Multiresidue determination of 256 pesticides in lavandin essential oil by LC/ESI/sSRM: advantages and drawbacks of a sampling method involving evaporation under nitrogen

The determination of 256 multiclass pesticides in lavandin essential oil has been performed by liquid chromatography–electrospray ionization tandem mass spectrometry using the scheduled selected reaction monitoring mode available on a quadrupole-linear ion trap mass spectrometer. With the aim of improving the limits of quantification (LOQs) of the target molecules, a sampling step based on evaporation of the essential oil under a nitrogen flow assisted by controlled heating was tested. The LOQs determined in this case were compared with the values obtained with the classic dilution preparation method. With sampling by dilution, 247 pesticides were detected and quantified at low concentration, with 74 % of the pesticides having LOQs of 10 μg L-1 or less. With the evaporation method, a global improvement of the LOQs was observed, with lower LOQs for 92 active substances and LOQs of 10 μg L-1 or less for 82.8 % of the pesticides. Almost twice as many active substances had an LOQ of 1 μg L-1 or less when the evaporation method was used. Some pesticides exhibited poor recovery or high variance caused by volatilization or degradation during the evaporation step. This behavior was evidenced by the case of thiophanate-methyl, which is degraded to carbendazim. Figure Sampling method by dilution or evaporation in the multiresidue determination of pesticides in essential oils by LC/M

Multiresidue Analysis of Multiclass Pesticides in Lavandin Essential Oil by LC/MS/MS Using the Scheduled Selected Reaction Monitoring Mode

In this paper we describe the development of the first multiclass pesticide residue method applied to essential oils. A total of 70 pesticides covering a wide range of polarity and currently used on essential oil crops have been included in the method. The procedure consists of a 10-fold dilution of lavandin essential oil followed by a direct injection analysis by liquid chromatography/tandem mass spectrometry. The system used is an API 4000 QTrap equipped with an electrospray ionization interface and operating in scheduled selected reaction monitoring acquisition mode. Matrix effects were evaluated by comparing the slopes of matrix-matched and solvent-based calibration curves. Weak signal suppression or enhancement (<20%) was observed for most of the compounds. Method sensitivity was determined statistically by the injection of five matrix-matched calibration curves with the distribution’s normality and the variance’s homogeneity checked before establishment of a suitable regression model. Limits of detection (LODs) and quantification (LOQs) were then determined using the blank standard’s deviation and the slope of the mean curve. The analytical method has been validated for 67 of the 70 pesticides and meets the following LOQs: ≤1 μg/L for 9 pesticides, ≤5 μg/L for 44, ≤10 μg/L for 9, and ≤20 μg/L for

Le caroubier, une espèce méditerranéenne à usages multiples -

En zone méditerranéenne, la surexploitation, le surpâturage et les incendies ont conduit à une régression souvent irréversible de la couverture forestière, avec de très graves conséquences sur l'environnement. Face à cette situation critique, l'utilisation des espèces arborescentes pionnières, à usages multiples, comme le caroubier, adaptée aux aléas climatiques, reste une bonne stratégie. L'objectif de la présente publication est de mettre en évidence l'importance socio-économique du caroubier et de son rôle écologique, dans la perspective d'une promotion de son utilisation pour un développement durable

Effet du stress hydrique osmotique sur la germination et la croissance in vitro du pistachier vrai (Pistacia vera L.).

Afin de mettre en évidence les potentialités d’adaptation du pistachier fruitier (Pistacia  vera L.) à la sécheresse, un stress hydrique osmotique a été induit en conditions in vitro. L’abaissement du potentiel hydrique du milieu de culture se fait par l’adjonction de polyéthylène glycol (PEG-6000). A cet effet, neuf concentrations croissantes ont été étudiées (0 ; 5 ; 10 ; 15 ; 20 ; 25 ; 30 ; 35 et 40 g l-1). Les résultats essentiels obtenus sont les suivants : la germination des axes embryonnaires n’a pas été affectée par la concentration de PEG-6000. Toutefois, le potentiel hydrique des milieux testés a influencé significativement le taux de survie et l’aspect qualitatif des jeunes plantules germées. En effet, plus la concentration de PEG augmente, plus les taux de mortalité et d’hyperhydrie accentuent. Nos résultats ont montré également un effet très marqué du stress hydrique sur la croissance des vitrosemis de Pistacia vera L. En effet, le taux moyen de réduction de différents paramètres de croissance étudiés par rapport au témoin, est de 51,3% pour la longueur de la partie aérienne, 22,8% pour le nombre de feuilles et 19,9% pour la longueur du système racinaire. En ce qui concerne la production des biomasses, l’analyse statistique a révélé un effet significatif de polyéthylène glycol. Les différentes concentrations étudiées ont entraîné une diminution des biomasses des parties aériennes alors que celles des racines ont été améliorées. Mots clés. Pistacia vera, stress hydrique, polyéthylène glycol, germination in vitro, croissance

