No, Dustox isn't worth it. Not only weak, but has a very shallow movepool. The only benefit t'wards the PKM is it's poison typing. There are several other better poison types like Vielplume or Muk which have better stats and better movepools (Vileplume's is questionable).
In my opinion, you should get a Venomoth for a Bug/Poison set. It has better stats, slightly bigger moovepool, and can learn almost every move that Dustox learns. There you go.
Feel free to comment. V78.