Publications

@article{nokey,

title = {Sunflower Pollen and Bumble Bee Health: Mechanisms, Modifiers and Trade‐Offs},

author = {Richard Odemer},

doi = {10.1002/ece3.73107},

year  = {2026},

date = {2026-02-17},

journal = {Ecology and Evolution},

abstract = {Bumble bees face increasing pressure from interacting stressors, including pathogens, nutritional limitations, and agricultural intensification. Among natural dietary factors that modulate disease, Asteraceae pollen—particularly sunflower (Helianthus annuus)—has repeatedly been shown to reduce infection by the trypanosomatid Crithidia bombi in bumble bees under laboratory conditions. Yet the mechanisms, generality, and ecological relevance of these effects remain incompletely resolved, and field-based evidence from European systems, particularly for Bombus terrestris, is scarce. Here, I synthesise current knowledge on how Asteraceae pollen traits influence bumble bee health, focusing on the interplay between pollen morphology, phenolamide chemistry, nutrient composition, gut microbiota, and host physiology. I evaluate evidence for three non-exclusive mechanistic pathways—mechanical abrasion, chemical activity, and microbiome-associated effects—and review emerging evidence for nutritional, immunological, and colony-level trade-offs associated with medicinal pollen. To place these mechanisms in a field-relevant context, I integrate pollen-trap data from B. terrestris and Apis mellifera colonies foraging in Central European agricultural landscapes, indicating strong seasonal reliance on Solanaceae pollen, no uptake of sunflower pollen by B. terrestris, and moderate use of Silphium perfoliatum, a perennial Asteraceae crop of growing agroecological interest. Together, these patterns highlight a mismatch between laboratory efficacy and field-level pollen use, indicating that sunflower pollen is unlikely to function as a standalone medicinal resource under realistic foraging conditions. Instead, potential health effects of Asteraceae pollen appear context dependent and embedded within diverse nutritional landscapes. I identify key knowledge gaps—including cultivar-level chemical variation, species-specific responses, and interactions with co-occurring stressors—and outline research priorities for evaluating when and how medicinal pollen may contribute to pollinator-supportive cropping systems.},

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tppubtype = {article}

}

@article{nokey,

title = {Pesticide impacts on honey bee foraging behaviour: a field-relevant scoping review},

author = {Ming Wang and Volker Grimm and Fabrice Requier and Jürgen Groeneveld and Holger Bargen and Silvio Knaebe and Richard Odemer },

doi = {10.1186/s12302-025-01325-0},

year  = {2026},

date = {2026-02-03},

journal = {Environmental Sciences Europe},

abstract = {Honey bees (Apis spp.) play a crucial role in agricultural productivity and ecosystem functioning through pollination. However, their foraging behaviour is increasingly affected by pesticide exposure, including insecticides, acaricides, fungicides, and herbicides. Reported effects range from adverse to negligible or even stimulatory, depending on the compound, dose, and experimental design. To support more ecologically realistic risk assessments, we conducted a targeted scoping review of 26 studies examining pesticide impacts on honey bee foraging under semi-field and field-realistic conditions. These studies were evaluated based on pesticide type, exposure route and duration, Apis species, foraging type (nectar vs. pollen), behavioural endpoint, level of observation (individual vs. colony), and proposed mechanisms. Our synthesis reveals a pronounced research bias toward neonicotinoid insecticides and Apis mellifera, with minimal investigation of other pesticide classes, chronic exposures, or non-mellifera species such as A. cerana and A. dorsata. Most studies assessed individual-level effects and nectar foraging, while colony-level endpoints and pollen foraging remain underexplored. Additionally, small and inconsistent sample sizes reduce the statistical robustness and generalisability of many findings. We identify critical gaps in current pesticide risk assessments and call for standardised experimental methodologies, including harmonised behavioural metrics, consistent dosing protocols, and endpoints that link individual- to colony-level responses. Strengthening colony-level indicators under field-realistic exposures is essential for improving the predictive power of regulatory assessments, guiding targeted mitigation strategies, and promoting more sustainable pesticide use in agroecosystems.},

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}

@article{nokey,

title = {Honey Bee Colony Health in Thiamethoxam-Treated Sugar Beet Fields: A Field-Based Case Study},

author = {Richard Odemer and Stefan Berg and Jens Pistorius and Ingrid Illies},

url = {https://richard.odemer.info/wp-content/uploads/2025/12/Odemer_et_al_2025_TMX_Sugar_Beet_Field_Study.pdf},

doi = {10.1002/ece3.72767},

year  = {2025},

date = {2025-12-23},

urldate = {2025-12-23},

journal = {Ecology and Evolution},

abstract = {Emergency use of thiamethoxam seed treatments in sugar beet was approved in Germany in 2021, despite EU restrictions on neonicotinoids because of pollinator risks. During the field experiment underlying this case study, residues in bee-relevant matrices were detected only at very low levels, and conservative exposure modeling indicated no acute or chronic concern for honey bees. Building on these exposure findings, the present analysis examined whether such exposures translated into measurable effects on honey bee colony performance. In Experiment 1, colony development was monitored at two geographically distinct sites across the 2021 sugar beet season. Colonies at both sites exhibited strong seasonal growth. Generalized linear mixed models detected no consistent adverse effects of thiamethoxam treatment on either adult bee populations or brood cell numbers. Although temporal fluctuations

and site-specific variability were evident, treatment effects were not statistically supported, highlighting the importance of multi-site approaches when assessing pesticide impacts and the need for continued multi-year evidence under diverse environmental conditions. In Experiment 2, survival of individual workers was evaluated using free-flying mini-hives. Mixed-effects Cox modeling, which accounted for colony variance, found no significant differences in worker longevity between treated and control groups. This indicates no evidence for reduced worker survival under a field-relevant neonicotinoid exposure scenario. Together, these two complementary experimental approaches show that thiamethoxam seed treatments in sugar beet did not cause consistent adverse effects on honey bee colonies under the tested agricultural conditions. By integrating residue analyses, statistical modeling, and colony-level monitoring, the study provides ecologically relevant evidence that current agricultural practices with thiamethoxam in sugar beet pose a low apparent risk to honey bee colony health, while underscoring the value of longer-term and broader-scale field evaluations.},

keywords = {},

pubstate = {published},

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@article{nokey,

title = {Development of a Modular 3D-Printed Pollen Trap for Bumble Bee Monitoring},

