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Dryad

Data from: Extreme heat reduces host and parasite performance in a butterfly-parasite interaction

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Dec 27, 2023 version files 138.94 KB

Abstract

Environmental temperature fundamentally shapes insect physiology, fitness, and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol, and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant temperature treatments spanning 18-34°C, we measured monarch development, survival, size, immune function, and parasite infection status and intensity. Monarch size and survival declined sharply at 34°C, as did infection probability, suggesting that hot temperatures decrease both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster larval development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, our experiment suggests that temperature increases above the upper thermal range will reduce the fitness of both monarchs and their parasites, with lower infection rates potentially mitigating the impact of extreme heat on future monarch abundance and distribution.