Lufenuron is a flea medicine for animals, and has no known toxicity any humans, or animals that do not depend on chitin. According to Wikipedia, even though it has no known toxicity, it is taken orally and has been known to cause upset stomachs and acid reflux http://en.wikipedia.org/wiki/Lufenuron.
It is used as crop protection, but interestingly it is thought to have antifungal properties to plants. It is not broken down in our body by the liver or kidneys, so it will not be harmful to eat plants treated with Lufenuron.
The believed reason for the antifungal properties are that fungus has the presence of chitin in their cell walls, and if it is broken down by Lufenuron then it would also be broken down.
So with that said, Lufenuron is not known to be toxic to humans and can fight against fungus because it breaks down the chitin in their cell walls, it should be effective for treating Candida in humans.
I do believe if you want to use Lufenuron, you should consult a doctor before hand as it is made to treat animals, and there are things in this world that are shown to not be toxic that have severe negative side effects when consumed. Lufenuron was not made to be consumed by humans, and you should be careful with anything that is not for human consumption.