Infectivity of a Bulgarian and an American strain of Steinernema carpocapsae against codling moth

A strain of Steinernema carpocapsae obtained from overwintering codling mot hs collected in Bulgaria was identified to species using the polymerase cha in reaction. The infectivity of this strain towards codling moth prepupae w as compared to that of a U.S. strain at three temperatures (11, 15 and 20 d egrees C). Infectivity was low at 11 degrees C with 8% mortality recorded f or both strains. Mortality was 61% and 62% at 15 degrees C, and 82% and 81% at 20 degrees C for the Bulgarian and U.S. strain, respectively. The mean percent mortality at each individual temperature was significantly differen t from each other when mortalities of the two strains were combined. Thus, the Bulgarian strain did not provide a low temperature infectivity advantag e compared to the U.S. strain.