author = {Richard Odemer and Marie Geiger and Lars Geiger},

editor = {Stefan Vidal},

url = {https://richard.odemer.info/wp-content/uploads/2025/09/JEN_2025_Odemer_3D_Pollentrap_Bumblebee.pdf},

doi = {10.1111/jen.70011},

year  = {2025},

date = {2025-09-01},

journal = {Journal of Applied Entomology},

abstract = {Accurate pollen collection is essential for understanding bumble bee foraging dynamics, assessing environmental risks, and monitoring colony health. Effective monitoring systems provide critical insights into pesticide exposure, floral resource availability, and pollinator health. This study compares the efficiency of two pollen trap designs, the newly developed JKI trap and the USDA 3D-printed trap, in collecting pollen from Bombus terrestris colonies. Field tests using traps with two entrance diameters (6.5 mm and 7.2 mm) showed that the JKI trap collected significantly more pollen than the USDA trap, with the statistical model predicting approximately 24 times higher yields (p < 0.001), and no significant effect of entrance diameter on pollen yield. The JKI trap’s effective performance, coupled with its design flexibility and potential for adaptation across different Bombus species and pollinators, makes it a valuable tool for long-term ecological monitoring, floral resource assessments, and pesticide risk studies.},

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pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In-hive flatbed scanners for non-destructive, long-term monitoring of honey bee brood, pathogens and pests},

author = {Parzival Borlinghaus and Marvin Gülzow and Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2024/11/Borlinghaus_et_al_2024_COMB_scanner.pdf},

doi = {10.1016/j.atech.2024.100655},

year  = {2024},

date = {2024-11-19},

journal = {Smart Agricultural Technology},

abstract = {Honey bee colonies face significant threats from pathogens and pests, including chalkbrood disease caused by Ascosphaera apis and Varroa destructor mites. Traditional monitoring methods for these issues are often destructive, hindering continuous and detailed observations. This study introduces a novel, non-destructive monitoring technique using a modified flatbed scanner integrated into a honey bee brood frame. The scanner, housed within a Dadant frame and connected to a Raspberry Pi, captures high-resolution images of the brood cells at regular intervals. This method enables continuous observation of the brood life cycle, including egg laying, larval development, and the presence of pathogens and mites. Over a three-month pilot study, the scanner successfully monitored 419 cells, capturing Image 1 images of each cell and documenting critical events such as Varroa infestations and chalkbrood development. The method demonstrated high-resolution imaging capabilities, enabling detailed analysis of pathogen dynamics and hygienic behaviors like Varroa-sensitive hygiene (VSH) without apparent disturbance of the colony. The results revealed a high frequency of brood removal and pathogen detection, providing insights into the natural behaviors of honey bees and their interactions with pests.},

keywords = {},

pubstate = {published},

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}

@article{nokey,

title = {Nurse honey bees filter fungicide residues to maintain larval health},

author = {Karoline Wueppenhorst and Abdulrahim T. Alkassab and Hannes Beims and Gabriela Bischoff and Ulrich Ernst and

Elsa Friedrich and Ingrid Illies and Martina Janke and Julia Kehmstedt and Wolfgang H. Kirchner and Richard Odemer

and Silvio Erler},

url = {https://richard.odemer.info/wp-content/uploads/2024/10/Wueppenhorstetal-2024-Nursehoneybeesfilterfungicideresidues.pdf},

doi = {10.1016/j.cub.2024.10.008},

year  = {2024},

date = {2024-10-29},

urldate = {2024-10-29},

journal = {Current Biology},

abstract = {Here is the text formatted for easy copying without numbered references:



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Residues of plant protection products (PPPs) are frequently detected in bee matrices due to foraging bees collecting contaminated nectar and pollen, which they bring back to their hive. The collected material is further used by nurse bees to produce glandular secretions for feeding their larvae. Potential exposure to PPPs occurs through direct oral ingestion, contact during foraging, or interaction with contaminated hive material. Contaminants can pose health risks to adult worker bees, queens, drones (males), or larvae, potentially impacting colony health and productivity. However, residue concentrations can vary significantly between analyzed matrices, and potential accumulation or dilution steps have not been widely investigated. Although research has provided valuable insights into contamination risks, there remain gaps in our understanding of the entire pathway from field, via foragers, stored products, nurse bees, and finally to food jelly, i.e., royal, worker, and drone jelly, and the larvae, including all possible processing steps. We collected samples of bee-relevant matrices following the in-field spray application of the product Pictor Active, containing the fungicides boscalid and pyraclostrobin. The samples were analyzed for residues along this entire pathway. Fungicide residues were reduced by a factor of 8–80 from stored product to nurse bees’ heads, suggesting a filtering function of nurse bees. Furthermore, detected residues in larval food jelly resulted from added pollen and not from nurse bee secretions. Calculated risk quotients were at least twice as low as the threshold values, suggesting a low risk to honey bee colonies from these fungicides at the tested application rate.},

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@article{nokey,

title = {Honey bee colonies can buffer short-term stressor effects of pollen restriction and fungicide exposure on colony development and the microbiome},

author = {Karoline Wueppenhorst and

Abdulrahim T. Alkassab and

Hannes Beims and



Ulrich Ernst and

Elsa Friedrich and

Ingrid Illies and

Martina Janke and

Wolfgang H. Kirchner and

Kim Seidel and

Michael Steinert and

Andrey Yurkov and

Silvio Erler and

Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2024/07/wueppenhorst_et_al.pdf},

doi = {10.1016/j.ecoenv.2024.116723},

year  = {2024},

date = {2024-07-17},

urldate = {2024-07-17},

journal = {Ecotoxicology and Environmental Safety},

abstract = {Honey bees (Apis mellifera) have to withstand various environmental stressors alone or in combination in agriculture settings. Plant protection products are applied to achieve high crop yield, but residues of their active substances are frequently detected in bee matrices and could affect honey bee colonies. In addition, intensified agriculture could lead to resource limitation for honey bees. This study aimed to compare the response of full-sized and nucleus colonies to the combined stressors of fungicide exposure and resource limitation. A large-scale field study was conducted simultaneously at five different locations across Germany, starting in spring 2022 and continuing through spring 2023. The fungicide formulation Pictor® Active (active ingredients boscalid and pyraclostrobin) was applied according to label instructions at the maximum recommended rate on oil seed rape crops. Resource limitation was ensured by pollen restriction using a pollen trap and stressor responses were evaluated by assessing colony development, brood development, and core gut microbiome alterations. Furthermore, effects on the plant nectar microbiome were assessed since nectar inhabiting yeast are beneficial for pollination. We showed, that honey bee colonies were able to compensate for the combined stressor effects within six weeks. Nucleus colonies exposed to the combined stressors showed a short-term response with a less favorable brood to bee ratio and reduced colony development in May. No further impacts were observed in either the nucleus colonies or the full-sized colonies from July until the following spring. In addition, no fungicide-dependent differences were found in core gut and nectar microbiomes, and these differences were not distinguishable from local or environmental effects. Therefore, the provision of sufficient resources is important to increase the resilience of honey bees to a combination of stressors.},

