Are they new to your collection or have you had them a while? Husbandry plays a large part in a BP's feeling secure. If they dont feel secure they stress and will generally refuse food. Proper humidity, temps, enough hides, proper sized hides, or an alteration in their environment can cause them to refuse as well. Some will just go on hunger strikes at certain times of the season and you just have to be patient. Being you asked about temperatures i asked how it was being measured, and i should have asked digital or analog thermometer. If temperatures vary a lot it could be an issue. If hes not useing his Hotspot, and he does in fact have 1 hide on each side of his tank (preferably identicle) he may not feel he needs the extra warmth and prefer to stay at a coller temp for now. If he doesnt have a hide on both sides, its say only on the cool side, he may sacrifice the heat for security in his hide, which isnt good.