Monarch Butterflies and OE (Ophryocystis elektroscirrha)

Oct 27, 2022

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Show notes:

Monarch butterflies have become an increasingly hot topic in recent decades, and especially in the last couple of years. Conversations about monarchs often revolve around topics like their migrations, the importance of milkweeds, or other flowers we can plant for monarchs. Rarely do the topics of monarch health or monarch diseases come up. Yet these can also be fascinating and important topics to learn about and discuss.

In this episode of the Backyard Ecology podcast, we are joined by Dr. Sonia Altizer and Kade Donaldson. Sonia is a Professor of Ecology at the University of Georgia and Kade is the Project Manager for Monarch Health which is a community science project based out of the University of Georgia.

Most of our conversation revolves around the tiny protozoan, Ophryocystis elektroscirrha, more commonly referred to by its initials: OE. OE is a parasite of monarch butterflies that has been interacting with monarchs for the past several centuries, at least, and likely for almost as long as there have been monarchs. However, over the last couple of decades, something has changed.

OE has gone from being relatively rare to infecting very high percentages of some monarch populations. Exactly what has changed is still a topic of ongoing research, but the increased prevalence of OE appears to correlate to changes in human activities. The goal, therefore, is to determine what has changed and find ways to keep OE from spreading any more than it would naturally spread.

One of the ways that OE infections are being studied is through Project Monarch Health. Project Monarch Health is a community science project that asks members of the public to help document OE infections throughout the country. Anyone can participate in this project which is based out of the University of Georgia, and we talk about Project Monarch Health quite a bit during our conversation.

Other topics that we discussed are some of the common questions they get through Project Monarch Health. Those questions include ways people can help monarch butterflies and inquiries about raising monarchs. We also talked about how monarchs are only one part of the larger ecosystem. Protecting and conserving monarchs can also help lots of other organisms, but we need to be careful not to get so focused on monarchs that we lose sight of the big picture.

Links:

Project Monarch Health:
- Email: monarchhealth@gmail.com
- Website: https://www.monarchparasites.org
- Facebook: https://www.facebook.com/ProjectMonarchHealth
- Instagram: https://www.instagram.com/projectmonarchhealth/?hl=en
Other monarch-related Backyard Ecology content:
- Monarch vs Viceroy – Easy Identification Sitting or Flying: https://www.youtube.com/watch?v=zL5RJokLhp4
- Everything You Need to Know about the IUCN Listing of the Monarch Butterfly: https://www.backyardecology.net/everything-you-need-to-know-about-the-iucn-listing-of-the-monarch-butterfly/
- Diversity Matters When Gardening for Monarchs: https://www.backyardecology.net/diversity-matters-when-gardening-for-monarchs/
- Plant Multiple Species of Native Milkweeds for Monarch Caterpillars: https://www.backyardecology.net/plant-multiple-species-of-native-milkweeds-for-monarch-caterpillars/
- What does the endangered species ruling for the monarch butterfly really mean?: https://www.backyardecology.net/what-does-the-endangered-species-ruling-for-the-monarch-butterfly-really-mean/
- Milkweeds in Urban and Suburban Monarch Waystations with Dr. Adam Baker: https://www.backyardecology.net/milkweeds-in-urban-and-suburban-monarch-waystations-with-dr-adam-baker/
- Plant Taller Milkweed Species for Monarchs: https://www.backyardecology.net/plant-taller-milkweed-species-for-monarchs/
Backyard Ecology:
- Website: https://backyardecology.net
- YouTube Channel: https://www.youtube.com/backyardecology
- Blog: https://www.backyardecology.net/blog/
- Patreon page: https://www.patreon.com/backyardecology
- Subscribe to Backyard Ecology emails: https://www.backyardecology.net/subscribe/

Episode image

Male monarch butterfly
Photo credit: Sonia Altizer, all rights reserved

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Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.

