Identification and evaluation of Escherichia coli strain ATCC 8739 as a surrogate for thermal inactivation of enterohemorrhagic Escherichia coli in fruit nectars: Impact of applied techniques on the decimal reduction time.

The objective of this study was to identify a suitable surrogate for E. coli O157:H7 strain 19685/91 and O113:H21 strain TS18/08, by assessing their thermal resistance at temperatures of 60 °C, 65 °C, and 72 °C in strawberry nectar. The influence of the matrix and the research methodology on the decimal reduction time (D-value) was investigated. Thermal kinetics and safety assessment demonstrated that E. coli ATCC 8739 is a suitable surrogate. The study demonstrated that the presence of fruit particles in the nectar increased thermal resistance of the tested strains. Variations in D-values were observed depending on the research method employed, with D-values in glass capillaries were up to 6.6 times lower compared to larger sample volumes. Encapsulation of E. coli ATCC 8739 exhibited high efficiency of 90.25 ± 0.26% and maintained stable viable counts after 26 days of storage in strawberry nectar at 4 °C. There were no significant differences in thermal resistance between surrogates directly inoculated into strawberry nectar and those encapsulated in alginate beads. Additionally, the encapsulated strains did not migrate outside the beads. Therefore, encapsulated E. coli ATCC 8739 in alginate beads can be effectively utilized in industrial settings to validate thermal treatments as a reliable and safe method.

Eco-evolutionary processes shaping floral nectar sugar composition.

Floral nectar sugar composition is assumed to reflect the nutritional demands and foraging behaviour of pollinators, but the relative contributions of evolutionary and abiotic factors to nectar sugar composition remain largely unknown across the angiosperms. We compiled a comprehensive dataset on nectar sugar composition for 414 insect-pollinated plant species across central Europe, along with phylogeny, paleoclimate, flower morphology, and pollinator dietary demands, to disentangle their relative effects. We found that phylogeny was strongly related with nectar sucrose content, which increased with the phylogenetic age of plant families, but even more strongly with historic global surface temperature. Nectar sugar composition was also defined by floral morphology, though it was not related to our functional measure of pollinator dietary demands. However, specialist pollinators of current plant-pollinator networks predominantly visited plant species with sucrose-rich nectar. Our results suggest that both physiological mechanisms related to plant water balance and evolutionary effects related to paleoclimatic changes have shaped floral nectar sugar composition during the radiation and specialisation of plants and pollinators. As a consequence, the high velocity of current climate change may affect plant-pollinator interaction networks due to a conflicting combination of immediate physiological responses and phylogenetic conservatism.

Following Regulation, Imidacloprid Persists and Flupyradifurone Increases in Nontarget Wildlife.

After regulation of pesticides, determination of their persistence in the environment is an important indicator of effectiveness of these measures. We quantified concentrations of two types of systemic insecticides, neonicotinoids (imidacloprid, acetamiprid, clothianidin, thiacloprid, and thiamethoxam) and butenolides (flupyradifurone), in off-crop nontarget media of hummingbird cloacal fluid, honey bee (Apis mellifera) nectar and honey, and wildflowers before and after regulation of imidacloprid on highbush blueberries in Canada in April 2021. We found that mean total pesticide load increased in hummingbird cloacal fluid, nectar, and flower samples following imidacloprid regulation. On average, we did not find evidence of a decrease in imidacloprid concentrations after regulation. However, there were some decreases, some increases, and other cases with no changes in imidacloprid levels depending on the specific media, time point of sampling, and site type. At the same time, we found an overall increase in flupyradifurone, acetamiprid, thiamethoxam, and thiacloprid but no change in clothianidin concentrations. In particular, flupyradifurone concentrations observed in biota sampled near agricultural areas increased twofold in honey bee nectar, sevenfold in hummingbird cloacal fluid, and eightfold in flowers after the 2021 imidacloprid regulation. The highest residue detected was flupyradifurone at 665 ng/mL (parts per billion [ppb]) in honey bee nectar. Mean total pesticide loads were highest in honey samples (84 ± 10 ppb), followed by nectar (56 ± 7 ppb), then hummingbird cloacal fluid (1.8 ± 0.5 ppb), and least, flowers (0.51 ± 0.06 ppb). Our results highlight that limited regulation of imidacloprid does not immediately reduce residue concentrations, while other systemic insecticides, possibly replacement compounds, concurrently increase in wildlife. Environ Toxicol Chem 2024;43:1497-1508. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Ultrastructure and development of the floral nectary from Borago officinalis L. and phytochemical changes in its secretion.

