Differences in the susceptibility of codling moth populations to Cydia pomonella granulovirus in the Czech Republic

Abstract

The Cydia pomonella granulovirus is a very important agent for the biological control of the codling moth, Cydia pomonella, in both organic and integrated apple and pear production. Three populations of Cydia pomonella originating from three separate areas of the Czech Republic were tested for their susceptibility to Cydia pomonella granulovirus in laboratory bioassays at several concentrations of Cydia pomonella granulovirus. A sensitive laboratory strain was chosen as a control. The larval mortality was checked 14 days after the infection. The mortality of Cydia pomonella larvae was similar in specimens originating from both the wild populations and the laboratory strain. Decreased susceptibility to Cydia pomonella granulovirus was demonstrated neither in samples from locality without Cydia pomonella granulovirus treatment nor from a locality experimentally treated with Cydia pomonella granulovirus for several years during the registration process. However, one population experimentally treated for more than 10 years was partially resistant to Cydia pomonella granulovirus. Based on our findings; the Cydia pomonella granulovirus biopesticides will be efficient due to the high susceptibility of field codling moth populations to Cydia pomonella granulovirus in the Czech Republic.