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@article{nokey,

title = {Brood indicators are an early warning signal of honey bee colony loss—a simulation-based study},

author = {Jürgen Groeneveld and Richard Odemer and Fabrice Requier},

url = {https://richard.odemer.info/wp-content/uploads/2024/05/Groeneveld_et_al_2024.pdf},

doi = {10.1371/journal.pone.0302907},

year  = {2024},

date = {2024-05-16},

urldate = {2024-05-16},

journal = {PLOS ONE},

abstract = {Honey bees (Apis mellifera) are exposed to multiple stressors such as pesticides, lack of forage and diseases. It is therefore a long-standing aim to develop robust and meaningful indicators of bee vitality to support beekeeping. While established indicators often focus on expected colony winter mortality based on adult bee abundance and honey stores at the beginning of the winter, it would be useful to have early warning indicators that allow detection of stress effects earlier in the year to allow for adaptive management. We used the established honey bee simulation model BEEHAVE to explore the potential of different indicators such as population size, number of capped brood cells, flight activity, abundance of varroa mites, honey stores and a brood-bee ratio. We implemented two stressor types in our simulations: 1) parasite pressure, i.e. sub-optimal Varroa treatment by the beekeeper (hereafter referred as Biotic stress) and 2) temporal forage gaps in spring and autumn (hereafter referred as Environmental stress). Neither stressor type could be detected by bee abundance or honey stores at the end of the first year. However, all response variables used in this study (population size, number of capped brood cells, flight activity, abundance of Varroa mites, honey stores, brood-bee ratio) did reveal early warning signals during the course of the year. The most reliable and useful measures seem to be related to brood and the abundance of Varroa mites at the end of the year. However, while in the model we have full access to time series of variables from stressed and unstressed colonies, knowledge of these variables in the field is challenging. We discuss how our findings can nevertheless be used to develop practical early warning indicators. As a next step in the interactive development of such indicators we suggest empirical studies on the importance of the number of capped brood cells at certain times of the year on bee population vitality. },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Natural color dispersion of corbicular pollen limits color-based classification},

author = {Parzival Borlinghaus and Frederic Tausch and Richard Odemer },

url = {https://richard.odemer.info/wp-content/uploads/2024/04/Borlinghaus_et_al_pollen_color_dispersion.pdf},

doi = {10.1016/j.ophoto.2024.100063},

year  = {2024},

date = {2024-04-16},

journal = {ISPRS Open Journal of Photogrammetry and Remote Sensing},

abstract = {Various methods have been developed to assign pollen to its botanical origin. They range from technically complex approaches to the less precise but sophisticated chromatic assessment, in which the pollen colors are used for identification. However, a common challenge lies in the similarity of colors of pollen from different plant species. The advent of camera-based bee monitoring systems has sparked renewed interest in classifying pollen based on color and offers potential advances for honey bee biomonitoring. Despite the promise of improved sensor accuracy, a critical examination of whether color diversity within a single species may be the primary limiting factor has been lacking. Our comprehensive analysis, which includes over 85,000 corbicular pollen from 30 major pollen species, shows that the average color variation within each species is distinguishable to a human observer, similar to the difference between two dissimilar colors. From today's perspective, the considerable color variation within a single pollen source makes the use of color alone to classify pollen impractical. When picking a single pollen color from the entire dataset, we report a correct pollen type classification rate of 67 %. The accuracy was highly dependent on the type and ranged from 0 % for rare types with common colors to 99 % for distinct colors. The large color dispersion within species highlights the need for complementary methods to improve the accuracy and reliability of color-based pollen identification in biomonitoring applications.},

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pubstate = {published},

tppubtype = {article}

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@article{nokey,

title = {Making way for the implementation of automated bee counters in regulatory risk assessment},

author = {Richard Odemer and Oliver Jakoby and Markus Barth and Silvio Knäbe and Jens Pistorius and Katharina Schmidt},

editor = {Stefan Vidal},

url = {https://richard.odemer.info/wp-content/uploads/2024/04/VIBEE_Odemer_Perspective_BeeCounter_RiskAssessment_2024.pdf},

doi = {10.1111/jen.13256},

year  = {2024},

date = {2024-04-04},

journal = {Journal of Applied Entomology},

abstract = {Measuring adverse effects on honey bees and their colonies requires a suitable methodology. For example, due to the large number of bees in a hive and the foraging activity, measuring the mortality of individuals is a difficult task that has not yet been adequately addressed. Knowing the natural daily mortality rate of a bee colony would be of great benefit in assessing whether and to what extent external influences and stress factors affect mortality. More precise mortality data could in turn help refining specific protection goals for regulatory purpose. The European Food Safety Authority (EFSA) recently published a document that estimated such mortality rates based on a systematic literature review, but none of these rates were assessed from continuous monitoring of colonies. Currently, bee mortality is routinely evaluated with various types of dead bee traps that prevent deceased bees from being removed from the colony. Both the literature review and the dead bee traps are relevant to regulatory risk assessment, but in our opinion are not describing the total mortality. Bee counters capable of precisely determining daily loss rates meet the above points and combine them with generating automated and continuous monitoring data. Lately, the field has gained a lot of importance in research and technological advances offer new possibilities in regulatory risk assessment. We will highlight these possibilities and discuss their future application in practice.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A call for clarity: Embracing the debate on pesticide regulation to protect pollinators},

author = {Richard Odemer and Abdulrahim T. Alkassab and Jakob H. Eckert and Ina P. Wirtz and Jens Pistorius},

url = {http://tinyurl.com/bioscience24},

doi = {10.1093/biosci/biad112},

year  = {2024},

date = {2024-02-20},

urldate = {2024-02-20},

journal = {BioScience},

abstract = {In response to the recent Forum article by Fisher and colleagues (2023) proposing a five-part solution for reforming pesticide regulations to safeguard pollinators, we, as a risk assessment authority, would like to engage in the discourse and provide essential clarifications regarding the regulatory framework in Europe. Although we wholeheartedly support any constructive discussions on the protection of solitary and social bees, our intent is to address specific points that may potentially give rise to misconceptions about the current situation in Europe.



