Bacteria that occur naturally in the intestines of bees and bumblebees were genetically engineered (top left) to produce a special ‘gene messenger’. This is a specific, so-called double-stranded ribonucleic acid, or dsRNA for short. (A) Once the bacteria have become established in the gut of the bee, the dsRNA enters all the cells and intervenes in gene regulation.* This is intended to influence certain characteristics of the insects, e.g. their feeding behaviour. dsRNAs can also be used to ward off parasites, such as mites, also via interference in their gene regulation. This kind of indirect manipulation of target organisms, i.e. by interfering with their gene regulation, is known as paratransgenesis. (B) These kinds of bacteria also occur naturally in other wild bee species, such as bumblebees. Consequently the genetically engineered bacteria could also become established in other bee species, and thus spread uncontrollably. Applications using the dsRNA described above have, as yet, only been tested in the laboratory and have not been authorised.
* The effect of the dsRNA is achieved via so-called RNA interference (RNAi). This means that the dsRNA specifically attaches itself to certain mRNA in the cells, which is subsequently degraded and unable to fulfil its function. The mRNA in the cells is itself a messenger for the production of proteins. It is part of gene regulation and therefore indispensable.
References and further reading:
Leonard et al. 2020: https://www.science.org/doi/10.1126/science.aax9039