Although Boraginaceae have been classified as good sources of nectar for many insects, little is still known about their nectar and nectaries. Thus, in the present contribution, we investigated the nectar production dynamics and chemistry in Borago officinalis L. (borage or starflower), together with its potential interaction capacity with pollinators. A peak of nectar secretion (∼5.1 µL per flower) was recorded at anthesis, to decrease linearly during the following 9 days. In addition, TEM and SEM analyses were performed to understand ultrastructure and morphological changes occurring in borage nectary before and after anthesis, but also after its secretory phase. Evidence suggested that nectar was transported by the apoplastic route (mainly from parenchyma to epidermis) and then released essentially by exocytotic processes, that is a granulocrine secretion. This theory was corroborated by monitoring the signal of complex polysaccharides and calcium, respectively, via Thiéry staining and ESI/EELS technique. After the secretory phase, nectary underwent degeneration, probably through autophagic events and/or senescence induction. Furthermore, nectar (Nec) and other flower structures (i.e., sepals, gynoecia with nectaries, and petals) from borage were characterized by spectrophotometry and HPLC-DAD, in terms of plant secondary metabolites, both at early (E-) and late (L-) phase from anthesis. The content of phytochemicals was quantified and discussed for all samples, highlighting potential biological roles of these compounds in the borage flower (e.g., antimicrobial, antioxidant, staining effects). Surprisingly, a high significant accumulation of flavonoids was registered in L-Nec, with respect to E-Nec, indicating that this phenomenon might be functional and able to hide molecular (e.g., defence against pathogens) and/or ecological (e.g., last call for pollinators) purposes. Indeed, it is known that these plant metabolites influence nectar palatability, encouraging the approach of specialist pollinators, deterring nectar robbers, and altering the behaviour of insects.

Chemical ecology of nectar-mosquito interactions: recent advances and future directions.

Mosquitoes, males and females, rely on sugar-rich resources, including floral nectar as a primary source of sugar to meet their energy and nutritional needs. Despite advancements in understanding mosquito host-seeking and blood-feeding preferences, significant gaps in our knowledge of the chemical ecology mediating mosquito-nectar associations remain. The influence of such association with nectar on mosquito behavior and the resulting effects on their fitness are also not totally understood. It is significant that floral nectar frequently acts as a natural habitat for various microbes (e.g. bacteria and yeast), which substantially alter nectar characteristics, influencing the nutritional ecology of flower-visiting insects, such as mosquitoes. The role of nectar-inhabiting microbes in shaping the nectar-mosquito interactions remains, however, under-researched. This review explores recent advances in understanding the role of such multitrophic interactions on the fitness and life history traits of mosquitoes and outlines future directions for research toward their control as disease vectors.

Exploring the Formation of Chemical Markers in Chaste Honey by Comparative Metabolomics: From Nectar to Mature Honey.

Identification of chemical markers is important to ensure the authenticity of monofloral honey; however, the formation of chemical markers in honey has received little attention. Herein, using comparative metabolomics, we first identified chemical markers in chaste honey and then explored their formation and accumulation from nectar to mature honey. We identified agnuside and p-hydroxybenzoic acid glucosides as chemical markers for chaste honey. Besides, we developed an UHPLC-MS/MS method for quantifying these markers and found that their levels varied significantly across sample sources. We compared the presence of these compounds in chaste nectar and mature honey. The outcomes underscore that these characteristic compounds are not simply delivered from nectar to mature honey, and activities of honeybees (collecting and processing) play a pivotal role in their formation and accumulation. These observations shed light on how mature honey can form its unique qualities with a rich assortment of natural bioactive compounds, potentially supporting health benefits.

