1. Key points

• Winter bees are not simply ageing summer bees: they have a distinct physiology.
• Their quality depends strongly on the period from July to September: varroa, nutrition, brood, and stress accumulate during this time.
• Varroa and associated viruses can directly reduce the longevity and biological reserves of winter bees.
• Autumn nutrition matters, but oversimplified prescriptions should be avoided: food stores, pollen, local context, and health status all interact.
• The figures in the original article are useful for reasoning, but must not be applied as universal thresholds.

2. What the study shows

This chapter summarises the central idea of the article: spring vigour depends largely on the quality of the winter bees produced in late summer.

Research question. The article asks how a colony should be managed between the end of the honey harvest and autumn in order to preserve the "vital capital" of the winter bees. The practical goal is to reach spring with enough bees still capable of heating the cluster, feeding brood, and supporting the colony's recovery (Artus et al., 2010).

Method. This is not a controlled experimental study, but a beekeeping management article based on demographic reasoning, simple calculations, and connections to the known physiology of winter bees. The authors compare two scenarios in particular: a winter bee with a useful lifespan of approximately 160 days, and another with a potential lifespan of approximately 210 days (Artus et al., 2010).

Results. In the shorter scenario, a large proportion of bees born before mid-September would disappear before the young spring bees are ready to take over. The colony would risk arriving very weak at the moment when laying truly resumes. In the more favourable scenario, the winter bees would survive long enough to ensure a generational overlap in spring, allowing a faster resumption of brood rearing and foraging (Artus et al., 2010).

The article identifies several factors liable to deplete this vital capital: varroosis and associated viral diseases, poorly conducted varroa treatment, inadequate feeding, still-substantial brood in the late season, winter disturbances, poor thermal regulation, and genetic factors. The key point is their interaction: it is not a single isolated factor that always determines the outcome, but the accumulation of stressors at the wrong moment (Artus et al., 2010).

Interpretation. The practical message is clear: the beekeeper must not think only in terms of "coming out of winter", but must act earlier, from the end of the honey harvest. The nurse bees rearing winter bees must carry a low mite burden, be well fed, and not be exhausted by excessive late brood rearing. This reasoning is consistent with current knowledge on winter bees: they exhibit well-developed fat bodies, higher protein reserves, greater vitellogenin levels, developed hypopharyngeal glands, and lower juvenile hormone titres than ageing summer bees (Fluri et al., 1977, 1982; Amdam & Omholt, 2002; Kunc et al., 2019; Knoll et al., 2020).

Feeding must therefore not be understood merely as topping up food stores. It also influences the space available for laying, the workload of the bees, brood dynamics, and indirectly varroa reproduction. The article is right to emphasise a gradual and considered management approach, even if the quantities and dates proposed must be adapted to the local climate, hive format, altitude, and the varroa management concept applied locally (Artus et al., 2010; Döke et al., 2015; Quinlan et al., 2023).

3. Critical appraisal

The strength of the article lies in its holistic reasoning, but its figures should not be read as universally valid scientific thresholds.

Strengths. The article correctly emphasises a period that is often underestimated: July to September. It usefully links varroa management, feeding, brood dynamics, and the preparation of winter bees. This holistic approach remains highly relevant for Swiss or temperate European apiaries, especially since recent work confirms the importance of the summer-to-autumn transition in overwintering biology (Döke et al., 2015; Knoll et al., 2020).

Limitations. The text does not present new experimental data. The lifespans of 160 or 210 days serve primarily to construct a demographic argument. They do not prove that all winter bees must live exactly 210 days, nor that this threshold would hold across all regions, bee races, or management systems (Artus et al., 2010).

The dates proposed — mid-July, mid-August, mid-September, 10 October — must also be placed in context. In Switzerland, they may vary according to altitude, nectar flow, weather conditions, hive format, colony strength, and the varroa management concept applied. The food store quantities mentioned in the article, notably 25 to 30 kg, must not be applied mechanically to all hive systems (Artus et al., 2010).

Possible misunderstandings. The article can give the impression that late brood is always negative. This is too simple. A small resumption of laying in autumn may occur depending on the climate, the queen, and available resources. The risk arises primarily when late brood rearing becomes substantial enough to exhaust winter bees, maintain a high temperature in the brood nest, and prolong varroa reproduction (Artus et al., 2010; Döke et al., 2015; Giacobino et al., 2023).

Recent literature strongly supports the role of varroa in weakening winter bees, but does not automatically validate every practical detail of the article. Studies show that infestation by Varroa destructor and associated viruses can reduce longevity, disrupt metabolism, alter protein reserves, and increase the risk of winter losses (Amdam et al., 2004; Dainat et al., 2011; Van Dooremalen et al., 2012; Steinmann et al., 2015; Kunc et al., 2022). This reinforces the message of acting early, but does not permit setting a single date that is valid everywhere.

The mention of a specific summer treatment product in the article reflects the publication context. For current Swiss practice, the authorised preparations, official instructions, and the varroa management concept currently in force must always be verified before any application: [TO BE VERIFIED].

