When the United Nations meets Sept. 21 in New York, they want the UN to reframe its action on the global antimicrobial drug resistance (AMR) crisis.
It's crucial. How crucial is it?
Antimicrobial drug resistance threatens both personal and planetary health and the issue is as crucial as the global threat of climate change, Carroll says.
In a paper titled “Use Antimicrobials Wisely,” published in the current edition of Nature, a nine-member international research team, including Carroll, explained their advocacy.
“We're concerned about what will happen if the proposed UN solutions focus mainly on incentives for new drug development, at a time when the drug industry itself is abandoning those efforts against infectious disease due to AMR,” said Carroll, who co-leads the international group on resistance to pesticides and antimicrobial drugs. He founded and directs the Institute for Contemporary Evolution, Davis, and is affiliated with the Sharon Lawler lab, UC Davis Department of Entomology and Nematology.
The paper, published in the Comment section, is the first product from a two-year working group sponsored by the National Socio-Environmental Synthesis Center in Annapolis, Md. “We are taking a similar socio-environmental approach in our concurrent work on pesticide stewardship,” Carroll said.
“While new drugs have a role, we think it's more important for society to learn how to steward pathogen susceptibility, so we develop that theme in the paper,” Carroll said. “And because we also depend on microbes for digestion, immunity, and general health, and microbes support ecosystem functioning through nutrient cycles and the maintenance of soil and water quality, we further argue that our AM drug habits and waste streams threaten both personal and planetary health. “
Lead authors of the paper are Peter Jorgensen of Stockholm, Sweden, and Didier Wernli of Geneva Switzerland. Jørgensen, who spent part of his Danish graduate program working with Carroll in Davis, is now a postdoctoral researcher at the Royal Swedish Academy of Science, Stockholm.
Carroll described AMR as more than a medical dilemma—it's a socio-ecological problem. “The vulnerability of pathogens to antimicrobial drugs is a communal resource, readily threatened by overuse, to be lost as a classic 'tragedy of the commons.' There is a lot of contemporary theory for social resilience in the face of socio-ecological challenges, and– linking to entomology– the early success of the pioneering management of Bt crop pest resistance evolution is an encouraging precedent.”
In its planetary health approach, the group seeks to be “more cognizant not only of preserving drug susceptibility in pathogenic microbes, but also protecting from wholesale destruction the community of microbes on which we depend for life,” Carroll said.
In the paper, the scientists pointed out that “Resistance affects animal and environmental health as well as human health, and so requires coordinated action across economic sectors. No single concern exemplifies this better than the high rate of antibiotic use in agriculture (largely as growth promoters or disease prevention).” They wrote that in the United States, 70 to 80 percent of all anti-microbials consumed are given to livestock.
An example of antimicrobial resistance involves the malaria mosquito, Anopheles gambiae. The World Health Organization (WHO) in a document, "Global Action Plan on Anti-Microbial Resistance," wrote:
"Antimicrobial resistance can affect all patients and families. Some of the commonest childhood diseases in developing countries – malaria, pneumonia, other respiratory infections, and dysentery – can no longer be cured with many older antibiotics or medicines. In lower- income countries, effective and accessible antibiotics are crucial for saving the lives of children who have those diseases, as well as other conditions such as bacterial blood infections. In all countries, some routine surgical operations and cancer chemotherapy will become less safe without effective antibiotics to protect against infections."
Expect to hear more about this alarming crisis--the global antimicrobial drug resistance crisis. Meanwhile, read the WHO Global Action Plan.
Forget the soaps; let's talk about soapberry bugs and an entomologist at the University of California, Davis, who studies them.
And why and how she decided to pursue entomology as a career. That we'll save until the end of this blog.
Doctoral candidate Meredith Cenzer of the Louie Yang lab, UC Davis just published her research on soapberry bugs, which are a classic evolutionary example of how rapidly insects can switch hosts, adapting from a native to an invasive plant.
Her research shows that soapberry bugs have not only lost adaptations to their native host plant but are regionally specializing on an invasive host.
The work, "Adaptation to an Invasive Host Is Driving the Loss of a Native Ecotype," published in the current edition of the journal Evolution, “collapses a classic and well-documented example of local adaptation,” said doctoral candidate Meredith Cenzer of the Louie Yang lab, UC Davis Department of Entomology and Nematology. The plant-host switch can lead to disruption of native plant communities and a breakdown of the ecosystem.