Generation, degradation mechanism, and toxicity evaluation of pigmented compounds in Leucosceptrum canum nectar.

Leucosceptrum canum nectar (LCN) emerges as a novel food resource, distinguished by its unique dark brown hue. This study delves into the composition and toxicity assessment of novel pigments within LCN. Through liquid chromatography-tandem mass spectrometry (LC-MS/MS) and chemical synthesis, seventeen 2,5-di-(N-(-)-prolyl)-para-benzoquinone (DPBQ) analogs in LCN were identified. These compounds are synthesized in LCN via the Michael addition reaction, utilizing p-benzoquinone (BQ), derived from phenol metabolism, and amino acids as substrates in an alkaline environment (pH = 8.47 ± 0.06) facilitated by dissolved ammonia and the presence of alkaloids. Analytical techniques, including principal component analysis (PCA), orthogonal partial least squares discrimination analysis (OPLS-DA), and volcano plot analysis, were employed to investigate DPBQ analog degradation within the nectar and honey's unique environments. Toxicity assays revealed that DPBQ analogs exhibited no toxicity, displaying a significant difference in toxicity compared to the precursor compound BQ at concentrations exceeding 25 µM.

Pesticide residues in ornamental plants marketed as bee friendly: Levels in flowers, leaves, roots and soil.

Ornamental plants rich in pollen and nectar are often marketed as "pollinator-friendly" by flower retailers. However, even though the plants are attractive from a foraging perspective, i.e pollen and nectar rich, bees and other pollinating insects could be at risk from exposure of pesticide residues on the plants or from pesticide used during production. Pesticides used in ornamental plant production could lead to environmental emissions both during cultivation, at retailer displays and when planted in gardens by the consumers. This study aims to investigate what pesticides that are used in the production of perennial ornamental plants sold in Sweden and if the residues could pose a risk for wild pollinators. We analyze an array of 536 pesticides in whole flowers, leaves, roots and soil of 54 individual (46 had flowers) perennial plants specifically marketed as "bee friendly". In addition, seeds from 65 seed bags were analyzed for the same pesticides. Our result show for the first time the distribution of pesticide residues between flowers, leaves, roots and soils of ornamental plants. We also show that all ornamental plants analyzed contained at least one pesticide, and that some samples contained up to 19 different substances.

An updated review of functional ingredients of Manuka honey and their value-added innovations.

Manuka honey (MH) is a highly prized natural product from the nectar of Leptospermum scoparium flowers. Increased competition on the global market drives MH product innovations. This review updates comparative and non-comparative studies to highlight nutritional, therapeutic, bioengineering, and cosmetic values of MH. MH is a good source of phenolics and unique chemical compounds, such as methylglyoxal, dihydroxyacetone, leptosperin glyoxal, methylsyringate and leptosin. Based on the evidence from in vitro, in vivo and clinical studies, multifunctional bioactive compounds of MH have exhibited anti-oxidative, anti-inflammatory, immunomodulatory, anti-microbial, and anti-cancer activities. There are controversial topics related to MH, such as MH grading, safety/efficacy, implied benefits, and maximum levels of contaminants concerned. Artificial intelligence can optimize MH studies related to chemical analysis, toxicity prediction, multi-functional mechanism exploration and product innovation.

Residue dynamics of a contact and a systemic fungicide in pollen, nectar, and other plant matrices of courgette (Cucurbita pepo L.).