Fisher and colleagues (2023) contend that the approval process only assesses the active substance, automatically granting marketing approval to any product containing it. What is important to underscore is that EU-wide approval of the active substance is a prerequisite for the authorization of plant protection products that contain the respective active substance within member states. These plant protection products, comprising authorized active substances, undergo a comprehensive risk assessment as formulated products during the zonal approval procedure, in accordance with EU regulation no. 1107/2009 and commission regulation (EU) no. 284/2013. Therefore, both the active substance and the formulated product are subjected to thorough risk assessments, involving comprehensive scientific reviews by the European Food Safety Authority (EFSA) and the relevant authorities in member states to ensure their safety. Important to mention is that renewal requirements for each active substance are mandated after a 10-year interval. If the approval for the active substance expires, the approval for all products containing this substance also expires. A new application must therefore be submitted once the active substance has been reapproved. To gain reapproval, all prevailing test criteria must be met once this timeframe has lapsed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A selected organosilicone spray adjuvant does not enhance lethal effects of a pyrethroid and carbamate insecticide on honey bees},

author = {Anna Wernecke and Jakob H. Eckert and Gabriela Bischoff and Rolf Forster and Jens Pistorius and Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2023/06/Wernecke_et_al_2023_Adjuvants_Organosilicone_Bees.pdf},

doi = {10.3389/fphys.2023.1171817},

year  = {2023},

date = {2023-06-01},

urldate = {2023-06-01},

journal = {Frontiers in Physiology},

abstract = {As part of the agricultural landscape, non-target organisms, such as bees, may be exposed to a cocktail of agrochemicals including insecticides and spray adjuvants like organosilicone surfactants (OSS). While the risks of insecticides are evaluated extensively in their approval process, in most parts of the world however, authorization of adjuvants is performed without prior examination of the effects on bees. Nevertheless, recent laboratory studies evidence that adjuvants can have a toxicity increasing effect when mixed with insecticides. Therefore, this semi-field study aims to test whether an OSS mixed with insecticides can influence the insecticidal activity causing increased effects on bees and bee colonies under more realistic exposure conditions. To answer this question a pyrethroid (Karate Zeon) and a carbamate (Pirimor Granulat) were applied in a highly bee attractive crop (oil seed rape) during bee flight either alone or mixed with the OSS Break-Thru S 301 at field realistic application rates. The following parameters were assessed: mortality, flower visitation, population and brood development of full-sized bee colonies. Our results show that none of the above mentioned parameters was significantly affected by the insecticides alone or their combination with the adjuvant, except for a reduced flower visitation rate in both carbamate treatments (Tukey-HSD, p < 0.05). This indicates that the OSS did not increase mortality to a biologically relevant extent or any of the parameters observed on honey bees and colonies in this trial. Hence, social buffering may have played a crucial role in increasing thresholds for such environmental stressors. We confirm that the results of laboratory studies on individual bees cannot necessarily be extrapolated to the colony level and further trials with additional combinations are required for a well-founded evaluation of these substances.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Introducing Pollenyzer: An App for Automatic Determination of Colour Diversity for Corbicular Pollen Loads},

author = {Parzival Borlinghaus and Jakob Jung and Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2023/06/Borlinghaus_et_al_Pollenyzer.pdf},

doi = {10.1016/j.atech.2023.100263},

year  = {2023},

date = {2023-06-01},

urldate = {2023-06-01},

journal = {Smart Agricultural Technology},

abstract = {Pollen is known to be the only source of proteins and fats for honey bees. Therefore, it is an important component of nutrition, essential for brood care and a good indicator for the availability of resources in a landscape. It is also known that a diverse diet is beneficial for bee health, also in relation to winter losses. In this work, an app is presented that allows to quantify the pollen from a pollen trap and to determine its colour diversity in an automatic way. The colour diversity is closely related to the actual plant diversity. This correlation allows conclusions to be drawn on the apicultural importance of a landscape and on biodiversity in general. In this way, the app provides beekeepers with important information about the nutritional condition of their colonies, while scientists can benefit from aggregated information about local biodiversity. The app is free of use and available as a web app on all devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Potential Risk of Residues From Neonicotinoid‐Treated Sugar Beet in Flowering Weeds to Honey Bees (Apis mellifera L.)},

author = {Richard Odemer and Elsa Friedrich and Ingrid Illies and Stefan Berg and Jens Pistorius and Gabriela Bischoff },

url = {https://richard.odemer.info/wp-content/uploads/2023/04/Odemer_et_al_2023_Sugarbeet_ETC.pdf},

doi = {10.1002/etc.5602},

year  = {2023},

date = {2023-04-08},

urldate = {2023-04-08},

journal = {Environmental Toxicology and Chemistry},

abstract = {In 2018 the European Union (EU) banned the three neonicotinoid insecticides imidacloprid, clothianidin (CLO), and thiamethoxam (TMX), but they can still be used if an EU Member State issues an emergency approval. Such an approval went into effect in 2021 for TMX‐coated sugar beet seeds in Germany. Usually, this crop is harvested before flowering without exposing nontarget organisms to the active ingredient or its metabolites. In addition to the approval, strict mitigation measures were imposed by the EU and the German federal states. One of the measures was to monitor the drilling of sugar beet and its impact on the environment. Hence we took residue samples from different bee and plant matrices and at different dates to fully map beet growth in the German states of Lower Saxony, Bavaria, and Baden‐Württemberg. A total of four treated and three untreated plots were surveyed, resulting in 189 samples. Residue data were evaluated using the US Environmental Protection Agency BeeREX model to assess acute and chronic risk to honey bees from the samples, because oral toxicity data are widely available for both TMX and CLO. Within treated plots, we found no residues either in pools of nectar and honey crop samples (n = 24) or dead bee samples (n = 21). Although 13% of beebread and pollen samples and 88% of weed and sugar beet shoot samples were positive, the BeeREX model found no evidence of acute or chronic risk. We also detected neonicotinoid residues in the nesting material of the solitary bee Osmia bicornis, probably from contaminated soil of a treated plot. All control plots were free of residues. Currently, there are insufficient data on wild bee species to allow for an individual risk assessment. In terms of the future use of these highly potent insecticides, therefore, it must be ensured that all regulatory requirements are complied with to mitigate any unintentional exposure.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Simulation of Varroa mite control in honey bee colonies without synthetic acaricides: Demonstration of Good Beekeeping Practice for Germany in the BEEHAVE model},

