I have not. I have had problems with mosquitos in the Caribbean (Grand Cayman is the only one I remember being bad) but that was on a 2 week vacation there and they came out at dusk - as they do here. Other than that, on all my 12 cruises I haven't received one bite, AND we tend to do "adventerous" types of excursions, so we've been into the rainforests & jungles, volcanos, mangroves at night kayaking, deserted beaches, etc. and the only thing I remember about bites on a cruise was sand fleas in Roatan, Honduras, and it wasn't from us. We were on a sailboat all day anchored off of the beach. When we returned to the ship, everyone on the beach had sand flea bites.
So, not much to worry about in the way of mosquitos. Yes, they do exist, but usually you are out to sea before they come out to play!
Mrsfuzzmo