Pollen and nectar can be contaminated with a range of pesticides, including insecticides, fungicides, and herbicides. Since these matrices are important food sources for pollinators and other beneficial insects, their contamination can represent a key route of exposure. However, limited knowledge exists with respect to pesticide residue levels and their dynamics in these matrices for many crops and active ingredients (AIs). We used controlled glasshouse studies to investigate the residue dynamics of a systemic (cyprodinil) and a contact (fludioxonil) fungicide in the floral matrices and other plant parts of courgette/zucchini (Cucurbita pepo L.). We aimed to better understand the processes behind residue accumulation and decline in pollen and nectar. Each AI was applied to plants, either by spraying whole plants or by targeted spraying onto leaves only. Samples of pollen, nectar, anthers, flowers, and leaves were taken on the day of application and each subsequent morning for up to 13 days and analysed for residues using LC-MS/MS. Significant differences in residue levels and dynamics were found between AIs and floral matrices. The present study allowed for the identification of potential routes by which residues translocate between tissues and to link those to the physicochemical properties of each AI, which may facilitate the prediction of residue levels in pollen and nectar. Residues of the contact AI declined more quickly than those of the systemic AI in pollen and nectar. Our results further suggest that the risk of oral exposure for pollinators may be considerably reduced by using contact AIs during the green bud stage of plants, but application of systemic compounds could still result in a low, but continuous long-term exposure for pollinators with limited decline.

Residues of sulfoxaflor and its metabolites in floral and extrafloral nectar from Hibiscus rosa-sinensis L. (Malvaceae) with or without co-application of tebuconazole.

Systemic pesticide exposure through nectar is a growing global concern linked to loss of insect diversity, especially pollinators. The insecticide sulfoxaflor and the fungicide tebuconazole are currently widely used systemic pesticides which are toxic to certain pollinators. However, their metabolisms in floral or extrafloral nectar under different application methods have not yet been well studied. Hibiscus rosa-sinensis was exposed to sulfoxaflor and tebuconazole via soil drenching and foliar spraying. Sulfoxaflor, tebuconazole, and their main metabolites in floral and extrafloral nectar, soil, and leaves were identified and quantified using liquid chromatography coupled with triple quadrupole mass spectrometry (LC-QqQ MS). The chemical compositions of unexposed and contaminated H. rosa-sinensis floral nectar or extrafloral nectar were compared using regular biochemical methods. The activities of two pesticide detoxifying enzymes, glutathione-s-transferase and nitrile hydratase, in H. rosa-sinensis nectar were examined using LC-MS and spectrophotometry. The floral nectar proteome of H. rosa-sinensis was analysed using high-resolution orbitrap-based MS/MS analysis to screen for sulfoxaflor and tebuconazole detoxifying enzymes. H. rosa-sinensis can absorb sulfoxaflor and tebuconazole through its roots or leaf surfaces and secrete them into floral nectar and extrafloral nectar. Both sulfoxaflor and tebuconazole and their major metabolites were present at higher concentrations in extrafloral nectar than in floral nectar. X11719474 was the dominant metabolite of sulfoxaflor in the nectars we studied. Compared with soil application, more sulfoxaflor and tebuconazole remained in their original forms in floral nectar and extrafloral nectar after foliar application. Sulfoxaflor and tebuconazole exposure did not modify the chemical composition of floral or extrafloral nectar. No active components, including proteins in the nectar, were detected to be able to detoxify sulfoxaflor.

Global assessment of honeybee exposure to pesticides through guttation consumption: An indicator approach.

