From Greenhouse Pest to Open-Field Invader: Widespread Distribution and Phenological Expansion of Tuta absoluta...

Invasive species pose increasing threats, particularly in agriculture. Here we assess the open-field distribution, population density, and phenology of Tuta absoluta (Lepidoptera: Gelechiidae), an invasive pest rapidly expanding its range into open-field habitats in Hungary. Countrywide monitoring using sex pheromone traps was conducted at 23 sites in 2023, complemented with detailed seasonal monitoring at two locations. The results reveal a wide open-field distribution of the pest in Hungary, occurring at 21 of the 23 sampled sites. Population densities were significantly higher in highly urbanised areas, suggesting that warmer climatic conditions enhance colonisation and population growth. Continuous adult flight activity was recorded from May to December, indicating prolonged reproductive activity and overlapping generations. Based on the degree-day requirements (approx. 460 °C days per generation), five generations per year were expected and detected at two intensively sampled sites. These findings demonstrate a marked shift from the "greenhouse pest" status toward successful colonisation of open fields, supported by increased overwintering potential. The observed expansion and phenological changes indicate that the climatic conditions of temperate Hungary are increasingly suitable for the persistence of T. absoluta populations outdoors. This study underscores the growing agricultural risk posed by T. absoluta in temperate regions and highlights the importance of early detection and integrated pest management strategies for mitigating its impact.