To be 100% sure I'd place it in the oven (set at 140 degC for a few hours), important the temperature of the entire piece reach the oven temperature and stay there for couple of hours.
But if too big to fit in the oven - F10sc made up 1:125 , immerse in this solution and let soak in for about day , may been to put a brick or two on top to ensure it stays completely submerged , then air dry ( this will drown any tiny unwanted insects and will kill virtually all moulds , spores , bacteria and viruses ).
There after a blast with garden hose to knock any sticky poo or urates off , and then a spray with F10sc made up 1:250 and airdried for about 30mins will do a great job at keeping it clean.