Rice paddy amphibians as indicators of endocrine disruption due to pesticide exposure Molly Shuman-Goodier, Grant Singleton, Catherine Propper

Rice paddy amphibians as indicators of endocrine disruption due to pesticide exposure Molly Shuman-Goodier, Grant Singleton, Catherine Propper Northern Arizona University, International Rice Research Institute

Global Pesticide Production and Imports Tillman et al. 2002 Tilman et al. 2001, Tilman et al. 2002 Horgan et al. 2016

Exposure to pesticide contaminants poses a significant threat to biodiversity as well as wildlife and human health (Colburn 1996, Mostafalou & Abohahi 2012, Köhler & Triebskorn 2013, Beketov et al. 2013)

Exposure A minimum to of pesticide 127 different contaminants pesticides poses are a currently significant threat recognized to biodiversity as endocrine as well disruptors as wildlife (McKinlay and 2008) human health (Colburn 1996, Mostafalou & Abohahi 2012, Köhler & Triebskorn 2013, Beketov et al. 2013)

52% of measured insecticide concentrations (MICs) exceed regulatory threshold levels (RTLs) There is a complete absence of monitoring data for 90% of world s croplands

Why amphibians?

CH 1: A meta-analysis synthesizing the effects of pesticides on swim speed and activity of aquatic vertebrates Pesticide Contaminants Behavior Ecology Physiology Eiko Jones

Do environmentally relevant concentrations of pesticides alter the activity level and swim speed of aquatic vertebrates? Which chemical classes are worse than others? How does exposure concentration, duration, and taxa influence the observed effect? Jan Hoover

Initial Search (Science Direct, PubMed) n = 3,000 Screening by Title Screening by abstract n = 1,238 Whole article screening n = 137 Data extraction (means, std. error, n, moderators) INCLUSION CRITERIA: Experimental studies from the primary literature with valid control and treatment(s) Reported means, variance, and sample size for either activity level (%) or swim speed (cm/s) Ecologically relevant exposure concentrations Moderators reported: Exposure duration, concentration, chemical class, replicate type, control type, taxa 222 experimental comparisons 39 studies 23 pesticide products 7 chemical classes Effect Size (LnR) calculations and data analysis in R

Environmentally relevant pesticide exposure consistently decreases swim speed and activity levels of aquatic vertebrates

On average swim speed decreased by 35 % and activity levels decreased by 72 % in response to pesticide exposure

Effects of chemical classes on swim speed Atrazine Permethrin, Deltamethrin, Bifinethrin Endosulfan Carbaryl

Does butachlor disturb development of two rice paddy amphibians?

Does butachlor exposure drive competitive outcomes in favor of the invasive R. marina?

4 replicates/treatment, 20 tadpoles/tank n = 24 tanks, n = 240 tadpoles/species

R. marina is more sensitive to butachlor Interspecific competition exacerbates the effect of butachlor on survival a a a a a a b c Kaplan-Meier analysis of survival curves w/ log rank tests to determine significant X 2 pairwise comparisons

Opposing effects of treatment on tadpole development a b b c

Opposing effects of treatment on tadpole development a b b b c bc c

Does a double stressor of butachlor & competition affect thyroid hormone sensitive gene expression? TH Receptors: THRα and THRβ Klf9: Krüppel-like factor 9 Mmp2: Matrix enzyme Reference gene: rpl8

Does a double stressor of butachlor & competition affect thyroid hormone sensitive gene expression?

Geometric morphometric analyses of tadpoles shape 13 mm Y X

Morphology of F. vittigera tadpoles is highly variable in response to treatments

Recap What have I learned so far? Huge gaps in our understanding of how pesticide contaminants affect vertebrate health and species interactions in rice agro-ecosystems Behavior is a highly sensitive measure that may be used to screen for sub-lethal effects and target pesticides of particular concern Butachlor exposure at environmentally relevant concentrations affects development of amphibian larva lower survival, shifted rates of development, altered morphology Butachlor exposure can also alter interspecific competition, but contrary to our hypotheses the invasive cane toad appears to be more susceptible Butachlor may act via thyroid hormone dependent pathways to disrupt development in vertebrates

What else?

Thanks! Questions? Rachel Rubin

Ecosystem Services Provided by Paddy Pest Control Human Consumption Nutrient Cycling Amphibians Castellano et al. 2007, Attademo et al. 2005 Valencia-Aguilar et al. 2013, Rantala et al. 2014 Sentinels for ecosystem health and human response to pesticide exposure