author = {Isabel Schödl and Richard Odemer and Matthias Becher and Stefan Berg and Christoph Otten and Volker Grimm and Jürgen Groeneveld},

url = {https://richard.odemer.info/wp-content/uploads/2022/11/Schoedl_et_al_2022.pdf},

doi = {10.1002/ece3.9456},

year  = {2022},

date = {2022-11-08},

journal = {Ecology & Evolution},

volume = {12},

issue = {11},

pages = {1-14},

abstract = {The BEEHAVE model simulates the population dynamics and foraging activity of a single honey bee colony (Apis mellifera) in great detail. Although it still makes numerous simplifying assumptions, it appears to capture a wide range of empirical observations. It could, therefore, in principle, also be used as a tool in beekeeper education, as it allows the implementation and comparison of different management options. Here, we focus on treatments aimed at controlling the mite Varroa destructor. However, since BEEHAVE was developed in the UK, mite treatment includes the use of a synthetic acaricide, which is not part of Good Beekeeping Practice in Germany. A practice that consists of drone brood removal from April to June, treatment with formic acid in August/September, and treatment with oxalic acid in November/December. We implemented these measures, focusing on the timing, frequency, and spacing between drone brood removals. The effect of drone brood removal and acid treatment, individually or in combination, on a mite-infested colony was examined. We quantify the efficacy of Varroa mite control as the reduction of mites in treated bee colonies

compared to untreated bee colonies. We found that drone brood removal was very effective, reducing mites by 90% at the end of the first simulation year after the introduction of mites. This value was significantly higher than the 50–67% reduction expected by bee experts and confirmed by empirical studies. However, literature reports varying percent reductions in mite numbers from 10 to 85% after drone brood removal. The discrepancy between model results, empirical data, and expert estimates indicate that these three sources should be reviewed and refined, as all are based on simplifying assumptions. These results and the adaptation of BEEHAVE to the Good Beekeeping Practice are a decisive step forward for the future use of BEEHAVE in beekeeper education in Germany and anywhere where organic acids and drone brood removal are utilized.},

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pubstate = {published},

tppubtype = {article}

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@article{nokey,

title = {Temporal increase of Varroa mites in trap frames used for drone brood removal during the honey bee season},

author = {Richard Odemer and Franziska Odemer and Gerhard Liebig and Doris de Craigher},

url = {https://richard.odemer.info/wp-content/uploads/2022/06/Odemer-et-al.-2022-Temporal-increase-of-Varroa-mites-in-trap-frames-used-for-drone-brood-removal-during-the-honey-bee-season.pdf},

doi = {10.1111/jen.13046},

year  = {2022},

date = {2022-06-29},

urldate = {2022-06-29},

journal = {Journal of Applied Entomology},

abstract = {Varroa mites are highly attracted to drone brood of honey bees (Apis mellifera), as it increases their chance of successful reproduction. Therefore, drone brood removal with trap frames is common practice among beekeepers in Europe and part of sustainable varroa control. However, it is considered labour-intensive, and there are doubts about the effectiveness of this measure. At present, it is mostly unknown how many mites a drone frame can carry at different times of the season, and how many mites can be removed on average if this measure is performed frequently. Therefore, we sampled a total of 262 drone frames with varying proportion of capped cells (5–100%) from 18 different apiaries. Mites were washed out from brood collected from mid-April to mid-July based on a standard method to obtain comparable results. We found that a drone frame carried a median of 71.5 mites, and with the removal of four trap frames, about 286 mites can be removed per colony and season. In addition, mite counts were significantly higher in June and July than in April and May (Tukey-HSD, P < 0.05). The number of mites and the proportion of capped cells, however, were not correlated (R2 < 0.01, P < 0.05). Our results suggest that drone brood removal is effective in reducing Varroa destructor numbers in colonies, supporting the findings of previous studies on the efficacy of this measure. Although mite counts varied, we believe that increasing sample size over different seasons and locations could elucidate infestation patterns in drone brood and ultimately improve drone brood removal as an integrated pest management tool for a wider audience of beekeepers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Honey bee counter evaluation – Introducing a novel protocol for measuring daily loss accuracy},

author = {Parzival Borlinghaus and Richard Odemer and Frederic Tausch and Katharina Schmidt and Oliver Grothe},

url = {https://richard.odemer.info/wp-content/uploads/2022/04/Borlinghaus_et_al_2022.pdf},

doi = {10.1016/j.compag.2022.106957},

year  = {2022},

date = {2022-04-26},

urldate = {2022-04-26},

journal = {Computers and Electronics in Agriculture},

volume = {197},

abstract = {Automated bee counters advanced over the last hundred years and became increasingly diverse. However, to date, there is no method for standardized validation of counting accuracy and thus no reliable data on daily bee losses, or background mortality in colonies. However, such data are in urgent need by regulators to establish future guidelines for pesticide risk assessment. In this work, existing approaches were combined to form a novel protocol for validating bee counters. In a case study, we demonstrated that the protocol is sufficiently feasible to determine the measurement accuracy of a commercial counting system. Measurement accuracy was modeled by the difficulty of specific measurement conditions. Daily loss, i.e., the difference between incoming and outgoing bees, can be used to assess colony health, environmental impacts, and infer the effect of pesticides on bee colonies. The developed protocol makes innovations in this field measurable and creates a foundation for the benchmarking of different types of bee counting systems. We discuss how it can be utilized in an effort to move the sector forward in the future.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Inert agricultural spray adjuvants may increase the adverse effects of selected insecticides on honey bees (Apis mellifera L.) under laboratory conditions},

author = {Anna Wernecke and Jakob H. Eckert and Rolf Forster and Nils Kurlemann and Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Wernecke_et_al_2021_Inert_Agricultural_Spray_Adjuvants.pdf},

