If you were trying to bond glass everyone would say 100% silicone. But since it sounds like you're trying to bind plastic, silicone is less effective, put perhaps not a bad option either since it's easily safe once it's cured. Maybe look for something like an aquarium acrylic adhesive or something that's aquarium safe. I can't vouch for any particular one.
Also, if you have ants already in it, it IS NOT SAFE to try to glue it while they are there. While the adhesive cures it will give off fumes that will probably be toxic and the adhesive won't be safe until about 24 hours after use in most cases.