What cannot be concluded. This article does not allow one to derive a standard lifespan for winter bees, a single feeding quantity, a fixed treatment date, or a universal prescription for insulation and ventilation. The underlying logic is, however, solid: preserving winter bees requires acting early, reducing varroa pressure, and avoiding unnecessary stressors at the end of the season.

4. What related studies show

Recent studies do not confirm all the numerical values in the article, but they strongly reinforce its central idea: the quality of winter bees depends on their physiology, varroa pressure, and late-summer conditions.

The literature confirms first of all that winter bees are not simply summer workers that live longer because they fly less. They exhibit a genuine seasonal phenotype: more developed fat bodies, higher protein and lipid reserves, elevated vitellogenin levels, hypertrophied hypopharyngeal glands, and lower juvenile hormone titres. These traits are associated with their longevity and their capacity to support the resumption of brood rearing in spring (Fluri et al., 1977, 1982; Amdam & Omholt, 2002; Kunc et al., 2019; Knoll et al., 2020; Koubová et al., 2021).

This strongly supports the reasoning of the original article: preserving winter bees means preserving a particular physiological state, not merely maintaining a sufficient number of bees in the hive. Research on storage proteins, vitellogenin, and seasonal metabolism shows that winter bees constitute a biological reserve for the colony, both for surviving winter and for feeding the first spring broods (Erban et al., 2013; Kunc et al., 2019; Lee et al., 2022).

The link with varroa is also well supported. Experimental and epidemiological studies show that Varroa destructor and associated viruses — in particular Deformed Wing Virus — reduce the physiological quality and lifespan of winter bees. Infestation can deplete protein reserves, alter immunity, disrupt metabolism, and shorten individual survival. Colonies that produce their winter bees under high varroa pressure therefore enter winter with a population less capable of lasting through it (Amdam et al., 2004; Dainat et al., 2011; Van Dooremalen et al., 2012; Steinmann et al., 2015; Kunc et al., 2022).

Management studies point in the same direction: autumn varroa levels strongly predict winter losses, and integrated management strategies — particularly when they reduce mite numbers before or during the production of winter bees — improve colony survival (Büchler et al., 2020; Calovi et al., 2021; Smoliński et al., 2021; Gray et al., 2024). This confirms the practical intuition of the article: treating too late may mean that winter bees have already been produced under poor conditions.

The role of nutrition is more nuanced. Several studies associate good pollen availability, adequate floral diversity, and digestible carbohydrate reserves with better autumn colonies and better winter survival (Ricigliano et al., 2018; Topal et al., 2022; Quinlan et al., 2023). However, results are not uniform: Mattila and Otis (2007) showed that manipulating autumn pollen supply did not always affect winter bee performance. A conclusion along the lines of "more protein feeding = better winter bees" should therefore be avoided. Context, the initial condition of the colony, pollen quality, and the level of health-related stress likely matter as much as the supply itself.

The question of late brood remains the most delicate. At the mechanistic level, the original article is coherent: brood rearing consumes resources and may engage winter bees in tasks that erode their longevity. Knowledge of vitellogenin, fat bodies, and hypopharyngeal glands makes this hypothesis plausible (Fluri et al., 1982; Amdam & Omholt, 2002; Kunc et al., 2019). The available literature does not, however, allow this to be made an absolute rule valid in all situations. Substantial late brood, sustained by excessive stimulation or abnormally mild autumn conditions, can become detrimental, especially if it also prolongs varroa reproduction (Giacobino et al., 2023).

Overall, recent studies reinforce three messages from the article: winter bees have a specific physiology; varroa must be reduced before it compromises this generation; and autumn nutrition should support the colony without unnecessarily prolonging a costly brood-rearing dynamic. They do not, however, mechanically validate the precise figures proposed in the article, notably the 210-day lifespan, fixed dates, or feeding quantities.

5. Practical implications for the apiary

For the beekeeper, the main value lies in translating the concept of the winter bee into concrete decisions from the end of the honey flow onwards.

• Do not wait until autumn to think about overwintering: the quality of winter bees is prepared from the end of the honey harvest, primarily through varroa management (Dainat et al., 2011; Van Dooremalen et al., 2012; Büchler et al., 2020).
• Monitor infestation and treat according to the current Swiss management concept, using authorised products and strictly following the official instructions: [TO BE VERIFIED].
• Feed according to actual food store levels, colony strength, hive format, and altitude; the goal is not to stimulate laying indefinitely, but to ensure digestible and accessible reserves (Quinlan et al., 2023).
• Pay attention to pollen availability and late-summer resources: a colony cannot produce good winter bees on sugar alone, but the benefit of protein supplements depends on context and does not substitute for a diverse floral environment (Mattila & Otis, 2007; Ricigliano et al., 2018; Topal et al., 2022).
• Limit unnecessary stressors in winter: disturbances, moisture, wind, rodents, poor ventilation, or inaccessible food stores can increase consumption and weaken the winter cluster (Artus et al., 2010).

