Computer worlds seldom *if ever* have farms. Many will have just factories. In a wartime situation, it should possible to starve these worlds out. Even 1 enemy scout in system, if not chased off, disrupts food transports (this has been done to me , many times). Each missing food is 250 k population starvation per turn (assuming the same rules for computer controlled races). At that point, blockading multiple worlds in theory should cripple an opponent relying on shipped in food. This does assume the computer has the same rules as the human player does.

I suppose for A.I it would be more efficient to have some farms on all worlds rather than what humans do that is specialist bread baskets.We understand the strategic importance.

a relevant point is that even the most fertile world literally cannot feed itself without farms. a blockaded world without a farm will always starve to death. I've taken to always building a farm on every world just to avoid massive casualties if a single ship blockades a system.

The AI is currently cheating a bit as regards Food and Metal (if I'm not mistaken).