Islamic extremists killed eight farmers and abducted 10 in an attack in northeastern Nigeria, officials said on Friday — the latest in a volatile region that is a key part of the country's breadbasket and where militants have threatened food supplies. The farmers were ambushed in the bush in the Borno state's Mafa district on Thursday. The attackers slit their throats, authorities said. Babagana Zulum, the state governor, said the attack was an attempt to “sabotage the successes of the government” as it struggles to have those displaced in Borno return to their villages and rebuild their lives.