Proteogenomic insight into the basis of the insecticide tolerance/resistance of the pollen beetle Brassicogethes (Meligethes) aeneus.

The pollen beetle is a major pest of oilseed rape. Although various resistance mechanisms have been identified, such as kdr (mutation in the sodium channel) and metabolic resistance (CYP overexpression), other "hidden" factors also exist. Some studies have stressed the importance of epistasis as a genetic background. The combination of kdr and metabolic resistance appears to be unfavorable under field conditions in the absence of pesticide selection. The regulation of detoxification enzymes can play an important role, but we highlight different detoxification markers compared to those emphasized in other studies. We also stress the importance of studying the role of markers identified as pathogenesis-related protein 5-like (PR5; upregulated by insecticides) and highlight the role of RNA (DEAD-box) helicases (downregulated by insecticides). Thus, we suggest the importance of epigenetic drivers of resistance/tolerance to pesticides. The key results are similar to those of our previous study, in which deltamethrin treatment of the pollen beetle was also investigated by a proteogenomic approach. Indeed, the mechanism leading to resistance of the pollen beetle may be an innate mechanism that the pollen beetle can also employ in natural habitats, but under field conditions (pesticide exposure), this mechanism is used to survive in response to insecticides. SIGNIFICANCE: Pesticide resistance is a serious problem that hampers the successful production of crops. Understanding the mechanisms of insecticide resistance is highly important for successful pest control, especially when considering integrated pest management. Here, using a proteogenomic approach, we identified novel markers for understanding pollen beetle resistance to pesticides. In addition, future studies will reveal the role of these markers in the multiresistance of pollen beetle populations. We highlight that the proteins identified as PR5, which are known to occur in beetles and are similar to those in plants, may be responsible for tolerance to multiple stresses. In addition, our results indicate that the RNA helicases that exhibited changes in expression may be the epigenetic drivers of multiresistance. The nature of these changes remains an open question, and their relevance in different situations (responses to different stresses) in natural habitats in the absence of pesticides can be proposed.

Neonicotinoids in the agroecosystem: In-field long-term assessment on honeybee colony strength and microbiome.

Bees can be severely affected by various plant protection products (PPP). Among these, neonicotinoid insecticides are of concern as they have been shown to be responsible for extensive honeybee colonies death when released into the environment. Also, sublethal neonicotinoid doses contaminating single honeybees and their colonies (e.g. through contaminated pollen) are responsible for honeybees physiological alterations with probable implication also on microbiome functionality. Honeybees show symbiotic interactions with specific gut bacteria that can enhance the adult host performances. Among the known mechanisms, the modulation of the immune system, the degradation of recalcitrant secondary plant metabolites, pollen digestion, and hormonal signaling, are the most important functional benefits for the host honeybee. To date, few research efforts have aimed at revealing the impact of PPP on the gut microbial community of managed and wild honeybees. The majority of the existing literature relays on cage or semifield tests of short duration for research investigating neonicotinoids-gut microbiome interactions. This research wanted to unravel the impact of two neonicotinoids (i.e. imidacloprid and thiacloprid) in natural field conditions up to 5 weeks of exposure. A long-term impact of neonicotinoids on gut microbial community of honeybees was observed. The alterations affected several microbial genera and species such as Frischella spp., lactobacilli and bifidobacteria, whose shifting is implicated in intestinal dysbiosis. Long-term impact leading to dysbiosis was detected in case of exposure to imidacloprid, whereas thiacloprid exposure stimulated temporary dysbiosis. Moreover, the microbial diversity was significantly reduced in neonicotinoid-treated groups. Overall, the reported results support a compromised functionality of the gut microbial community, that might reflect a lower efficiency in the ecosystemic functionality of honeybees.

Simultaneous determination of neonicotinoids and fipronils in tea using a modified QuEChERS method and liquid chromatography-high resolution mass spectrometry.

