Field-based thermal requirements study to improve Tuta absoluta (Lepidoptera: Gelechiidae) management

For effective integrated pest management (IPM) programs, it is essential to determine the thermal requirements and apply an accurate forecasting method based on daily degree units of pests. The present study investigated the physiological time (Degree-Days) and the number of generations of tomato leaf miner (TLM), Tuta absoluta (Meyrick) in Varamin region (Tehran, Iran) on two tomato cultivars (Cal JN3 and Early Urbana Y) under field-cage and open-field conditions during tomato growing seasons in 2015 and 2016. The environmental temperature was recorded hourly using an electronic data logger. The results indicated that TLM completed three generations during tomato growing seasons on the two tomato cultivars in both years. Degree-days for each generation and the thermal requirements of immature stages were a little different under field-cage and open-field conditions in 2015 and 2016. Furthermore, the pest completed each generation, one to three days earlier in the open-field conditions depending on tomato cultivars. On the whole, findings of this study can improve monitoring and forecasting phenological events of T. absoluta and thereby assist in timely adoption of management practices in IPM programs.