Complex interactive effects of water mold, herbicide, and the fungus Batrachochytrium dendrobatidis on Pacific
John M Romansic1, James E Johnson, R Steven Wagner
1Department of Integrative Biology, 3029 Cordley Hall, Oregon State University, Corvallis, Oregon 97331, USA.
Abstract:
Infectious diseases pose a serious threat to global biodiversity. However, their ecological impacts are not independent of environmental conditions. For example, the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. We examined the combined effects of Bd, a water mold (Achlya sp.), and the herbicide Roundup® Regular (hereafter, Roundup®) on larval Pacific treefrog Hyliola regilla hosts. We employed a 2 wk, fully factorial laboratory experiment with 3 ecologically realistic levels (0, 1, and 2 mg l-1 of active ingredient) of field-formulated Roundup®, 2 Achlya treatments (present and absent), and 2 Bd treatments (present and absent). Our results were consistent with sublethal interactive effects involving all 3 experimental factors. When Roundup® was absent, the proportion of Bd-exposed larvae infected with Bd was elevated in the presence of Achlya, consistent with Achlya acting as a synergistic cofactor that facilitated the establishment of Bd infection. However, this Achlya effect became nonsignificant at 1 mg l-1 of the active ingredient of Roundup® and disappeared at the highest Roundup® concentration. In addition, Roundup® decreased Bd loads among Bd-exposed larvae. Our study suggests complex interactive effects of a water mold and a contaminant on Bd infection in amphibian hosts. Achlya and Roundup® were both correlated with altered patterns of Bd infection, but in different ways, and Roundup® appeared to remove the influence of Achlya on Bd.
Insights
The water mold Achlya can worsen chytrid fungus (Batrachochytrium dendrobatidis) infections in frogs, but the herbicide Roundup mitigates this effect. Roundup also reduces fungal loads in infected amphibians.
Area of Science:
- Ecology
- Environmental Toxicology
- Amphibian Disease Ecology
Background:
- Infectious diseases significantly impact global biodiversity, with amphibian populations threatened by pathogens like Batrachochytrium dendrobatidis (Bd).
- Environmental factors can modulate disease impacts, but interactions between pathogens, other microbes, and contaminants are poorly understood.
- The synergistic effects of Bd, water mold (Achlya sp.), and herbicides on amphibian hosts require further investigation.
Purpose of the Study:
- To investigate the combined effects of Batrachochytrium dendrobatidis (Bd), Achlya sp., and the herbicide Roundup® on larval Pacific treefrogs (Hyliola regilla).
- To determine if Achlya and Roundup® interact to influence Bd infection prevalence and intensity in amphibian hosts.
Main Methods:
- A 2-week laboratory experiment using a fully factorial design with larval Pacific treefrogs.
- Treatments included three levels of Roundup® (0, 1, 2 mg l-1 active ingredient), presence/absence of Achlya, and presence/absence of Bd.
- Quantified Bd infection prevalence and fungal loads in response to experimental treatments.
Main Results:
- When Roundup® was absent, Achlya presence increased Bd infection proportion in larvae, suggesting synergistic facilitation.
- This synergistic effect of Achlya on Bd infection diminished significantly at 1 mg l-1 Roundup® and disappeared at 2 mg l-1.
- Roundup® exposure significantly reduced Bd fungal loads in infected larvae, irrespective of Achlya presence.
Conclusions:
- Complex interactions exist between the water mold Achlya, the herbicide Roundup®, and the amphibian pathogen Bd.
- Roundup® can counteract the synergistic effect of Achlya on Bd infection establishment and reduce Bd pathogen loads.
- These findings highlight the intricate interplay of environmental contaminants and microbial pathogens in amphibian disease dynamics.
More Related Videos
06:49Reduced Itraconazole Concentration and Durations Are Successful in Treating Batrachochytrium dendrobatidis Infection in Amphibians
Published on: March 14, 2014
05:08Application of I TASSER, trRosetta, UCSF Chimera, HADDOCK server, and HEX loria for De Novo and In Silico Design of Proteins
Published on: July 8, 2025
