Determination of the Best Time to Control the Codling moth, Cydia pomonella L., 1758 (Lep: Tortricidae) , Based on the Estimation of Thermal Units (GDH)

Codling moth, Cydiapomonella L. is the key pest of apple orchards in Iran. In order to succeed in chemical control of this pest and reduce the number of spraying, application of modern and accurate methods is very important. Nowadays, the total environmental efficient temperature based on Degree-Days is the most accurate forecasting method to forecast the development of different phenological stages of the pests. In this regard, this study was conducted to prepare a predictive model of Codling moth phenology based on the estimation of total efficient environmental temperature in two locations of Kamyaran and Saqez. In order to determine the start of recording environmental temperature and the calculation of efficient temperature, the biofix was determined based on the hunting of pheromone traps. From this date to the harvesting time, fluctuation of environment temperature was recorded in the garden hourly and the efficient temperature from the environment was calculated based on the hourly temperature indices of the growth and development of Codling moth. In the following to the apple harvesting, the population fluctuations of the different biological stages of the Codling moth were recorded in both regions weekly. Based on the results, in both of the studied areas, there were three flying peaks indicating two complete and one partial or incomplete generation of Codling moth in Kurdistan province. Considering that the best time to perform chemical control of Codling moth is at the peak of the larvae population of the first instar and before entering them into fruits, the results of two years of research in both Kamyaran and Saghez showed that the peak population of the first-generation larvae of the winter-generations is 6634±430 GDH, and in the summer generation is 23700± 846 GDH.