Mapping the distribution and density of the chestnut gall wasp (dryocosmus kuriphilus yasumatsu) in the Karacabey forest Enterprise directorate

This study was conducted to determine the spatial and temporal distribution of the chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu) in naturally occurring chestnut stands within the boundaries of the Karacabey Forest Enterprise Directorate. Invasive pest species cause significant economic and ecological losses in forest ecosystems today, which makes it necessary to support monitoring and control efforts with modern technological tools. The research aimed to identify individual trees affected by the pest and to map the infested areas by employing unmanned aerial vehicles (UAVs) and multispectral imaging techniques. Within the scope of the study, DJI Mavic 3M and DJI Matrice 210 v2 UAV platforms equipped with a Micasense RedEdge MX multispectral camera were utilized. This combination of equipment was found to be highly suitable for generating high-resolution datasets and for calculating vegetation indices across multiple spectral bands. The research was carried out in different periods in 2020, 2021, 2023, and 2024, during which more than 30 flights were performed. Images acquired in each flight enabled the calculation of several vegetation indices, primarily the Normalized Difference Vegetation Index (NDVI). NDVI computations served as a principal reference for quantitatively assessing the vigor of vegetation. The imagery was processed in Agisoft Metashape software to produce orthophotos, dense point clouds, and digital elevation models, which were subsequently analyzed and mapped in the ArcMap environment. The findings revealed that in 2020 and 2021, pest damage was widespread across the study area. NDVI distribution maps for this period indicated large surfaces characterized by low index values, suggesting reduced photosynthetic activity and overall plant vigor. In subsequent monitoring flights conducted in 2023 and 2024, a partial increase in NDVI values was observed. The narrowing extent of low NDVI zones and the improvement in photosynthetic activity implied either a decline in pest population density or the onset of physiological recovery processes in the chestnut trees. The temporal aspect of this study demonstrates that the effects of the invasive pest can fluctuate over time and underscores the importance of conducting regular monitoring. Another significant result of the research is that multispectral imaging techniques proved capable of producing more detailed and rapid data compared to conventional field observations. The capacity of the multispectral camera to record synchronized data in five spectral bands, together with the use of a calibrated reflectance panel to minimize illumination-related errors, contributed to the high reliability of the outputs. Moreover, it is suggested that incorporating additional indices (such as NDRE and SAVI) alongside NDVI could further enhance diagnostic accuracy in future applications. In conclusion, this study has shown that UAV-based multispectral imaging methods offer an effective and practical solution for determining the distribution dynamics of the chestnut gall wasp. Integrating these methods into sustainable forestry practices holds promise for developing early warning systems and for monitoring the success of biological control programs. The findings of this research are expected to provide methodological contributions to future monitoring efforts conducted in similar ecosystems. Keywords: Unmanned aerial vehicle (UAV), Normalized difference vegetation index (NDVI), Dryocosmus kuriphilus, Multispectral camera.