Evaluating the chronic effect of two varroacides using multiple biomarkers and an integrated biological response index

A systematic meta-analysis of the efficacy of treatments for a global honey bee pathogen - the Varroa mite

The western honey bee Apis mellifera is the world's most important managed pollinator. However, globally honey bees have been facing increasing colony losses due to a combination of stress factors. Foremost among these is the invasive mite Varroa destructor, which is the pathogen most commonly linked to colony losses. Despite intensive research focus on this problem, V. destructor management remains extremely challenging, with no definitive treatment approach. A variety of synthetic chemical, agriculturally organic chemical, biological, and physical treatments have been trialled and used in V. destructor management, each with benefits and drawbacks. Here, we carried out a first systematic meta-analysis of the comparative effectiveness of V. destructor treatment methods. We incorporated data from 138 studies from 30 countries, across five continents and found that overall, synthetic chemicals show high effectiveness as a treatment due to their ability to suppress the V. destructor mite. In our analyses of honey bee responses, there was some evidence that synthetic chemicals may have an overall negative impact on them, even while suppressing V. destructor. For improving honey bee health measures, biological treatment methods showed the most positive effect, but with a relatively low sample size. Our study highlights that there is a relative lack of studies on biological management methods, with far more focus in the literature on chemical treatments. We show that, until biological methods receive greater research attention, agriculturally organic methods likely provide the best current treatment option, because they are well studied, nearly as effective at suppressing V. destructor as synthetic chemicals, and less associated with negative impacts on honey bees. Varroa destructor remains a major threat to honey bees globally, with the last large V. destructor free zone (Australia) having now been invaded, emphasising the need to fill these knowledge gaps.

Evaluation of the efficacy of diosmin and chrysin against tau-fluvalinate exposure in rats

Tau-fluvalinate is a type 2 pyrethroid insecticide. Diosmin and chrysin are flavonoids with antioxidant and anti-apoptotic effects. Role of diosmin and chrysin against infavorable toxic effects caused by tau-fluvalinate and the underlying mechanisms of these effects were investigated. Six groups were formed and diosmin, chrysin, tau-fluvalinate, tau-fluvalinate + diosmin and tau-fluvalinate + chrysin were administered orally to rats at a dose of 20 mg/kg.bw except for the control group, once a day for 21 days, respectively. Tau-fluvalinate elevated MDA and NO levels while diminishing the activities of antioxidant enzymes (SOD, CAT, GSH-Px, GR, GST, G6PD) and GSH levels in the majority of the analyzed blood and tissues, statistically significant. Serum triglyceride, cholesterol, total protein and albumin levels as well as LDH and PChE activities decreased. Conversely, serum creatinine, AST, ALT and ALP levels/activities increased. Elevated protein levels of caspase 3, caspase 9, p53 and Bax and decreased protein levels of Bcl-2 were observed in the liver. There were negative changes in body/some organ weights. Diosmin and chrysin administration resulted in a marked recovery in tau-fluvalinate-induced toxic effects, but this improvement was not complete. These flavonoids may be considered as promising potential therapeutic options to alleviate the adverse effects associated with tau-fluvalinate intoxication.

Flumethrin exposure perturbs gut microbiota structure and intestinal metabolism in honeybees (Apis mellifera)

Flumethrin mitigates Varroa's harm to honeybee colonies; however, its residues in colonies threaten the fitness of honeybee hosts and gut microbiota. Our previous research has shown that flumethrin induces significant physiological effects on honeybee larvae; but the effects of flumethrin on the gut microbiota and metabolism of adult honeybees are still unknown. In this study, 1-day-old honeybees were exposed to 0, 0.01, 0.1, and 1 mg/L flumethrin for 14 days and the impacts of flumethrin on the intestinal system were evaluated. The results showed that exposure to 1 mg/L flumethrin significantly reduced honeybee survival and the activities of antioxidative enzymes (superoxide dismutase and catalase) and detoxification enzymes (glutathione S-transferase) in honeybee heads. Moreover, exposure to 0.01, 0.1, and 1 mg/L flumethrin significantly decreased the diversity of the honeybee gut microbiota. Results from untargeted metabolomics showed that long-term exposure to 0.01, 0.1, and 1 mg/L flumethrin caused changes in the metabolic pathways of honeybee gut microbes. Furthermore, increased metabolism of phenylalanine, tyrosine, and tryptophan derivatives was observed in honeybee gut microbes. These findings underscore the importance of careful consideration in using pesticides in apiculture and provide a basis for safeguarding honeybees from pollutants, considering the effects on gut microbes.

