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Olfaction is a major sense in Varroa destructor. In natural conditions, it is known that this honey bee parasite relies on kairomones to detect its host or to reproduce. Yet, in artificial conditions, the parasite is able to feed and survive for a few days even though most honey bee pheromones are lacking. Other key cues are thus probably involved in V. destructor perception of its close environment. Here, we used several artificial feeding designs to explore the feeding behaviour of the parasite when it is deprived of olfactory cues. We found that V. destructor is still able to feed only guided by physical cues. The detection of the food source seems to be shape-related as a 3D membrane triggers arrestment and exploration more than a 2D membrane. The tactile sense of V. destructor could thus be essential to detect a feeding site, although further studies are needed to assess the importance of this sense combined with olfaction in natural conditions.

The nutritional physiology of parasites is often overlooked although it is at the basis of host-parasite interactions. In the case of Varroa destructor, one of the major pests of the Western honey bee Apis mellifera, the nature of molecules and tissues ingested by the parasite is still not completely understood. Here, the V. destructor feeding biology was explored through artificial feeding, dissection of the mite's gut and proteomic analyses. More specifically, the proteome of guts extracted from starved mites and honey bee-fed mites was compared to highlight both the parasite proteins likely involved in food processing and the honey bee proteins actually ingested by the mite. We could identify 25 V. destructor candidate proteins likely involved in the parasite digestion. As the host developmental stages infested by the mite are diverse, we also focused on the identity and on the origin of honey bee proteins ingested by the mite when it feeds on larvae, pupae or adults. We highlighted profiles of consumed honey bee proteins and their variations throughout the V. destructor life cycle. These variations matched the ones observed in the honey bee hemolymph, showing that this tissue is an important part of the mite's diet. Based on the variations of abundance of the most consumed honey bee proteins and on their functions, the potential implication of these key candidate nutrients in V. destructor reproduction is also discussed.

Abstract Background Varroa destructor is the major ectoparasite of the western honey bee (Apis mellifera). Through both its parasitic life-cycle and its role as a vector of viral pathogens, it can cause major damage to honey bee colonies. The deformed wing virus (DWV) is the most common virus transmitted by this ectoparasite, and the mite is correlated to increased viral prevalence and viral loads in infested colonies. DWV variants A and B (DWV-A and DWV-B, respectively) are the two major DWV variants, and they differ both in their virulence and transmission dynamics. Methods We studied the transmission of DWV between bees, parasitic mites and their offspring by quantifying DWV loads in bees and mites collected in in vitro and in situ environments. In vitro, we artificially transmitted DWV-A to mites and quantified both DWV-A and DWV-B in mites and bees. In situ, we measured the natural presence of DWV-B in bees, mites and mites’ offspring. Results Bee and mite viral loads were correlated, and mites carrying both variants were associated with higher mortality of the infected host. Mite infestation increased the DWV-B loads and decreased the DWV-A loads in our laboratory conditions. In situ, viral quantification in the mite offspring showed that, after an initially non-infected egg stage, the DWV-B loads were more closely correlated with the foundress (mother) mites than with the bee hosts. Conclusions The association between mites and DWV-B was highlighted in this study. The parasitic history of a mite directly impacts its DWV infection potential during the rest of its life-cycle (in terms of variant and viral loads). Regarding the mite’s progeny, we hypothesize that the route of contamination is likely through the feeding site rather than by vertical transmission, although further studies are needed to confirm this hypothesis. Graphical Abstract

The nutritional physiology of parasites is often overlooked although it is at the basis of host-parasite interactions. In the case of Varroa destructor, one of the major pests of the Western honey bee Apis mellifera, the nature of molecules and tissues ingested by the parasite is still not completely understood. Here, the V. destructor feeding biology was explored through artificial feeding, dissection of the mite's gut and proteomic analyses. More specifically, the proteome of guts extracted from starved mites and honey bee-fed mites was compared to highlight both the parasite proteins likely involved in food processing and the honey bee proteins actually ingested by the mite. We could identify 25 V. destructor candidate proteins likely involved in the parasite digestion. As the host developmental stages infested by the mite are diverse, we also focused on the identity and on the origin of honey bee proteins ingested by the mite when it feeds on larvae, pupae or adults. We highlighted profiles of consumed honey bee proteins and their variations throughout the V. destructor life cycle. These variations matched the ones observed in the honey bee hemolymph, showing that this tissue is an important part of the mite's diet. Based on the variations of abundance of the most consumed honey bee proteins and on their functions, the potential implication of these key candidate nutrients in V. destructor reproduction is also discussed. Author summary: Varroa destructor is one of the major parasitic pests in modern beekeeping worldwide. Since it shifted host from Eastern to Western honey bees, it was shown to weaken colonies by feeding on both immature and adult stages while transmitting several deadly viruses in the process. Nutrition, an overlooked aspect of parasite biology, is thus a key to comprehend the V. destructor life cycle and its impacts on its honey bee host. We explored the feeding physiology of this ectoparasite by analysing the protein content of its isolated gut to compare it with the protein composition of the honey bee tissues ingested. We highlighted several mite proteins probably involved in digestion and many honey bee derived proteins acquired during the feeding. Honey bee hemolymph is an important part of the mite's diet although the diet could vary throughout the cycle, especially when mites feed on adult bees. The abundance of the most regularly ingested honey bee proteins such as Vitellogenin or Hexamerin varies throughout the bee development and could directly impact the parasite physiology. The analysis and identification of key proteins required for the mite's survival and reproduction will pave the way for the development of more specific control strategies. [ABSTRACT FROM AUTHOR]

