TOKYO (Reuters) - Nippon Life Insurance Co, Japan's biggest private life insurer, is likely to have no choice but to increase currency-hedged foreign bond investment as domestic bond yields have plunged to negative levels, its chief investment officer said on Wednesday. Hiroshi Ozeki also told Reuters that the company expected a moderate recovery in the U.S. economy to continue and that the dollar was unlikely to fall below 110 yen. (Reporting by Tomo Uetake; Editing by Jacqueline Wong)