Effects of pesticide exposure and the amphibian chytrid fungus on gray treefrog (Hyla chrysoscelis) metamorphosis

Abstract

Pesticides are detectable in most aquatic habitats and have the potential to alter host-pathogen interactions. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been associated with amphibian declines around the world. However, Bd-associated declines are more prominent in some areas, despite nearly global distribution of Bd, suggesting other factors contribute to disease outbreaks. In a laboratory study, the authors examined the effects of 6 different isolates of Bd in the presence or absence of a pesticide (the insecticide carbaryl or the fungicide copper sulfate) to recently hatched Cope's gray treefrog (Hyla chrysoscelis) tadpoles reared through metamorphosis. The authors found the presence or absence of pesticides differentially altered the mass at metamorphosis of tadpoles exposed to different Bd isolates, suggesting that isolate could influence metamorphosis but not in ways expected based on origin of the isolate. Pesticide exposure had the strongest impact on metamorphosis of all treatment combinations. Whereas copper sulfate exposure reduced the length of the larval period, carbaryl exposure had apparent positive effects by increasing mass at metamorphosis and lengthening larval period, which adds to evidence that carbaryl can stimulate development in counterintuitive ways. The present study provides limited support to the hypothesis that pesticides can alter the response of tadpoles to isolates of Bd and that the insecticide carbaryl can alter developmental decisions.

Here today, gone tomorrow: Short‐term retention of pesticide‐induced tolerance in amphibians

“…Previous studies have found that amphibians are also able to reverse behavioral and morphological changes within hours to days after predatory cues are removed from aquatic systems . This rapid reversion of induced plastic responses may offset fitness tradeoffs experienced with longer exposure to environmental cues . Therefore, the short length of increased pesticide tolerance observed in response to a single, short (72‐h) sublethal carbaryl exposure may have been offset by the reversion to noninduced phenotypes.…”

A pesticide paradox: Fungicides indirectly increase fungal infections

“…Corresponding Editor: Trenton W. J. Garner. 6 E-mail: jasonrohr@gmail.com (Gahl et al 2011, Buck et al 2015, Jones et al 2017, insecticides (Davidson et al 2007, Gaietto et al 2014, Buck et al 2015, Jones et al 2017, fungicides (Johnson et al 2003, Woodhams et al 2012, Gaietto et al 2014, Hudson et al 2016, and agricultural disinfectants (Johnson et al 2003, Bosch et al 2015. Additionally, many researchers are exploring biocides as management tools to control Bd (Woodhams et al 2011).…”

Malathion acute toxicity in tadpoles of Duttaphrynus melanostictus, morphological and behavioural study

“…However, the exact time at which tadpole tails are sensitive to malathion and other contaminants is merely unknown (Gaietto et al, 2014). But based on the present study and observation, it can nevertheless be said that even at a low concentration of 0.5 mg/l of malathion can have an outcome of inducing bent tail axis in tadpoles of D. melanostictus, thereby compromising its overall survival.…”