The players involved are the soapberry bug (Jadera haematoloma), also known as “the red-shouldered bug”; its native host plant, the balloon vine (Cardiospermum corindum), and the invasive host, the golden rain tree or Taiwanese rain tree (Koelreuteria elegans).
The study, which took place in Florida, expands on the 1989 groundbreaking research of UC Davis evolutionary ecologist and soapberry expert Scott Carroll, who documented local adaptation in beak length, survival, and development time and other traits between soapberry bugs, balloon vine and the golden rain tree in Florida.
Said Carroll: "Meredith Cenzer's findings carry an important message for those concerned with biodiversity conservation, because she shows that even highly distinct adaptive specializations can disappear rapidly due to human influence on the environment– even in cases where the key native habitat has not been lost."
The soapberry bug, which lives throughout the United States and much of the world, feeds on seeds within the soapberry plant family, Sapindaceae, which includes soapberries, boxelders and maples. Mostly black, it has red eyes, red lateral stripes on the sides of its head and red on its “shoulders” (pronotum). It is often mistaken for the boxelder bug.
“As part of my doctoral dissertation, I documented that this pattern of local adaptation has been lost in the last 27 years,” Cenzer said, “and that all populations of soapberry bugs in Florida-- even those still found on the native --are now adapted only to the invasive host.“
“Locally adapted populations are often used as model systems for the early stages of rccological speciation, but most of these young divergent populations will never become complete species,” Cenzer noted in her abstract. “The maintenance of locally adapted populations relies on the strength of natural selection overwhelming the homogenizing effects of gene flow; however, this balance may be readily upset in changing environments.”
“All populations that were adapted to the native host--including those still found on that host today--are now better adapted to the invasive host in multiple phenotypes,” she wrote in her abstract.” Weak differentiation remains in two traits, suggesting that homogenization across the region is incomplete. This study highlights the potential for adaptation to invasive species to disrupt native communities by swamping adaptation to native conditions through maladaptive gene flow.”
Cenzer characterized local adaptation as “high performance in one habitat coming at the cost of performance in other habitat types, such that populations specialized on each habitat will have higher fitness in that environment than immigrants from other habitats.”
“This results directly in two types of ecological reproductive isolation between locally adapted populations: 1) selection against migrants, who will be outcompeted by residents, and 2) selection against hybridization (if hybrids show intermediate phenotypes), as hybrid offspring will be outcompeted in each habitat by one parental type,” she wrote in her research paper. “However, such reproductive isolation relies on ongoing differential selection balanced with low rates of gene flow between habitats. In most well studied systems demonstrating local adaptation, we do not know how perturbation – either to selection pressures or gene flow – will influence the long-term stability of differentiation.”
Carroll, who maintains a website, “Soapberries of the World,” says the soapberry bugs are “very approachable native guides to how evolution is taking place on earth day.” His website shows “how evolution happens every day and why it matters.”
How did Meredith Cenzer, a native of Gainesville, Fla., become interested in entomology? We love her answer.
"I first became interested in entomology as a kid," she recalled. "The defining moment in my memory is when my gifted science teacher, Ms. Linda Osborne, told me in third grade that there are people who study insects for a living and that they're called entomologists. She was going to put me in timeout for being too loud (a lifelong problem), but told me she'd let it slide this time if I promised to become an entomologist."
"Two years later, she let me come in and teach her first graders about insects. For my first science fair project, in sixth grade, I tracked the progress of tent caterpillar aggregations; we weren't allowed to manipulate animals, so I photographed them every day and made notes on their behavior - my parents still have the poster from that one."
So, she promised her teacher she'd become an entomologist. And she kept her promise. She received her bachelor of science degree in entomology at the University of Florida in 2009.
Future plans, after receiving her doctorate in entomology from UC Davis?
“I am broadly interested in evolutionary ecology, particularly in plant-insect interactions, and the balancing roles of selection, gene flow, and plasticity on determining the phenotypes we see in nature,” she said. After receiving her doctorate in entomology from UC Davis in the fall, she will start a postdoctoral position at Florida State University with biology professor Leithen M'Gonigle, developing theory on the evolution of dispersal in patchy landscapes.
A tip of the insect net to Meredith Cenzer!
(Editor's Note: Meredith Cenzer participated in the Entomological Society of America's Linnaean Games competition in 2011. See Bug Squad blog of Nov. 22, 2011.)
And unleash the secret of soapberry bugs?
