Maggi Federico, Bosco Domenico, Galetto Luciana, Palmano Sabrina, Marzachì Cristina
School of Civil Engineering, The University of Sydney, Sydney NSW, Australia.
Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle RicercheTurin, Italy; Dipartimento di Scienze Agrarie, Forestali e Alimentari, Entomologia, Università degli Studi di TorinoTurin, Italy.
Front Plant Sci. 2017 Jan 6;7:1987. doi: 10.3389/fpls.2016.01987. eCollection 2016.
Analyses of space-time statistical features of a flavescence dorée (FD) epidemic in plants are presented. FD spread was surveyed from 2011 to 2015 in a vineyard of 17,500 m surface area in the Piemonte region, Italy; count and position of symptomatic plants were used to test the hypothesis of epidemic Complete Spatial Randomness and isotropicity in the space-time static (year-by-year) point pattern measure. Space-time dynamic (year-to-year) point pattern analyses were applied to newly infected and recovered plants to highlight statistics of FD progression and regression over time. Results highlighted point patterns ranging from disperse (at small scales) to aggregated (at large scales) over the years, suggesting that the FD epidemic is characterized by multiscale properties that may depend on infection incidence, vector population, and flight behavior. Dynamic analyses showed moderate preferential progression and regression along rows. Nearly uniform distributions of direction and negative exponential distributions of distance of newly symptomatic and recovered plants relative to existing symptomatic plants highlighted features of vector mobility similar to Brownian motion. These evidences indicate that space-time epidemics modeling should include environmental setting (e.g., vineyard geometry and topography) to capture anisotropicity as well as statistical features of vector flight behavior, plant recovery and susceptibility, and plant mortality.
本文对植物黄化病（FD）疫情的时空统计特征进行了分析。2011年至2015年期间，在意大利皮埃蒙特地区一个面积为17500平方米的葡萄园对FD的传播情况进行了调查；利用有症状植株的数量和位置，在时空静态（逐年）点模式测量中检验疫情完全空间随机性和各向同性的假设。对新感染和恢复的植株进行时空动态（逐年）点模式分析，以突出FD随时间推移的进展和消退统计数据。结果表明，多年来点模式从小尺度的分散状态到大规模的聚集状态不等，这表明FD疫情具有多尺度特性，可能取决于感染发生率、传病媒介种群和飞行行为。动态分析显示，沿行方向有适度的优先进展和消退。新出现症状和恢复的植株相对于现有有症状植株的方向近乎均匀分布，距离呈负指数分布，突出了类似于布朗运动的传病媒介移动特征。这些证据表明，时空疫情建模应纳入环境因素（如葡萄园的几何形状和地形），以捕捉各向异性以及传病媒介飞行行为、植株恢复和易感性以及植株死亡率的统计特征。
