Data from: Museum specimen data reveal emergence of a plant disease may be linked to increases in the insect vector population

The emergence rate of new plant diseases is increasing due to novel introductions, climate change, and changes in vector populations, posing risks to agricultural sustainability. Assessing and managing future disease risks depends on understanding the causes of contemporary and historical emergence events. Since the mid-1990s, potato growers in the western United States, Mexico, and Central America have experienced severe yield loss from Zebra Chip disease and have responded by increasing insecticide use to suppress populations of the insect vector, the potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae). Despite the severe nature of Zebra Chip outbreaks, the causes of emergence remain unknown. We tested the hypotheses that 1) B. cockerelli occupancy has increased over the last century in California and 2) such increases are related to climate change, specifically warmer winters. We compiled a dataset of 87,000 museum specimen occurrence records across the order Hemiptera collected between 1900 and 2014. We then analyzed changes in B. cockerelli distribution using a hierarchical occupancy model using changes in background species lists to correct for collecting effort. We found evidence that B. cockerelli occupancy has increased over the last century. However, these changes appear to be unrelated to climate changes, at least at the scale of our analysis. To the extent that species occupancy is related to abundance, our analysis provides the first quantitative support for the hypothesis that B. cockerelli population abundance has increased, but further work is needed to link B. cockerelli population dynamics to Zebra Chip epidemics. Finally, we demonstrate how this historical macro-ecological approach provides a general framework for comparative risk assessment of future pest and insect vector outbreaks.

受外来物种引入、气候变化以及媒介种群变化等因素影响，新型植物病害的出现率正持续攀升，对农业可持续性构成威胁。对未来病害风险开展评估与管理，有赖于厘清当代与历史病害暴发的成因。自20世纪90年代中期以来，美国西部、墨西哥及中美洲的马铃薯种植户饱受斑马纹病（Zebra Chip）侵害，出现严重减产；农户因此加大杀虫剂施用量，以压制其媒介昆虫——马铃薯木虱（*Bactericera cockerelli*，半翅目：个木虱科）的种群规模。尽管斑马纹病暴发危害严重，但其暴发成因至今不明。本研究验证了两项假说：其一，过去一个世纪以来，加利福尼亚州内马铃薯木虱的分布占比有所上升；其二，这类分布占比的上升与气候变化——尤其是冬季气温升高——存在关联。研究团队收集了1900年至2014年间采集的、隶属于半翅目（Hemiptera）的87000份博物馆标本分布记录，以此构建数据集。随后，本研究采用分层占据模型（hierarchical occupancy model）分析马铃薯木虱的分布变化，并通过背景物种名录的变化校正采集努力度偏差。研究结果显示，过去一个世纪以来马铃薯木虱的分布占比确实有所上升，但至少在本研究的分析尺度下，这类分布变化似乎与气候变化并无关联。鉴于物种分布占比与种群丰度存在相关性，本研究的分析结果首次为“马铃薯木虱种群丰度有所上升”这一假说提供了定量支撑，但仍需开展后续研究，以明确马铃薯木虱的种群动态与斑马纹病流行之间的关联。最后，本研究展示了该历史宏观生态学研究方法如何为未来害虫及媒介昆虫暴发的比较风险评估提供通用研究框架。