My understanding is that interceptors defend with there weapon, but do not gain the +100% ASM bonus. Generally, attackers are more powerfull than defenders ( usually enemy needlejets use the best weapon available, while interceptors are considered low priority for weapon upgrades). This means the odds are usually going to be something like 6:4, 8:6, or so on. Also X-jets have the +50% bonus which applies in airbattle also.
These factors tend to mean that interceptors will never have better than 1:1 odds, and usually worse odds, so interceptors
will usually lose.
That said if you have good weapon tech and/or are caretakers interceptors can be quite effective at defense, but they are a waste of time at tech parity (or against X-jets). Interceptors can make effective ZOC blockers, because they can defend. Also interceptors dont suffer the FM drone penalty (the only factor which really justifies the increased cost).
Back on thread
I have seen the AI build fungicide military units quite often, and dee once started mass producing clean chaos rovers after probing one from me.