Abstract
Varroa destructor is among the greatest biological threats to western honey bee (Apis mellifera L.) health worldwide. Beekeepers routinely use chemical treatments to control this parasite, ...though overuse and mismanagement of these treatments have led to widespread resistance in Varroa populations. Integrated Pest Management (IPM) is an ecologically based, sustainable approach to pest management that relies on a combination of control tactics that minimize environmental impacts. Herein, we provide an in-depth review of the components of IPM in a Varroa control context. These include determining economic thresholds for the mite, identification of and monitoring for Varroa, prevention strategies, and risk conscious treatments. Furthermore, we provide a detailed review of cultural, mechanical, biological, and chemical control strategies, both longstanding and emerging, used against Varroa globally. For each control type, we describe all available treatments, their efficacies against Varroa as described in the primary scientific literature, and the obstacles to their adoption. Unfortunately, reliable IPM protocols do not exist for Varroa due to the complex biology of the mite and strong reliance on chemical control by beekeepers. To encourage beekeeper adoption, a successful IPM approach to Varroa control in managed colonies must be an improvement over conventional control methods and include cost-effective treatments that can be employed readily by beekeepers. It is our intention to provide the most thorough review of Varroa control options available, ultimately framing our discussion within the context of IPM. We hope this article is a call-to-arms against the most damaging pest managed honey bee colonies face worldwide.
A successful Integrated Pest Management approach to Varroa destructor Anderson and Trueman control in managed colonies of western honey bees Apis mellifera Linnaeus (Hymenoptera: Apidae) must be an ...improvement over conventional control methods and include cost-effective treatments that can be readily employed by beekeepers. Herein, we tested the efficacy of oxalic acid (OA) vaporization and brood interruption as Varroa controls. Sixty experimental colonies were randomly assigned to one of six treatment groups with 10 colonies per group.The six treatments were: 1) OA applied once, 2) OA applied three times, 3) brood interruption, 4) OA applied once + brood interruption, 5) OA applied three times + brood interruption, and 6) no OA or brood interruption. The OA was applied via vaporization, with each application being 1 g OA applied through the hive entrance (label rate), on the bottom board. Brood interruption was accomplished by caging a colony's queen in a queen cage for a period of 24 d. An additional 10 colonies were treated with amitraz (Apivar - positive control). Varroa levels were estimated before, during, and after treatment applications using sticky boards left in colonies for 3 d. Our data suggest that queen caging to achieve brood interruption during the fall season can negatively impact colony strength and survival. We observed high colony mortality in some treatments, despite diligent colony management to alleviate the side effects of the treatments. Colonies treated with amitraz were healthier and had better survival than those treated with OA vaporization. In conclusion, OA and/or brood interruption did not provide sufficient Varroa control.
Impacts to honey bees due to exposure to agricultural pesticides is one of the most serious threats to the beekeeping industry. Our research evaluated toxicity of the formulated insecticides ...Lufenuron+Emamectin benzoate (Proclaim Fit
®
) on the European honey bee
Apis mellifera
L. at field-realistic concentration (worst-case scenario). Newly emerged (≤24-h old) and forager (unknown age) worker bees were treated with the field recommended concentration of Proclaim Fit
®
using three routes of exposure including residual contact, oral, and spray within the laboratory. We also assessed the effects of Proclaim Fit
®
on the specific activity of some well-known detoxifying enzymes including α-esterase, β-esterase, and Glutathione S-transferase (GST) in the honey bees. In addition, toxicity of the formulation was tested on 4
th
instar larvae within the hive. Based on estimated median survival times (MSTs), Proclaim Fit
®
was highly toxic to the bees, especially when applied as spray. According to our estimated relative median potency (RMP) values, newly emerged bees were 1.72× more susceptible than foragers to Proclaim Fit
®
applied orally. Enzyme assays revealed the considerable involvement of the enzymes, especially GST and α-esterase, in detoxification of the Proclaim Fit
®
, but their activities were significantly influenced by route of exposure and age of bee. Notably, Proclaim Fit
®
was highly toxic to 4
th
instar honey bee larvae. Our results generally indicate a potent toxicity of Proclaim Fit
®
toward honey bees. Therefore, its application requires serious consideration and adherence to strict guidelines, especially during the flowering time of crops.
