One of the keys to insects’ successful survival in the open air lies in their outer covering — a hard waxy layer that helps prevent their tiny bodies from dehydrating. To take oxygen from the air, they use narrow breathing holes in the body-segments, which take in air passively and can be opened and closed as needed. Instead of blood contained in vessels, they have free-flowing hemolymph, which helps keep their bodies rigid, aids movement, and assists the transportation of nutrients and waste materials to the appropriate parts of the body. The nervous system is modular — in a sense, each of the body segments has its own individual and autonomous brain — and some other body systems show a similar modularization. These are just a few of the many ways in which insect bodies are structured and function completely differently from our own. Original text
I searched for the word in Cambridge Dictionary.
in a way that does not act to influence or change a situation; in a way that allows other people to be in control:
I want to know if this passively means automatically or manually. I think these two words can't be interchangeable in this context.
(In my opinion) If the meaning is toward automatically, it means the insect isn't conscious of breathing holes, which can open and close independent of insect.
(In my opinion) If the meaning is toward manually, It means the insect is conscious of a variable surrounding environment (e.g oxygen content), so it opens or closes the breathing hole for its survival depending on the surrounding.