biological control of the codling moth by trichogramma embryophagum based on degree-hours forecasting model

the codling moth, cydia pomonella, is the most important pest insect in apple orchards. efficacy of a native strain of the egg parasitoid wasp, trichogramma embryophagum, was statistically compared with chemical control and check treatments in an apple orchard. the best times for releasing the parasitoid wasps were determined by using a forecasting model based on estimation of growing degree hours (gdh). codling moth biofix was determined by using pheromone traps, and environmental temperature in the apple orchard was recorded hourly for estimation of gdh. based on the recorded temperatures and by using phenological forecasting model, the best times for releasing egg parasitoid wasps were determined. the wasps were released five times for two generations of the codling moth. the results of the efficacy test, showed that there was no statistically difference between chemical and biological control treatments using tukey range test (p < 0.05), considering the percentage of damage. while, the percentage of damage was statistically more than the mentioned above treatments in check treatment. additionally, considering the results, it is confirmed that the percentage of fruit damage by the codling moth in biological and chemical treatments were 47.76 and 50.73 lower than the value was estimated for check treatment, respectively. finally, based on the findings of the present study, it can be said that acceptable biological control of the codling moth by using t. embryophagum is possible, considering all the technical advises from selection of a suitable biocontrol strain to its application and evaluation of the obtained results.