Infestation with Varroa destructor is a serious cause of bee colony (Apis mellifera) losses on a global level. However, the presence of untreated survivor populations in many different regions supports the idea that selection for resistance can be successful. As colony survival is difficult or impossible to measure, differences in mite infestation levels and tests for specific behavioral traits are used for selective breeding for Varroa resistance. In this paper we looked into different definitions of mite infestation and linked these with brood hygiene (pin test), brood recapping and suppressed mite reproduction. We based our analyses on datasets of Apis mellifera carnica from three countries: Austria (147 records), Croatia (135) and Germany (207). We concluded that bee infestation in summer, adjusted for the level of natural mite fall in spring, is a suitable trait in the breeding objective, and also suggested including brood infestation rate and the increase rate of bee infestation in summer. Repeatability for bee infestation rate was about 0.55, for cells opened in pin test about 0.33, for recapping 0.35 and for suppressed mite reproduction (SMR) virtually zero. Although in most cases we observed correlations with the expected sign between infestation parameters and behavioral traits, the values were generally low (<0.2) and often not significantly different from zero.

The honey bee (Apis mellifera) is an ecologically and economically important species that provides pollination services to natural and agricultural systems. The biodiversity of the honey bee in parts of its native range is endangered by migratory beekeeping and commercial breeding. In consequence, some honey bee populations that are well adapted to the local environment are threatened with extinction. A crucial step for the protection of honey bee biodiversity is reliable differentiation between native and nonnative bees. One of the methods that can be used for this is the geometric morphometrics of wings. This method is fast, is low cost, and does not require expensive equipment. Therefore, it can be easily used by both scientists and beekeepers. However, wing geometric morphometrics is challenging due to the lack of reference data that can be reliably used for comparisons between different geographic regions. Here, we provide an unprecedented collection of 26,481 honey bee wing images representing 1,725 samples from 13 European countries. The wing images are accompanied by the coordinates of 19 landmarks and the geographic coordinates of the sampling locations. We present an R script that describes the workflow for analyzing the data and identifying an unknown sample. We compared the data with available reference samples for lineage and found general agreement with them. The extensive collection of wing images available on the Zenodo website can be used to identify the geographic origin of unknown samples and therefore assist in the monitoring and conservation of honey bee biodiversity in Europe.

The Carniolan honey bee (Apis mellifera carnica) is an indigenous subspecies of the Western honey bee in Central Europe. Croatia represents a large part of its native range. Hybridization and introgression is a realistic possibility due to unmonitored imports by beekeepers. In this study, we focused on honey bee colonies managed by beekeepers from all over Croatia and Slovenia. The identification of the subspecies was based on wing geometric morphometrics. The similarity of all investigated colonies to A. m. carnica was substantial, which indicates that the native subspecies continues to be present in the study area. However, some of the colonies differed markedly from the currently available reference of this subspecies. The low similarity with reference samples can be related both to hybridization with non-native subspecies and to natural geographical variation within A. m. carnica. The data and results obtained from this morphometric analysis will provide a deeper insight into the phenotypic characterization of the studied honey bee populations and directions for future conservation strategies.

In this study, we investigated the effect of queen caging on honey bee colonies’ post-treatment development and the optimal timing of method application on honey production during the main summer nectar flow. We conducted the study in nine apiaries (N = 9) across six Mediterranean countries, with a total of 178 colonies. The colonies were divided into three test groups: QC1, QC2, and C. The QC1 group involved queens caged for a total of 28 days before the expected harvesting day. In the QC2 group, queens were caged for 28 days, but only 14 days before the expected harvesting day. The C group consisted of queens that were not caged, and the colonies received common local treatments. In both the QC1 and QC2 groups, the colonies were treated with a 4.2% oxalic acid (OA) solution by trickling after the queen release. Our findings revealed no significant adverse effects (p > 0.05) on colony strength at the end of the study resulting from queen caging. However, significantly lower amounts of honey were extracted from the QC1 group compared to both the QC2 group (p = 0.001) and the C group (p = 0.009). Although there were no initial differences in Varroa destructor infestation between the groups, ten weeks later, a significantly higher infestation was detected in the C group compared to both the QC1 group (p < 0.01) and the QC2 group (p = 0.003). Overall, our study demonstrates that queen caging, in combination with the use of OA, is an effective treatment for controlling V. destructor. However, the timing of caging plays a crucial role in honey production outcomes.

The positive effects of honey bee venom on human health and the high market price are the main reasons for beekeepers' increasing interest in its production. However, until today there is no standardized technology for honey bee venom collection. Today's methods are mainly based on collectors placed at the hive entrance. The main problems with this method are the application of the collector, and the contamination that collected venom may contain which consequently reduces its quality. The disadvantages of this technology can at least partially be eliminated by the use of collectors placed inside the hive. Therefore, this study aimed to evaluate the effect of the collection method on the honey bee venom quality and quantity. The results of the study showed that significantly higher amounts of venom could be collected with collectors within the hive, while at the same time the quality of the venom, considering the melittin content, remained equal. Having in mind that honey bee venom collection has not had a significant impact on strength of the colonies (in comparison to control colonies that were not subjected to venom collection), collection technology with collectors placed inside the hive is a better option.