Estimation of the low temperature threshold and thermal requirement of the established codling moth populations in West Azerbaijan, Tehran and Isfahan provinces

The codling moth, Cydia pomonella (Linnaeus), is the most important pest in apple orchards. In order to successfully control of the pest, using phenological forecasting models is necessary. Phenological forecasting models are basically provided using temperature-dependent phenology of the pests. Estimation of the most important eco-physiological indices of pests is essential for the preparation and use of a high-performance, accurate forecasting model. Therefore, current study was conducted to determine temperature-dependent development trend and to estimate the most important thermal indices of three established populations of the codling moth in Tehran, West Azerbaijan, and Esfahan provinces. Results showed differences among the values of the estimated thermal index in studied populations. Estimated values of the low temperature threshold were 8.32, 8.19, and 9.85°C for total immature stages of Tehran, West Azerbaijan, and Esfahan provinces, respectively. Additionally, estimated values of the thermal requirement were 622.74, 633.20, and 695.84 Degree-Days for the total immature stages of the mentioned populations, respectively. The results of this study showed differences in thermal adaptations of different populations of codling moth located in different regions of Iran. This information is necessary to develop a precise forecasting model based on the heat requirement (GDD or GDH) of key pests in each geographical locations.