Ohlendorf, who was recalled to start Tuesday night's game against the Milwaukee Brewers, began the season in the rotation but left his April 8 outing against the Colorado Rockies with left shoulder discomfort and hasn't pitched in the majors since.
Ohlendorf went 1-1 with a 3.65 ERA in seven minor league starts. He is 0-0 with a 7.37 ERA in two starts with Pittsburgh.
Pearce, who fractured his right index finger, was hitting .202 in 94 at-bats over 50 games. Ciriaco is 3 for 11 in 10 games with the Pirates this season.
Beimel, a veteran reliever, went 1-1 with a 5.33 ERA in 35 games for Pittsburgh but has struggled this month. He gave up eight runs in 5 2/3 innings, including a two-run homer to Milwaukee's Ryan Braun on Monday night.