New research shows that higher temperatures may increase the harm caused by the parasite Ophryocystis elektroscirrha. The study reports infections have more than tripled since 2002 and found that monarchs exposed to elevated temperatures were 22% less tolerant of infection. The parasite can reduce wingspan, lower weight and shorten adult lifespan, and it can affect migration.
Researchers raised both parasite-exposed and uninfected monarchs on nonnative tropical milkweed or native swamp milkweed under ambient or elevated, fluctuating temperatures in the field. They expected fewer infections in hotter treatments and more protection from the toxic tropical milkweed, but those expectations did not hold.
Warmer temperatures eliminated the protective effect of tropical milkweed. The team also found that plant toxins were slightly higher in warmth, and strong toxins can slow development or be excreted, which may remove protection.
Difficult words
- parasite — a small organism that lives on hosts
- infection — when a disease organism enters a hostinfections
- tolerant — able to endure harm or difficult conditions
- migration — seasonal long-distance movement of animals
- toxin — a harmful chemical produced by plants or animalstoxins
- elevated — higher than normal in level or amount
- eliminate — to remove or get rid of somethingeliminated
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could lower tolerance to infection affect monarch migration?
- Would you plant native swamp milkweed or nonnative tropical milkweed for monarchs? Explain your choice.
- The article says strong toxins can slow development or be excreted. Why might this remove protection for monarchs?
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