doi = {10.1007/s41348-021-00541-z},

year  = {2021},

date = {2021-10-22},

urldate = {2021-10-22},

journal = {Journal of Plant Diseases and Protection},

abstract = {Currently, more than 360 spray adjuvants are registered in Germany (September 2021). Unlike plant protection products (PPPs), adjuvants are not subjected to regulatory risk assessment. In practice, numerous combinations of PPPs and adjuvants are therefore possible. Thus, tank mixtures containing insecticides that are classified as non-hazardous to bees up to the highest approved application rate or concentration may raise pollinator safety concerns when mixed with efficacy increasing adjuvants and applied in bee attractive crops. This study analyzes whether selected “PPP-adjuvant” combinations result in increased contact mortality and pose an elevated risk to honey bees. To answer this question, we chose six common spray adjuvants of different classes for laboratory screening. These were then tested in a total of 30 tank mixtures, each with a neonicotinoid (acetamiprid), pyrethroid (lambda-cyhalothrin), diamide (chlorantraniliprole), carbamate (pirimicarb), and butenolide (flupyradifurone) formulation. We adapted an acute contact test (OECD Test Guideline 214) to our needs, e.g. by using a professional spray chamber for more realistic exposures. Our results showed that, in total, 50% of all combinations significantly increased the mortality of caged honey bees in comparison to individual application of insecticides. In contrast, none of the adjuvants alone affected bee mortality (Cox proportional hazard model, p > 0.05). With four of the five insecticide formulations, the organosilicone surfactant Break-Thru® S 301 significantly increased bee mortality within 72 h (for all insecticides except chlorantraniliprole). Furthermore, acetamiprid yielded the highest and second-highest mortality increases from a tank mixture with the crop oil surfactant LI 700® (hazard ratio = 28.84, p < 0.05) and the organosilicone Break-Thru® S 301 (hazard ratio = 14.66, p < 0.05), respectively. To assess risk in a more practical setting, field trials should be performed to provide a more realistic exposure scenario under colony conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Approaches, challenges, and recent advances in automated bee counting devices – a review},

author = {Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_2021_BeeCounter_Review.pdf},

doi = {10.1111/aab.12727},

year  = {2021},

date = {2021-08-08},

urldate = {2021-08-08},

journal = {Annals of Aplied Biology},

abstract = {For nearly 100 years, electronic bee counters have been developed using various technologies to track the foraging activity of mostly honey bee colonies. These counters should enable remote monitoring of the hives without disturbing natural flight behavior while generating precise scientific data. Today, however, there are not many counters on the market, that are able to fulfill this task. One main challenge is the lack of standardized methods to validate a counter’s precision, but validation is crucial to categorize and judge the data produced by the counter, especially for scientific purposes. Another challenge is the interpretation of flight data to measure the effects of environmental or anthropogenic sources. Nevertheless, recent developments in the field are promising. This review describes the historic development of automated bee flight measurement and critically compares validation methods to encourage their improvement. Lastly, to increase the comparability of future analyses with bee counters, current advances in data interpretation are also presented.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Odemer_et_al_2020,

title = {Chronic High Glyphosate Exposure Delays Individual Worker Bee (Apis mellifera L.) Development under Field Conditions},

author = {Richard Odemer and Abdulrahim T. Alkassab and Gabriela Bischoff and Malte Frommberger and Anna Wernecke and Ina P. Wirtz and Jens Pistorius and Franziska Odemer 

},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_et_al_2020_Glyphosate_Brood_Development.pdf},

doi = {10.3390/insects11100664},

year  = {2020},

date = {2020-09-27},

urldate = {2020-09-27},

journal = {Insects},

abstract = {The ongoing debate about glyphosate-based herbicides (GBH) and their implications for beneficial arthropods gives rise to controversy. This research was carried out to cover possible sublethal GBH effects on the brood and colony development, adult survival, and overwintering success of honey bees (Apis mellifera L.) under field conditions. Residues in bee relevant matrices, such as nectar, pollen, and plants, were additionally measured. To address these questions, we adopted four independent study approaches. For brood effects and survival, we orally exposed mini-hives housed in the “Kieler mating-nuc” system to sublethal concentrations of 4.8 mg glyphosate/kg (T1, low) and 137.6 mg glyphosate/kg (T2, high) over a period of one brood cycle (21 days). Brood development and colony conditions were assessed after a modified OECD method (No. 75). For adult survival, we weighed and labeled freshly emerged workers from control and exposed colonies and introduced them into non-contaminated mini-hives to monitor their life span for 25 consecutive days. The results from these experiments showed a trivial effect of GBH on colony conditions and the survival of individual workers, even though the hatching weight was reduced in T2. The brood termination rate (BTR) in the T2 treatment, however, was more than doubled (49.84%) when compared to the control (22.11%) or T1 (20.69%). This was surprising as T2 colonies gained similar weight and similar numbers of bees per colony compared to the control, indicating an equal performance. Obviously, the brood development in T2 was not “terminated” as expected by the OECD method terminology, but rather “slowed down” for an unknown period of time. In light of these findings, we suggest that chronic high GBH exposure is capable of significantly delaying worker brood development, while no further detrimental effects seem to appear at the colony level. Against this background, we discuss additional results and possible consequences of GBH for honey bee health.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bermig2020,

title = {Experimental validation of an electronic counting device to determine flight activity of honey bees (Apis mellifera L.)},

author = {Sven Bermig and Richard Odemer and Alina J. Gombert and Malte Frommberger and Ralf Rosenquist and Jens Pistorius},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/JKPF_BeeCheck_Artikel_final.pdf},

doi = {10.5073/JfK.2020.05.03},

issn = {1867-0938},

year  = {2020},

date = {2020-05-01},

urldate = {2020-05-01},

journal = {Journal für Kulturpflanzen},

abstract = {In this work, a functional prototype of the BeeCheck counting device was evaluated for its accuracy to validate its suitability for scientific purposes. Two different approaches were applied: (i) we manually compared electronic data of the counting device by video recordings of entry and exit events, and (ii) by using the so-called “robber’s test” in a tunnel tent. The results showed an expected temperature dependency of the general flight activity. Difficulties occurred with certain activities at the hive entrance. The various running speeds of individuals, approaching or stuck bees, and bees moving back and forth in the tube were a challenge for sensor technology and the mathematical algorithm. To minimize such mistakes and to increase the counting accuracy, it is necessary to correct the algorithm accordingly. This will be addressed in the “V-I-Bee” follow-up project and future perspectives of using an improved counting device are discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Odemer2020,

