# Detecting Symptoms and Dispersal of Pine Tortoise Scale Pest in an Urban Forest by Remote Sensing
###### Abstract  
Forests provide essential ecosystem services but face increasing threats from invasive species like _Toumeyella parvicornis_ (pine tortoise scale). Since its introduction to Italy in 2014, this pest has severely impacted _Pinus pinea_ forests, with a major outbreak in 2019 affecting an urban forest in the Rome municipality area. This study aims to develop a tool for detecting forest dieback symptoms caused by the scale and assess the role of prevailing winds in its dispersal by integrating multispectral and hyperspectral earth observation systems, including Sentinel-2 and the Hyperspectral Precursor of the Application Mission (PRISMA). At a 6000-hectare protected area with diverse vegetation, a binary Random Forest classifier, trained on near-infrared and short-wave infrared reflectance data, identified symptomatic stands. A generalized linear mixed model compared uniform and wind-influenced probabilistic dispersal models, assessing the pest spread relative to the initial infestation hotspot. The results confirmed a sharp decline in near-infrared reflectance in 2019, indicating severe defoliation and a shift from evergreen to deciduous canopy phenology by 2021. The classifier achieved 82% accuracy, effectively detecting symptomatic pine forests (91% precision). The scale spread to 51% of the pine forest area by 2021, with no strong correlation to prevailing winds, suggesting other augmenting dispersal drivers, such as vehicles along congested routes, wind tunnels, pest-resistant forests, and the potential mitigating role of alternating coastal wind patterns that are effective in the study area. stone pine; reflectance; alien species; airborne dispersal; forest dieback +
Footnote †: journal: _Land_  
0000-0002-0001-9300-3300]G. A.  
climate events that can create favorable ecological niches [8; 9; 12]. Pine tortoise scale, _Toumeyella parvicornis_ (Cockerell) (Hemiptera: Coccidae, hereafter \"PTS\"), is a recent example of an invasive species in the Mediterranean area and is seriously endangering the urban forests and public green areas of several cities. PTS is native to North America, where it is widespread from the Southern USA (i.e., Florida and Georgia) to Canada, and lives and reproduces on _Pinus_ spp. [18]. The first PTS record in Italy dates from 2014 when it was identified in Campania [19]. It then moved gradually northward and southward, becoming established in forests and urban areas [20]. More recently, it was found in France [20] and Albania [21]. In Italy, the infestations of PTS were recorded mainly on _Pinus pine_ L. (stone pine) trees located in urban areas. The disease symptoms were at times severe, including a reduction in shoot development, desiccation and yellowing of the needles, lack of vegetative renewal, and release of a considerable amount of honeybee that, in turn, favors the development of sooty molds [22]. This damage phenology is similar to that caused by other scale species affecting pine trees in Italy, mainly _Matsucoccus fytuudi_ (Ducasse), which is responsible for infestations on _Pinus pinaster_ (maritime pine), and _Crisococcus pini_ (Kuwana) that has, so far, been recorded only in the northern part of the country [23; 24]. The impact of such infestations in the invaded areas is of particular importance due to the widespread presence of stone pine. Indeed, this host tree is an important species in the Italian landscape and is included in several Natura 2000 Network areas and in the European Red List of Habitats for its significant naturalistic, historical, and social interest [13]. Stone pine plantations are described as \"Mediterranean coniferous coastal dune woodland\" and cover a considerable part of coastal areas in the Mediterranean basin [25]. Urban forests that feature stone pine as the dominant species are present in major Italian cities along the Tyrrhenian coast, where they provide ecosystem services or socio-ecological services for citizens [26]. Since the 19 th century, extensive reforestation programs have predominantly resorted to _Pinus_ ssp.