Varroa destructor is one of the major parasites threatening the Western honeybee Apis mellifera if not managed. Yet, sustainable treatments are rare due to the difficulty to impact the mite without disturbing the host. One current soft acaricide used by beekeepers is lactic acid, although its way of action on the parasite remains poorly understood. We undertook the first investigation about lactic acid on V. destructor at the individual level under artificial conditions. We found that lactic acid does not kill V. destructor but rather interferes with its attachment skills. In particular we focused on its arolia, mite's soft pads, and highlighted shape and fluid modifications induced by lactic acid. We also analysed fitness costs and behavioural effects of impaired attachment due to lactic acid on mites. We observed a reduced locomotion as well as a potential lower reproduction but no impact on nutrition. Even if conducted under artificial conditions, these results significantly improve our understanding of lactic acid effect on the parasite's biological abilities. They also provide new perspectives to apply differently this organic acid in the field against V. destructor. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are key antigen-presenting cells that control the induction of both tolerance and immunity. Understanding the molecular mechanisms regulating DCs commitment toward a regulatory- or effector-inducing profile is critical for better designing prophylactic and therapeutic approaches. Initially identified in dexamethasone-treated thymocytes, the glucocorticoid-induced leucine zipper (GILZ) protein has emerged as a critical factor mediating most, but not all, glucocorticoids effects in both non-immune and immune cells. This intracellular protein exerts pleiotropic effects through interactions with transcription factors and signaling proteins, thus modulating signal transduction and gene expression. GILZ has been reported to control the proliferation, survival, and differentiation of lymphocytes, while its expression confers anti-inflammatory phenotype to monocytes and macrophages. In the past twelve years, a growing set of data has also established that GILZ expression in DCs is a molecular switch controlling their T-cell-priming capacity. Here, after a brief presentation of GILZ isoforms and functions, we summarize current knowledge regarding GILZ expression and regulation in DCs, in both health and disease. We further present the functional consequences of GILZ expression on DCs capacity to prime effector or regulatory T-cell responses and highlight recent findings pointing to a broader role of GILZ in the fine tuning of antigen capture, processing, and presentation by DCs. Finally, we discuss future prospects regarding the possible roles for GILZ in the control of DCs function in the steady state and in the context of infections and chronic pathologies.

Beekeepers can use a variety of treatments against Varroa destructor, the parasitic mite of Apis mellifera. However, sustainable and easy-to-use solutions are still scarce, considering the complexity of reaching the parasite alone. Current treatments involve soft acaricides, although their mechanism of action is not well understood. We investigated the effects of organic acids such as tartaric, lactic, formic, and citric acids on the attachment abilities of V. destructor under laboratory conditions. Preventing parasites from gripping or holding on to their hosts is a crucial target for mite control strategies. We challenged grip skills through the Rotavar setup after the direct application of acids to mites' arolia. We also tested the potential for mites to fall off honeybees after bee treatment. We found that tartaric, citric, and lactic acids were good candidates to impair the attachment of V. destructor twenty-four hours post-treatment. However, lactic acid remained the only candidate at a reasonable concentration to destabilise mites after the honey bee's treatment without reducing their lifespan. While we conducted these experiments under artificial conditions, our results improved our comprehension of the organic acids' potential impact on V. destructor. They can also help with the development of new methods for hive application for beekeepers worldwide. [ABSTRACT FROM AUTHOR]

