Gene drives at tipping points : precautionary technology assessment and governance of new approaches to genetically modify animal and plant populations

Abstract

‘Self-propagating artificial genetic elements’ (SPAGEs), in particular gene drives (GD), represents a new quality in several respects in regard to the intended release of genetically modified organisms (GMOs). Their implementation (e.g. to control insects as disease vectors or to suppress invasive species) would imply a release with consequences far beyond the range of hitherto existing GM crops. The spatial and temporal spread of gene drive-equipped organisms is enormously enhanced by overcoming the limits of Mendelian inheritance, and most tasks aim at a genetic modification of wild species populations. The spectrum of application targets includes the suppression, if not (regional) extinction, of wild populations. If unforeseen problems occur after a release, corrective action can hardly be taken. The results presented here were aimed at the identification of hazard and exposure potentials emanating from SPAGEs with the help of a prospective and precaution-oriented technology assessment and a vulnerability analysis of potentially affected (agro-)ecological systems. In addition, options for a better control of gene drives and design options for possible risk-reducing alternatives were examined with regard to technical reliability and the early developmental stage of the technology. A comparative technology characterisation of various types of SPAGEs and a fundamental consideration of tipping points, their identification and predictability, lay the ground for a differentiated assessment. Two case studies further illustrate potential applications of SPAGEs in an agricultural context. Different approaches to modelling the population dynamics of gene drives installed in olive flies were examined in order to test the suitability and informative value of these models. The incidence of phase transitions and tipping points is discussed in both the qualitative and the quantitative parts of these cases. The case study of the olive fly (Bactrocera oleae) was carried out in close co-operation with scientific and practical actors of olive cultivation in Greece and Spain. For the case about oilseed rape (Brassica napus), extensive material from previous studies on genetically modified rape was processed. As a counterpart to the technology analysis of the SPAGE technology, a methodological approach for the vulnerability analysis of affected ecosystems was developed.