badgerofshambles:speciesofleastconcern:zoo-logic:The Zoological Society of London has today an

badgerofshambles: speciesofleastconcern: zoo-logic: The Zoological Society of London has today announced the incredibly exciting news that they have successfully eliminated the lethal chytrid fungus from a wild amphibian population for the first time. Tadpoles of the Mallorcan midwife toad (Alytes muletensis), a fascinating and unique species that until a few decades ago was believed to be extinct, were collected from all infected ponds on the island and kept in a laboratory for a week. Whilst there, they were bathed daily in a treatment solution containing an antifungal known as itraconazole, before being returned to the wild. In the meantime, the environment surrounding each pond was sprayed liberally with a chemical disinfectant, including gravel, rocks and plants where the toads would spend time after they metamorphosed and left the water. Early results show that the combined treatment of both tadpoles and environment successfully eliminated chytridiomycosis from local populations, and that the effects can carry over to tadpoles in subsequent years without the need for repeat treatments. Using these methods, researchers are coming close to eradicating chytrid fungus from the entire island of Mallorca and therefore eliminating the lethal threat it poses to this extraordinary amphibian.Ref: Bosch J. et al., 2015. Successful elimination of a lethal wildlife infectious disease in nature. Biology Letters 11: 20150874 [link] Wow this is huge–not sure about disinfecting the ecosystem tho, sounds made up to me yeeeeeaaaah I don’t know about this. So, I spent the last four years of my life at a university in Virginia doing undergrad research with a B. dendrobatidis expert (not naming names; you can figure it out pretty easily just from that info if you’re really interested). He’s been in the field probably since ‘the beginning’  (the Panamanian Golden Frog dieoff, the R. muscosa breakthrough in Colorado, etc) and has never been a strong advocate for throwing chemicals or any foreign substance into an environment in order to control Bd outbreaks. We know that certain beneficial bacteria can out-compete Bd for space on amphibian skin, and that some amphibians simply don’t get Bd (or, get it and then manage to live with it as more of a mutuality than a pathogen; lookin’ at you, African Clawed frogs). I am very understanding of the author’s very apparent frustration over the lack of an implementable probiotic strategy (MAYBE if we could get consistent funding we’d have a satisfactory answer by now), but microbial ecology is a brand-spankin’ new field and it’s going to take a long time to pin down the mechanisms of what makes for a stable, transmissible probiotic community (and even if that’s a realistic goal for all species of concern). The amphibian arks and frozen zoos are our best bet for maintaining amphibian biodiversity until we get this fixed. It’s not a great solution, no, but neither is opening a can of worms in exchange for quick results. Now, I understand the desperation of the situation; everyone freaked out pretty good about the presence of Bd in Madagascar earlier this year, self included. But we also know that there are non-amphibian hosts for Bd, and personally (again, biased as heck) I don’t think that part of the equation has been studied enough for us to spray down the environment, treat the amphibians and call it a day. The downstream march is always there. The pet trade is always there, legal or not. This is a system with too many moving parts, and throwing something so static as an antifungal at it is not a long-term solution. This also doesn’t consider the capability of many other pathogenic fungi to develop resistance to antifungal compounds over time ; long-term-low-dose usage of any chemical agent against an organism tends to lead to resistance, and there’s no reason to think that Bd is any different in that respect from  Candida or Aspergillus. In a similar vein: what’s the ‘bycatch’ here? What other organisms -maybe pathogenic, maybe not- will we be killing along with Bd, and what impact will that have on the rest of the ecosystem? If this works for Mallorca, I’m thrilled; and I’ve no doubt that this lab has done their homework in spades to make this publication possible. My concern is that this will turn the tide towards chemical amelioration of wildlife disease, and I will call it in the air right here, right now: that will not end well. tl;dnr: fund probiotics, dammit (Other herps/micro people- feel free to sound off/correct/etc. This is something we all need to talk about, both in field and out. ) I completely agree that it’s right to be cautious about the applications of this method - and the paper shows the authors feel that way too:The development of disinfection strategies alone cannot eliminate the threat of chytridiomycosis, as evidence continues to accumulate that lethal amphibian-associated chytrid fungi are frequently being introduced into Europe and beyond [12,20]. Clearing site-level infection is no guarantee against pathogen reintroduction or the introduction of novel pathogens. […] We acknowledge that Virkon S is a controversial chemical to use environmentally and our use of it was driven by the urgency of midwife decline on Mallorca [21]. […] Research on the application of these chemicals for control of wildlife diseases must also include investigation of the potential impacts of chemical application to other biodiversity, the environment and associated ecosystem services.Their results are from a relatively simple system, with only one amphibian host species covering an area of occupancy of less than 10 square kilometres, so I imagine its applications for more extensive populations would probably be limited. Even so, I think it’s a useful addition to the toolkit that might help to protect species where situations become critical as with the midwife toad, or perhaps where chytrid has only recently been discovered in a population and could be rapidly eradicated before it becomes widespread. I’d definitely be interested to know if they were conducting any long-term monitoring of the impacts of the disinfectant on the ecosystem as a whole as part of their research though. I would hope that blanket chemical treatments wouldn’t become widespread until we could confirm that they’re not going to make matters worse in the long run. -- source link
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