A weird one to name, since afaik, this doesn't fall into the normal definition of "synthetic biology", since it's not building an organism (or a gene circuit, or anything more than the RNA itself). My guess is it's just RNAi, which puts the complexity on the scale of "pesticide" and not "genetically engineered machine" (Complete with the ability to replicate). At worst, a bug picks up the sequence and figures out some way to (1) ligate the RNA into a continuous sequence, (2) turn that RNA into DNA, (3) integrate that DNA into its genome, (4) express that DNA and turn it back into dsRNA somehow. Alternatively, a RNA-based virus could (1) integrate that RNA into its genome, (2) chop up its genome at those exact points of integration while inside the target pest. Neither are outside the realm of possibility, but both would be a tricky task for even a trained scientist to do... Wherever the line will be drawn will be in grey territory, but this seems pitch black with only a few photons from distant stars...For example, dsRNA crop sprays[1] disrupt the action of genes, which may kill targeted pest, but will also affect other organisms in unpredictable ways by silencing genes.