Question: what makes different fungi poisonous?

Eleanor Spence answered on 13 Mar 2020:

Some mushrooms are poisonous to eat because they produce chemicals called toxins. Some toxins lead to diarrhoea or other illnesses, a few mushrooms are even deadly. They can cause liver damage or attack kidneys.

The insect killing fungi that I work with can produce toxins, but they also spread inside the insects body, taking nutrients from the insects body and filling its insides with hyphae (like fungus fingers).