Toxicity interaction between chlorpyrifos, mancozeb and soil moisture to the terrestrial isopod Porcellionides pruinosus

Abstract

A main source of uncertainty currently associated with environmental risk assessment of chemicals is the poor understanding of the influence of environmental factors on the toxicity of xenobiotics. Aiming to reduce this uncertainty, here we evaluate the joint-effects of two pesticides (chlorpyrifos and mancozeb) on the terrestrial isopod Porcellionides pruinosus under different soil moisture regimes. A full factorial design, including three treatments of each pesticide and an untreated control, were performed under different soil moisture regimes: 25%, 50%, and 75% WHC. Our results showed that soil moisture had no effects on isopods survival, at the levels assessed in this experiment, neither regarding single pesticides nor mixture treatments. Additivity was always the most parsimonious result when both pesticides were present. Oppositely, both feeding activity and biomass change showed a higher sensitivity to soil moisture, with isopods generally showing worse performance when exposed to pesticides and dry or moist conditions. Most of the significant differences between soil moisture regimes were found in single pesticide treatments, yet different responses to mixtures could still be distinguished depending on the soil moisture assessed. This study shows that while soil moisture has the potential to influence the effects of the pesticide mixture itself, such effects might become less important in a context of complex combinations of stressors, as the major contribution comes from its individual interaction with each pesticide. Finally, the implications of our results are discussed in light of the current state of environmental risk assessment procedures and some future perspectives are advanced.

Pesticides and Soil Invertebrates: A Hazard Assessment

“…Pesticides negatively affected 80% of 20 behavioral parameters measuring Isopod feeding rate, feces production, avoidance, and locomotion and 85.7% of 35 biochemical biomarkers, including enzymatic activity and metabolism (Supplementary Table 3). Survival of Porcellio scaber, P. dilatatus, and Porcellionides pruinosus was reduced by diazinon (Drobne et al, 2008), dimethoate (Engenheiro et al, 2005;Ferreira et al, 2015), lambda-cyhalothrin (Jänsch et al, 2005), chlorpyrifos (Morgado et al, 2016), and pyrethrins (Zidar et al, 2012). Isopod growth was also negatively impacted in four out of seven tested parameters, reduced by imidacloprid (Drobne et al, 2008), dimethoate (Fischer et al, 1997), chlorpyrifos, and mancozeb (Morgado et al, 2016).…”

“…Survival of Porcellio scaber, P. dilatatus, and Porcellionides pruinosus was reduced by diazinon (Drobne et al, 2008), dimethoate (Engenheiro et al, 2005;Ferreira et al, 2015), lambda-cyhalothrin (Jänsch et al, 2005), chlorpyrifos (Morgado et al, 2016), and pyrethrins (Zidar et al, 2012). Isopod growth was also negatively impacted in four out of seven tested parameters, reduced by imidacloprid (Drobne et al, 2008), dimethoate (Fischer et al, 1997), chlorpyrifos, and mancozeb (Morgado et al, 2016). Reproduction was negatively affected in two out of three tested parameters by dimethoate (Fischer et al, 1997) and lambda-cyhalothrin (Jänsch et al, 2005), and the epithelial thickness of P. scaber was significantly reduced by imidacloprid (Drobne et al, 2008).…”

Scientific Opinion addressing the state of the science on risk assessment of plant protection products for in‐soil organisms

“…ISO or OECD guideline) on isopods, there is a vast experience in the literature on using them as model organisms for ecotoxicological evaluations of PPPs, ranging from assessing individual and population‐level parameters (e.g. Jänsch et al., ; Morgado et al., ; Vink et al., ; Zidar et al., ) to ecotoxicogenomic studies (e.g. Costa et al., ,b).…”

The fungicide mancozeb affects soil invertebrates in two subtropical Brazilian soils

“…Despite of the active ingredient Mancozeb has been widely used and commercialized beyond Brazil, in all European Union countries for example (EU, 2009) there are few data available about its toxicity to soil fauna. Some adverse effects in non-target organisms have been reported, such as negative influence on the community structure of oribatid mites and impact on feeding and growth performance of terrestrial isopod Porcellionides pruinosus (Al-Assiuty et al, 2014;Morgado et al, 2016).…”