The extracellular matrix (ECM) is composed of complex fibrillar proteins, proteoglycans, and macromolecules, generated by stromal, immune, and cancer cells. The components and organisation of the ...matrix evolves as tumours progress to invasive disease and metastasis. In many solid tumours, dense fibrotic ECM has been hypothesised to impede therapy response by limiting drug and immune cell access. Interventions to target individual components of the ECM, collectively termed the matrisome, have, however, revealed complex tumour-suppressor, tumour-promoter, and immune-modulatory functions, which have complicated clinical translation. The degree to which distinct components of the matrisome can dictate tumour phenotypes and response to therapy is the subject of intense study. A primary aim is to identify therapeutic opportunities within the matrisome, which might support a better response to existing therapies. Many matrix signatures have been developed which can predict prognosis, immune cell content, and immunotherapy responses. In this review, we will examine key components of the matrisome which have been associated with advanced tumours and therapy resistance. We have primarily focussed here on targeting matrisome components, rather than specific cell types, although several examples are described where cells of origin can dramatically affect tumour roles for matrix components. As we unravel the complex biochemical, biophysical, and intracellular transduction mechanisms associated with the ECM, numerous therapeutic opportunities will be identified to modify tumour progression and therapy response.
Nosema ceranae is a widely prevalent microsporidian parasite in the western honey bee. There is considerable uncertainty regarding infection dynamics of this important pathogen in honey bee colonies. ...Understanding the infection dynamics at the colony level may aid in development of a reliable sampling protocol for N. ceranae diagnosis, and provide insights into efficient treatment strategies. The primary objective of this study was to characterize the prevalence (proportion of the sampled bees found infected) and intensity (number of spores per bee) of N. ceranae infection in bees from various age cohorts in a colony. We examined N. ceranae infection in both overwintered colonies that were naturally infected with N. ceranae and in quadruple cohort nucleus colonies that were established and artificially inoculated with N. ceranae. We also examined and quantified effects of N. ceranae infection on hypopharyngeal gland protein content and gut pH. There was no correlation between the prevalence and intensity of N. ceranae infection in composite samples (pooled bee samples used for analysis). Our results indicated that the prevalence and intensity of N. ceranae infection is significantly influenced by honey bee age. The N. ceranae infection prevalence values from composite samples of background bees (unmarked bees collected from four different locations in a colony) were not significantly different from those pertaining to marked-bee age cohorts specific to each sampling date. The foraging-aged bees had a higher prevalence of N. ceranae infection when compared to nurse-aged bees. N. ceranae did not have a significant effect on hypopharyngeal gland protein content. Further, there was no significant difference in mean gut pH of N. ceranae infected bees and non-infected bees. This study provides comprehensive insights into N. ceranae infection dynamics at the colony level, and also demonstrates the effects of N. ceranae infection on hypopharyngeal gland protein content and midgut pH.
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•N. ceranae spore intensity, but not prevalence, decreased as pollen content decreased.•Honey bee survival decreased as pollen concentration decreased.•Nosema ceranae decreased ...hypopharyngeal gland protein content in bees.•Nosema ceranae had no significant effect on midgut proteolytic enzyme activity.
Multiple stressors are currently threatening honey bee health, including pests and pathogens. Among honey bee pathogens, Nosema ceranae is a microsporidian found parasitizing the western honey bee (Apis mellifera) relatively recently. Honey bee colonies are fed pollen or protein substitute during pollen dearth to boost colony growth and immunity against pests and pathogens. Here we hypothesize that N. ceranae intensity and prevalence will be low in bees receiving high pollen diets, and that honey bees on high pollen diets will have higher survival and/or increased longevity. To test this hypothesis we examined the effects of different quantities of pollen on (a) the intensity and prevalence of N. ceranae and (b) longevity and nutritional physiology of bees inoculated with N. ceranae. Significantly higher spore intensities were observed in treatments that received higher pollen quantities (1:0 and 1:1 pollen:cellulose) when compared to treatments that received relatively lower pollen quantities. There were no significant differences in N. ceranae prevalence among different pollen diet treatments. Interestingly, the bees in higher pollen quantity treatments also had significantly higher survival despite higher intensities of N. ceranae. Significantly higher hypopharyngeal gland protein was observed in the control (no Nosema infection, and receiving a diet of 1:0 pollen:cellulose), followed by 1:0 pollen:cellulose treatment that was inoculated with N. ceranae. Here we demonstrate that diet with higher pollen quantity increases N. ceranae intensity, but also enhances the survival or longevity of honey bees. The information from this study could potentially help beekeepers formulate appropriate protein feeding regimens for their colonies to mitigate N. ceranae problems.
