Parasite dynamics in North American monarchs predicted by host density and seasonal migratory culling
Parasite dynamics in North American monarchs predicted by host density and seasonal migratory culling
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通过寄主密度和季节性迁徙扑杀预测北美帝王蝶的寄生虫动态
DOI：
10.1111/1365-2656.13678
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发表时间：
2022
影响因子：
4.8
通讯作者：
de Roode, Jacobus C.
中科院分区：
文献类型：
--
作者：
Majewska, Ania A.;Davis, Andrew K.;Altizer, Sonia;de Roode, Jacobus C.
昆虫病原体的动态可以显示出随昆虫丰度和气候的波动而变化的季节性和年际变化。尤其需要长期的分析来追踪迁徙昆虫中的寄生虫动态，部分原因是它们广阔的栖息地范围和高流动性可能会削弱当地密度和气候对感染流行率的影响。由于这种寄生虫降低了帝王蜂的存活率和飞行性能，而且近几十年来迁徙帝王蜂的数量有所下降，了解感染的模式和驱动因素非常重要。这里我们收集了美国、加拿大和墨西哥夏季繁殖、秋季迁徙和越冬期间采集的野生帝王蜂50年来的感染数据。我们分别研究了北美东部和西部的帝王，询问丰度估计、资源可获得性、气候和繁殖季节长度如何影响感染趋势。我们进一步评估了迁徙扑杀的强度，即在迁徙过程中将受感染的个体从种群中移除时发生的。西部的平均感染率是东部亚群的四倍。在北美东部，自本世纪头十年中期以来，感染君主的比例增加了三倍。在西部地区，从2000年到2015年，感染君主的比例急剧下降，此后又有所上升。对于东部和西部亚群，夏季成虫丰度较高的年份预示着感染流行率更高，这表明传播随着宿主繁殖密度的增加而增加。环境变量(温度和NDVI)与感染成人比例的变化无关。我们发现了迁徙捕杀受感染蝴蝶的证据，这是基于秋季迁徙期间寄生率的下降。我们估计，由于Ofoe，到达墨西哥越冬地点的君主减少了数千万只，这突显了将这种寄生虫视为对君主种群的潜在威胁的必要性。2002年后，北美东部君主感染人数的增加表明，宿主生态或环境的变化加剧了寄生虫的传播。还需要进一步的工作来检验人类的做法，如大规模饲养毛虫和广泛种植外来乳草，在多大程度上促进了这一趋势。
Insect–pathogen dynamics can show seasonal and inter‐annual variations that covary with fluctuations in insect abundance and climate. Long‐term analyses are especially needed to track parasite dynamics in migratory insects, in part because their vast habitat ranges and high mobility might dampen local effects of density and climate on infection prevalence.Monarch butterfliesDanaus plexippusare commonly infected with the protozoanOphryocystis elektroscirrha(OE). Because this parasite lowers monarch survival and flight performance, and because migratory monarchs have experienced declines in recent decades, it is important to understand the patterns and drivers of infection.Here we compiled data onOEinfection spanning 50 years, from wild monarchs sampled in the United States, Canada and Mexico during summer breeding, fall migrating and overwintering periods. We examined eastern versus western North American monarchs separately, to ask how abundance estimates, resource availability, climate and breeding season length impact infection trends. We further assessed the intensity of migratory culling, which occurs when infected individuals are removed from the population during migration.Average infection prevalence was four times higher in western compared to eastern subpopulations. In eastern North America, the proportion of infected monarchs increased threefold since the mid‐2000s. In the western region, the proportion of infected monarchs declined sharply from 2000 to 2015, and increased thereafter. For both eastern and western subpopulations, years with greater summer adult abundance predicted greater infection prevalence, indicating that transmission increases with host breeding density. Environmental variables (temperature and NDVI) were not associated with changes in the proportion of infected adults. We found evidence for migratory culling of infected butterflies, based on declines in parasitism during fall migration. We estimated that tens of millions fewer monarchs reach overwintering sites in Mexico as a result ofOE, highlighting the need to consider the parasite as a potential threat to the monarch population.Increases in infection among eastern North American monarchs post‐2002 suggest that changes to the host’s ecology or environment have intensified parasite transmission. Further work is needed to examine the degree to which human practices, such as mass caterpillar rearing and the widespread planting of exotic milkweed, have contributed to this trend.