Biological control of the codling moth based on the DegreeHours forecasting model in Damavand regionύ

The codling moth, Cydia pomonella (Linnaeus), is the most important pest insect in apple, walnut, pear, and queince orchards. In order to control of the codling moth, entomologists have evaluated different management methods from few years ago, e.g. biological control by using egg parasitoid wasps, belonging to the family of Trichogrammatidae. Efficacy of a native strain of the trichogrammatid wasp, as biological control treatment, was statistically compared with chemical control and check treatments in an economically important apple orchard located in Damavand region. The best times for releasing the parasitoid wasps were determined by using a forecasting model based on estimation of Growing Degree Hours (GDH). Three species of the trichogrammatid wasps were collected and identified from the studied area as native strains of the egg parasitoid; Trichogramma brassicae, T. pintoi, and T. embryophagum. Acording to the laboratory experiments, regarding fecundity, longevity, and parasitism rates on the codling moth eggs, T. embryophagum was selected as the best species among evaluated wasp species, for biological control of the codling moth in apple orchard. Moreover, codling moth biofix was determined by using pheromone traps, and environmental temperature in the apple orchard was recorded hourly for estmation 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 in five estimated physiological times, 3167, 4480, 6451, 19344, and 21580 GDH for two generations of the codling moth. The results of efficacy test, showed that there was no statistically difference between chemical and biological control treatments by using tukey range test (P 0.05), considering the percentage of damage. While, the percentage of the codling moth 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 47.46 and 50.73 lower than the value was estimated for check treatment, respectivel. 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.