Varroa destructor, a major ectoparasite of the Western honey bee Apis mellifera, is a widespread pest that damages colonies in the Northern Hemisphere. Throughout their lifecycle, V. destructor females feed on almost every developmental stage of their host, from the last larval instar to the adult. The parasite is thought to feed on hemolymph and fat body, although its exact diet and nutritional requirements are poorly known. Using artificial Parafilm™ dummies, we explored the nutrition of V. destructor females and assessed their survival when fed on hemolymph from bee larvae, pupae, or adults. We compared the results with mites fed on synthetic solutions or filtered larval hemolymph. The results showed that the parasites could survive for several days or weeks on different diets. Bee larval hemolymph yielded the highest survival rates, and filtered larval plasma was sufficient to maintain the mites for 14 days or more. This cell-free solution therefore theoretically contains all the necessary nutrients for mite survival. Because some bee proteins are known to be hijacked without being digested by the parasite, we decided to run a proteomic analysis of larval honey bee plasma to highlight the most common proteins in our samples. A list of 54 proteins was compiled, including several energy metabolism proteins such as Vitellogenin, Hexamerin, or Transferrins. These molecules represent key nutrient candidates that could be crucial for V. destructor survival. [ABSTRACT FROM AUTHOR]

Varroa destructor is a parasitic mite of the honeybee that causes thousands of colony losses worldwide. The parasite cycle is composed of a phoretic and a reproductive phase. During the former, mites stay on adult bees, mostly on nurses, to feed on hemolymph. During the latter, the parasites enter brood cells and reproduce. We investigated if the type of bees on which Varroa stays during the phoretic phase and if the duration of this stay influenced the reproductive success of the parasite and the damage caused to bees. For that purpose, we used an in vitro rearing method developed in our laboratory to assess egg laying rate and the presence and number of fully molted daughters. The expression level of two Varroa vitellogenin genes (VdVg1 and VdVg2), known to vary throughout reproduction, was also quantified. Results showed that the status of the bees or time spent during the phoretic phase impacts neither reproduction parameters nor the Varroa vitellogenin genes levels of expression. However, we correlated these parameters to the gene expression and demonstrated that daughters expressed the vitellogenin genes at lower levels than their mother. Regarding the damage to bees, the data indicated that a longer stay on adult bees during the phoretic phase resulted in more frequent physical deformity in newborn bees. We showed that those mites carry more viral loads of the Deformed Wing Virus and hence trigger more frequently overt infections. This study provides new perspectives towards a better understanding of the Varroa-honeybee interactions.

Identification and monitoring of urban fabric and preservation of existing ecosystems have become major issues to maintain or increase biodiversity in areas under urban influence in most of European cities. While many studies have shown the interest of using optical remotely sensed data for that purpose, a consolidated and reproducible methodological framework was still missing. In this context, a multi-scale methodology has been proposed in the framework of the project VALI-URB to map built-up and vegetated land features in urban and suburban areas based on Pleiades images and existing ancillary data (vector databases or the Open Street Map database). The objective of this paper is to highlight the interest of using land cover/use maps derived from Pleiades images and vector databases to semi-automatically characterize grey and green infrastructures at a scale of 1:10,000. First results are presented on two medium-sized cities with different urban forms: Strasbourg and Rennes (France).

The study and the restoration of two sphynges in terra-cotta, particularly degraded by their outdoor installation, allowed to deepen the knowledge of stamping techniques, to characterize the properties of terra-cottas and mechanisms of degradation bound to the frost. The different techniques used were the opportunity to think about limits of intervention for garden installed sculptures.

