Untargeted metabolomics as a tool to monitor biocontrol product residues' fate on field-treated Prunus persica

Abstract

Evidence of chemical plant protection products' (PPPs) long-term impact has been found in all environmental compartments. Therefore, other types of PPPs are developed to complement chemical PPPs like PPPs from natural sources, namely biocontrol products (BPs). Little is known about those new BPs, and it is important to assess their potential long-term environmental impact. Recently, the Environmental Metabolic Footprinting (EMF) approach was developed. It permits studying sample's entire meta-metabolome (endometabolome and xenometabolome) through a kinetics tracking of metabolomes of treated and untreated samples. Those metabolomes are compared time-by-time to estimate the "resilience time" of the samples after treatment. The current study aims to investigate BP residues' dissipation on peach fruits (Prunus persica). For that, an untargeted Liquid Chromatography-Mass Spectrometry metabolomics approach based on the EMF was optimised to separate the xenometabolome of the PPP from the endometabolome of the fruits. This "new version" of the EMF approach is able to target the BP treatment residues' (xenometabolome) dissipation exclusively. Thus, it is able to determine the time needed to have no more residues in the studied matrix: the "dissipation interval". Field experiment was conducted on peach tree orchard against brown rot treated with (i) a plant extract BP (Akivi); (ii) a reference mineral extract BP (Armicarb®); and (iii) a Chemical reference treatment campaign. Formulated Akivi and its by-products' dissipation was monitored, a degradation kinetics appeared but the sampling did not last long enough to allow the determination of the "dissipation interval". Armicarb® and the Chemical reference's residues and by-products showed a persistence pattern along the sampling kinetics. These results indicate that the EMF approach, formerly developed on soil and sediment, is applicable for fruit matrices and can be used to investigate the fate of complex BP treatment on the matrix through the xenometabolome tracking on treated fruits.

Keywords: Biocontrol products; Liquid Chromatography-Mass Spectrometry; Metabolomics; Pesticide dissipation; Residues monitoring.