Question

Some fungal species live in plants and can kill herbivores that feed on the plant. what type of relationship does this fungus have with its host?

Answer 1

I believe it is a mutualistic relationship. Mutualism is an association or relationship between two organisms of different species in which each organisms benefits. For example in this case the plants provides a shelter for the fungal species while the fungal species kills the herbivores who feed  and destroy the plant.