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Abstract: Pesticide use remains a problem in agriculture, contaminating natural ecosystems and affecting bees. Fungicides have been widely used worldwide, and honey bees can bring contaminated pollen and nectar to the colony, exposing the larvae. Studies on larval exposure to fungicides are still rare. Therefore, this work aimed to evaluate the effects of larval exposure to the fungicide picoxystrobin on biological parameters and cellular stress in the fat body. The larvae were single exposure on the fourth day (D4) to picoxystrobin at concentrations of 5 ng a.i./μL (PCX5), 45 ng a.i./μL (PCX45), 135 ng a.i./μL (PCX135), and 400 ng a.i./μL (PCX400). The effects on larval and pupal mortality, pupation rate, and emergence were evaluated. Additionally, cellular stress in the fat body was assessed in newly emerged bees. Exposure to PCX400 increased larval mortality by 26% and reduced the emergence of adult bees. The other concentrations did not affect larval and pupal mortality, or pupation and emergence rates. A cytotoxicity effect was observed in newly emerged bees from PCX400, indicated by positive immunolabeling of HSP70. Thus, a single exposure to picoxystrobin can impair larval development, induce a cellular stress response, and may interfere with colony dynamics.
Keywords: development, honey bee, non-target organism, strobilurin, toxicity
Published in DKUM: 23.04.2025; Views: 0; Downloads: 2
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Abstract: A high concentration of hydroxymethylfurfural (HMF) (e.g., 15 mg HMF per kg honey) indicates quality deterioration for a wide range of foods. In honey bee colonies, HMF in stored honey can negatively affect bee health and survival. Therefore, in the laboratory, we experimentally determined the effects of HMF on the longevity and midgut integrity of worker Apis mellifera carnica by feeding bees standard diets containing five concentrations of HMF (100, 500, 1000, and 1500 ppm). Simultaneously, we also examined HMF%s effect on Nosema ceranae spore counts within infected honey bees. We performed an immunohistochemical analysis of the honey bee midgut to determine possible changes at the cellular level. No correlation was established between HMF concentration and N. ceranae spore counts. Negative effects of HMF on bees were not observed in the first 15 days of exposure. However, after 15 to 30 days of exposure, HMF caused midgut cells to die and an increased mortality of honey bee workers across treatment groups.
Keywords: hydroxymethylfurfural, honey bee, cell death, immunohistochemistry, Nosema ceranae
Published in DKUM: 21.01.2025; Views: 0; Downloads: 8
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Abstract: Bees are the major pollinators in natural ecosystems and in the agricultural production of several crops used for human consumption. However, they are exposed to multiple stressors that are causing a serious decline in their population. We highlight a major one among them, the Varroa destructor mite (Varroa) that causes severe impacts on the health of honey bee colonies, transmitting a variety of viruses that can affect the survival ability of individual bees and entire colonies. Diagnosis and mite control methods have been intensively studied in recent decades, with many studies in different areas of knowledge having been conducted. This overview summarizes these studies with a focus on colony defense systems, biological characteristics of the parasite Varroa, diagnostic methods used to establish the infestation level of colonies, and currently used control methods.
Keywords: diagnosis, honey bee disease, mite, parasite, Varroa destructor
Published in DKUM: 18.07.2024; Views: 151; Downloads: 11
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Abstract: Monitoring virus infections can be an important selection tool in honey bee breeding. A recent study pointed towards an association between the virus-free status of eggs and an increased virus resistance to deformed wing virus (DWV) at the colony level. In this study, eggs from both naturally surviving and traditionally managed colonies from across Europe were screened for the prevalence of different viruses. Screenings were performed using the phenotyping protocol of the ‘suppressed in ovo virus infection’ trait but with qPCR instead of end-point PCR and a primer set that covers all DWV genotypes. Of the 213 screened samples, 109 were infected with DWV, 54 were infected with black queen cell virus (BQCV), 3 were infected with the sacbrood virus, and 2 were infected with the acute bee paralyses virus. It was demonstrated that incidences of the vertical transmission of DWV were more frequent in naturally surviving than in traditionally managed colonies, although the virus loads in the eggs remained the same. When comparing virus infections with queen age, older queens showed significantly lower infection loads of DWV in both traditionally managed and naturally surviving colonies, as well as reduced DWV infection frequencies in traditionally managed colonies. We determined that the detection frequencies of DWV and BQCV in honey bee eggs were lower in samples obtained in the spring than in those collected in the summer, indicating that vertical transmission may be lower in spring. Together, these patterns in vertical transmission show that honey bee queens have the potential to reduce the degree of vertical transmission over time.
Keywords: honey bee, suppressed in ovo virus infection, vertical transmission, virus resistance
Published in DKUM: 18.08.2023; Views: 457; Downloads: 56
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Abstract: The socio-economic impacts of COVID-19 on society have yet to be truly revealed; there is no doubt that the pandemic has severely affected the daily lives of most of humanity. It is to be expected that the research activities of scientists could be impacted to varying degrees, but no data exist on how COVID-19 has affected research specifically. Here, we show that the still ongoing COVID-19 pandemic has already diversely and negatively affected bee research at a global level. An online survey disseminated through the global COLOSS honey bee research association showed that every participant (n = 230 from 56 countries) reported an impact on one or more of their activities. Activities that require travelling or the physical presence of people (meetings and conferences, teaching and extension) were affected the most, but also laboratory and field activities, daily operations, supervision and other activities were affected to varying degrees. Since the basic activities are very similar for many research fields, it appears as if our findings for bee research can be extrapolated to other fields. In the light of our data, we recommend that stakeholders such as governments and funding bodies who support research should facilitate the wide implementation of web-based information technology required for efficient online communication for research and education, as well as adequately loosened restriction measures with respect to field and laboratory work. Finally, increased flexibility in administration and extension of research grants and fellowships seem to be needed. It is apparent that adequate responses by all stakeholders are required to limit the impact of COVID-19 and future pandemics on bee science and other research fields.
Keywords: COLOSS, Apis mellifera, coronavirus, COVID-19, honey bee, pandemic, research, extension
Published in DKUM: 12.11.2020; Views: 1029; Downloads: 218
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