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Varroa destructor parasitism is associated with extreme honey bee (Apis mellifera) colony losses in the northern hemisphere. Varroa destructor causes severe damage, including a decrease in bee longevity and immunosuppression, and acts as a vector for viruses, such as Deformed wing virus (DWV-A). The surveillance of viral pathogens in V. destructor samples is essential to assess risks of emerging virulent viral variants (such as VDV-1) and evaluate their impact on honey bee health. Thus, the objective of this study was to identify viral pathogens in V. destructor and honey bee samples collected in Ontario, Canada, from 2015 to 2019 with the use of metagenomics and real time PCR (qPCR). DWV-A and VDV-1 had the highest abundance of viral transcripts (7.5 log2 and 5.72 log2, respectively). Acute bee paralysis virus (ABPV) and Bee macula virus were also identified. Viral identification and quantification in V. destructor samples using metagenomics will facilitate the surveillance of viral pathogens. This surveillance technique will assist diagnostic laboratories in delivering timely and accurate diagnoses and risk assessments, which in turn will help honey bee producers to take adequate measures to mitigate the damage caused by V. destructor and associated viruses.

The honey bee (Apis mellifera) parasitic mite, Varroa destructor, is considered one of the main causes of colony losses in European honey bee (EHB) populations around the world. However, some EHB and Africanized honey bee (AHB) populations (derived from the African subspecies A. m. scutellata) that inhabit tropical and subtropical regions of the Americas, have survived varroa mite infestations in the absence of acaricide treatments. It is conceivable to expect that these honey bee populations, which have been subjected to natural selection over decades, would have developed resistance against V. destructor or possess pre-existing adaptations that allow them to survive mite parasitism. Here, we present a comprehensive literature review describing the spread of V. destructor and the honey bee populations occurring in Latin America (LA), and summarize the evidence of resistance of those populations to V. destructor. We also analyze reports describing the potential mechanisms of mite resistance and how they operate in those honey bee populations. Studies of a few EHB, as well as of numerous AHB populations exhibiting resistance to V. destructor in LA, unveil the existence of evolutionary adaptations that restrain V. destructor population growth and provide insight into the current host-parasite relationship. This review supports the notion that selective breeding of local honey bee populations from LA could be a viable strategy to manage varroa mite infestations in colonies. [ABSTRACT FROM AUTHOR]

Highbush blueberry pollination depends on managed honey bees (Apis mellifera L.) for adequate fruit sets; however, beekeepers have raised concerns about the poor health of colonies after pollinating this crop. Postulated causes include agrochemical exposure, nutritional deficits, and interactions with parasites and pathogens, particularly Melisococcus plutonius [(ex. White) Bailey and Collins, Lactobacillales: Enterococcaceae], the causal agent of European foulbrood disease, but other pathogens could be involved. To broadly investigate common honey bee pathogens in relation to blueberry pollination, we sampled adult honey bees from colonies at time points corresponding to before (t1), during (t2), at the end (t3), and after (t4) highbush blueberry pollination in British Columbia, Canada, across 2 years (2020 and 2021). Nine viruses, as well as M. plutonius , Vairimorpha ceranae, and V. apis [Tokarev et al. Microsporidia: Nosematidae; formerly Nosema ceranae (Fries et al.) and N. apis (Zander)], were detected by PCR and compared among colonies located near and far from blueberry fields. We found a significant interactive effect of time and blueberry proximity on the multivariate pathogen community, mainly due to differences at t4 (corresponding to ~6 wk after the beginning of the pollination period). Post hoc comparisons of pathogens in near and far groups at t4 showed that detections of sacbrood virus (SBV), which was significantly higher in the near group, not M. plutonius , was the primary driver. Further research is needed to determine if the association of SBV with highbush blueberry pollination is contributing to the health decline that beekeepers observe after pollinating this crop. [ABSTRACT FROM AUTHOR]

