Wintersterfte van bijenvolken 2018-2019 : Resultaten enquête wintersterfte bijenvolken in Nederland in de winter van 2018-2019

Sinds 2003 wordt in Nederland jaarlijks de wintersterfte van bijenvolken gemonitord. Dit geeft een indicatie van de gezondheidstoestand van de gehouden populatie honingbijen in Nederland. Aan de wintersterfte-enquête van 2018-2019 deden 2032 bijenhouders mee. Dit is ongeveer 20% van alle bijenhouders in Nederland in 2018. De enquête bestond uit 3 gedeeltes, het eerste gedeelte ging over de gegevens van de bijenhouder, het tweede gedeelte over de bepaling van de wintersterfte en het laatste gedeelte was de COLOSS-enquête met een aantal toegevoegde vragen die relevant zijn voor de Nederlandse bijenhouderij. De wintersterfte van bijenvolken in Nederland in de winter van 2018-2019 was 9,2%. Dit is lager dan de twee voorgaande winters (14,3% en 15,7%). Van de respondenten gaf 69% te kennen geen wintersterfte van bijenvolken te hebben gehad in 2018-2019. Van diegene met sterfte van volken in de winter, gaf 68% te kennen koninginnenproblemen als oorzaak van de sterfte te zien. Verder werd berekend dat bijenhouders in Nederland gemiddeld genomen 8 bijenvolken hadden in 2018 en dat de totaalpopulatie gehouden bijenvolken ongeveer 75.000 bijenvolken bedroeg (najaar 2018). Per volk werd gemiddeld 13 kg honing geoogst. Per respondent was de gemiddelde honingopbrengst 101kg in 2018. Een gemiddelde prijs van €7,71 werd gevraagd voor een kilo honing en de respondenten hadden gemiddeld €448,- aan productiekosten. Het overgrote deel van de respondenten (88%) gaf te kennen varroa te bestrijden en de meerderheid (60%) monitort de varroabesmetting op enigerlei wijze. De resultaten van de COLOSS-enquête worden in internationaal verband geanalyseerd en vergeleken met de resultaten uit andere landen. In totaal doen zo’n 35 landen mee aan de COLOSS-enquête. De resultaten worden in de loop van 2020 ter publicatie aan een wetenschappelijk tijdschrift aangeboden

Kennisbundel kleine bijenkastkever : Wetenschappelijke achtergrond bij handelingsperspectieven ten behoeve van de uitroeiing en beheersing van de kleine bijenkastkever

De kleine bijenkastkever is een aangifteplichtige parasiet van de westerse honingbij (Apis mellifera spp.). In 2014 is deze kever aangetroffen in Zuid-Italië. Dit document bundelt de kennis die in het kader van het beleidsondersteunend onderzoek en ander onderzoek in de laatste jaren is ontwikkeld. De kennis is geformuleerd ten behoeve van het handelingsperspectief van beleidsmedewerkers en uitvoerders van de NVWA en bijengezondheidscoördinatoren

Controlling small hive beetles, Aethina tumida, in western honey bee (Apis mellifera) colonies by trapping wandering beetle larvae

The small hive beetle (SHB, Aethina tumida) is an invasive honey bee pest. It has been introduced into many countries worldwide and it will continue to spread. The lifecycle of the SHB is divided between a feeding and reproduction phase inside honey bee colonies and a pupation phase in the soil, surrounding colonies. Once larvae have achieved their ideal weight, they leave the hive in search of suitable soil in which to pupate. Trapping larvae when they leave the hive could reduce the reproductive success of SHBs, as this would break their lifecycle. Therefore, we investigated the larvae containment rate of different trap designs. Dry and wet larvae were released into traps and left to wander for 12 h, after which we counted the larvae remaining in the trap. Similarly, we tested the permeability of different mesh sizes for dry and wet larvae. Finally, we investigated the speed dry larvae are capable of crawling, by recording the time it took them to crawl a known distance. Dry larvae were contained by all traps. While most designs were unable to contain wet larvae, a trap with walls of sandpaper was able to contain all larvae successfully. Larvae could not pass through a mesh size of 1 mm in dry or wet conditions. The mean wandering larvae speed observed was 0.42 cm/sc. We recommend the use of traps for wandering SHB larvae as a mitigative measure for new introductions and a control method for established populations.</p

Osteoblasts secrete miRNA-containing extracellular vesicles that enhance expansion of human umbilical cord blood cells

Osteolineage cells represent one of the critical bone marrow niche components that support maintenance of hematopoietic stem and progenitor cells (HSPCs). Recent studies demonstrate that extracellular vesicles (EVs) regulate stem cell development via horizontal transfer of bioactive cargo, including microRNAs (miRNAs). Using next-generation sequencing we show that human osteoblast-derived EVs contain highly abundant miRNAs specifically enriched in EVs, including critical regulators of hematopoietic proliferation (e.g., miR-29a). EV treatment of human umbilical cord blood-derived CD34 + HSPCs alters the expression of candidate miRNA targets, such as HBP1, BCL2 and PTEN. Furthermore, EVs enhance proliferation of CD34 + cells and their immature subsets in growth factor-driven ex vivo expansion cultures. Importantly, EV-expanded cells retain their differentiation capacity in vitro and successfully engraft in vivo. These discoveries reveal a novel osteoblast-derived EV-mediated mechanism for regulation of HSPC proliferation and warrant consideration of EV-miRNAs for the development of expansion strategies to treat hematological disorders

