Effect of Sulfometuron Methyl and Nicosulfuron on Development and Metamorphosis in Xenopus Laevis: Impact of Purity

Abstract

Abstract-Analytically impure (ϳ85-88%) and purified (99.5%) preparations of two sulfonylurea herbicides, sulfometuron methyl and nicosulfuron, were evaluated for short-and long-term developmental effects on organogenesis (0-4 d) and limb development (0-30 d), and impact on metamorphosis (tail resorption [50-64 d]). Overall, the analytically impure sulfonylurea herbicides were more developmentally toxic than the purified preparations. Purified preparations did not induce early embryo-larval developmental effects or effects on hind limb development, although the rate of tail resorption was slowed at relatively high concentrations. Tail resorption rates were slowed significantly and abnormal limb development was induced by the analytically impure sulfonylurea herbicides. The process of organogenesis as monitored by the traditional frog embryo teratogenesis assay-Xenopus (FETAX) test was the least sensitive stage of development monitored in this study. Although some maldevelopment was induced at the limit of aqueous solubility of the analytically impure material, the severity of the malformations with the impure preparations was moderate. Based on this study, the analytically impure herbicides were more developmentally toxic than purified preparations of the same herbicides, which exerted little effect at maximum soluble concentrations. Thus, the capacity of purified nicosulfuron and sulfometuron methyl to interfere with amphibian development and maturation seems to be relatively low.

Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact?

“…The few studies that have previously examined the effects of nicosulfuron (Fort et al 1999), metolachlor (Mazanti 1999; Mazanti et al 2003; Osano et al 2002), and alachlor (Howe et al 1998; Osano et al 2002) on amphibians have examined concentrations 10,000 times higher than those used in the present study. All but four previous studies (Howe et al 1998; Mazanti 1999; Mazanti et al 2003; Relyea 2004) examined single pesticide exposures, and most examined mortality and teratogenesis, with only two studies addressing effects of these pesticide mixtures on larval growth and development (Howe et al 2004; Relyea 2004).…”

Spatial Conservation Prioritisation as Part of a General Land Use Planning Process 

“…Spatial Conservation Prioritisation (SCP) is one practical approach for Systematic Conservation Planning. SCP refers to approaches that value the study area based on biodiversity and other values usually using a computational software package such as Marxan (Ball and Possingham 2000), C-Plan (Pressey et al 2009) or Zonation (Moilanen et al 2005(Moilanen et al , 2011a; Lehtomäki and Moilanen 2013). These software packages utilise georeferenced information on biodiversity (species, habitats, etc.…”