In Japan and other asian countries with wet seasons, fungus and other mold growths are a serious problem for camera collectors and users. How do you keep the little critters from growing on your prized possessions? Fungus requires two things to grow: moisture and dark. Take either of these away and you'll be spared the shock of finding your prize Summilux with white spiderwebs or spots growing on the lens surfaces.
Use it or lose it: Simply using your camera frequently is a good way to prevent mold from growing. Sunlight and UV light both kill fungi. Take your camera out often and the sunlight will naturally kill off anything in it. Nothing hurts a camera more than storage. Even if you can't use it, take the lens off the camera and put both in the sun for a few hours. It's important to take the lens off because the sun coming through the lens can burn a hole in your camera's shutter. Remember to take all your lenses, auxiliary viewfinders, and filters out for this treatment. Fungus is contagious.