Great music and great artwork ! The whole theme made me think of Nausicaa of the valley of the Wind (wild guessing that it was your main inspiration, as there's also this mecanic in the movie of dying if you breath the poisonous air for too long).
Maybe power ups could have been more varied (like Downwell for instance). Also it was quite frustrating to not be able to look back and shoot the insects on the ship, and I thought i'd lose if too much of them got on the ship, like a lifebar... In the end I ignored them and finished the game without too much trouble