The influence of effective microorganisms (EM) and yeast on the degradation of strobilurins and carboxamides in leafy vegetables monitored by LC-MS/MS and health risk assessment.

Elżbieta Wołejko,Jolanta Piekut,Magdalena Jankowska,Bożena Łozowicka,Piotr Kaczyński

doi:10.1007/s10661-015-5022-4

Abstract

The aim of this study was to determine the behaviour of strobilurin and carbocyamides commonly used in chemical protection of lettuce depending on carefully selected effective microorganisms (EM) and yeast (Y). Additionally, the assessment of the chronic health risk during a 2-week experiment was performed. The statistical method for correlation of physico-chemical parameters and time of degradation for pesticides was applied. In this study, the concentration of azoxystrobin, boscalid, pyraclostrobin and iprodione using liquid chromatography–mass spectrometry (LC–MS/MS) in the matrix of lettuce plants was performed, and there was no case of concentration above maximum residues levels. Before harvest, four fungicides and their mixture with EM (1 % and 10 %) and/or yeast 5 % were applied. In our work, the mixtures of 1%EM + Y and 10%EM + Y both stimulated and inhibited the degradation of the tested active substances. Adding 10%EM to the test substances strongly inhibited the degradation of iprodione, and its concentration decreased by 30 %, and in the case of other test substances, the degradation was approximately 60 %. Moreover, the addition of yeast stimulated the distribution of pyraclostrobin and boscalid in lettuce leaves. The risk assessment for the pesticides ranged from 0.4 to 64.8 % on day 1, but after 14 days, it ranged from 0.0 to 20.9 % for children and adults, respectively. It indicated no risk of adverse effects following exposure to individual pesticides and their mixtures with EM and yeast.

Highlights

Pyraclostrobin and azoxystrobin belong to strobilurins, a new class of fungicides included in the quinone outside inhibitors (QoI) group, which have a novel mode of action, and are very safe from an environmental point of view
These results showed that the validation parameters were good; target pesticides were satisfactorily determined in lettuce samples
The addition of effective microorganisms to analysed fungicides resulted in the significant inhibition of decomposition, strengthening the final result and maintaining the active substance at a very high level, in iprodione

Summary

Introduction

The innovative generation of fungicides, which includes such groups as strobilurins and carboxamides, have a broad spectrum of fungicide which are intensively employed throughout the world to fight against highly destructive plant pathogens, such as Botrytis cinerea, Sclerotinia spp., Leveillula taurica, or Spherotheca macularis (Mendoza et al 2005; Kretschmer et al 2009; Łozowicka 2015) which are found on many kinds of fruits and vegetables (Łozowicka 2015). 64 Page 2 of 14 belong to the carboxamide group of pesticides, and they show a biological mode of action consisting in the inhibition of the enzyme succinate-ubiquinone reductase, known as complex II, in the mitochondrial electron transport chain (Mendoza et al 2005; Camoutsis et al 2010). The effectiveness of strobilurins lies in their inhibition of the mitochondrial respiration of the fungus (Manna et al 2013)

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Methods

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Discussion

Conclusion