Wonderful, amazing, mice eat butterflies too

The monarch butterfly may be the most beautiful butterfly in the world, but it is not a delicious food
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During the caterpillar period, the plants they eat are full of toxic cardiac glycosides that build up in their bodies, making them disliked by most predators

In a new study, biologists at the University of Utah found that rodents prey on monarch butterflies in Pismo Beach, California, where they overwinter
.
They found that the big-eared rat ( Reithrodontomys megalotis ) attacked monarch butterflies that fell to the ground

The authors do not believe rodents are responsible for the decline in monarch butterfly numbers, nor do they believe that monarch butterflies are the only things mice eat
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Instead, documenting this new feeding behavior is a reminder that we know very little about the interactions that may disappear as insect populations dwindle

Sara Weinstein, a postdoctoral researcher who led the study, said: "We are now in the insect doomsday
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It is estimated that 40% of invertebrate species are endangered and more than 70% of insect biomass has disappeared

To study the interactions between mice and monarch butterflies, researchers first trapped mice in the woods in February 2020

However, the number of monarch butterflies has plummeted
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Pismo Beach has long been known for its monarch butterfly groves

Weinstein placed lab-raised monarch butterfly carcasses under camera traps and captured footage of wild mice eating butterflies
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She also caught six mice and provided them with monarch butterflies

"Many rodents may be somewhat resistant to cardiac glycosides in monarchs due to genetic changes in the binding sites of these toxins," Weinstein said
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"Pismo Beach, California is home to monarch butterflies, and rodents in this habitat may supplement their winter diets with monarch butterflies

However, this dinner may be hard to find afterward, as over 90% of monarch butterflies have disappeared over the past 40 years
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These disappearing beautiful butterflies are sure to affect the ecosystems that feed on them

"When the monarch butterfly population plummeted last year and the project started to go wrong, Sara cleverly saved it by breeding the monarchs herself and obtaining frozen monarchs from the researchers," said senior author of the study, Calif.
Professor Denise Dearing of the University said
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"Her creative proposals deepen our understanding of the interactions between mice and monarch butterflies
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These lay the groundwork for future research in this field
.
"

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Harvest mice (Reithrodontomys megalotis) consume monarch butterflies (Danaus plexippus)

https://doi.
org/10.
1002/ecy.
3607