The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive pest of solanaceous crop plants, especially tomato, threatening worldwide tomato production. It has been a quarantine pest for Iran since 2010. However, it is now dispersed to all the main tomato production sites across the country. To assess crop loss and determine economic injury level (EIL), a field study was conducted in a 600 m2 common research field for two consecutive years (2014-2015). Each tomato seedling (Super Strain B c.v.) was infested by different densities of the pest, including control, 1, 2, 4, and 8 tomato leafminer eggs in the first year and control, 2, 4, 8, and 16 leafminer eggs in the second year of study under cages. There was a significant relationship between the number of infested fruits and the number of leaf galleries made by tomato leafminer larvae. The EIL of tomato leafminer, according to the field experiments, was estimated to be 6.3 and 5.7 larvae/plant in 2014 and 2015, respectively. Evaluating the impact on crops and estimating the EIL are essential elements within a cost-efficient integrated pest management strategy, which provide practical tools for making informed decisions regarding the application of pesticides against T. absoluta.