We probe, here, a family of 2D Hofmann-type frameworks, FeII(Pd(CN)4)(bztrzX)2·nH2O X·nH2O; X = F, Cl, Br; n = 1 (X = Cl, Br) and 3 (X = F); bztrzX = ...(E)-1-(2-Xphen-1-yl)-N-(4H-1,2,4-triazol-4-yl)methanimine, with halogen-appended ligands. In all cases, there are two crystallographically distinct FeII sites, ({Fe1–Fe2}), driven by the presence of a range of host–host and host–guest interactions. We find that lattice modification through X variation influences the elastic coupling between the FeII sites, the emergence of ferroelastic or antiferroelastic interactions between these sites, and the relative spin-state stabilization/destabilization at each site. In Cl·H2O, the FeII sites show strong elastic coupling, as evidenced by both FeII sites undergoing a spin transition in a single cooperative step, as driven by the volume strain over the high-spin (HS)-to-low-spin (LS) transition. The FeII sites in F·3H2O are also elastically coupled; however, the change of the X atom characteristics and increased guest molecules in the pores result in an antiferroelastic interaction characteristic between Fe1 and Fe2 and a resultant two-step spin-state transition. The change of the X atom to Br in Br·H2O results in the FeII sites being decoupled due to halogen atom steric bulk, resulting in the independent spin-state transition of Fe1 and Fe2 sites and a two-step spin-state transition pathway. Uniquely, all three possible spin-state transition pathways of a two-site switching system are observed in this family (1) {HS–HS} ↔ {HS–LS} ↔ {LS–LS} for Br·H2O, (2) {HS–HS} ↔ {LS–HS} ↔ {LS–LS} for F·3H2O, and (3) {HS–HS} ↔ {LS–LS} for Cl·H2O for {Fe1–Fe2}. Overall, these findings broadly support recent theoretical models but highlight that additional structural and topological complexities are needed to form a holistic picture of the drivers of elastic frustration.
Gaining a fundamental understanding of charge transfer mechanisms in three-dimensional Metal–Organic Frameworks (MOFs) is crucial to the development of electroactive and conductive porous materials. ...These materials have potential in applications in porous conductors, electrocatalysts and energy storage devices; however the structure–property relationships pertaining to charge transfer and its quantification are relatively poorly understood. Here, the cofacial Cd( ii )-based MOF Cd(BPPTzTz)(tdc)·2DMF (where BPPTzTz = 2,5-bis(4-(pyridin-4-yl)phenyl)thiazolo5,4- d thiazole, tdc 2− = 2,5-thiophene dicarboxylate) exhibits Intervalence Charge Transfer (IVCT) within its three-dimensional structure by virtue of the close, cofacial stacking of its redox-active BPPTzTz ligands. The mixed-valence and IVCT properties are characterised using a combined electrochemical, spectroelectrochemical and computational approach. Single crystal electronic absorption spectroscopy was employed to obtain the solid-state extinction coefficient, enabling the application of Marcus–Hush theory. The electronic coupling constant, H ab , of 145 cm −1 was consistent with the localised mixed-valence properties of both this framework and analogous systems that use alternative methods to obtain the H ab parameter. This work demonstrates the first report of the successful characterisation of IVCT in a MOF material using single crystal electronic absorption spectroscopy and serves as an attractive alternative to more complex methods due to its simplicity and applicability.
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