The ecology of the young stages of allis shad Alosa alosa is poorly documented, although they can be exposed to many pressures during their freshwater phase and their downstream migration. When passing through systems such as the Gironde‐Garonne‐Dordogne watershed (GGD, SW France), they can be subjected to high temperatures and low levels of oxygen (hypoxia). The aim of this work is to assess the tolerance of young Alosa alosa at four ages (c. 10, 30, 60 and 85 days old) by challenging them to different temperatures (18, 22, 26 and 28°C) together with decreasing oxygen saturation levels (from 100% to 30%). Survival of the 10‐day‐old individuals was not influenced by oxy‐thermic conditions, but high stress levels were detected and perhaps this age class was too fragile regarding the constraint of the experimental design. Survival at 30 and at 60 days old was negatively influenced by the highest temperatures tested alone (from 26°C and from 28°C, respectively) but no effect was detected at 85 days old up to 28°C. A combined effect of temperature and oxygen level was highlighted, with heat accelerating survival decrease when associated with oxygen level depletion: essentially, survival was critical (<50%) at 30 days old at temperature ≥22°C together with 30% O2; at 60 days old, at temperature = 28°C with 30% O2; at 85 days old, at temperature ≥26°C with ≤40% O2. Tolerance to oxy‐thermic pressures appeared to be greater among the migratory ages (60 and 85 days old) than among the 30‐day‐old group. Based on environmental data recorded in the GGD system and on our experimental results, an exploratory analysis allowed a discussion of the possible impact of past oxy‐thermic conditions on the local population dynamics between 2005 and 2018. The oxy‐thermic conditions that may affect Alosa alosa at ages when they migrate downstream (60 and 85 days old) were not frequently recorded in this period, except in cases of extreme episodes of heat together with hypoxia that occurred in some years, in summertime in the turbidity maximum zone of the Gironde estuary (particularly in the year 2006). Interestingly, oxy‐thermic conditions that are likely to threaten the 30‐day‐old individuals occurred more frequently in the lower freshwater parts of the GGD system between the years 2005 and 2018. In the context of climate change, a general increase in temperature is predicted, as well as more frequent and severe hypoxic events, therefore we suggest that local Alosa alosa population recruitment could encounter critical oxy‐thermic conditions more frequently in the future if no adaptive management of water resources occurs. [ABSTRACT FROM AUTHOR]

A considerable part of the knowledge about the honey bee parasite Varroa destructor emerged from rearing protocols in semi-natural or laboratory conditions, yet a durable protocol over several generations of mites is still lacking. The development of such multigenerational rearing relies on the emergence of a sufficient number of new fertile females in the first generation of V. destructor. The optimization of the parasite's reproductive success in laboratory conditions thus represents an important prerequisite. The number of foundress mites in a cell is known to impact the probability of male survival and thus the number of mated daughters. We therefore investigated the effect of the degree of bee larvae infestation under laboratory conditions. The results showed that the probability of finding at least one foundress alive at the end of the rearing was significantly higher in doubly infested cells. This leads to the improvement of the reproductive parameters and more specifically of the number of daughters per mite. In doubly infested cells with one dead foundress, the presence of a surviving female would in fact allow both its descendants and those of the dead mite to complete their development. The mated daughters from this system were used in a subsequent experiment to test their ability to complete their reproductive cycle in laboratory conditions, from the perspective of developing a multigenerational rearing. The reproduction and development of the offspring measured were similar to those of the first generation. However, many of the females from the second generation died before the completion of their first reproductive cycle. We suggest that these females are fertile but might lack the energy necessary to survive throughout reproduction. The results from our bioassay could constitute a basis for the development of a durable V. destructor laboratory rearing and for the improvement of our understanding of the parasite's reproductive cycle. [ABSTRACT FROM AUTHOR]

More diverse forests are generally more resistant to insect herbivores. This might be due to positive effects of tree diversity on predation. Although the enemies hypothesis has received conflicting evidence in forest ecosystems.Carabids were sampled by pitfall trapping in a tree diversity experiment, at the centre of plots ranging from one to five tree species mixtures. The composition and vertical structure of the vegetation was assessed at three scales, in the understorey, in the canopy of the experimental plots, and in the surrounding area of each plot.None of the tested vegetation variables had an effect on the species richness of carabids. In contrast, the vegetation compositional diversity at the understorey, canopy and surrounding scales had additive and positive effects on the activity‐density of the carabids.Our findings indicate that more diverse forests can host a higher activity‐density of predatory carabids, as a result of the combined effect of horizontal and vertical vegetation diversity, which might increase both habitat quality and the amount of feeding resources. This highlights the relevance of manipulative tree diversity experiments to identify the ecological filters shaping local carabid communities. [ABSTRACT FROM AUTHOR]