title = {Reproductive capacity of Varroa destructor in four different honey bee subspecies},

author = {Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_2020-_Varroa_Reproduction.pdf},

doi = {10.1016/j.sjbs.2019.09.002},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {Saudi Journal of Biological Sciences},

abstract = {Varroa tolerance as a consequence of host immunity may contribute substantially to reduce worldwide colony declines. Therefore, special breeding programs were established and varroa surviving populations investigated to understand mechanisms behind this adaptation. The aim of this study was to investigate the reproductive capacity in the three most common subspecies of the European honey bee (Carnica, Mellifera, Ligustica) and the F2 generation of a varroa surviving population, to identify if managed host populations possibly have adapted over time already. Both, singly infested drone and worker brood were assessed to determine fertility and fecundity of varroa foundresses in their respective group. We found neither parameter to be significantly different within the four subspecies, demonstrating that no adaptations have occurred in terms of the reproductive success of Varroa destructor. In all groups mother mites reproduce equally successful and are potentially able to cause detrimental damage to their host when not being treated sufficiently. The data further suggests that a population once varroa tolerant does not necessarily inherit this trait to following generations after the F1, which could be of particular interest when selecting populations for resistance breeding. Reasons and consequences are discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{OdemerRosenkranz2020,

title = {Chronic exposure to a neonicotinoid pesticide and a synthetic pyrethroid in full-sized honey bee colonies},

author = {Richard Odemer and Peter Rosenkranz},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_Rosenkranz-_2020_Thiacloprid_Fluvalinate_Colony_Development.pdf},

doi = {10.1080/00218839.2019.1675337},

year  = {2019},

date = {2019-10-22},

urldate = {2019-10-22},

journal = {Journal of Apicultural Research},

volume = {59},

number = {1},

pages = {2-11},

abstract = {In the last decade, the use of neonicotinoid insecticides increased significantly in the agricultural landscape and they are meanwhile considered a risk to honey bees. Besides the exposure to pesticides, colonies are treated frequently with various acaricides that beekeepers are forced to use against the parasitic mite Varroa destructor. Here we have analyzed the impact of chronic exposure to sublethal concentrations of the common neonicotinoid thiacloprid (T) and the widely used acaricide τ-fluvalinate (synthetic pyrethroid, F) - applied alone or in combination - to honey bee colonies under field conditions. Thiacloprid was administered in sugar syrup at a concentration of 2 mg/kg and in a frequency of 1 kg per week, no pollen was provided in addition. All colonies were kept on an organic farm and they were free to forage. The population dynamics of bees and brood were assessed in all colonies according to the Liebefeld method. Four groups (T, F, F + T, control) with 8-9 colonies each were analyzed in two independent replications, each lasting from spring/summer until spring of the consecutive year. In late autumn, all colonies were treated with oxalic acid against Varroosis. Under these specific conditions and with the doses tested, we could not find a negative impact of the chronic neonicotinoid exposure on the population dynamics or overwintering success of the colonies, irrespective of whether applied alone or in combination with τ-fluvalinate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{OdemerOdemer2020,

title = {Effects of radiofrequency electromagnetic radiation (RF-EMF) on honey bee queen development and mating success},

author = {Richard Odemer and Franziska Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer-Odemer-2019_EMF_Qeen_Development.pdf},

doi = {10.1016/j.scitotenv.2019.01.154},

year  = {2019},

date = {2019-01-23},

urldate = {2019-01-23},

journal = {Science of The Total Environment},

volume = {661},

pages = {553-562},

abstract = {Mobile phones can be found almost everywhere across the globe, upholding a direct point-to-point connection between the device and the broadcast tower. The emission of radiofrequency electromagnetic fields (RF-EMF) puts the surrounding environment inevitably into contact with this radiation. We have therefore exposed honey bee queen larvae to the radiation of a common mobile phone device (GSM band at 900 MHz) during all stages of their pre-adult development including pupation. After 14 days of exposure, hatching of adult queens was assessed and mating success after further 11 days, respectively. Moreover, full colonies were established of five of the untreated and four of the treated queens to contrast population dynamics. We found that mobile phone radiation had significantly reduced the hatching ratio but not the mating success. If treated queens had successfully mated, colony development was not adversely affected. We provide evidence that mobile phone radiation may alter pupal development, once succeeded this point, no further impairment has manifested in adulthood. Our results are discussed against the background of long-lasting consequences for colony performance and the possible implication on periodic colony losses.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Odemer_et_al_2018,

title = {Sublethal effects of clothianidin and Nosema spp. on the longevity and foraging activity of free flying honey bees},

author = {Richard Odemer and Lisa Nilles and Nadine Linder and Peter Rosenkranz },

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_et_al_2018_Nosema_Clothinaidin_Colony_Level.pdf},

doi = {10.1007/s10646-018-1925-5},

year  = {2018},

date = {2018-03-19},

urldate = {2018-03-19},

journal = {Ecotoxicology},

volume = {27},

pages = {527-538},

abstract = {Neonicotinoids alone or in combination with pathogens are considered to be involved in the worldwide weakening of honey bees. We here present a new approach for testing sublethal and/or synergistic effects in free flying colonies. In our experiment individually marked honey bees were kept in free flying mini-hives and chronically exposed to sublethal doses of the neonicotinoid clothianidin. Additional groups of bees were challenged with Nosema infections or with combinations of the pesticide and pathogens. Longevity and flight activity of the differentially treated bees were monitored for a period of 18 days. In contrast to previous laboratory studies, no effect of the neonicotinoid treatment on mortality or flight activity could be observed. Although the lifespan of Nosema infected bees were significantly reduced compared to non-infected bees a combination of pesticide and pathogen did not reveal any synergistic effect. Our results indicate that individual bees are less impaired by neonicotinoids if kept within the social environment of the colony. The effect of such a “social buffering” should be considered in future risk assessments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Retschnig_et_el_2015,

title = {Effects, but no interactions, of ubiquitous pesticide and parasite stressors on honey bee (Apis mellifera) lifespan and behaviour in a colony environment},

author = {Gina Retschnig and Geoffrey R. Williams and Richard Odemer and Janina Boltin and Cornelia Di Poto and Marion M. Mehmann and Peter Retschnig and Pius Winiger and Peter Rosenkranz and Peter Neumann},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Retschnig_et_al_2015_Nosema_Thiacloprid_effect_observation_hive.pdf},

