Baculovirus resistance in codling moth is virus isolate-dependent and the consequence of a mutation in viral gene pe38

Registered in 34 countries worldwide, Cydia pomonella granulovirus (CpGV) is a highly important biological agent to control the codling moth in pome fruit production. Since 2005, 38 codling moth field populations resistant to CpGV products containing the Mexican isolate (CpGV-M) were discovered in Europe, and this was the first demonstrated field resistance against commercial baculovirus products. By identifying and sequencing different resistance-breaking CpGV isolates, it was found that resistance of codling moth is directed toward CpGV-M only. As shown by mutation experiments, CpGV-M is prone to resistance because of a 24-nucleotide repeat within the viral gene pe38. Thus, pe38 can be used as a genetic marker to identify resistance-breaking CpGV isolates for resistance management programs.