By Oriana Boselli BORGO VIRGILIO, Italy (Reuters) – Heatwaves sweeping Europe this summer have brought not just record high temperatures and scorched fields: the drought-stricken waters of Italy’s River Po are running so low they revealed a previously submerged World War Two bomb. Military experts defused and carried out a controlled explosion on Sunday of the 450-kg (1,000-pound) bomb, which was discovered on July 25 near the northern village of Borgo Virgilio, close to the city of Mantua. “The bomb was found by fishermen on the bank of the River Po due to a decrease in water levels caused by…