About
Monarch butterflies sometimes visit dry or injured parts of certain plants to take up chemical compounds called pyrrolizidine alkaloids (PAs). They do this by regurgitating saliva onto the surface of the plant to dissolve the chemicals, creating a solution that they then suck up using their proboscides.
This behavior, known as PA pharmacophagy, likely plays an important role in the life history of Danaus plexippus. It's already well-known that many insects use PAs in their defenses, and males of most milkweed butterflies species synthesize PAs into pheromones used in courtship. But monarchs have a different mating strategy, and the reasons for their PA gathering remain elusive. To better understand the behavior and its implications, we need much more data.
That's why we started Monarch Rx, a community science project that invites naturalists, scientists, gardeners, and others in the U.S., Latin America, Australia, the Pacific and Atlantic Islands -- and wherever else monarchs occur -- to contribute observations. We'd like to know which plants monarchs are relying on for PAs and under what conditions. (PAs are only detectable when a confluence of circumstances align, including appropriate humidity levels, sufficient wilting or injury to the plant, and other factors.)
For more information, check out the articles and tips in our Resources tab. We hope to see you soon on our Monarch Rx project page on iNaturalist! (To see past observations, also check out our CitSci.org page.)
Michael Boppré, chemical ecologist and professor emeritus, Albert-Ludwigs-University of Freiburg, Germany
Nancy Lawson, nature writer and naturalist, Humane Gardener, Maryland, USA
This behavior, known as PA pharmacophagy, likely plays an important role in the life history of Danaus plexippus. It's already well-known that many insects use PAs in their defenses, and males of most milkweed butterflies species synthesize PAs into pheromones used in courtship. But monarchs have a different mating strategy, and the reasons for their PA gathering remain elusive. To better understand the behavior and its implications, we need much more data.
That's why we started Monarch Rx, a community science project that invites naturalists, scientists, gardeners, and others in the U.S., Latin America, Australia, the Pacific and Atlantic Islands -- and wherever else monarchs occur -- to contribute observations. We'd like to know which plants monarchs are relying on for PAs and under what conditions. (PAs are only detectable when a confluence of circumstances align, including appropriate humidity levels, sufficient wilting or injury to the plant, and other factors.)
For more information, check out the articles and tips in our Resources tab. We hope to see you soon on our Monarch Rx project page on iNaturalist! (To see past observations, also check out our CitSci.org page.)
Michael Boppré, chemical ecologist and professor emeritus, Albert-Ludwigs-University of Freiburg, Germany
Nancy Lawson, nature writer and naturalist, Humane Gardener, Maryland, USA