Students in the Entomology 1 class, offered by the UC Davis Department of Entomology and Nematology, studied soapberry bugs under the tutelage of evolutionary ecologists/soapberry scientists Scott Carroll and Jenella Loye. The students then created screen-printed tile mosaics (like the photo at right).
The popular class, headed by Diane Ullman, professor of entomology, UC Davis Department of Entomology and Nematology, fuses art with science. Ullman, not only a noted entomologist but an accomplished artist, co-founded and co-directed the UC Davis Art/Science Fusion Program.
Where can you see the students' art? It will be among the work featured at "The Secret World of Insects" exhibition and reception, set from 5 to 8 p.m., Wednesday, June 3 in the Third Space Art Collective, 946 Olive Drive. It's free and open to the public.
"Soapberry bugs are beautiful insects that are found in many parts of the world. Their most defining ecological characteristic is their specialized diet," Carroll says on his website, Soapberry Bugs of the World. "They feed on the seeds of the soapberry family, which includes well known plants like boxelders, maples, soapberries (or soapnuts), jacket plums, rambutans, and litchis. These plants have evolved many ways to protect their seeds from soapberry bugs: flying seeds, seeds protected in inflated spheres, seeds with cyanide, and seeds that are held unfilled on the plant for months while the bugs slowly starve. Yet these insects work around the plants' co-evolved defenses and use the seeds to fuel their own development and reproduction."
Carroll directs the UC Davis Institute for Contemporary Evolution. Both he and Loye, husband and wife, are members of the Sharon Lawler lab, UC Davis Department of Entomology and Nematology.
Ullman said that 70 students participated in the Entomology 1 class last quarter. "We had four sections," she added. They were:
- Ceramics. The students created a screen-printed tile mosaic about evolution of the soapberry bug with the support and scientific advice of Jenella Loye and Scott Carroll. Also, this quarter, self-described rock artist Donna Billick, co-founder and former co-director of the UC Davis Art/Science Fusion Program, assisted the students.
- Sculpture with reuse materials. The students made sculptural story boards about insects.
- Painting and multimedia.The students did trip tic-like canvases about a diversity of insects.
- Bioart. The students created insect drawings with fungi on agar.
Ah, soapberry bugs...
They'll never get top billing in a racy novel, let alone star in an R-rated movie.
The "R" word comes into play only when they're referred to as "the rapidly evolving soapberry bugs" or when scientists talk about reproduction.
Evolutionary ecologist Scott Carroll of the UC Davis Department of Entomology and Nematology is a soapberry scientist. In fact, he is the "resident soapberry scientist" behind the spectacular website, "Soapberry Bugs of the World." Scott, who holds a doctorate in biology from the University of Utah, directs the UC Davis-based Institute for Contemporary Evolution, which "observes and experiments with patterns of ongoing evolution in wild and anthropogenic environments."
Explore the soapberry website--it's the work of Carroll, Crystal Perreira and Trevor Fowels--and you'll learn all about these insects.
"Small but powerful, soapberry bugs are quickly adapting as humans alter the world," Carroll writes on the website. "These beautiful insects artfully show how evolution happens every day and why it matters."
"Here at soapberrybug.org, we are collecting and integrating the world's information on all 65 species of soapberry bugs. We present this information in a variety of formats accessible to students, scientists, and anyone with interest."
Soapberry bugs belong to the order Hemiptera, often known as the true bugs. "Their lack of relatively well-developed scent glands places them in the family Rhopalidae," Carroll says. "Soapberry bugs specifically encompass all species within the subfamily Serinethinae. Serinethinae contains three genera: Jadera, Leptocoris, and Boisea."
They encourage you to check out their website:
• Comics, videos, and photos
• Identification guides
• Research results and scientific papers
And if you see soapberry bugs, you're welcome to send your observations to the soapberry scientists.
Well, on a glorious spring day at the UC Davis Arboretum's Storer Garden, we saw about 50 of these intriguing bugs. Fifty Shades of Gray (and Red). They were looking for mates on a tree trunk. Up, down, around. Repeat. Up, down, around. Well, hello, there!
The "R" word came into play: reproduction.
"The soapberry bug life cycle seems straightforward: male and female mate, the female lays eggs, the young hatch from the eggs, grow, and cast off their skin (molt) as they go through several developmental stages called instars" Carroll says. "Finally, adulthood (along with a fully developed set of wings) and reproductive maturity are achieved and the cycle begins again. However, several aspects of this cycle are more complex than they initially appear. Firstly, just because a male mates with a female, does not necessarily mean that he will father her offspring. In soapberry bugs (and many other organisms), the sperm of the male that was the last to mate with the female has precedence over the sperm deposited by those that mated with her previously. Thus, natural selection favors males with the behavior, morphology, and physiology that increase the chance that they will be the last male to mate with any given female before she lays her eggs. This phenomenon inevitably contributes to reproductive competition between males."
