Current and proposed insect targets for gene drive development (1st Edition)

Summary of findings

There are currently 32 insect targets from six different orders proposed or under development.1

• While nine of the proposed insect targets are vectors of human disease2, in particular malaria, the majority (21) are agricultural pests3, including four livestock pests or livestock disease vectors, which partially overlap with human disease vectors.
• Only three species are proposed as targets because of wider biodiversity impacts or combined economic loss and biodiversity impacts4, as well as one for forest management purposes and one for conservation5, the latter again overlapping with human disease vectors.
• The majority of gene drive proposals are based on eradication/suppression approaches. Only a very few are projects that are actually aiming to modify characteristics of insects in the wild.
• At the present time no projects are close to producing a usable and proven ‘product’. But some are closer to potential field trials, pending on regulation, risk assessment and further (technical) developments.

Contextualisation

The emergence of gene drive technology opens-up unprecedented prospects of modifying, suppressing, or even eliminating wild species to serve human purposes. The consequences of choosing to go down this path are very difficult to foresee, especially in the longer term. To help frame further discussion on this topic, we have conducted a survey of gene drive development in insects, screening the the scientific literature up until April 2022. The survey also includes development of so-called ‘x-shredders’, a sex ratio distortion system with close similarities to gene drive technology.
We do not cover issues regarding risks, difficulties in performing robust risk assessments, or the lack of proven methods to confine, halt or reverse engineered gene drives.

Our survey gives an overview of:

• What research has taken place or is ongoing.
• Which species and taxa are current or proposed targets for gene drive development, and which types of gene drives are being put forward. 6
• How far along developments have progressed and what the next stages of experimentation might be.

Detail of findings
The following table shows the detailed findings of our survey (pp. 3 - 17) and is sorted according to taxa, with those species or orders that are most advanced in gene drive development placed first. Please see page 17 for explanation of development levels of gene drives.

Footnotes:

1. The vast majority of the targets identified in the literature are single species or species complexes, however some early stage proposals relate to broader taxonomic groups, namely the Glossina genus (Testse flies - row 31), the Scolytinae subfamily (Bark beetles - row 44) and the Thysanoptera order (Thrips - row 51).
2. All 6 mosquito species listed in rows 1-17, flies in rows 30 and 31, and the bug Rhodnius prolixus in rows 39-40.
3. Targets impacting crops are detailed in rows 18-25, 28, 32-38, 41-43, 45-47, 50-51; targets impacting livestock are listed in rows 26, 27, 29 and 31.
4. Targets impacting wider biodiversity (and economics) are detailed in rows 48-50.
5. Proposed targets for forestry are bark beetles in row 44, and for conservation is the mosquito Culex quinquefasciatus, a vector for bird malaria as well as for human and animal diseases, and listed in rows 13-15.
6. Many experimental gene drive systems are being developed and tested in the model organism Drosophila melanogaster. Because we are not aware of any plans to target this organism