Pheromone traps are widely used for monitoring or managing insect pest populations. However, it is important to know their range of attraction to optimize the setting of pheromone trap networks.We propose an easy method based on the use of pairs of adjacent traps located at decreasing distance from each other. The range of attraction is deduced from the observation of reduced trap capture when the attraction range of two adjacent traps starts overlapping. The relationship between the relative trap capture and the distance between paired traps is fitted with a logistic curve.To empirically test these predictions, we conducted trapping experiments with the beetle Monochamus galloprovincialis, the insect vector of the pine wood nematode. Fifteen pairs of traps separated by 25 to 300 m, in France, and 18 pairs of traps distant from 25 to 400 m, in Portugal, were installed in maritime pine plantation landscapes.In both countries, the relative percentage of capture per trap per week was best fitted by a logistic model with two parameters. The estimated attraction ranges were 92 m (confidence interval = 62–211 m) in France and 123 m (confidence interval = 64–491 m) in Portugal.The interference between paired traps thus provides a simple and robust method for estimating the attraction range of pheromone traps. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are key antigen-presenting cells that control the induction of both tolerance and immunity. Understanding the molecular mechanisms regulating DCs commitment toward a regulatory- or effector-inducing profile is critical for better designing prophylactic and therapeutic approaches. Initially identified in dexamethasone-treated thymocytes, the glucocorticoid-induced leucine zipper (GILZ) protein has emerged as a critical factor mediating most, but not all, glucocorticoids effects in both non-immune and immune cells. This intracellular protein exerts pleiotropic effects through interactions with transcription factors and signaling proteins, thus modulating signal transduction and gene expression. GILZ has been reported to control the proliferation, survival, and differentiation of lymphocytes, while its expression confers anti-inflammatory phenotype to monocytes and macrophages. In the past twelve years, a growing set of data has also established that GILZ expression in DCs is a molecular switch controlling their T-cell-priming capacity. Here, after a brief presentation of GILZ isoforms and functions, we summarize current knowledge regarding GILZ expression and regulation in DCs, in both health and disease. We further present the functional consequences of GILZ expression on DCs capacity to prime effector or regulatory T-cell responses and highlight recent findings pointing to a broader role of GILZ in the fine tuning of antigen capture, processing, and presentation by DCs. Finally, we discuss future prospects regarding the possible roles for GILZ in the control of DCs function in the steady state and in the context of infections and chronic pathologies. [ABSTRACT FROM AUTHOR]

As the main source of lipids and proteins in honey bees, pollen is a major nutrient provider involved in development and health and has been studied for tolerance stimulation against pathogens and parasites. In the case of Varroa destructor Anderson & Trueman (Acari, Mesostigmata: Varroidae) parasitization, the lack of a complete laboratory system to rear both the bee larva and the acarian parasite limited the studies concerning larval nutrition effects on the bee tolerance and resistance against varroatosis. Due to the development of this complete rearing protocol, we managed to feed young honey bee larvae with pollen supplemented solutions and to study the effect on their later development under parasitism conditions. In our experimental conditions, pollen influences neither the deformity rate, nor the survival of bees both parasitized and unparasitized. However, pollen extract supplementation seems to significantly impact the weight of the spinning bee larvae without having an effect on the physiological weight loss during pupation, so the differences found at the larval stage remain the same as at emergence. Varroa has a deleterious effect on bee pupae and led to a steady increase of the physiological weight loss experienced during metamorphosis. Interestingly, this ponderal loss associated with Varroa parasitization seems to be reduced in the polyfloral pollen supplementation condition. Altogether, this work is to our knowledge the first to study in laboratory conditions the impact of larval nutrition on the tolerance to parasitism. A diverse pollen diet may be beneficial to the bees’ tolerance against V. destructor parasitism. [ABSTRACT FROM AUTHOR]

Varroa destructor is a parasitic mite of the honeybee that causes thousands of colony losses worldwide. The parasite cycle is composed of a phoretic and a reproductive phase. During the former, mites stay on adult bees, mostly on nurses, to feed on hemolymph. During the latter, the parasites enter brood cells and reproduce. We investigated if the type of bees on which Varroa stays during the phoretic phase and if the duration of this stay influenced the reproductive success of the parasite and the damage caused to bees. For that purpose, we used an in vitro rearing method developed in our laboratory to assess egg laying rate and the presence and number of fully molted daughters. The expression level of two Varroa vitellogenin genes (VdVg1 and VdVg2), known to vary throughout reproduction, was also quantified. Results showed that the status of the bees or time spent during the phoretic phase impacts neither reproduction parameters nor the Varroa vitellogenin genes levels of expression. However, we correlated these parameters to the gene expression and demonstrated that daughters expressed the vitellogenin genes at lower levels than their mother. Regarding the damage to bees, the data indicated that a longer stay on adult bees during the phoretic phase resulted in more frequent physical deformity in newborn bees. We showed that those mites carry more viral loads of the Deformed Wing Virus and hence trigger more frequently overt infections. This study provides new perspectives towards a better understanding of the Varroa-honeybee interactions. [ABSTRACT FROM AUTHOR]

