Gene drive modified insects: informing the environmental risk assessment and post-market environmental monitoring
A new EFSA report presents the results of a literature review and analysis across five domains relevant for future risk assessment of gene drive modified insects.
Oct 21, 2026
A new report published by the European Food Safety Authority (EFSA) examines recent scientific developments in gene drive modified insects (GDMIs) and their implications for environmental risk assessment (ERA) and post-market environmental monitoring (PMEM).
Gene drives are genetic elements that are inherited at rates above the 50% expected under Mendelian inheritance. As a result, they can spread through a population over successive generations, even when they give the organism no fitness advantage. Gene drives occur naturally as selfish genetic elements.
Engineered gene drives are designed to carry a desired trait through a target population. Most are homing-based systems built with CRISPR-Cas9 genome editing, in which the drive copies itself onto the homologous chromosome so that heterozygotes are converted into homozygotes. Other designs use different mechanisms, such as toxin-antidote systems or underdominance. Depending on their purpose, engineered gene drives can be used for population suppression, which reduces the number of a pest or disease vector, or for population replacement, which spreads a trait such as reduced capacity to transmit a pathogen. Some drives are designed to be self-sustaining and others to be self-limiting in space or time. Because they are designed to spread and persist in wild populations, they pose specific challenges for environmental risk assessment.
In 2020, the EFSA GMO Panel concluded that its existing guidance on genetically modified animals gave an appropriate basis for assessing GDMIs. The Panel also identified knowledge gaps that would need to be addressed before any future risk assessment. A new report presents the results of a literature review and analysis across five domains.
Molecular designs. A review of 142 publications from 2003 to 2024 shows that engineered gene drives have been introduced into 17 species. Homing-based drives predominate (73%), and 27% rely on other mechanisms, such as toxin-antidote systems or underdominance. Future guidance should therefore not be tailored to a single design. The existing guidance on molecular characterisation was judged adequate and sufficient, provided “stability” is interpreted more broadly.
Relevant cases. Three species were retained as relevant to the EU and its Outermost Territories: Aedes aegypti, Drosophila suzukii and Plutella xylostella. Anopheles spp. were excluded because their relevance to these regions is limited. Problem formulation was then used to identify plausible pathways to harm and risk hypotheses for the three retained species.
Comparators. The report recommends a broader and more flexible set of comparators. In addition to the parental organism, these should include the target population and alternative control approaches.
Modelling. Mathematical models are important tools for evaluating the potential spread, persistence and ecological effects of gene drives. However, limitations remain regarding model validation, ecological realism and the integration of relevant genetic and ecological processes. Of 177 publications on modelling, fewer than 1% address model validation. The report recommends bespoke, stochastic models embedded in statistical frameworks.
Post-market environmental monitoring. The limited practical experience with environmental releases of GDMIs creates challenges for designing monitoring programmes. Experience from other insect-release programmes shows that case-specific monitoring is likely to be the most informative approach. General surveillance faces major difficulties in establishing causality.
Engineered gene drives are designed to carry a desired trait through a target population. Most are homing-based systems built with CRISPR-Cas9 genome editing, in which the drive copies itself onto the homologous chromosome so that heterozygotes are converted into homozygotes. Other designs use different mechanisms, such as toxin-antidote systems or underdominance. Depending on their purpose, engineered gene drives can be used for population suppression, which reduces the number of a pest or disease vector, or for population replacement, which spreads a trait such as reduced capacity to transmit a pathogen. Some drives are designed to be self-sustaining and others to be self-limiting in space or time. Because they are designed to spread and persist in wild populations, they pose specific challenges for environmental risk assessment.
In 2020, the EFSA GMO Panel concluded that its existing guidance on genetically modified animals gave an appropriate basis for assessing GDMIs. The Panel also identified knowledge gaps that would need to be addressed before any future risk assessment. A new report presents the results of a literature review and analysis across five domains.
Molecular designs. A review of 142 publications from 2003 to 2024 shows that engineered gene drives have been introduced into 17 species. Homing-based drives predominate (73%), and 27% rely on other mechanisms, such as toxin-antidote systems or underdominance. Future guidance should therefore not be tailored to a single design. The existing guidance on molecular characterisation was judged adequate and sufficient, provided “stability” is interpreted more broadly.
Relevant cases. Three species were retained as relevant to the EU and its Outermost Territories: Aedes aegypti, Drosophila suzukii and Plutella xylostella. Anopheles spp. were excluded because their relevance to these regions is limited. Problem formulation was then used to identify plausible pathways to harm and risk hypotheses for the three retained species.
Comparators. The report recommends a broader and more flexible set of comparators. In addition to the parental organism, these should include the target population and alternative control approaches.
Modelling. Mathematical models are important tools for evaluating the potential spread, persistence and ecological effects of gene drives. However, limitations remain regarding model validation, ecological realism and the integration of relevant genetic and ecological processes. Of 177 publications on modelling, fewer than 1% address model validation. The report recommends bespoke, stochastic models embedded in statistical frameworks.
Post-market environmental monitoring. The limited practical experience with environmental releases of GDMIs creates challenges for designing monitoring programmes. Experience from other insect-release programmes shows that case-specific monitoring is likely to be the most informative approach. General surveillance faces major difficulties in establishing causality.
The report contributes to the scientific evidence base for possible future development of EFSA guidance on the environmental risk assessment and post-market environmental monitoring of gene drive modified insects.