Here is the full list of all 13 Mighty Aphid trophies - there are 1 silver, 11 gold and 1 platinum.
Unlock all other trophies
Defeat the boss of level 6
Complete level 6
Defeat the boss of level 5
Complete level 5
Defeat the boss of level 4
Complete level 4
Defeat the boss of level 3
Complete level 3
Defeat the boss of level 2
Complete level 2
Defeat the boss of level 1
Complete level 1