Effects of variant springs on a wetland community

Climate change is increasingly altering the environment by shifting weather patterns, raising temperatures, and causing more frequent extreme weather events. These changes can alter species’ phenology leading to phenological mismatches. Asynchrony between producers and consumers can disrupt ecological relationships affecting ecosystem function. This study explores how extreme temperature fluctuations in the spring affect the relationship between Baltimore Checkerspot Butterflies (Euphydryas phaeton phaeton) and their main host plant White Turtlehead (Chelone glabra). We used growth chambers to expose plants (54 plants, 160 seeds) and herbivores (25 maternal lines, 2764 caterpillars) to four realistic thermal regimes: control, extreme oscillation, late frost, and extreme oscillation with a late frost. We measured survival and phenology of both species. To assess whether herbivory pressure depends on the thermal environment, we also measured caterpillar foliage consumption, Caterpillars experiencing more extreme oscillation fed 2.89 times more and began feeding 3.3 days earlier than control larvae. Plants experiencing extreme oscillation emerged from the ground and leafed out earlier, although the timing of later phenophases, when caterpillars feed more, did not significantly differ among treatments. The frost killed back most plants, but did not affect the caterpillars' feeding or survival. Consequently, larvae in the oscillation treatment required earlier and more leaves, but the effects on their host plant were not as clear. Lastly, while a frost did not harm the caterpillars, it destroyed their food source, increasing the risk of starvation. Our results highlight the importance of considering biotic interactions when assessing the effects of thermal stress.