Yes! I would recommend wearing a spray on your bod that contains DEET! There are lots of the little buggers in the tropics. You don't want to be itching and scratching on your vacation. Note: The bugs love sweat, and sweat you will. You are going to love the cruise.
Never cruised through the canal, but actually stayed at a resort on the canal for a few days. THe bugs were not as bad as I had imagined they might be in the rainforest. (except for the humongous spider in our room!!!) ANyway, I am usually the forst one to get bit, and I fared much better than on camping trips up north!