Haemolymph removal by Varroa mite destabilizes the dynamical interaction between immune effectors and virus in bees, as predicted by Volterra's model.

The association between the deformed wing virus and the parasitic mite Varroa destructor has been identified as a major cause of worldwide honeybee colony losses. The mite acts as a vector of the viral pathogen and can trigger its replication in infected bees. However, the mechanistic details underlying this tripartite interaction are still poorly defined, and, particularly, the causes of viral proliferation in mite-infested bees. Here, we develop and test a novel hypothesis that mite feeding destabilizes viral immune control through the removal of both virus and immune effectors, triggering uncontrolled viral replication. Our hypothesis is grounded on the predator-prey theory developed by Volterra, which predicts prey proliferation when both predators and preys are constantly removed from the system. Consistent with this hypothesis, we show that the experimental removal of increasing volumes of haemolymph from individual bees results in increasing viral densities. By contrast, we do not find consistent support for alternative proposed mechanisms of viral expansion via mite immune suppression or within-host viral evolution. Our results suggest that haemolymph removal plays an important role in the enhanced pathogen virulence observed in the presence of feeding Varroa mites. Overall, these results provide a new model for the mechanisms driving pathogen-parasite interactions in bees, which ultimately underpin honeybee health decline and colony losses.

A mutualistic symbiosis between a parasitic mite and a pathogenic virus undermines honey bee immunity and health.

Honey bee colony losses are triggered by interacting stress factors consistently associated with high loads of parasites and/or pathogens. A wealth of biotic and abiotic stressors are involved in the induction of this complex multifactorial syndrome, with the parasitic mite Varroa destructor and the associated deformed wing virus (DWV) apparently playing key roles. The mechanistic basis underpinning this association and the evolutionary implications remain largely obscure. Here we narrow this research gap by demonstrating that DWV, vectored by the Varroa mite, adversely affects humoral and cellular immune responses by interfering with NF-κB signaling. This immunosuppressive effect of the viral pathogen enhances reproduction of the parasitic mite. Our experimental data uncover an unrecognized mutualistic symbiosis between Varroa and DWV, which perpetuates a loop of reciprocal stimulation with escalating negative effects on honey bee immunity and health. These results largely account for the remarkable importance of this mite-virus interaction in the induction of honey bee colony losses. The discovery of this mutualistic association and the elucidation of the underlying regulatory mechanisms sets the stage for a more insightful analysis of how synergistic stress factors contribute to colony collapse, and for the development of new strategies to alleviate this problem.

Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees.

Large-scale losses of honey bee colonies represent a poorly understood problem of global importance. Both biotic and abiotic factors are involved in this phenomenon that is often associated with high loads of parasites and pathogens. A stronger impact of pathogens in honey bees exposed to neonicotinoid insecticides has been reported, but the causal link between insecticide exposure and the possible immune alteration of honey bees remains elusive. Here, we demonstrate that the neonicotinoid insecticide clothianidin negatively modulates NF-κB immune signaling in insects and adversely affects honey bee antiviral defenses controlled by this transcription factor. We have identified in insects a negative modulator of NF-κB activation, which is a leucine-rich repeat protein. Exposure to clothianidin, by enhancing the transcription of the gene encoding this inhibitor, reduces immune defenses and promotes the replication of the deformed wing virus in honey bees bearing covert infections. This honey bee immunosuppression is similarly induced by a different neonicotinoid, imidacloprid, but not by the organophosphate chlorpyriphos, which does not affect NF-κB signaling. The occurrence at sublethal doses of this insecticide-induced viral proliferation suggests that the studied neonicotinoids might have a negative effect at the field level. Our experiments uncover a further level of regulation of the immune response in insects and set the stage for studies on neural modulation of immunity in animals. Furthermore, this study has implications for the conservation of bees, as it will contribute to the definition of more appropriate guidelines for testing chronic or sublethal effects of pesticides used in agriculture.

Synergistic parasite-pathogen interactions mediated by host immunity can drive the collapse of honeybee colonies.

The health of the honeybee and, indirectly, global crop production are threatened by several biotic and abiotic factors, which play a poorly defined role in the induction of widespread colony losses. Recent descriptive studies suggest that colony losses are often related to the interaction between pathogens and other stress factors, including parasites. Through an integrated analysis of the population and molecular changes associated with the collapse of honeybee colonies infested by the parasitic mite Varroa destructor, we show that this parasite can de-stabilise the within-host dynamics of Deformed wing virus (DWV), transforming a cryptic and vertically transmitted virus into a rapidly replicating killer, which attains lethal levels late in the season. The de-stabilisation of DWV infection is associated with an immunosuppression syndrome, characterized by a strong down-regulation of the transcription factor NF-κB. The centrality of NF-κB in host responses to a range of environmental challenges suggests that this transcription factor can act as a common currency underlying colony collapse that may be triggered by different causes. Our results offer an integrated account for the multifactorial origin of honeybee losses and a new framework for assessing, and possibly mitigating, the impact of environmental challenges on honeybee health.

