors of animal and human disease for over 50 years. Sterile males can be generated in a variety of ways, from irradiation to the introduction of a sterilizing pathogen or transgene.A major bottleneck in implementing SIT against many species is the difficulty and expense in generating large numbers of males that reliably fail to produce viable offspring but are otherwise fit and effective at mating.Brandeis inventors have developed a simple and generalizable molecular genetic strategy for generating such males. One way to create sterile males that are otherwise fit for mating would be to use animals harboring a stable, knock-out mutation in a gene specifically required for fertility. Inventors use CRISPR/Cas9 technology to create two-color knock-ins in the key reproductive gene and replacing them with RFP, GFP & following Mendelian genetics.

Advantages

  • This approach enables the production of large numbers of sterile animals with specific mutations
  • This method generates stable heterozygous individuals in one generation that can be used to produce more sterile animals in the next generation
  • Any genetically modified insect will be sterile in nature hence no chance of escaping and propagating in the environment (sterile insects are not considered as GM)
  • This platform technology can be used for a range of insect and non-insect species

Potential Applications

– Mitigation or elimination of crop pests

– Mitigation or elimination of disease vectors