It's (intrinsically) fine to kill non-sentient life. It's akin to unplugging a computer.
How do you define sentience? How are you able to say for certain that a bacterium is non-sentient but an insect is sentient, even though you haven't lived the experience of either?
Shouldn't you avoid harming bacteria just to be on the safe side? If you can just assume bacteria are non-sentient, then what's to stop a beekeeper from assuming bees are non-sentient and doing whatever he pleases?
https://en.wikipedia.org/wiki/Sentience
Sentience comes from the brain and nervous system
How do you know that? Even the wikipedia article you linked describes positions opposed to sentience as a function of nervous system...
On the flip side, how do you know that everything that has a nervous system is sentient?
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