Trying to remember a scifi book name about man (soldier?) who lands on remote planet and fights the hostile alien flora and fauna, until he is overpowered, then he awakes when a bug-like alien inserted his feelers into his ear. He tries to pull them out and fails as it causes an intense pain. The man is sure that the alien going to eat his brain(?) and he is done for, while he suddenly hears a voice and the alien says it cleared some kind of a block (cork?) that the man had and now he can communicate with them telepathically (apparently the said block is present at all the humans preventing them from communicating telepathically).
After learning more about the aliens and discovering they are actually sentient and friendly, and are under the human attacks, the man eventually joins their fight against the invading human forces. The aliens are masters in biology manipulations, and they adapt his body to survive on the hostile planet without his exoskeleton, and they also add some improvements, for example metal claws, which help in fight with the invaders.
The bug alien becomes man's best friend, working with him through the whole story. Later in story, a woman joins him, who also has her telepathic block cleared and her body adapted to the planet, and fighting modifications added (as much as having argon-based lasers shoot from her hands?), and the man gets romantically involved with her.
In the end of the story, the aliens with the man's and woman's help are able to repel the human invaders, and start studying the human space ships, planing to build their own biological forms of these ships and reach the stars.
I've read the book about 20-25 years ago and these the key points that I remember, will appreciate any pointers!