The widespread use of neonicotinoids (NEOs) and fipronils (FIPs) as insecticides in modern agriculture has been widely investigated because of their adverse effects on human health. This study aimed to develop an accurate quantitative approach to analyze NEOs and FIPs in tea by using a modified QuEChERS method based on dispersive solid-phase extraction procedure coupled with liquid chromatography-high resolution mass spectrometry. To minimize matrix interferences largely, we selected polyvinylpolypyrrolidone (PVPP) and strong cationic exchange adsorbent (PCX) as dispersive adsorbents to eliminate polyphenols and caffeine from tea extract, respectively. Under optimal conditions, a slight matrix effect was observed for NEOs and FIPs due to the highest reductions of polyphenols and caffeine (94% and 88%, respectively). The method was validated by the European Medicines Agency and Eurachem guidelines and was successfully applied to tea samples for NEOs and FIPs analysis. NEOs and FIPs were commonly detected in tea.

Persistence of thiacloprid and deltamethrin residues in tea grown at different locations of North-East India.

In order to examine the residues of thiacloprid (90 and 180 g a.i./ha) and deltamethrin (10 and 20 g a.i./ha) in fresh tea leaves, made tea and tea infusion, field experiments were conducted at three different locations viz. Kamalpur tea estate, Darjeeling; West Bengal, Teok tea Estate and AAU, Jorhat; Assam in India. Regardless of location and doses, residues of both the insecticides dissipated following first order kinetics. The half-life of Thiacloprid (4.93-5.38 days) was longer than that of deltamethrin (1.78-1.94 days). Processing of green tea leaves reduced the residue level of thiacloprid and deltamethrin in made tea. No residues of both these insecticides could be detected in tea infusion. With respect to the phenolic distribution in tea, a marked increase in total catechin monomers with thiacloprid and greater accumulation of EGCG and ECG (indices of phenol quality) with deltamethrin were observed.

Ameliorative effect of flaxseed oil against thiacloprid-induced toxicity in rats: hematological, biochemical, and histopathological study.

The present study was carried out to evaluate the hematological, biochemical, and histopathological changes due to thiacloprid toxicity, and the potential protective role of flaxseed oil in male Wistar albino rats. Subacute thiacloprid intoxication induced a significant increase in RBCs, Hb, PCV, and WBCs count, and bone marrow micronucleus (MN) formation. Moreover, there was a significant increase in serum biochemical parameters related to hepatic injury: alanine aminotransferase (ALT) and alkaline phosphatase (ALP). Serum total protein and albumin levels were significantly reduced. Thiacloprid increases tumor necrosis factor-alpha (TNF-α) and interleukine-2(IL-2). There was a significant decrease in glutathione-S-transferase, while the lipid peroxidation (MDA) and cytochrome P450 activity were significantly increased. Flaxseed oil coadministration partially retrieved the changes in all studied parameters. Thiacloprid induced histopathological liver damage, which was minimized as a result of flaxseed oil treatment. In general, it was concluded that, flaxseed oil able to protect against thiacloprid-induced hepatoxicity.

Molecular recognition of thiaclopride by Aplysia californica AChBP: new insights from a computational investigation.

The binding of thiaclopride (THI), a neonicotinoid insecticide, with Aplysia californica acetylcholine binding protein (Ac-AChBP), the surrogate of the extracellular domain of insects nicotinic acetylcholine receptors, has been studied with a QM/QM' hybrid methodology using the ONIOM approach (M06-2X/6-311G(d):PM6). The contributions of Ac-AChBP key residues for THI binding are accurately quantified from a structural and energetic point of view. The importance of water mediated hydrogen-bond (H-bond) interactions involving two water molecules and Tyr55 and Ser189 residues in the vicinity of the THI nitrile group, is specially highlighted. A larger stabilization energy is obtained with the THI-Ac-AChBP complex compared to imidacloprid (IMI), the forerunner of neonicotinoid insecticides. Pairwise interaction energy calculations rationalize this result with, in particular, a significantly more important contribution of the pivotal aromatic residues Trp147 and Tyr188 with THI through CH···π/CH···O and π-π stacking interactions, respectively. These trends are confirmed through a complementary non-covalent interaction (NCI) analysis of selected THI-Ac-AChBP amino acid pairs.