Müller-Theissen Maria L, Gottdenker Nicole L, Altizer Sonia M
Odum School of Ecology University of Georgia Athens GA USA.
Center for the Ecology of Infectious Diseases University of Georgia Athens GA USA.
Ecol Evol. 2025 Mar 4;15(3):e70979. doi: 10.1002/ece3.70979. eCollection 2025 Mar.
Understanding host specificity and cross-species transmission of parasites is crucial for predicting the risk and consequences of parasite spillover. We experimentally examined these dynamics in two closely related, sympatric, milkweed butterfly hosts: monarchs () and queens (). The debilitating protozoan () infects wild monarchs throughout their range, and similar neogregarine parasites have been reported from queens. We compared host resistance and tolerance to infection between hosts exposed to parasites of conspecific and heterospecific origin and examined whether differences in immune investment reflected variation in infection outcomes. Results showed that monarchs were highly susceptible to both conspecific and heterospecific parasites. In contrast, queens were susceptible almost exclusively to conspecific parasites. Queens showed greater tolerance to infection and greater immune defense in the form of melanization activity and concentration of encapsulating hemocytes. Additionally, monarch parasites caused higher pre-adult mortality and more wing deformities than queen parasites. Given that can reduce monarch abundance and migratory performance, quantifying cross-infection outcomes is important for conservation management of these two butterfly species. The greater susceptibility and costs of infection in monarchs suggest potential fitness trade-offs against resistance and tolerance to infection in migratory hosts and underscore the need to identify factors that limit hosts' adaptation to parasites.
了解寄生虫的宿主特异性和跨物种传播对于预测寄生虫溢出的风险和后果至关重要。我们通过实验研究了两种密切相关、同域分布的马利筋蝴蝶宿主中的这些动态：黑脉金斑蝶（Danaus plexippus）和君主斑蝶（Danaus gilippus）。这种使人衰弱的原生动物奥氏新簇虫（Ophryocystis elektroscirrha）在其整个分布范围内感染野生黑脉金斑蝶，并且从君主斑蝶中也报道了类似的新簇虫寄生虫。我们比较了暴露于同种和异种寄生虫的宿主之间的宿主抗性和对感染的耐受性，并研究了免疫投入的差异是否反映了感染结果的变化。结果表明，黑脉金斑蝶对同种和异种寄生虫都高度敏感。相比之下，君主斑蝶几乎只对同种寄生虫敏感。君主斑蝶对感染表现出更大的耐受性，并以黑化活性和包囊血细胞浓度的形式表现出更强的免疫防御。此外，黑脉金斑蝶的寄生虫比君主斑蝶的寄生虫导致更高的成虫前死亡率和更多的翅膀畸形。鉴于奥氏新簇虫会降低黑脉金斑蝶的数量和迁徙能力，量化交叉感染结果对于这两种蝴蝶物种的保护管理很重要。黑脉金斑蝶对感染的更高易感性和成本表明，在迁徙宿主中，感染抗性和耐受性之间可能存在潜在的适应性权衡，并强调需要确定限制宿主对寄生虫适应的因素。