Varroa destructor is an effective vector of Israeli acute paralysis virus in the honeybee, Apis mellifera.

The Israeli acute paralysis virus (IAPV) is a significant marker of honeybee colony collapse disorder (CCD). In the present work, we provide the first evidence that Varroa destructor is IAPV replication-competent and capable of vectoring IAPV in honeybees. The honeybees became infected with IAPV after exposure to Varroa mites that carried the virus. The copy number of IAPV in bees was positively correlated with the density of Varroa mites and time period of exposure to Varroa mites. Further, we showed that the mite-virus association could possibly reduce host immunity and therefore promote elevated levels of virus replication. This study defines an active role of Varroa mites in IAPV transmission and sheds light on the epidemiology of IAPV infection in honeybees.

Characterization of a new type of mead fermented with Cannabis sativa L. (hemp).

Mead, one of the oldest existing drinks, is a fermented product based on honey, water, and the possible addition of spices and selected yeasts. In this work, various parts (inflorescences, leaves, and steams) of Cannabis sativa L. at different concentrations and Saccharomyces cerevisiae biotype M3/5 were added during mead fermentation. The physicochemical parameters (pH, alcoholic content, sugar content, titratable acidity, and organic acids) of the mead were assessed at the beginning and end of fermentation. Moreover, polyphenols, cannabidiol and volatile organic compounds were identified at the end of fermentation and compared with the control sample prepared without hemp and with only indigenous yeasts. The mead fermented with hemp showed the highest quantity of polyphenols (227 to 256 mg GAE/L) and a level of cannabidiol ranging from 0.26 to 0.49 mg/kg. The volatile organic compounds found were mainly alcohols, esters and terpenes, which were present at higher concentrations in the mead prepared with C. sativa L. than in the control mead and conferred freshness and "hemp aroma" characteristics. PRACTICAL APPLICATION: Inflorescences, leaves, and steams of Cannabis sativa L. were added at different concentrations during mead fermentation. This type of mead showed high quantity of polyphenols (227 to 256 mg GAE/L) and a level of cannabidiol ranging from 0.26 to 0.49 mg/kg which have anxiolytic and neuro-protective properties. Moreover the volatile organic compounds found (mainly alcohols, esters, and terpenes) conferred freshness and "hemp aroma" characteristics.

New Approaches on Japanese Knotweed (Fallopia japonica) Bioactive Compounds and Their Potential of Pharmacological and Beekeeping Activities: Challenges and Future Directions.

Known especially for its negative ecological impact, Fallopia japonica (Japanese knotweed) is now considered one of the most invasive species. Nevertheless, its chemical composition has shown, beyond doubt, some high biological active compounds that can be a source of valuable pharmacological potential for the enhancement of human health. In this direction, resveratrol, emodin or polydatin, to name a few, have been extensively studied to demonstrate the beneficial effects on animals and humans. Thus, by taking into consideration the recent advances in the study of Japanese knotweed and its phytochemical constituents, the aim of this article is to provide an overview on the high therapeutic potential, underlining its antioxidant, antimicrobial, anti-inflammatory and anticancer effects, among the most important ones. Moreover, we describe some future directions for reducing the negative impact of Fallopia japonica by using the plant for its beekeeping properties in providing a distinct honey type that incorporates most of its bioactive compounds, with the same health-promoting properties.

Neonicotinoid Clothianidin reduces honey bee immune response and contributes to Varroa mite proliferation.

The neonicotinoid Clothianidin has a negative impact on NF-κB signaling and on immune responses controlled by this transcription factor, which can boost the proliferation of honey bee parasites and pathogens. This effect has been well documented for the replication of deformed wing virus (DWV) induced by Clothianidin in honey bees bearing an asymptomatic infection. Here, we conduct infestation experiments of treated bees to show that the immune-suppression exerted by Clothianidin is associated with an enhanced fertility of the parasitic mite Varroa destructor, as a possible consequence of a higher feeding efficiency. A conceptual model is proposed to describe the synergistic interactions among different stress agents acting on honey bees.

Microbial characterization of bee pollen from the Vesuvius area collected by using three different traps.

Flower pollen is collected by honeybee foragers, adhered on their rear legs and transported into the hives in the form of pellets. Once in the hives, bee pollen is moisturised with nectar and bee mouth secretions and due to enzymatically modifications it becomes the so-called bee-bread, the protein reservoir of young bees. Bee pollen can be artificially removed from bee legs and collected by using specific systems, the bee pollen traps. Bee pollen is commercialized for human consumption as fresh product and after freezing or drying. Although bee pollen is nowadays largely consumed in developed countries, as food or food supplement according to local legislation, little is known on its safety related to microbiological hazards. In this work, we aimed to characterize for the first time the microbiological profile of Italian bee pollen in fresh, frozen and dried form collected along an entire harvesting season. Moreover, monthly microbiological analyses were performed on frozen (storage at -18°C) and dried (storage at room temperature) bee pollen over a 4 months period. Further aim of this work was the evaluation of the possible impact on production level of three different traps used for pollen collection. Our results on microbial contamination of fresh and frozen bee pollen show that a more comprehensive microbiological risk assessment of bee pollen is required. On the other side, dried pollen showed very low microbial contamination and no pathogen survived after the drying process and during storage.

