Jason Corso, a 38 year old insurance company manager, was arraigned yesterday on charges of arranging a sex tryst online with an undercover FBI agent posing as an underage Queens girl.  Corso, of Danbury, Connecticut, was arrested Thursday at Queens Center Mall as he waited to rendezvous with a girl he thought was 15 year old and named Laurie.  Corso, who is manager of the Mutual of Omaha branch in Parsippany, was released on $250,000 bond after his arraignment.  He told investigators he previously chatted on the Internet with a 16 year old Long Island girl whom he later met at her high school.  He has been charged with traveling across state lines for the purpose of engaging in sexual acts with a minor.