He is an expert in parasitology and conducts many researches.

This parasite lives inside the human body.

He is a specialist in that field.

This festival is held every year.

He spends a lot of time studying.

He reads a lot of books.

Parasitism is a part of nature and a form of interaction between organisms.

The insect lives by parasitizing plants.

His specialty is physics.

He has a deep interest in entomology.