Amphibians can become tolerant to pesticides, but at a cost

July 17, 2017
Binghamton University Assistant Professor of Biological Sciences Jessica Hua. Credit: Binghamton University, State University of New York

Amphibians can develop tolerance to pesticides, but this tolerance can lead to increased susceptibility to parasites, according to new research from Binghamton University, State University of New York.

Past research by Binghamton University Assistant Professor of Biological Sciences Jessica Hua and researchers from Purdue University and Rensselaer Polytechnic Institute (RPI) showed that amphibians can evolve tolerance to pesticides in one of two ways. Amphibians that live closer to can evolve higher baseline tolerance by passing tolerance on from generation to generation. Alternatively, if exposed to low levels of pesticides early in life, amphibians that live farther from agriculture have evolved the ability to induce higher pesticide tolerance within a few days (i.e. inducible tolerance).

"While it is optimistic that amphibians can evolve tolerance to chemicals using multiple mechanisms, it is important to consider that pesticides are not the only stressor amphibians face," said Hua. "Amphibians are declining worldwide and other stressors such as can interact with pesticides to contribute to these declines."

To understand whether land use or evolving pesticide tolerance comes at a cost when facing other stressors such as parasites, Hua and the team of researchers identified 15 wood frog populations that varied in proximity to agriculture and mechanisms of pesticide tolerance (i.e. higher baseline tolerance vs. inducible tolerance). Using these populations, they measured the relationship between land use and evolutionary responses to a pesticide and susceptibility to two common parasites: a trematode (i.e. echinoparyphium) and a virus (i.e. ranavirus).

The new findings showed that amphibian susceptibility to parasites was related to their proximity to agriculture and their evolutionary responses to pesticide but this relationship differed between the two parasites.

For the trematode, wood frogs living closer to agriculture with high baseline tolerance had lower trematode loads than populations living far from agriculture with inducible pesticide tolerance. In contrast for ranavirus, a highly virulent pathogen capable of decimating amphibian populations, populations living close to agriculture with high baseline tolerance had higher viral loads than populations far from agriculture with inducible tolerance.

"Our results suggest that it is not enough to consider the effects of contaminants or parasites in isolation. Nature is complex," said Hua. "Not only do different stressors interact in ways that can be difficult to predict but evolutionary responses to one stressor can shape amphibian responses to other stressors. This work highlights the importance of considering ecological and evolutionary processes when evaluating the effects of contaminants."

"Across their lifetime, amphibians encounter many different types of parasites and the parasite-specific responses we detected highlight the complexity of pesticide-parasite interactions," said Jason Hoverman, associate professor of Forestry and Natural Resources at Purdue University.

"Collectively, this study highlights how an interdisciplinary approach using evolutionary theory, disease ecology, and toxicology can help elucidate the contribution of multiple stressors on populations, which are declining around the world," said Rick Relyea, professor of Biological Sciences and director of the Darrin Fresh Water Institute at Rensselaer.

Hua and her fellow researchers were recently awarded a National Science Foundation grant to continue investigating how land use and evolved pesticide tolerance can shape disease outcome.

The paper, "Evolved pesticide influences susceptibility to parasites in amphibians," was published in Evolutionary Applications.

Explore further: Common pesticides kill amphibian parasites, study finds

More information: Jessica Hua et al, Evolved pesticide tolerance influences susceptibility to parasites in amphibians, Evolutionary Applications (2017). DOI: 10.1111/eva.12500

Related Stories

Common pesticides kill amphibian parasites, study finds

April 4, 2016

The combined effects of pesticides and parasites threaten wildlife populations worldwide (e.g. amphibians, honeybees). Pesticides are predicted to exacerbate the effects of parasites on their hosts by reducing the host's ...

Study examines pesticides' impact on wood frogs

March 1, 2017

A new study looks at how neonicotinoid pesticides affect wood frogs, which use surface waters in agricultural environments to breed and reproduce. Neonicotinoids are widely used insecticides that are applied to a variety ...

Recommended for you

Good fighters are bad runners

July 21, 2017

For mice and men, a strength in one area of Darwinian fitness may mean a deficiency in another. A look at Olympic athletes shows that a wrestler is built much differently than a marathoner. It's long been supposed that strength ...

Genome study offers clues about history of big cats

July 21, 2017

(Phys.org)—A large international team of researchers has conducted a genetic analysis and comparison of the world's biggest cats to learn more about their history. In their paper published on the open source site Science ...

Researchers discover mice speak similarly to humans

July 21, 2017

Grasshopper mice (genus Onychomys), rodents known for their remarkably loud call, produce audible vocalizations in the same way that humans speak and wolves howl, according to new research published in Proceedings of the ...

Researchers discover biological hydraulic system in tuna fins

July 20, 2017

Cutting through the ocean like a jet through the sky, giant bluefin tuna are built for performance, endurance and speed. Just as the fastest planes have carefully positioned wings and tail flaps to ensure precision maneuverability ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.