There you have it. No soap opera. No romance. No playing around. Just 50 Shades of Gray (and Red).
Evolutionary biology techniques can and must be used to help solve global challenges in agriculture, medicine and environmental sciences, they said.
Science Express makes important papers available to readers before they appear in the journal Science. The first-of-its-kind study will appear in a November edition of the journal.
“Evolutionary biology is often overlooked in the study of global challenges,” said lead author Scott, with the UC Davis Department of Entomology and Nematology and the Institute for Contemporary Evolution, also in Davis. “By looking at humanity's problems across the domains of nature conservation, food production and human health, it is clear that we need to strengthen evolutionary biology throughout the disciplines and develop a shared language among them.”
The study calls attention to how evolutionary biology techniques can be used to address challenges in agriculture, medicine and environmental sciences, said Carroll, noting that these techniques, although seemingly unrelated, work within a similar set of evolutionary processes.
“These techniques range from limiting the use of antibiotics to avoid resistant bacteria and breeding crops with desired benefits such as flood tolerant rice, to less commonly implemented strategies such as gene therapy to treat human disease, and planting non-native plants to anticipate climate change,” Carroll said.
“A particular worry is the unaddressed need for management of evolution that spans multiple sectors, such as occurs in the spread of new infectious diseases and antimicrobial resistance genes between natural, human health and agricultural systems.”
In their paper, the nine researchers—two from UC Davis, one from UCLA and six from universities in Denmark, New Zealand, Maine, Minnesota, Washington state and Arizona--crafted a graphic wheel divided into three sectors, food, health and environment and cited the challenges that link them together, including rapid revolution and phenotype environment mismatch in more slowly reproducing or threatened species.
Carroll said the underlying causes of societal challenges such as food security, emerging disease and biodiversity loss “have more in common than we think.”
“Humans, pathogens and all other life on earth adapt to their environment through evolution, but some adaptation happens too quickly and some too slowly to benefit human society,” Carroll said. “Current efforts to overcome societal challenges are likely only to create larger problems if evolutionary biology is not swiftly and widely implementedto achieve sustainable development.”
Society faces two sorts of challenges from evolution, the research team said. “The first occurs when pests and pathogens we try to kill or control persist or even prosper because the survivors and their offspring can resist our actions,” Carroll said. “The second challenge arises when species we value adapt too slowly, including humans.”
Although practices in health, agriculture and environmental conservation differ, each field can better target challenges using the same applications of evolutionary biology, they said.
For example, when a farmer plants a crop that is susceptible to pests, he might actually help the agricultural community as a whole by slowing down evolution of pesticide resistance, the authors said, citing an applied evolutionary biology tactic used in agriculture.
Planting pest-friendly crops has been used in the United States with good results, the team said. Farmers planting these crops slow the evolution of resistance to genetically modified corn and other crops. Pests then reproduce in abundance eating the susceptible plants, and when a rare resistant mutant matures on a toxic diet, it is most likely to mate with a susceptible partner, keeping susceptibility alive. This approach works to suppress the unwanted evolution on the whole, but farmers will have sacrificed a short-term gain for the long-term good.
Similar innovative solutions exist across the fields of medicine and environmental conservation, they said.
“This is an example of how implementing applied evolutionary biology without a plan for regulatory measures may come at short-term costs to some individuals that others may avoid.” Jorgensen said. “By using regulatory tools, decision makers such as local communities and governments play a crucial role in ensuring that everybody gains from the benefits of using evolutionary biology to realize the long-term goals of increasing food security, protecting biodiversity and improving human health and well-being.”
Other co-authors are Michael T. Kinnison, University of Maine; Carl Bergstrom, University of Washington; R. Ford Denison, University of Minnesota; Peter Gluckman, University of Auckland, New Zealand; Thomas B. Smith, UCLA; Sharon Strauss, UC Davis Department of Evolution and Ecology and Center for Population Biology, and Bruce Tabashnik, University of Arizona.
Carroll is an affiliate of the Sharon Lawler lab, UC Davis Entomology and Nematology. The research was funded in part by the National Science Foundation and the Australian-American Fulbright Commission.