Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Canceled flights: For monarch butterflies, loss of migration means more disease

30.01.2015

Planting tropical milkweed, available at many garden centers, makes the problem worse

Human activities are disrupting the migration patterns of many species, including monarch butterflies. Some monarchs have stopped migrating to their traditional overwintering sites in Mexico, remaining in the southern U.S. to breed during the winter.


A monarch caterpillar munches on tropical milkweed in a garden at The Landings in Savannah, Ga., in January 2014.

Credit: Dara Satterfield/University of Georgia

A new study by University of Georgia ecologists, just published in the journal Proceedings of the Royal Society B, has found that these sedentary winter-breeding butterflies are at increased risk of disease, a finding that could apply to other migratory species as well. But, for the monarchs at least, there may be a relatively simple solution.

Every year, millions of monarch butterflies travel from breeding grounds in the eastern U.S. and Canada to spend the winter in central Mexico. In recent years, however, their numbers have declined sharply as changing agricultural practices and land use patterns have reduced the availability of milkweed, the plant on which monarchs lay their eggs.

In response, concerned gardeners have started planting milkweed to help replace some of the butterflies' lost breeding habitat. The most readily available commercially grown milkweed sold by garden centers is the exotic species Asclepias curassavica, or tropical milkweed. Monarchs love it, but, according to the study's lead author Dara Satterfield, a doctoral student in the UGA Odum School of Ecology, tropical milkweed does not naturally die back in fall like perennial milkweeds native to North America. In fact, in parts of the southern U.S. from the Gulf Coast to the Atlantic, tropical milkweed can produce foliage and flowers year-round. This allows monarchs in those areas to stay put and keep breeding all winter.

And that's how problems with disease arise.

Satterfield and her colleagues processed more than 5,000 samples taken from monarchs at over 100 sites across the U.S., Canada and Mexico, testing them for infection by a debilitating protozoan parasite. The non-destructive samples, about half of which were collected by citizen scientists through Project Monarch Health, were taken by gently pressing clear tape against the butterfly's abdomen; the samples were then viewed under a microscope.

The researchers found that the non-migratory, winter-breeding monarchs in the southern U.S. were five times more likely to be infected with parasites than migratory monarchs sampled in their summer breeding range or at overwintering sites in Mexico.

Satterfield said that previous studies by co-author Sonia Altizer, Odum School associate dean and UGA Athletic Association Professor in Ecology, showed that for some wildlife species, including monarchs, long distance migration helps to reduce infectious disease transmission.

"Long distance migration can reduce disease in animal populations when it weeds out infected individuals during the strenuous journey, or when the migrating animals get to take a break and move away from contaminated habitats where parasites accumulate," she said. "Our non-migratory monarchs don't have those benefits of migration, so we see that in many cases the majority of monarchs at winter breeding sites are infected."

Satterfield said that this pattern is part of a larger problem.

"Many animal migrations are changing in response to human activities, whether climate change, habitat destruction or barriers to migration," she said. "Some migrations are changing in terms of timing or distance traveled. Some animals have stopped migrating altogether. So in these animals, some pathogens that have been historically kept in check by migration might now become a problem."

Fortunately for the monarchs, there is a large and dedicated core of gardeners and citizen scientists eager to help.

"It was members of the public and citizen scientists who alerted us to the winter breeding behaviors of monarchs in their gardens to begin with," Satterfield said. "So the public has helped us recognize the shift in monarch ecology and document the disease outcomes in a scientific way. And I think they can now help us manage monarch habitats in ways that might reduce disease problems."

Because the monarchs' winter-breeding behavior is made possible by the presence of tropical milkweed, Satterfield recommended that gardeners gradually replace it with native milkweeds as they become available.

"We encourage the planting of native milkweeds whenever possible," she said. "But if you do have tropical milkweed, we recommend cutting it back every few weeks to within 6 inches of the ground in fall and winter. That's especially important in coastal areas of the southern U.S. where we now know disease is a problem." Some locations such as the extreme southern portions of Texas and Florida have supported tropical milkweed for many decades or longer, and Satterfield said that tropical milkweed there can be left in place.

Satterfield's recommendations are based in part on ongoing research by Altizer and Ania Majewska, an Odum doctoral student and Wormsloe Fellow at the UGA Center for Research and Education at Wormsloe in Savannah, where they are testing butterflies' responses to native and non-native host plants in a series of experimental pollinator gardens.

Satterfield said that while the chief driver of the monarch's decline is the loss of native milkweeds in the U.S. and Canada, it's important to tackle the issue of pathogen transmission in winter-breeding populations. "Things could get worse for the monarchs if we don't solve this problem now with the tropical milkweed supporting high levels of disease," she said.

###

More information about monarchs, parasites and milkweed is available online at http://www.monarchparasites.org and monarchjointventure.org/images/uploads/documents/Oe_fact_sheet.pdf. A list of native milkweeds by region is available at monarchjointventure.org/images/uploads/documents/MilkweedFactSheetFINAL.pdf.

The study's third co-author was John Maerz of the UGA Warnell School of Forestry and Natural Resources. The research, available online at http://rspb.royalsocietypublishing.org/content/282/1801/20141734.full, was supported by the National Science Foundation and the U.S. Forest Service.

Media Contact

Dara Satterfield
dara7@uga.edu
706-542-3485

 @universityofga

http://www.uga.edu

Dara Satterfield | EurekAlert!

Further reports about: UGA animals breeding citizen scientists migrating monarch butterflies native parasites tropical

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Nagoya physicists resolve long-standing mystery of structure-less transition

21.08.2017 | Materials Sciences

Chronic stress induces fatal organ dysfunctions via a new neural circuit

21.08.2017 | Health and Medicine

Scientists from the MSU studied new liquid-crystalline photochrom

21.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>