Identification of osteolineage cell-derived extracellular vesicle cargo implicated in hematopoietic support

Osteolineage cell-derived extracellular vesicles (EVs) play a regulatory role in hematopoiesis and have been shown to promote the ex vivo expansion of human hematopoietic stem and progenitor cells (HSPCs). Here, we demonstrate that EVs from different human osteolineage sources do not have the same HSPC expansion promoting potential. Comparison of stimulatory and non-stimulatory osteolineage EVs by next-generation sequencing and mass spectrometry analyses revealed distinct microRNA and protein signatures identifying EV-derived candidate regulators of ex vivo HSPC expansion. Accordingly, the treatment of umbilical cord blood-derived CD34+ HSPCs with stimulatory EVs-altered HSPC transcriptome, including genes with known roles in cell proliferation. An integrative bioinformatics approach, which connects the HSPC gene expression data with the candidate cargo in stimulatory EVs, delineated the potentially targeted biological functions and pathways during hematopoietic cell expansion and development. In conclusion, our study giv

Winter Survival of Individual Honey Bees and Honey Bee Colonies Depends on Level of Varroa destructor Infestation

Background: Recent elevated winter loss of honey bee colonies is a major concern. The presence of the mite Varroa destructor in colonies places an important pressure on bee health. V. destructor shortens the lifespan of individual bees, while long lifespan during winter is a primary requirement to survive until the next spring. We investigated in two subsequent years the effects of different levels of V. destructor infestation during the transition from short-lived summer bees to long-lived winter bees on the lifespan of individual bees and the survival of bee colonies during winter. Colonies treated earlier in the season to reduce V. destructor infestation during the development of winter bees were expected to have longer bee lifespan and higher colony survival after winter. Methodology/Principal Findings: Mite infestation was reduced using acaricide treatments during different months (July, August, September, or not treated). We found that the number of capped brood cells decreased drastically between August and November, while at the same time, the lifespan of the bees (marked cohorts) increased indicating the transition to winter bees. Low V. destructor infestation levels before and during the transition to winter bees resulted in an increase in lifespan of bees and higher colony survival compared to colonies that were not treated and that had higher infestation levels. A variety of stress-related factors could have contributed to the variation in longevity and winter survival that we found between years. Conclusions/Significance: This study contributes to theory about the multiple causes for the recent elevated colony losses in honey bees. Our study shows the correlation between long lifespan of winter bees and colony loss in spring. Moreover, we show that colonies treated earlier in the season had reduced V. destructor infestation during the development of winter bees resulting in longer bee lifespan and higher colony survival after winter

Honey bee colony winter loss rates for 35 countries participating in the COLOSS survey for winter 2018–2019, and the effects of a new queen on the risk of colony winter loss

peer-reviewedThis article presents managed honey bee colony loss rates over winter 2018/19 resulting from using the standardised COLOSS questionnaire in 35 countries (31 in Europe). In total, 28,629 beekeepers supplying valid loss data wintered 738,233 colonies, and reported 29,912 (4.1%, 95% confidence interval (CI) 4.0–4.1%) colonies with unsolvable queen problems 79,146 (10.7%, 95% CI 10.5–10.9%) dead colonies after winter and 13,895 colonies (1.9%, 95% CI 1.8–2.0%) lost through natural disaster. This gave an overall colony winter loss rate of 16.7% (95% CI 16.4–16.9%), varying greatly between countries, from 5.8% to 32. 0%. We modelled the risk of loss as a dead/empty colony or from unresolvable queen problems and found that, overall, larger beekeeping operations with more than 150 colonies experienced significantly lower losses (p<0.001), consistent with earlier studies. Additionally, beekeepers included in this survey who did not migrate their colonies at least once in 2018 had significantly lower losses than those migrating (p<0.001). The percentage of new queens from 2018 in wintered colonies was also examined as a potential risk factor. The percentage of colonies going into winter with a new queen was estimated as 55.0% over all countries. Higher percentages of young queens corresponded to lower overall losses (excluding losses from natural disaster), but also lower losses from unresolvable queen problems, and lower losses from winter mortality (p<0.001). Detailed results for each country and overall are given in a table, and a map shows relative risks of winter loss at regional level

Supplementary information for the article: Brodschneider, R.; Schlagbauer, J.; Arakelyan, I.; Ballis, A.; Brus, J.; Brusbardis, V.; Cadahía, L.; Charrière, J.-D.; Chlebo, R.; Coffey, M. F.; Cornelissen, B.; da Costa, C. A.; Danneels, E.; Danihlík, J.; Dobrescu, C.; Evans, G.; Fedoriak, M.; Forsythe, I.; Gregorc, A.; Johannesen, J.; Kauko, L.; Kristiansen, P.; Martikkala, M.; Martín-Hernández, R.; Mazur, E.; Mutinelli, F.; Patalano, S.; Raudmets, A.; Simon Delso, N.; Stevanovic, J.; Uzunov, A.; Vejsnæs, F.; Williams, A.; Gray, A. Spatial Clusters of Varroa Destructor Control Strategies in Europe. J Pest Sci 2022. https://doi.org/10.1007/s10340-022-01523-2.

Table S1. Utilized packages of the statistical software R version 4.0.4.Supplementary material for: [https://vet-erinar.vet.bg.ac.rs/handle/123456789/2469]Related to the published version: [https://vet-erinar.vet.bg.ac.rs/handle/123456789/2469