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Copyright of Revue Francaise de Photogrammetrie et de Teledetection is the property of Societe Francaise de Photogrammetrie et de Teledetection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background Arthropod venoms are invaluable sources of bioactive substances with biotechnological application. The limited availability of some venoms, such as those from ants, has restricted the knowledge about the composition and the potential that these biomolecules could represent. In order to provide a global insight on the transcripts expressed in the venom gland of the Brazilian ant species Tetramorium bicarinatum and to unveil the potential of its products, high-throughput approach using Illumina technology has been applied to analyze the genes expressed in active venom glands of this ant species. Results A total of 212,371,758 pairs of quality-filtered, 100-base-pair Illumina reads were obtained. The de novo assemblies yielded 36,042 contigs for which 27,873 have at least one predicted ORF among which 59.77% produce significant hits in the available databases. The investigation of the reads mapping toxin class revealed a high diversification with the major part consistent with the classical hymenopteran venom protein signature represented by venom allergen (33.3%), followed by a diverse toxin-expression profile including several distinct isoforms of phospholipase A1 and A2, venom serine protease, hyaluronidase, protease inhibitor and secapin. Moreover, our results revealed for the first time the presence of toxinlike peptides that have been previously identified from unrelated venomous animals such as waprin-like (snakes) and agatoxins (spiders and conus). The non-toxin transcripts were mainly represented by contigs involved in protein folding and translation, consistent with the protein-secretory function of the venom gland tissue. Finally, about 40% of the generated contigs have no hits in the databases with 25% of the predicted peptides bearing signal peptide emphasizing the potential of the investigation of these sequences as source of new molecules. Among these contigs, six putative novel peptides that show homologies with previously identified antimicrobial peptides were identified. Conclusions To the best of our knowledge, this work reports the first large-scale analysis of genes transcribed by the venomous gland of the ant species T. bicarinatum and helps with the identification of Hymenoptera toxin arsenal. In addition, results from this study demonstrate that de novo transcriptome assembly allows useful venom gene expression analysis in a species lacking a genome sequence database. [ABSTRACT FROM AUTHOR]

Abstract: Little attention has been given to the relevance of habitat complementation concept to the population dynamics of insect herbivores. Late instar larvae of the pine processionary moth (PPM) Thaumetopoea pityocampa move in late winter from pine stands, their feeding habitat, to neighbouring habitats where they pupate until next summer. They search for sunny exposed soil which they can find in open areas. We investigated the effect of both forest cover and soil origin, with three matching types (pine stand, broadleaved stand and open area) on the survival of PPM pupae. The microclimatic soil variables which significantly differentiated cover types and soil origins were the maximum temperature and the mean relative humidity in spring, soon after pupation has occurred. A significant effect of the cover type, but not of the soil origin, was detected on the proportion of dead, emerged or diapausing pupae. Open areas were more suitable for pupae survival than forest covers (pine or broadleaved stands), due to warmer and more humid soil conditions. In this study, we provide one of the first examples of habitat complementation for an insect herbivore, as PPM population can benefit from the combination of pine habitats for the feeding of larvae with open habitats for pupation. The presence of broadleaved stands next to pine stands might also represent an ecological trap for PPM pupae, as broadleaved habitats may turn to be less suitable for pupae survival in spring when the apparition of leaves creates cooler conditions. [Copyright &y& Elsevier]

Abstract: A series of tests were carried out to design pheromone-based monitoring of the pine processionary moth (PPM), Thaumetopoea pityocampa. In a dose–response field test the number of male captures increased significantly with the dosage of pityolure to a plateau around 10mg. The activity of pheromone dispensers persisted for at least 11 weeks, enough to cover the entire flight period of T. pityocampa. In a comparison of several saturating and non-saturating trap designs, plate sticky traps always showed the highest trapping efficiency. Captures were significantly higher in regularly cleaned traps than in traps without cleaning, and at tree canopy height; however, the latter were positively correlated with captures from traps positioned at breast height. The relationship between the number of PPM males captured in pheromone traps and the density of winter nests was investigated in 14 stands of the maritime pine (Pinus maritima) using 10 traps baited with low doses of pityolure. Mean trap captures calculated from 3 traps schemes to 10 traps were significantly correlated with nest density, indicating that four plate sticky traps baited with 0.2mg of pityolure would provide a cost-effective tool for monitoring population densities of PPM per hectare. The reliability of this design was tested in 33 pine stands of different age and tree species across a range of geographic regions (France, Italy, Portugal), both in the core and expansion areas of the pest. The results were remarkably consistent, showing significant and positive correlations between mean male captures per day and total number of winter nests per hectare irrespective of the regions. The correlations with the level of infestation in the following generation was also positive for all regions although less significant. Our findings suggest that pheromone-baited traps provide a suitable tool for monitoring of T. pityocampa populations. [Copyright &y& Elsevier]

