Became known as the world's greatest entomologist

Jean Henri Fabre.

the french born naturalist and entomologists  is renowned as the world's greatest entomologist. Born to a poor family, the scholars was largely an autodidact. His seminal works include the inspiring Souvenirs Entomologiques is a series of texts on insects and arachnids, which inspired later scholars such as Charles Darwin.

high entry costs prevent new producers from entering the market.

explanation:

an oligopoly is a term used to clarify the structure of a particular market, industry, or organization. a market is considered oligopolistic or amazingly focused when it is shared between a few companies.