Seite - 109 - in Critical Issues in Science, Technology and Society Studies - Conference Proceedings of the 17th STS Conference Graz 2018

reaction comes to an end. Strategies to overcome this obvious disadvantage are discussed but could not be demonstrated so far. Furthermore, one could expect that such strategies working with multiple guide-RNAs would increase the complexity and non-linear behaviour of a gene drive construct. In consequence, its instability could be increased again. • Anopheles mosquitos possess a large genetic variety and evolutionary adaptability. Therefore, it is unclear whether genetically modified mosquitos will react efficiently with wild populations. A single gene drive might not be effective so that the development and use of many gene drive constructs might be needed to cover the range of genetic variants of Anopheles. • Trends so far indicate that genetic modifications of wild-type mosquitoes make them less evolutionary fit. Such generated disadvantages could also limit gene drives. • Cross-fertilization has been reported among various mosquito species. Thus, one insect can overtake the role of transmitting malaria to another. Therefore, eradicating or modifying only one vector species might be futile. These examples demonstrate that development risks are numerous. But imagine it could be done. Many scientists are eager to overcome the briefly sketched hurdles on the way to efficient gene drives. If they could succeed, will that be the solution for the malaria challenge? In the end, control of Plasmodium falciparum and other parasites is the crucial point. It has to be done much more than attacking the genetic code of vectors (mosquitos): the parasite cycle itself has to be interrupted in a sustainable manner. That is much more a question of health care and access to suitable simple measures than a new sophisticated technological tool. Social organisation and behaviour, access to modern healthcare, a functioning health care system in regions concerned, preventive and curative measures and availability and affordability of suitable means are of utmost importance when fighting malaria. The question arises whether the promise of gene drives against malaria is tenable. Anticipatable risks, consequences, and uncertainties Imagine it could be demonstrated that gene drives against malaria transmitting mosquitos could work in the wild. What risks would be involved in gene drive usage? Questions arising related to suppression drives: • An efficient mutagenic chain reactions could work across many or even all national borders. (The danger – or hope – exists that an extinction programme will work globally.) This will raise very serious and difficult questions concerning decision making and regulation unparalleled so far. • The specificity of guide RNAs targeting cleavage points of the DNA of a targeted species is below 100%. Unintended gene variants could be generated that way. Thus off-target effects could produce unwanted mutations and unwanted mosquito variants could emerge. • As mentioned above, the pathogen could possibly find a way to change its currently most favoured host mosquito. Would that require efforts to eradicate more and more mosquito species by more and more gene drives unleashed on nature? We know already about 30 109