Neonicotinoid binding, toxicity and expression of nicotinic acetylcholine receptor subunits in the aphid Acyrthosiphon pisum

Neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. They are widely used in crops protection to fight against aphids, which cause severe damage. In the present study we evaluated the susceptibility of the pea aphid Acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (IMI), thiamethoxam (TMX) and clothianidin (CLT). Binding studies on aphid membrane preparations revealed the existence of high and low-affinity binding sites for [3H]-IMI (Kd of 0.16 ± 0.04 nM and 41.7 ± 5.9 nM) and for the nicotinic antagonist [125I]-α-bungarotoxin (Kd of 0.008 ± 0.002 nM and 1.135 ± 0.213 nM). Competitive binding experiments demonstrated that TMX displayed a higher affinity than IMI for [125I]-α-bungarotoxin binding sites while CLT affinity was similar for both [125I]-α-bungarotoxin and [3H]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 µg/ml) and TMX (LC50 = 0.034 µg/ml) were more toxic than CLT (LC50 = 0.118 µg/ml). The effect of TMX could be associated to its metabolite CLT as demonstrated by HPLC/MS analysis. In addition, we found that aphid larvae treated either with IMI, TMX or CLT showed a strong variation of nAChR subunit expression. Using semi-quantitative PCR experiments, we detected for all insecticides an increase of Apisumα10 and Apisumβ1 expressions levels, whereas Apisumβ2 expression decreased. Moreover, some other receptor subunits seemed to be differently regulated according to the insecticide used. Finally, we also demonstrated that nAChR subunit expression differed during pea aphid development. Altogether these results highlight species specificity that should be taken into account in pest management strategies

Using neutral cline decay to estimate contemporary dispersal: a generic tool and its application to a major crop pathogen

Dispersal is a key parameter of adaptation, invasion and persistence. Yet standard population genetics inference methods hardly distinguish it from drift and many species cannot be studied by direct mark-recapture methods. Here, we introduce a method using rates of change in cline shapes for neutral markers to estimate contemporary dispersal. We apply it to the devastating banana pest Mycosphaerella fijiensis, a wind-dispersed fungus for which a secondary contact zone had previously been detected using landscape genetics tools. By tracking the spatio-temporal frequency change of 15 microsatellite markers, we find that σ, the standard deviation of parent–offspring dispersal distances, is 1.2 km/generation1/2. The analysis is further shown robust to a large range of dispersal kernels. We conclude that combining landscape genetics approaches to detect breaks in allelic frequencies with analyses of changes in neutral genetic clines offers a powerful way to obtain ecologically relevant estimates of dispersal in many species

Le comunità energetiche montane. I casi studio di Champdepraz, La Salle e Venaus

A fronte della trasformazione del quadro energetico nazionale causato dai cambiamenti climatici, vi è la necessità di trovare soluzioni alternative per quanto riguarda la produzione, il consumo, la gestione e lo scambio di energia. In questo lavoro vengono esaminati diversi scenari e soluzioni che propongono l'auto-produzione e l'auto-consumo di energia considerando le tecnologie con fonti energetiche rinnovabili (FER) disponibili localmente. In particolare, l’obiettivo è quello di studiare la fattibilità tecnica, economica e ambientale di diverse comunità energetiche montane in Italia, precisamente a La Salle e Champdepraz in Valle d’Aosta e a Venaus in Piemonte. Il progetto individua le potenzialità del territorio partendo da una pianificazione energetica ad ampia scala e successivamente valuta un'aggregazione di utenti con una certa domanda di energia adatti a formare una comunità energetica rinnovabile. Infine si calcolano indicatori e flussi di energia ed emissioni che consentono di valutare i diversi scenari sfruttando anche l’incentivo del Decreto MISE 16/09/2020