Guttation consumption is a potential pathway of pesticide residue exposure in honeybees. However, modeling tools for assessing honeybee exposure to pesticide residues in guttation drops are lacking. In this study, we propose an indicator-based approach for qualitatively or quantitatively analyzing the guttation-based exposure pathway, allowing us to conduct region-specific pesticide residue exposure assessments for honeybees. Exposure scores (the product of guttation production and residue level scores) were established to compare or rank honeybee exposure to pesticide residues via guttation intake across locations using three specified indicators (i.e., air temperature, relative humidity, and precipitation intensity). Warm, dry regions had high residue level scores (indicating high residue levels in guttation), whereas cold, wet regions had high guttation production scores (indicating high possibilities of guttation formation on leaf surfaces); their exposure scores were a combination of these two values. We evaluated and ranked honeybee exposure to imidacloprid residue across regions in Brazil, China, the United States, and selected European Union member states, revealing that pesticide application in many Brazilian federative units may raise honeybee risks due to high exposure scores. We also compared the guttation pathway to other common exposure pathways (nectar and pollen), suggesting that for some moderately lipophilic compounds, the guttation exposure pathway may not be ignored and should be further evaluated.

A critical review on the accumulation of neonicotinoid insecticides in pollen and nectar: Influencing factors and implications for pollinator exposure.

Neonicotinoids are a class of neuro-active insecticides widely used to protect major crops, primarily because of their broad-spectrum insecticidal activity and low vertebrate toxicity. Owing to their systemic nature, plants readily take up neonicotinoids and translocate them through roots, leaves, and other tissues to flowers (pollen and nectar) that serve as a critical point of exposure to pollinators foraging on treated plants. The growing evidence for potential adverse effects on non-target species, especially pollinators, and persistence has raised serious concerns, as these pesticides are increasingly prevalent in terrestrial and aquatic systems. Despite increasing research efforts, our understanding of the potential toxicity of neonicotinoids and the risks they pose to non-target species remains limited. Therefore, this critical review provides a succinct evaluation of the uptake, translocation, and accumulation processes of neonicotinoids in plants and the factors that may affect the eventual build-up of neonicotinoids in pollen and nectar. The role of plant species, as well as the physicochemical properties and application methods of neonicotinoids is discussed. Potential knowledge gaps are identified, and questions meriting future research are suggested for improving our understanding of the relationship between neonicotinoid residues in plants and exposure to pollinators.

In Which Way Do the Flower Properties of the Specialist Orchid Goodyera repens Meet the Requirements of Its Generalist Pollinators?

This article is the next part of a series of studies documenting the influence of flower traits on the reproductive success (RS) of orchids. Knowledge of factors influencing RS helps to understand the mechanisms and processes crucial for shaping plant-pollinator interactions. The aim of the present study was to determine the role of flower structure and nectar composition in shaping the RS of the specialist orchid Goodyea repens, which is pollinated by generalist bumblebees. We found a high level of pollinaria removal (PR) and female reproductive success (fruiting, FRS) as well as a high level of variation between populations, although in certain populations pollination efficiency was low. Floral display traits, mainly inflorescence length, influenced FRS in certain populations. Among the flower traits, only the height of flowers was correlated with FRS in one population, suggesting that the flower structure of this orchid is well adapted to pollination by bumblebees. The nectar of G. repens is diluted and dominated by hexoses. Sugars were less important in shaping RS than amino acids. At the species level, twenty proteogenic and six non-proteogenic AAs were noted, along with their differentiated amounts and participation in particular populations. We found that distinct AAs or their groups mainly shaped PR, especially when correlations were considered at the species level. Our results suggest that both the individual nectar components and the ratios between them have an impact on G. repens RS. Because different nectar components influence the RS parameters in different ways (i.e., negatively or positively), we suggest that different Bombus species play the role of main pollinators in distinct populations.

Nectar guides and floral nectary in Lamium album L. subsp. album: structure and histochemistry in light, fluorescence, and electron microscopy.

