Ace Ltd last night estimated losses of between $200 million to $250 million from the Japanese earthquake.The insurer also announced preliminary losses for the first quarter for the Ace Group of companies from natural catastrophes, including the New Zealand earthquake, the Australian floods and Cyclone Yasi, and the US winter storms, estimated at $210 million, including reinstatement premiums.Of the total, $115 million is attributable to the New Zealand earthquake, $80 million to the Australian events in aggregate, and $15 million to the US winter storms.