Simple Summary: Metabolic changes in adult honey bee brains associated with the seasons and aging in honey bees (Apis mellifera) were assessed using nuclear magnetic resonance (NMR) spectroscopy. Brains were dissected from newly emerged, 14-day– old, and 28-day– old bees that were collected over the summer, as well as brood nest bees collected in the fall, winter, and spring. Changes in the brain metabolome indicated that worker bees undergo adaptations throughout their lives, with notable shifts occurring between newly emerged and older individuals. Furthermore, the seasons affected the honey bee brain metabolome, highlighting differences in metabolic responses to changes in the environment and resource availability. While previous studies have reported differences in the metabolome of whole bodies between summer and winter bees, or in the brains of forager bees infected with a virus, the present study has revealed the metabolome of the honey bee brain as it ages. Several potential markers were identified for assessing aging of the bee brain, such as the potential neurotransmitter β-alanine and neurotransmitter-precursors/intermediates, phenylalanine, tyrosine, tryptophan, and O-phosphocholine. Honey bees (Apis mellifera) provide a useful model for studying aging because of the differences in longevity between the relatively short-lived summer and long-lived winter bees, as well as bees lacking signs of cognitive senescence as they age. Bee brains were dissected from newly emerged, 14-day–, and 28-day– old bees in mid- and late summer, as well as brood nest bees in fall, winter, and spring, before, during, and after overwintering, respectively. Brains were examined with nuclear magnetic resonance (NMR) spectroscopy to analyze their metabolome. Nine variable importance in projection (VIP) variables were identified, primarily amino acids and choline derivatives. Differences in metabolite concentrations were found with different ages of summer bees, mostly between newly emerged and 14-day– old bees, such as a decrease in phenylalanine and an increase in β-alanine, but there were also changes in older adults, such as o-phosphocholine that declined in 28-day– old bees. Differences in brood nest bees were observed, including a decline in tryptophan and an increase in β-alanine. These may provide distinct metabolomic signatures with age and season. Such research holds promise for a better understanding of the complex interplays between bee physiology, development, and aging, which has implications for improving bee health and management. [ABSTRACT FROM AUTHOR]

The ecto-parasitic mite Varroa destructor is an extremely damaging biotic factor of honey bees (Apis mellifera) worldwide. The magnitude of the damage that V. destructor causes to the health of honey bees is well documented, but little is known about how it affects their behavior. For example, it is not known whether parasitism by V. destructor influences the bees' defensive behavior, and since this behavior has evolutionary and practical implications, its study is of importance. In this research, we used a constant-current stimulator to expose worker bees to a 0.5 mA electric stimulus after being parasitized by Varroa mites to test the hypothesis that V. destructor parasitism affects the stinging response threshold of individual honey bees. Bees exposed to V. destructor parasitism stung significantly faster than control bees in each of three trials (p < 0.05) and thus, it is concluded that the irritation caused by V. destructor reduces the stinging response threshold of honey bees. The implications of these findings are discussed, as well as the need for further studies to understand how V. destructor affects neuronal processes in the honey bee to make them more defensive. [ABSTRACT FROM AUTHOR]

The need for the increased production of honey bee (Apis mellifera) queens has led beekeepers to use different substrates in artificial queen cups where larvae destined to become queens are deposited (grafting). However, not enough scientific evidence exists that indicates that this practice is useful and what substance offers the best results. This study was conducted to determine with the Doolittle queen rearing method the acceptance rate of larvae deposited on different substrates during grafting and to determine if the sugar content and pH of the substrates used affect the acceptance of larvae in cell builder colonies. The evaluated substrates were coconut water, apple nectar, royal jelly, cola soda and distilled water, plus control (without substrate). Grafted larvae of the six treatments were introduced into cell builder colonies and their acceptance verified after 72 h. Apple nectar provided the highest rate of larvae acceptance with 81.06%, followed by cola soda with 62.93%, coconut water with 60.90%, royal jelly with 57.82% and distilled water with 58.99%. The larvae acceptance rates of all substrates were significantly higher than the control, which had an acceptance rate of 47.04%. No significant relationship was found between the sugar content of the substrates and larvae acceptance. However, although not significant, a high negative correlation was found between the substrate pH and the number of accepted larvae (Rho = - 0.90, p = 0.07). These results suggest that the use of liquid acidic substrates during larvae grafting, in particular apple nectar, may increase the production of honey bee queens.

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This document is an editorial published in the journal Frontiers in Insect Science. It discusses the current status of honey bee genetic and breeding programs, highlighting the progress made and future perspectives. The editorial emphasizes the importance of honey bees in food production and biodiversity, as well as the challenges they face due to agriculture intensification, climate change, and diseases. The article also mentions the value of honey bee products and the interest of geneticists and breeders in their genetic and behavioral attributes. The editorial concludes by highlighting the potential benefits of incorporating genetic knowledge into honey bee breeding programs, particularly in relation to Varroa resistance and the reduction of synthetic acaricides. However, it notes that these advancements are not yet widely applied in commercial breeding programs. [Extracted from the article]