Lamium album is a native common plant growing in Eurasia. It is used in medicine and cosmetics and is highly valued in apiculture. The aim of the study was to investigate the structure of the floral nectary in three stages of flower development. Additionally, histochemical studies of the nectary and nectar guides present on the lower corolla lobe were carried out. No detailed analyses of nectary tissues in this species have been conducted to date. The present analyses were performed with the use of light, fluorescence, and scanning electron microscopy. The nectary gland in the flowers of Lamium album subsp. album formed an incomplete ring at the ovary base. The nectarostomata were arranged in clusters only in the adaxial epidermis of the anterior part of the nectary. During the secretory activity of the nectary (1st day of flowering), numerous small vacuoles and cells with large lobulate nuclei with surrounding plastid clusters were observed in the epidermis and glandular parenchyma cells. The vascular bundles contained xylem and phloem elements. Corolla wilting (3rd day of flowering) was accompanied by destructive changes in the nectary parenchyma, leading to the formation of empty spaces and appearance of cell remnants on the nectary surface. The histochemical analyses revealed the presence of starch and phenolic compounds as well as acidic and neutral lipids, which are characteristic of essential oils, in the nectary tissues. The nectar guides were composed of large yellow papillae containing phenolic compounds and acidic and neutral lipids, which were also present in glandular trichomes and abaxial parenchyma cells. The present study has demonstrated that the scent of Lamium album subsp. album flowers is produced with the involvement of essential oils contained in adaxial and abaxial epidermis cells, glandular trichomes, and nectary tissues.

Dihydroxyacetone in the Floral Nectar of Ericomyrtus serpyllifolia (Turcz.) Rye (Myrtaceae) and Verticordia chrysantha Endl. (Myrtaceae) Demonstrates That This Precursor to Bioactive Honey Is Not Restricted to the Genus Leptospermum (Myrtaceae).

Ma̅nuka honey is known for its strong bioactivity, which arises from the autocatalytic conversion of 1,3-dihydroxyacetone (dihydroxyacetone, DHA) in the floral nectar of Leptospermum scoparium (Myrtaceae) to the non-peroxide antibacterial compound methylglyoxal during honey maturation. DHA is also a minor constituent of the nectar of several other Leptospermum species. This study used high-performance liquid chromatography to test whether DHA was present in the floral nectar of five species in other genera of the family Myrtaceae: Ericomyrtus serpyllifolia (Turcz.) Rye, Chamelaucium sp. Bendering (T.J. Alford 110), Kunzea pulchella (Lindl.) A.S. George, Verticordia chrysantha Endl., and Verticordia picta Endl. DHA was found in the floral nectar of two of the five species: E. serpyllifolia and V. chrysantha. The average amount of DHA detected was 0.08 and 0.64 µg per flower, respectively. These findings suggest that the accumulation of DHA in floral nectar is a shared trait among several genera within the family Myrtaceae. Consequently, non-peroxide-based bioactive honey may be sourced from floral nectar outside the genus Leptospermum.

Diversity of staminal nectariferous appendages in disymmetric and zygomorphic flowers of Fumarioideae (Papaveraceae).

Staminal nectaries show diversity in their position, size, shape, color, and number in Ranunculales. In Papaveraceae, nectaries only appear at the base of stamen in these lineages with disymmetric and zygomorphic flowers. However, the diversity of the staminal nectaries' developmental characteristics and structure is unknown. The diversity of staminal nectaries of Hypecoum erectum, Ichtyoselmis macrantha, Adlumia asiatica, Dactylicapnos torulosa, Corydalis edulis, and Fumaria officinalis (six species belonging to six genera, respectively) in the Fumarioideae was investigated under scanning electron microscopy, light microscopy, and transmission electron microscopy. In all species studied, according to the developmental characteristics of the nectaries, four developmental stages can be divided into initiation, enlargement, differentiation, and maturation, and the number of nectaries can be determined at the stage of initiation (stage 1), and morphological differentiation occurs at the developmental stage 3. The staminal nectaries consist of secretory epidermis, parenchyma tissue, and phloem with some sieve tube elements reaching the secretory parenchyma cells; however, the number of cell layers of parenchyma can vary from 30 to 40 in I. macrantha and D. torulosa, to only 5 to 10 like in F. officinalis. Secretory epidermis cells are larger than secretory parenchyma cells with abundant microchannels on the outer cell wall. There were abundant mitochondria, Golgi bodies, rough endoplasmic reticulum, and plastids in secretory parenchyma cells. Nectar is stored in the intercellular space and exuded to the exterior via microchannels. In A. asiatica, according to the evidence of small secretory cell characteristics such as dense cytoplasm, and numerous mitochondria, together with the filamentous secretions present on the surface of epidermal cells on groove, it can be inferred that the U-shaped sulcate which is located in the white projection formed at the filament of triplets in A. asiatica is nectariferous.

