Leading a band with an egotistical musician!!?

How do you lead a band with a guy who has an ego? Plays lead trumpet in a volunteer community band. Is mediocre..has good range but doesn't always read well nor play with any feeling and somewhat out of tune most times. Tells everyone in the section how to "play better" and they seem to resent or don't come back. We only have 3 other players in the section and they sit away from him. Doesn't matter if you talk to him, he gives examples of other reasons why he wants to help the section. It undermines the leader and his grumpiness seems to permeate through the group. WHAT TO DO????