The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is an invasive pest difcult to control. Insecticide application is quite common and remains the prevalent control method particularly in open-feld cultivation systems. As a result, insecticide resistance to many chemical classes of insecticides has been described both in South America and in Europe. The development of insecticide resistance is relatively fast in this species, and the main mechanisms involved are altered target-site sensitivity and/or enhanced detoxifcation, depending on the chemical class. However, insecticide resistance mechanisms do not difer between South America and Europe and are mainly due to simple genotype variations leading to high levels of resistance. The presence of resistance alleles at low frequency, especially against newer chemistry, is of major concern, as they tend to spread with the invasions making tomato pinworm particularly difcult to control. The monitoring methods and management programmes developed for the species benefted from the pro-activity of the Insecticide Resistance Action Committee and its country groups, particularly in Brazil and Spain. Bioassay methods were developed, resistance monitoring activities initiated and resistance management guidance was provided. The implementation of integrated control programmes and appropriate resistance management strategies as part of such programs is of utmost importance to keep tomato pinworm infestations under economic damage thresholds, thus guaranteeing sustainable yields.