There are a couple of situations where pests are noted. On Mars, there's talk of "wild artificial", mechanical drones or bots which have run wild with incomplete or damaged programming, doing whatever. Biobrug district of Noctis-Qianjao has suffered from some land piranha outbreaks. And on Luna, in places like Erato where they have a high volume of open space and nature parks, they have things like Macaques (I think) running loose, noted as pest animals. Swarm Cats might be considered a pest, and Poisonous Marmoset Swarms definitely are (thanks Genehackers). The thing about pests is that unless something was deliberately placed or generated in an environment, there's no call for it to be there. To my knowledge, rats don't get on space ships. Assuming you're doing any kind of decent customs, that should probably have stayed reasonably into the transhuman future. Even in the chaos of the Fall, unless someone was dragging a rat-filled suitcase onto the transports desperately leaving Earth, pest animals wouldn't be lining up to get onto spacecraft. So most of your "pest" situations will be genehacking or other animal preservation efforts running loose. Somebody makes a Spider with vacuum sealing, or a Moth with a plasma sail or something and it gets out or is deliberately released, you might get pest populations. Technically, if it spreads from an origin point, that might be a not deliberate introduction, but still given the security concerns of the Post Fall world, most places who have the means to support live pest animals probably have tight enough security to prevent them being accidentally brought from somewhere else. Wild Artificials can be pests, but hopefully aren't self-replicating. So basically, in some big places who have a lot of greenspace or other decent replication of a biosphere might have some imported animals which end up running loose and developing pest habits (Monkeys, Rats, Space Pigeons, etc.). Otherwise, probably going to get a lot of genehacked odd-ball creatures which are transgenetic or neogenetic who get out. Like Landsharks or Space Tarantulas, or Polymer-Eating Vacuum Moths or the terrifying SPACE WASPS or whatever.