A conserved hymenopteran-specific family of cytochrome P450s protects bee pollinators from toxic nectar alkaloids.

Many plants produce chemical defense compounds as protection against antagonistic herbivores. However, how beneficial insects such as pollinators deal with the presence of these potentially toxic chemicals in nectar and pollen is poorly understood. Here, we characterize a conserved mechanism of plant secondary metabolite detoxification in the Hymenoptera, an order that contains numerous highly beneficial insects. Using phylogenetic and functional approaches, we show that the CYP336 family of cytochrome P450 enzymes detoxifies alkaloids, a group of potent natural insecticides, in honeybees and other hymenopteran species that diverged over 281 million years. We linked this function to an aspartic acid residue within the main access channel of CYP336 enzymes that is highly conserved within this P450 family. Together, these results provide detailed insights into the evolution of P450s as a key component of detoxification systems in hymenopteran species and reveal the molecular basis of adaptations arising from interactions between plants and beneficial insects.

Floral Phytochemistry: Impact of Volatile Organic Compounds and Nectar Secondary Metabolites on Pollinator Behavior and Health.

Plants produce a plethora of phytochemicals including sugars, amino acids (AAs), volatile organic compounds (VOCs) and secondary metabolites (SMs) with different ecological functions. To attract pollinators and defenders and ensure reproductive success, plants mainly rely on VOCs, while to reward insects, plants synthesize nectar rich in sugars and AAs. Furthermore, plant SMs can play various roles. Some components are able to interact with the nervous system of insects by binding to neuron receptor proteins and thus manipulate pollinator behavior. Others, like alkaloids and phenolics, protect from nectar robbers and enhance memory and foraging efficiency, or, as in the case of flavonoids, exhibit high antioxidant activities supporting pollinator well-being. This review discusses the impact of VOCs and nectar SMs on insect behavior and pollinator health.

Pesticide mixtures detected in crop and non-target wild plant pollen and nectar.

Cultivation of mass flowering entomophilous crops benefits from the presence of managed and wild pollinators, who visit flowers to forage on pollen and nectar. However, management of these crops typically includes application of pesticides, the presence of which may pose a hazard for pollinators foraging in an agricultural environment. To determine the levels of potential exposure to pesticides, their presence and concentration in pollen and nectar need assessing, both within and beyond the target crop plants. We selected ten pesticide compounds and one metabolite and analysed their occurrence in a crop (Brassica napus) and a wild plant (Rubus fruticosus agg.), which was flowering in field edges. Nectar and pollen from both plants were collected from five spring and five winter sown B. napus fields in Ireland, and were tested for pesticide residues, using QuEChERS and Liquid Chromatography tandem mass spectrometry (LC-MS/MS). Pesticide residues were detected in plant pollen and nectar of both plants. Most detections were from fields with no recorded application of the respective compounds in that year, but higher concentrations were observed in recently treated fields. Overall, more residues were detected in B. napus pollen and nectar than in the wild plant, and B. napus pollen had the highest mean concentration of residues. All matrices were contaminated with at least three compounds, and the most frequently detected compounds were fungicides. The most common compound mixture was comprised of the fungicides azoxystrobin, boscalid, and the neonicotinoid insecticide clothianidin, which was not recently applied on the fields. Our results indicate that persistent compounds like the neonicotinoids, should be continuously monitored for their presence and fate in the field environment. The toxicological evaluation of the compound mixtures identified in the present study should be performed, to determine their impacts on foraging insects that may be exposed to them.