Comments

2 responses to “Monarch Butterflies and OE (Ophryocystis elektroscirrha)”

guidoLaMoto

August 24, 2023

Very interesting– never heard of OE before– but confusing: if OE is spread mainly vertically from parent to offspring and is increasing in the popualtion, then that implies infection must have some survival/fitness value– possibly a “thinning the herd” phenomenon?..It could be that carryng OE does not cause pathology in “naturally immune” individuals, or that only certain strains of the bug are pathgenic (cf- relatively rare invasive or toxin producing strains of the usually innocuous E.coli in human colonic flora)….

Is infection with OE increasing in the Monarch population or is there merely increased awareness by researchers +/- improved diagnostic techniques or criteria? (cf- increasing rates of asthma, colon ca or ADHD in humans– probably not really increasing but improved senstivity of diagnostic tech and relaxed diagnostic criteria have artfically increased the number of diagnoses).

Reply
1. Backyard Ecology
  
  August 25, 2023
  
  Hi,
  Good questions. The answers aren’t simple, and I’m not sure we fully have the answers in some cases.
  
  We know by looking at historic monarch specimens that OE appears to have “always been here,” or at least for as far back as we can tell. OE also only infects monarchs and closely related species which implies that it has had time to evolve with those species, but that doesn’t necessarily convey any evolutionary fitness to the butterflies.
  
  The way OE is spread is that an infected monarch lands on a milkweed. OE spores fall off the infected monarch, kind of like dandruff. If a monarch egg happens to be on that milkweed, then when the caterpillar emerges it runs the risk of accidentally ingesting an OE spore as it munches on the milkweed. (Kind of like us accidentally eating a speck of dust that landed on our food.)
  
  Once the OE spore is in the caterpillar, that’s when the OE protozoan emerges and does it’s thing. By the time the caterpillar emerges from its chrysalis as an adult butterfly, the protozoan has already gone through its entire life cycle and the new generation of protozoans are safely in their spore stage and coating the outside of the new butterfly.
  
  So, the parent isn’t necessarily passing the OE to its offspring. Any monarch that lands on the milkweed could inadvertently pass OE to any caterpillars on that milkweed. Females laying their eggs are going to spend more time on the milkweed and thus any spores on the females may have more opportunity to fall onto an egg or the surrounding vegetation. But, the spores aren’t being directly passed from Mom to offspring.
  
  Also, just because OE needs monarchs to survive, doesn’t mean that there is any advantage for monarchs who have OE. It could be that the monarchs just haven’t been able to evolve any defense against the OE. (People have been getting ticks for eons. The ticks don’t give us any fitness benefits and can sometimes give us diseases. But humans haven’t evolved any sort of immunity against ticks. That analogy isn’t quite the same situation, but it’s the closest I can come up with right now.)
  
  Is increased awareness and screening leading to increased OE detection? Possibly, maybe even probably. Does that explain all, or even the majority, of the increase? Probably not.
  
  What we know for sure is that non-migratory monarch populations which breed year-round have the highest rates of OE infection. It is believed that at least part of the reason for this high infection rate is because the year-round availability of milkweed never allows for a break in the cycle. Without a break in the cycle, the OE spores continually build up (like dust in a house that is never ever dusted or cleaned).
  
  We also know that the introduction of tropical milkweed species into the horticulture trade has allowed those species to be planted outside of their native range. In some areas, especially around the Gulf Coast, those tropical milkweed species are able to grow year-round instead of dying back in the winter like the milkweed species that are native to those regions.
  
  New winter breeding populations of monarch are starting to be discovered in some of those Gulf Coast areas with high tropical milkweed populations. Those monarch populations tend to also have high OE infection rates, most likely for the same reason as other non-migratory, year-round breeding monarch populations do.
  
  So, OE populations and infections overall are likely increasing, at least in part, because we’ve inadvertently created a new situation that benefits OE. That’s very much a human-caused issue. Is OE increasing in other areas or for other non-human-caused reasons? I don’t know. I’m not sure anyone does. It’s a complicated subject and I doubt one answer is going to fit all the different situations.
  
  Take care,
  Shannon
  
  Reply