Maul is a pretty decent counter against bugs if you have him built up, he's great for a sith b/c-team if you have alot of sith like I do.
Traya against bugs however, it's best to use Traya and Sion plus some random sith like Sidious or whatever, I find. Nihilus is best saved for a Palp or even Maul squad in such a situation. Of course using a 7* Traya as a dedicated bug counter is a complete waste, a full Triumvirate team still packs a serious punch.
As for zetas, you'd want them all, Nihilus too, but I'd rate Traya's lead as 1st with Sion and Traya tied for second. Do Nihilus last.