With this gorgeous Tampa weather, the last thing anyone at SICB 2019 wants to think about is snow and ice. Everyone except for Megan Kobiela, a PhD candidate from University of Minnesota, who studies the effects of deicing salt on monarch butterflies. By using salt to keep roads safe in the winter, humans have dramatically increased the level of sodium in roadside environments. Sodium is essential for function of neural and muscle tissue and small increases can cause animals to allocate more to these tissues, but in high doses sodium is toxic.
Butterfly host plants are often found roadside, and because caterpillars are unable to move out of these high-sodium environments, their development could be susceptible to the effects of road salt. Kobiela wondered how elevated sodium would affect the life history of monarchs, as well as how sodium-stressed individuals would respond to additional stressors. By treating milkweed plants with a salt solution that mimicked levels found in Minnesota roadside soils, Kobiela showed that butterflies reared on high-sodium plants had lower survival and males grew to a smaller body size. These patterns varied between maternal families, and no single family showed consistent positive or negative responses across traits to the sodium treatment. To determine how sodium stress interacted with other stressors, Kobiela examined the butterflies’ cold tolerance by exposing them to a brief period of extreme cold and found that males reared on high-salt plants showed a faster recovery time after the cold event.
Urban animals deal with multiple stressors in addition to an altered thermal environment. Kobiela’s work highlights this, and shows that to determine the effects of urban toxins they cannot be considered as isolated stressors.
- SICB 2019: Artificial Light at Night Has Various Effects on Wildlife - January 5, 2019
- SICB 2019: How Does Road Salt Affect Monarch Butterfly Life History? - January 5, 2019
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