# Near-Real-Time Detection of Insect Outbreaks in Urban Trees Using a PlanetScope Time Series
## 1 Introduction  
Vegetation cover, such as cropland, grassland, and forest, provides various benefits to ecosystems and humanity [1]. In particular, urban forests are important because they enhance the quality of life of urban residents by strengthening social connections and improving physical and mental health [2, 3, 4]. They also reduce air and water pollution and heating and cooling costs and increase real estate values while mitigating the impacts of climate change [5]. According to the Millennium Ecosystem Assessment, these benefits can be classified into three categories: regulation, provisioning, and cultural services [6]. Regulation services include air quality climate and water regulation, as well as pollination control. In contrast, provisioning services involve the supply of materials such as wood, fuelwood, and food products, whereas cultural services are relevant for recreation and ecotourism. The provision of ecosystem services makes the management and maintenance of forest areas important [7]. Italian cities--which are spread throughout different climatic, altitudinal, and latitudinal gradients--host a variety of tree species, including _Pinus pinea_ L., which is particularly common in the largest Mediterranean cities, such as Rome. Monitoring _P. pinea_ in Mediterranean urban environments is crucial due to its prevalence and representation. The current management of these trees in the urban environment must also consider frequent falls (due to inadequate maintenance, pests, pollution, or incorrect planting), which are dangerous for both people and structures [8]. Particularly challenging factors include (i) proximity to heavily developed areas; (ii) problems related to forest structure and management; and (iii) climate change, which causes droughts and rising average temperatures [9]. Root development is significantly impacted by the proximity to roads and pavement. The growth of tap roots is consistently impeded due to the complex pedological conditions of compact and asphyxiated soil [10]. Continuous work on the road surface can permanently damage the roots, leading to collapses. Biotic and abiotic factors cause plant stress, making trees and forests highly vulnerable to fire and pests [11]. Moreover, climate change, as an anthropogenic factor, intensifies extreme environmental conditions that are expected to increase and significantly impact existing forests [12]. The potential effects of changes may interact with the dynamics of pest development in ways that are difficult to predict [13]. Particularly representative is the situation in Rome, where, in addition to increasingly warm and stressful temperatures for trees, a high anthropogenic density persists. At present, _P. pinea_ forests are infested by the biotic agent _Toumeyella parvicornis_ (Cockerell) (Hemiptera: Cockidae) in Rome. This scale species originates from North America, and it has expanded to the Caribbean region and Europe [14]. It was first detected in Italy in 2014 and is under the official control of the EFSA Panel on Plant Health. This alien pest produces sticky honeydew related to feeding activity, which causes the development of sooty molds that cover branches and needles. Infested plants suffer yellowing, reduced growth, phyllotopsis, decline, and death [15]. In addition to the spread of this alien species across Europe due to globalized world trade, global warming is contributing to its proliferation [16]. At the end of 2014, the pine tortoise scale _T. parvicornis_ was recorded in Naples for the first time [17]. The insect rapidly spread (specifically in the regions of Abruzzo, Campania, Lazio and Apulia), infesting stone pine trees, a species that is representative in the Mediterranean landscape. In 2018, _T. parvicornis_ was also reported in Rome and led to the decay and death of many plants around Central and South Italy [18]. Monitoring insect infestations is a crucial element in safeguarding urban forests.