doi = {10.1111/1462-2920.12825},

year  = {2015},

date = {2015-03-02},

urldate = {2015-03-02},

journal = {Environmental Microbiology},

abstract = {Interactions between pesticides and parasites are believed to be responsible for increased mortality of honey bee (Apis mellifera) colonies in the northern hemisphere. Previous efforts have employed experimental approaches using small groups under laboratory conditions to investigate influence of these stressors on honey bee physiology and behaviour, although both the colony level and field conditions play a key role for eusocial honey bees. Here, we challenged honey bee workers under in vivo colony conditions with sublethal doses of the neonicotinoid thiacloprid, the miticide tau-fluvalinate and the endoparasite Nosema ceranae, to investigate potential effects on longevity and behaviour using observation hives. In contrast to previous laboratory studies, our results do not suggest interactions among stressors, but rather lone effects of pesticides and the parasite on mortality and behaviour, respectively. These effects appear to be weak due to different outcomes at the two study sites, thereby suggesting that the role of thiacloprid, tau-fluvalinate and N. ceranae and interactions among them may have been overemphasized. In the future, investigations into the effects of honey bee stressors should prioritize the use of colonies maintained under a variety of environmental conditions in order to obtain more biologically relevant data.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Wang_et_al_2014,

title = {Putative orthologues of genetically identified Drosophila melanogaster chitin producing and organising genes in Apis mellifera},

author = {Yiwen Wang and Richard Odemer and Peter Rosenkranz and Bernard Moussian},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Wang_et_al_2014_Chitin_Drosophila_Apis_mellifera.pdf},

doi = {10.1007/s13592-014-0292-3},

year  = {2014},

date = {2014-05-28},

urldate = {2014-05-28},

journal = {Apidologie},

volume = {45},

pages = {733-747},

abstract = {The cuticle is a versatile coat allowing insects to survive in a variety of ecological situations. The polysaccharide chitin is a major cuticle component defining cuticle function. The key players of chitin synthesis and organisation, including chitin synthase-1 (CS-1), the chitin deacetylases vermiform (Verm) and serpentine (Serp), the extracellular obstructor-A (Obst-A) protein, the membrane-bound Knickkopf (Knk) and retroactive (Rtv) proteins, the cytoplasmic mummy (Mmy) protein and the transcription factor grainyhead (Grh) have been characterised genetically in the fruit fly Drosophila melanogaster. Here, we report on the identification of putative orthologues of these factors in Apis mellifera and on their expression at different developmental stages. Overall, differences in gene organisation and expression pattern between these two species may compile different cuticle compositions that reflect their life style and ecology. Our data will serve to elucidate the honeybee-specific mechanisms of cuticle formation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Odemer2013,

title = {Nosema ceranae, a new threat to honey bees (Apis mellifera L.)?},

author = {Richard Odemer},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Odemer_2013_Nosema_ceranae_new_threat.pdf},

doi = {10.31219/osf.io/47df8},

year  = {2013},

date = {2013-04-01},

urldate = {2013-04-01},

journal = {Tierärztliche Umschau},

volume = {68},

number = {4},

pages = {126-131},

abstract = {Back in 1900 already, the Mikrosporidium Nosema apis was described in Apis mellifera. Thereby the Nosemosis remains without symptoms in the beehive to a certain degree. Studies indicate that infected bees have a shortened life span, due to a series of changes in physiological parameters. The consequence of these changes are diarrheal symptoms and the spread of infectious spores in the hive. There is also a seasonal infection course observed, which has its peak in spring time (April, May). Colloquially, the Nosemosis is therefore also known as spring shrinking craze. More recently, a new Nosema species in the European honey bee has been described, where a host-switch from the Asian honey bee A. cerana to A. mellifera has occurred. N. ceranae is blamed for colony losses in the south of Spain, many general colony losses during wintertime in Europe and has also a contribution to the Colony Collapse Disorder (CCD) in the U.S. it seems likely that the original Nosema species (N. apis) is displaced more and more by N. ceranae for unknown reasons. Within the EUproject "BEE DOC", monitoring studies on colonies in southern Germany, Switzerland, southern France, Sweden and Finland were performed. Although the high prevalence of N. ceranae could be confirmed, no increased colony mortality due to Nosemosis was recorded. This was also observed by other colleagues and thus the "new threat" is open to debate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Frey_et_al_2013,

title = {Activation and interruption of the reproduction of Varroa destructor is triggered by host signals (Apis mellifera)},

author = {Eva Frey and Richard Odemer and Thomas Blum and Peter Rosenkranz},

url = {https://richard.odemer.info/wp-content/uploads/2021/10/Frey_et_al_2013_Varroa_Reproduction_Activation.pdf},

doi = {10.1016/j.jip.2013.01.007},

year  = {2013},

date = {2013-01-30},

urldate = {2013-01-30},

journal = {Journal of Invertebrate Pathology},

volume = {113},

number = {1},

pages = {56-62},

abstract = {The reproductive cycle of the parasitic mite Varroa destructor is closely linked to the development of the honey bee host larvae. Using a within colony approach we introduced phoretic Varroa females into brood cells of different age in order to analyze the capacity of certain stages of the honey bee larva to either activate or interrupt the reproduction of Varroa females. Only larvae within 18 h (worker) and 36 h (drones), respectively, after cell capping were able to stimulate the mite’s oogenesis. Therewith we could specify for the first time the short time window where honey bee larvae provide the signals for the activation of the Varroa reproduction. Stage specific volatiles of the larval cuticle are at least part of these activation signals. This is confirmed by the successful stimulation of presumably non-reproducing mites to oviposition by the application of a larval extract into the sealed brood cells. According to preliminary quantitative GC–MS analysis we suggest certain fatty acid ethyl esters as candidate compounds.



If Varroa females that have just started with egg formation are transferred to brood cells containing host larvae of an elder stage two-thirds of these mites stopped their oogenesis. This confirms the presence of an additional signal in the host larvae allowing the reproducing mites to adjust their own reproductive cycle to the ontogenetic development of the host. From an adaptive point of view that sort of a stop signal enables the female mite to save resources for a next reproductive cycle if the own egg development is not sufficiently synchronized with the development of the host.



The results presented here offer the opportunity to analyze exactly those host stages that have the capacity to activate or interrupt the Varroa reproduction in order to identify the crucial host signals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}