Let us consider a one dimensional flow in a cylindrical tube, a portion of which is flexible. It can be a shell structure or a membrane equipped with actuators in order to reduce and if possible to cancel the acoustic perturbations transferred by the flow. The goal of this paper is to discuss the efficiency of such a noise insulator in a mathematical framework. [ABSTRACT FROM AUTHOR]

Simple Summary: Varroa destructor (Anderson and Trueman) is known as a major pest of Apis mellifera L. Research about this parasite is very active and dynamic, yet only a few studies focus on an organ in particular. These targeted works are very important as they can enhance our comprehension of the mite, as they did for its host. Dissection is unavoidable when trying to isolate a specific organ. This technical article aims to give illustrated guidelines to conduct female V. destructor dissection. Thanks to photos and videos, this work will constitute a helpful tool to anyone interested in V. destructor dissection, anatomy, or organ function. Varroa destructor (Anderson and Trueman) is known as a major pest of Apis mellifera L, especially in the Northern Hemisphere where its effects can be deleterious. As an obligate parasite, this mite relies entirely on its host to reproduce and complete its cycle. Studies focusing on isolated organs are needed to better comprehend this organism. To conduct such targeted molecular or physiological studies, the dissection of V. destructor mites is crucial as it allows the extraction of specific organs. Here, we propose a technical article showing detailed steps of females V. destructor dissection, illustrated with pictures and videos. These illustrated guidelines will represent a helpful tool to go further in V. destructor research. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are key players in the control of tolerance and immunity. Glucocorticoids (GCs) are known to regulate DC function by promoting their tolerogenic differentiation through the induction of inhibitory ligands, cytokines, and enzymes. The GC-induced effects in DCs were shown to critically depend on increased expression of the Glucocorticoid-Induced Leucine Zipper protein (GILZ). GILZ expression levels were further shown to control antigen-presenting cell function, as well as T-cell priming capacity of DCs. However, the pattern of GILZ expression in DC subsets across tissues remains poorly described, as well as the modulation of its expression levels in different pathological settings. To fill in this knowledge gap, we conducted an exhaustive analysis of GILZ relative expression levels in DC subsets from various tissues using multiparametric flow cytometry. This study was performed at steady state, in the context of acute as well as chronic skin inflammation, and in a model of cancer. Our results show the heterogeneity of GILZ expression among DC subsets as well as the complexity of its modulation, that varies in a cell subset- and context-specific manner. Considering the contribution of GILZ in the control of DC functions and its potential as an immune checkpoint in cancer settings, these results are of high relevance for optimal GILZ targeting in therapeutic strategies. [ABSTRACT FROM AUTHOR]

Abstract Lactic acid is an alternative treatment to hard chemicals against Varroa destructor, the parasitic mite of the Western honey bee Apis mellifera. This soft acaricide is used only for small apiaries due to its laborious administration. However, the mode of action of this honey bee medication remains unknown. Previous studies showed that a direct contact between the arolia of V. destructor and lactic acid altered their morphology and led to an impairment of grip. Yet, there is no evidence for the way of action of lactic acid in a realistic in-hive scenario, i.e. after an indirect exposure of the mite through honey bees. We investigated the nature of lactic acid activity in the hive treatment context. The local and/or systemic way of action of this honey bee treatment against V. destructor was studied through a behavioural and toxicological approach at the individual level. On one hand, we confirmed the altered morphology for the arolia of mites and studied the evolution of the process over time. On the other hand, we found that haemolymph contaminated with lactic acid did not kill the feeding parasitic mite. These findings support a local mode of action. In order to unravel the sequence of events leading to the local contact between the acid and the mite on bees, we also documented the olfactory valence of lactic acid for A. mellifera and V. destructor. This work provides a new comprehension of lactic acid activity against the parasitic mite through honey bee exposure and gives new opportunities for control strategies against V. destructor.

