It looks like a heating element to stop the propellor blade icing up in flight. Turboprops have a hard time with ice as unlike jets they fly in the weather rather than above it. Typical turbo prop cruising altitudes are perfect for encountering icing conditions and once it accumulates the extra weight and drag are a significant penalty, not to mention the reduction in lift and handling qualities.

If you looked closely at the front of the wings they would also have an ice protection system, possibly using heated air drawn from the engines or an inflatable rubber strip to pop the ice off once it forms. There are various forms of protection.