Effects of a fungicide formulation on embryo-larval development, metamorphosis, and gonadogenesis of the South American toad Rhinella arenarum.

G. SVARTZ; F. MEIJIDE; C. PEREZ COLL

ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 45 p. 1 - 7

1382-6689

Sublethal toxicity of the formulated fungicideMaxim® XL on embryonic, larval and juvenile development of Rhinella arenarumwas evaluated by means of standardized bioassays. Maxim® XL, one of the mostused fungicides in Argentina, is based on a mixture of two active ingredients:Fludioxonil and Metalaxyl-M. Maxim® XL exposure induced severe sublethaleffects on the embryos, expressed as general underdevelopment, axial flexures,microcephaly, cellular dissociation, abnormal pigmentation, underdevelopedgills, marked edema and wavy tail. As the embryo development advanced,alterations in behavior as spasmodic contractions, general weakness andinanition were observed. Maxim® XL did not affect neither the time required tocomplete metamorphosis nor sex proportions, but gonadal development anddifferentiation were impaired. Gross gonadal analysis revealed a significantproportion of exposed individuals with underdevelopment of one or both gonads.Histological analysis confirmed that 18% and 10% of the individuals exposed to0.25 and 2 mg/L Maxim® XL, respectively, exhibited undifferentiated gonadscharacterized by a reduced number (or absence) of germ cells. Taking intoaccount the risk evaluation performed by means of Hazard Quotients, thisfungicide could be a threat to R.arenarum populations under chronic exposure. This study represents thefirst evidence of toxic effects exerted by Maxim® XL on amphibians. Finally,our findings highlight the properties of this fungicide that might jeopardizenon-target living species exposed to it in agricultural environments.