Attack of the Aliens
We are doing the same thing sometimes with Genetically Engineered (GE) crops. Many of them certainly meet the criteria to be called an “alien species,” first because they have never existed before (they are somebody’s new invention), and additionally because they have never existed alongside natural crops. Often the GE crops cross-pollinate with the natural crops, resulting in a sort of hybrid, and often they supplant them entirely. Sometimes it is nearly impossible to get rid of the GE species once it has gained a foothold.
While countries around the world are trying to prevent the spread of “alien species” maybe they could do something about Genetically Engineered species as well. Not everyone views them as the boon that some scientists and businessmen do.