Nice, the contrast works well.
That's the great thing about B&W, you only need to worry about the contrast and I can paint that in almost anywhere I like. The more detail or texture, the more you can play with it. Too bad this shot was less than perfect; I did an attempt to obscure the fact the lens should have been closed down some more. Sadly I lacked the light to do that.
When doing macro, the shooting is fun but the processing is a bit of a chore. In B&W it's almost the opposite; the shots themselves are less exciting but the processing is a real joy. You can turn what looked in color like a dull shot into a rather powerful B&W simply because it contains the right elements to do so.