A new strategy to generate nanobodies for the coumaphos based on the synthesized nanobody libraries

To break through the bottleneck in preparation of nanobody (Nb) for chemical contaminants induced by the difficulties in the synthesis of immunogen, complexity and unexpectable efficiency of immunization, a novel strategy to generate Nbs based on the designed synthetic Nb libraries with final size up to 109 cfu/mL was adopted and succeeded in selection of anti-coumaphos Nb A4. Furthermore, an affinity-matured mutant Nb 3G was obtained from the secondary library. Finally, an ic-ELISA was established with the limit of detection for coumaphos low to 1.90 ng/mL, 6.4-fold improved than the parent Nb A4, and the detection range from 3.06 to 15.77 ng/mL. Meanwhile, the recovery rate of vegetable samples was from 89.9% to 98.5%. Finally, the accuracy was testified by the standard UPLC-MS/MS method with R2 up to 0.99. Overall, fully synthetic Nb libraries constructed in this work provided an alternative possibility to generate the specific Nbs for chemical contaminants.

Biomarker responses and lethal dietary doses of tau-fluvalinate and coumaphos in honey bees: Implications for chronic acaricide toxicity

Evidence suggests that acaricide residues, such as tau-fluvalinate and coumaphos, are very prevalent in honey bee colonies worldwide. However, the endpoints and effects of chronic oral exposure to these compounds remain poorly understood. In this study, we calculated LC50 and LDD50 endpoints for coumaphos and tau-fluvalinate, and then evaluated in vivo and in vitro effects on honey bees using different biomarkers. The LDD50 values for coumaphos were 0.539, and for tau-fluvalinate, they were 12.742 in the spring trial and 8.844 in the autumn trial. Chronic exposure to tau-fluvalinate and coumaphos resulted in significant changes in key biomarkers, indicating potential neurotoxicity, xenobiotic biotransformation, and oxidative stress. The Integrated Biomarker Response was stronger for coumaphos than for tau-fluvalinate, supporting their relative lethality. This study highlights the chronic toxicity of these acaricides and presents the first LDD50 values for tau-fluvalinate and coumaphos in honey bees, providing insights into the risks faced by colonies.

Phytotoxicity assessment of dandelion exposed to microplastics using membership function value and integrated biological response index

Microplastic (MP) pollution is a critical environmental issue. Dandelions could be used as a biomonitor of environmental pollution. However, the ecotoxicology of MPs in dandelions remains unclear. Therefore, the toxic effects of polyethylene (PE), polystyrene (PS), and polypropylene (PP) at concentrations of 0, 10, 100, and 1000 mg L-1 on the germination and early seedling growth of dandelion were investigated. PS and PP inhibited seed germination and decreased root length and biomass while promoting membrane lipid peroxidation, increasing O2•-, H2O2, SP, and proline contents, and enhancing the activities of SOD, POD, and CAT. Principal component analysis (PCA) and membership function value (MFV) analysis indicated that PS and PP could be more harmful than PE in dandelion, especially at 1000 mg L-1. In addition, according to the integrated biological response (IBRv2) index analysis, O2•-, CAT, and proline were sensitive biomarkers of dandelion contamination by MPs. Here we provide evidence that dandelion has the potential to be a biomonitor to assess the phytotoxicity of MPs pollution, especially PS with high toxicity. Meanwhile, we believe that if dandelion is to be used as a biomonitor for MPs, attention should also be paid to the practical safety of dandelion.

Effects of dietary fluoranthene on tissue-specific responses of carboxylesterases, acetylcholinesterase and heat shock protein 70 in two forest lepidopteran species

In this study, responses of carboxylesterases, acetylcholinesterase, and stress protein Hsp70 were examined in the midgut and midgut tissue, and brain of fifth instar larvae of Lymantria dispar L. and Euproctis chrysorrhoea L. following chronic exposure to dietary fluoranthene. Specific carboxylesterase activity increased significantly in the midgut tissue of E. chrysorrhoea larvae treated with a lower fluoranthene concentration. The specific patterns of isoforms expression, recorded in larvae of both species, enable efficient carboxylesterase activity as a significant part of defense mechanisms. Increased Hsp70 concentration in the brain of L. dispar larvae points to a response to the proteotoxic effects of a lower fluoranthene concentration. Decreased Hsp70 in the brain of E. chrysorrhoea larvae in both treated groups can suggest induction of other mechanisms of defense. The results indicate the importance of the examined parameters in larvae of both species exposed to the pollutant, as well as their potential as biomarkers.