Effectiveness of mating disruption and granulovirus against codling moths in Central Bulgaria
Abstract: Due to economical changes, problems of resistance and the parceling of agricultural area, mating disruption (MD) was studied on its own or in combination with granulosis virus (CpGV) against the codling moth (CM), Cydia pomonella L., in the region of Plovdiv (Bulgaria). The effectiveness of MD and CpGV was tested in small orchards with high pest density. Until the 5th of July 2005, the percentage of CM-damaged fruits was at an acceptable level of 5.1% in the 0.5ha apple orchard treated with Isomate C LR® dispensers. The number of trapped CM males was 11 times lower than in a conventionally treated orchard, which served as a reference. Except for Rhynchites spp. and Stephanitis pyri, fruit damage by other pests was around the economical threshold. In 2007, Isomate C plus® dispensers together with the CpGV as Madex® were applied in a 19 years old orchard of 1.3ha. Once again, fruit damage by CM was bellow the economical threshold until the beginning of July. Thereafter, five treatments with chlorpyrifos-ethyl and chlorpyrifos-methyl were made to avoid higher infestation levels. At pre-harvest, only 1.9% of apples had CM larvae, compared to 17.0% in the reference orchard that was treated 11 times with conventional insecticides. The combination of MD and CpGV showed the best results in an 8-year old apple orchard. In this orchard, only 1.5% of apples were infested with CM larvae at pre-harvest and we detected 1.5 diapausing CM larvae per tree. In the accompanying reference orchard, the density of hibernating CM larvae was 23-times higher. Overall, the development of alternative IPM strategies incorporating mating disruption and granulosis viruses seems to be promising.