The effect of two glyphosate formulations on a small, diurnal lizard (Oligosoma polychroma)

Abstract

Formulations of glyphosate-based herbicides continue to dominate the global herbicide market, while there continue to be concerns regarding the impact of this herbicide on non-target organisms. Research also indicates that the additives within certain glyphosate formulations, such as surfactants, are actually more toxic than the glyphosate active ingredient alone. Concerns arise in particular when glyphosate formulations are proposed for vegetation control in areas inhabited by rare or threatened species. Although the effect of glyphosate on birds and mammals is well studied, reptiles remain neglected in ecotoxicological studies. We investigated whether dermal exposure to two different commercial glyphosate formulations affected performance measures in the New Zealand common skink (Oligosoma polychroma). Fifty-eight skinks were each placed in a box of straw to simulate field conditions and sprayed once with Agpro Glyphosate 360, Yates Roundup Weedkiller (both at the label-specified concentrations of 144 mg glyphosate per 1 L water), or water (control). Agpro Glyphosate 360 contained ethoxylated tallow amine at a concentration of <200 g/L, while the surfactant within Yates Roundup Weedkiller was unknown. Following treatment skinks were kept in captivity and sampled for selected temperature and mass over a four-week period. Neither glyphosate formulation had a significant impact on mass. However, skinks treated with Yates Roundup Weedkiller selected significantly higher temperatures across 3 weeks following exposure. This heat-seeking behaviour could be a fever response to increase metabolism and thereby counteract physiological stress.

Acute toxicity and risk to lizards of rodenticides and herbicides commonly used in New Zealand

“…The biochemical pathway appears to be unique to plants and some microorganisms, and is generally of low toxicity to animals (Giesy et al 2000). However, preliminary research on glyphosates and their adjuvants suggests herbicides used in New Zealand can have measurable physiological effects on native lizards (Carpenter et al 2016). As such, research into potential sub-lethal effects of rodenticides and herbicides on reptiles is warranted.…”

“…Importantly, we have not considered chronic exposure nor sub-lethal toxicity (e.g. Carpenter et al 2016). Our data represent a first attempt to quantify the toxicity of several pesticides to reptiles, but more data are needed to ensure that native New Zealand reptiles are adequately protected from the use of pesticides to control invasive species.…”

Ecotoxicology of Glyphosate-Based Herbicides on Aquatic Environment

“…Therefore, it is assumed that glyphosate is capable of causing DNA damage, promoting chromatin fragmentation of epidermal cells, impairing cell division. Exposure to glyphosate does not alter the thermoregulatory behavior of lizards of the species Oligosoma polychroma [78]. Sub-lethal concentrations of the commercial glyphosate formulation (Roundup®) cause genotoxic damage and chromosome breaks in Anguilla anguilla.…”

Abiotic Factors Influence Surface Water Herbicide Concentrations Following Silvicultural Aerial Application in Oregon's North Coast Range

“…On average, 1 to 3 herbicide products are applied during 1 to 2 application events in a rotation of 30 to 80 y. Although applications of forestry herbicides are infrequent and at lower rates than agricultural and other commercial uses, concerns remain regarding perceived nontargeted exposure and the potential human health risk (Bernstein et al ) and aquatic biota (Murdock et al ; Carpenter et al ). Nontarget exposure may occur through herbicide mobilization, which can potentially contaminate surface water via drift and runoff, and groundwater via infiltration (Sopper ; Louchart et al ; Fulton and West ), all of which are dependent on product solubility and soil sorption potential, climatic conditions, topography, and soil properties (Wauchope ; Capel et al ).…”

“…Nontarget exposure may occur through herbicide mobilization, which can potentially contaminate surface water via drift and runoff, and groundwater via infiltration (Sopper ; Louchart et al ; Fulton and West ), all of which are dependent on product solubility and soil sorption potential, climatic conditions, topography, and soil properties (Wauchope ; Capel et al ). Consumption of contaminated water is a public health concern (Gasnier et al ; Bernstein et al ; Mesnage et al ), and nontarget impacts on aquatic biota within treated areas pose an ecological concern (Hayes et al ; Murdock et al ; Orton and Tyler ; Carpenter et al ). Consequently, research has focused on assessing potential herbicide exposure vectors (Bundschuh and McKie 2015), environmental fate and persistence (Capel et al ; de Jonge et al ; Tatum ; Newton et al ; Chang et al ), and risks to sensitive species that may encounter biologically relevant concentrations in the environments they inhabit (McComb et al ; Forbes et al ).…”