I've noticed the AI offering to buy food from me a lot recently, which I'm happy to do since I usually have thousands of it stockpiled. I can't imagine how the AI would fail to produce enough food on its own since the sector AI, left to its own devices, will generally produce like +50 extra food per planet... at least if you tell it to respect tile resources. I'm guessing the full empire AI tries to be clever and focus on whatever it's running short on instead of strictly matching tile bonuses, but still.
This speaking of food reminds me that I took care of my marauder empire problem. After they extorted literally my entire food stockpile from me early on, I swore revenge. After building up a 20K fleet of battleships, I flew into their systems and started systematically destroying their fleets, which was trivial. Now, the problem I ran into is that their space habitats are also armed, so my ships immediately got into battle with them and destroyed them too. Oops, I committed accidental genocide. Well, I felt bad at first, but then remembered they've been doing this to everyone nearby for a hundred years, so I committed accidental genocide in two more systems until they were completely gone.
I got an announcement from one of them threatening to burn my homes for destroying theirs, and the announcement warned that there was a fleet appearing out of hyperspace in one of my central systems without defenses, but nothing ever actually showed up there. Not sure if it was a bug or if it needed an actual fleet from them to still exist.
And it looks like I'm going to have to pay the little snail men a similar visit since they keep threatening me (and losing ships) or being bought by my rivals to raid me (and losing their ships).