Desiccant...no... Mechanical dehumidifier...yes and it worked great for a while.
Essentially I have found that keeping the plastic bag or canister sealed is the best defense. I have used the huge ziplocks (big enough to fit a basketball or two) to store grain and had better luck.
Essentially, the air is going to have enough moisture to slowly stale the grain. The more moisture, the faster...so the desiccant will help, but the sealed plastic bag is the best.