Simple Summary: Varroa destructor is a parasitic organism feeding and living among honeybees. It transmits viruses like the Deformed Wing Virus which can lead to the decline and death of the colony. Many treatments have been developed over the years like formamidine amitraz, pyrethroid tau-fluvalinate, organophosphate coumaphos or even acids like formic and oxalic to control the spread of the mite. However, none of this solution provides long-term sustainability for honeybees and no resistance from V. destructor. Therefore, the development of alternative tools remains open. This will require the combination of both laboratory and field results through an integrative approach based on the identification of V. destructor health biomarkers. Here we review what has been done and what can be done from the laboratory to the field against the parasitic pressure held on honeybees. Varroa destructor is a real challenger for beekeepers and scientists: fragile out of the hive, tenacious inside a bee colony. From all the research done on the topic, we have learned that a better understanding of this organism in its relationship with the bee but also for itself is necessary. Its biology relies mostly on semiochemicals for reproduction, nutrition, or orientation. Many treatments have been developed over the years based on hard or soft acaricides or even on biocontrol techniques. To date, no real sustainable solution exists to reduce the pressure of the mite without creating resistances or harming honeybees. Consequently, the development of alternative disruptive tools against the parasitic life cycle remains open. It requires the combination of both laboratory and field results through a holistic approach based on health biomarkers. Here, we advocate for a more integrative vision of V. destructor research, where in vitro and field studies are more systematically compared and compiled. Therefore, after a brief state-of-the-art about the mite's life cycle, we discuss what has been done and what can be done from the laboratory to the field against V. destructor through an integrative approach. [ABSTRACT FROM AUTHOR]

In the present study we investigated the effects of various doses of γ-irradiation, followed by induction of granulocytic differentiation with all-trans-retinoic acid (ATRA), on proliferative rate, differentiation capability and oxidative metabolism of leukaemic cells from two different myeloid leukaemia cell lines, HL-60 and PLB-985. Regarding the effects of such combined treatment on the proliferative capabilities of HL-60 and PLB-985 cell lines, we showed that their growth kinetics were similar after 2 Gy γ-irradiation combined with ATRA. However, with doses >2 Gy, the behaviour of the cell lines differed largely. Indeed, HL-60 appeared to be more radiosensitive than PLB-985 regarding cell viability and proliferation. Besides, whatever dose of irradiation (2, 5 or 10 Gy) was applied, ATRA was still able to induce differentiation of HL-60 and PLB-985 into granulocytes that retained the capacity to produce superoxide anion. The results of these in vitro studies suggest that leukaemia cell lines retain their ability to respond to ATRA, a granulocytic-differentiating inducer following high doses of irradiation. This may have implications for the use of radiation therapy in combination with ATRA for the treat-ment of extramedullary infiltrations of myeloid leukaemias in humans. [ABSTRACT FROM AUTHOR]

Ag sampling is a key process in dendritic cell (DC) biology. DCs use constitutive macropinocytosis, receptor-mediated endocytosis, and phagocytosis to capture exogenous Ags for presentation to T cells. We investigated the mechanisms that regulate Ag uptake by DCs in the steady-state and after a short-term LPS exposure in vitro and in vivo. We show that the glucocorticoid-induced leucine zipper protein (GILZ), already known to regulate effector versus regulatory T cell activation by DCs, selectively limitsmacropinocytosis, but not receptor-mediated phagocytosis, in immature and recently activated DCs. In vivo, the GILZ-mediated inhibition of Ag uptake is restricted to the CD8α+ DC subset, which expresses the highest GILZ level among splenic DC subsets. In recently activated DCs, we further establish that GILZ limits p38 MAPK phosphorylation, providing a possible mechanism for GILZ-mediated macropinocytosis control. Finally, our results demonstrate that the modulation of Ag uptake by GILZ does not result in altered Ag presentation to CD4 T cells but impacts the efficiency of cross-presentation to CD8 T cells. Altogether, our results identify GILZ as an endogenous inhibitor of macropinocytosis in DCs, the action of which contributes to the fine-tuning of Ag cross-presentation. [ABSTRACT FROM AUTHOR]

Beekeepers can use a variety of treatments against Varroa destructor, the parasitic mite of Apis mellifera. However, sustainable and easy-to-use solutions are still scarce, considering the complexity of reaching the parasite alone. Current treatments involve soft acaricides, although their mechanism of action is not well understood. We investigated the effects of organic acids such as tartaric, lactic, formic, and citric acids on the attachment abilities of V. destructor under laboratory conditions. Preventing parasites from gripping or holding on to their hosts is a crucial target for mite control strategies. We challenged grip skills through the Rotavar setup after the direct application of acids to mites’ arolia. We also tested the potential for mites to fall off honeybees after bee treatment. We found that tartaric, citric, and lactic acids were good candidates to impair the attachment of V. destructor twenty-four hours post-treatment. However, lactic acid remained the only candidate at a reasonable concentration to destabilise mites after the honey bee’s treatment without reducing their lifespan. While we conducted these experiments under artificial conditions, our results improved our comprehension of the organic acids’ potential impact on V. destructor. They can also help with the development of new methods for hive application for beekeepers worldwide.