The neonicotinoid insecticide Clothianidin adversely affects immune signaling in a human cell line.

Clothianidin is a widely used neonicotinoid insecticide, which is a potent agonist of the nicotinic acetylcholine receptor in insects. This neurotoxic compound has a negative impact on insect immunity, as it down-regulates the activation of the transcription factor NF-κB. Given the evolutionary conserved role of NF-κB in the modulation of the immune response in the animal kingdom, here we want to assess any effect of Clothianidin on vertebrate defense barriers. In presence of this neonicotinoid insecticide, a pro-inflammatory challenge with LPS on the human monocytic cell line THP-1 results both in a reduced production of the cytokine TNF-α and in a down-regulation of a reporter gene under control of NF-κB promoter. This finding is corroborated by a significant impact of Clothianidin on the transcription levels of different immune genes, characterized by a core disruption of TRAF4 and TRAF6 that negatively influences NF-κB signaling. Moreover, exposure to Clothianidin concurrently induces a remarkable up-regulation of NGFR, which supports the occurrence of functional ties between the immune and nervous systems. These results suggest a potential risk of immunotoxicity that neonicotinoids may have on vertebrates, which needs to be carefully assessed at the organism level.

Experimental and numerical evaluations on palm microwave heating for Red Palm Weevil pest control.

The invasive Red Palm Weevil is the major pest of palms. Several control methods have been applied, however concern is raised regarding the treatments that can cause significant environmental pollution. In this context the use of microwaves is particularly attractive. Microwave heating applications are increasingly proposed in the management of a wide range of agricultural and wood pests, exploiting the thermal death induced in the insects that have a thermal tolerance lower than that of the host matrices. This paper describes research aiming to combat the Red Palm pest using microwave heating systems. An electromagnetic-thermal model was developed to better control the temperature profile inside the palm tissues. In this process both electromagnetic and thermal parameters are involved, the latter being particularly critical depending on plant physiology. Their evaluation was carried out by fitting experimental data and the thermal model with few free parameters. The results obtained by the simplified model well match with both that of a commercial software 3D model and measurements on treated Phoenix canariensis palms with a ring microwave applicator. This work confirms that microwave heating is a promising, eco-compatible solution to fight the spread of weevil.

Honey Bees (Apis mellifera, L.) as Active Samplers of Airborne Particulate Matter.

Honey bees (Apis mellifera L.) are bioindicators of environmental pollution levels. During their wide-ranging foraging activity, these hymenopterans are exposed to pollutants, thus becoming a useful tool to trace the environmental contaminants as heavy metals, pesticides, radionuclides and volatile organic compounds. In the present work we demonstrate that bees can also be used as active samplers of airborne particulate matter. Worker bees were collected from hives located in a polluted postmining area in South West Sardinia (Italy) that is also exposed to dust emissions from industrial plants. The area is included in an official list of sites of national interest for environmental remediation, and has been characterized for the effects of pollutants on the health of the resident population. The head, wings, hind legs and alimentary canal of the bees were investigated with Scanning Electron Microscopy coupled with X-ray spectroscopy (SEM-EDX). The analyses pointed to specific morphological and chemical features of the particulate, and resulted into the identification of three categories of particles: industry-, postmining-, and soil-derived. With the exception of the gut, all the analyzed body districts displayed inorganic particles, mostly concentrated in specific areas of the body (i.e. along the costal margin of the fore wings, the medial plane of the head, and the inner surface of the hind legs). The role of both past mining activities and the industrial activity close to the study area as sources of the particulate matter is also discussed. We conclude that honey bees are able to collect samples of the main airborne particles emitted from different sources, therefore could be an ideal tool for monitoring such a kind of pollutants.

Dynamics of persistent and acute deformed wing virus infections in honey bees, Apis mellifera.

The dynamics of viruses are critical to our understanding of disease pathogenesis. Using honey bee Deformed wing virus (DWV) as a model, we conducted field and laboratory studies to investigate the roles of abiotic and biotic stress factors as well as host health conditions in dynamics of virus replication in honey bees. The results showed that temperature decline could lead to not only significant decrease in the rate for pupae to emerge as adult bees, but also an increased severity of the virus infection in emerged bees, partly explaining the high levels of winter losses of managed honey bees, Apis mellifera, around the world. By experimentally exposing adult bees with variable levels of parasitic mite Varroa destructor, we showed that the severity of DWV infection was positively correlated with the density and time period of Varroa mite infestation, confirming the role of Varroa mites in virus transmission and activation in honey bees. Further, we showed that host conditions have a significant impact on the outcome of DWV infection as bees that originate from strong colonies resist DWV infection and replication significantly better than bee originating from weak colonies. The information obtained from this study has important implications for enhancing our understanding of host­pathogen interactions and can be used to develop effective disease control strategies for honey bees.