ABSTRACT
The accelerating development of modern biotechnology, resulting continuously in new molecular techniques, has significantly increased the potential of understanding and modifying the genetic information in various organisms, from mammals to many insect species. Key molecular techniques developed over the past three decades include classical transformation technologies via transposable elements, and site-specific genome modification techniques using recombinases, both permitting the introduction of new genes or regulatory elements into the genome and their subsequent modification or (partial) removal. Tools like TALEN or CRISPR permit the precise editing of genomes at pre-defined positions, ranging from single-base changes to the knockout of complete genes, or the introduction of exogenous genetic material. On the other hand, RNA interference (RNAi) does not change genomic information but instead influences gene expression levels to various degrees, including complete suppression of expression. All of these tools can be used to develop or refine insect strains to improve the efficiency of existing pest control programmes, or to develop new SIT-based control systems. Modern biotechnology tools are being exploited to develop self-limiting as well as self-sustaining approaches. While the latter aim at population replacement strategies using gene drive or Wolbachia-based approaches and are mostly developed for vector and disease control, SIT-based control systems are self-limiting strategies that are supposed to leave no ecological footprint. Molecular technologies have already been applied to create sterility and sexing strains, and to introduce stable markers for monitoring in several insect species including the Mediterranean fruit fly, Mexican fruit fly, Australian sheep blow fly, New World screwworm, pink bollworm, and various mosquito species. Moreover, several of these strains have undergone an initial evaluation under mass-rearing scenarios or in open-field trials, although their wider adoption has so far been slow in view of low public acceptance of transgenic approaches, and the regulatory requirements and approvals that are required in most countries for their application.