Read the original article

Original article: José Artus, with writing by Estelle Carton de Wiart and Janine Kievits, Préserver le capital de vie des abeilles, published in Abeilles & Cie, no. 136, 3-2010, pp. 25–28. This is a beekeeping management article, not an experimental study in the strict sense.

Further reading on ApiSavoir

• Overwintering in the honey bee: a very particular phase of its biological cycle
• Vitellogenin and the keys to the colony
• Development and dynamics of bees and varroa throughout the year
• Practical Guide 1.1: Varroa management concept
• Which syrup to choose for winter feeding

Bibliography

Amdam, G. V., Hartfelder, K., Norberg, K., Hagen, A., & Omholt, S. W. (2004). Altered physiology in worker honey bees infested with the mite Varroa destructor: A factor in colony loss during overwintering? Journal of Economic Entomology, 97(3), 741–747. https://doi.org/10.1603/0022-0493(2004)097[0741:APIWHB]2.0.CO;2

Amdam, G. V., & Omholt, S. W. (2002). The regulatory anatomy of honeybee lifespan. Journal of Theoretical Biology, 216(2), 209–228. https://doi.org/10.1006/jtbi.2002.2545

Artus, J., Carton de Wiart, E., & Kievits, J. (2010). Préserver le capital de vie des abeilles. Abeilles & Cie, 136, 25–28.

Büchler, R., Uzunov, A., Kovačić, M., Prešern, J., Pietropaoli, M., Hatjina, F., Pavlov, B., Charistos, L., Formato, G., Galarza, E., Gerula, D., Gregorc, A., Malagnini, V., Meixner, M. D., Nedić, N., Puškadija, Z., Rivera-Gomis, J., Jenko, M., Škerl, M., Vallon, J., Vojt, D., Wilde, J., & Nanetti, A. (2020). Summer brood interruption as integrated management strategy for effective Varroa control in Europe. Journal of Apicultural Research, 59(5), 764–773. https://doi.org/10.1080/00218839.2020.1793278

Calovi, M., Grozinger, C. M., Miller, D. A., & Goslee, S. C. (2021). Summer weather conditions influence winter survival of honey bees (Apis mellifera) in the northeastern United States. Scientific Reports, 11, 1553. https://doi.org/10.1038/s41598-021-81051-8

Dainat, B., Evans, J. D., Chen, Y. P., Gauthier, L., & Neumann, P. (2011). Dead or alive: Deformed wing virus and Varroa destructor reduce the life span of winter honeybees. Applied and Environmental Microbiology, 78(4), 981–987. https://doi.org/10.1128/AEM.06537-11

Döke, M. A., Frazier, M., & Grozinger, C. M. (2015). Overwintering honey bees: Biology and management. Current Opinion in Insect Science, 10, 185–193. https://doi.org/10.1016/j.cois.2015.05.014

Erban, T., Jedelský, P. L., & Titěra, D. (2013). Two-dimensional proteomic analysis of honeybee, Apis mellifera, winter worker hemolymph. Apidologie, 44, 404–418. https://doi.org/10.1007/s13592-012-0190-5

Fluri, P., Wille, H., Gerig, L., & Lüscher, M. (1977). Juvenile hormone, vitellogenin and haemocyte composition in winter worker honeybees (Apis mellifera). Experientia, 33, 1240–1241. https://doi.org/10.1007/BF01922354

Fluri, P., Lüscher, M., Wille, H., & Gerig, L. (1982). Changes in weight of the pharyngeal gland and haemolymph titres of juvenile hormone, protein and vitellogenin in worker honey bees. Journal of Insect Physiology, 28(1), 61–68. https://doi.org/10.1016/0022-1910(82)90023-3

Giacobino, A., Miotti, C., Molineri, A., Orellano, E., Signorini, M., & Pacini, A. (2023). Varroa destructor re-invasion dynamics during autumn and winter in Apis mellifera colonies from a temperate climate. Journal of Invertebrate Pathology, 199, 107890. https://doi.org/10.1016/j.jip.2023.107890

Gray, D., Goslee, S., Kammerer, M., & Grozinger, C. M. (2024). Effective pest management approaches can mitigate honey bee (Apis mellifera) colony winter loss across a range of weather conditions in small-scale, stationary apiaries. Journal of Insect Science, 24. https://doi.org/10.1093/jisesa/ieae043

Knoll, S., Pinna, W., Varcasia, A., Scala, A., & Cappai, M. G. (2020). The honey bee (Apis mellifera L., 1758) and the seasonal adaptation of productions. Highlights on summer to winter transition and back to summer metabolic activity: A review. Livestock Science, 235, 104011. https://doi.org/10.1016/j.livsci.2020.104011

Koubová, J., Sábová, M., Brejcha, M., Kodrík, D., & Frydrychová, R. Č. (2021). Seasonality in telomerase activity in relation to cell size, DNA replication, and nutrients in the fat body of Apis mellifera. Scientific Reports, 11, 592. https://doi.org/10.1038/s41598-020-79912-9

Kunc, M., Dobeš, P., Hurychová, J., Vojtek, L., Poiani, S. B., Danihlík, J., Havlík, J., Titěra, D., & Hyršl, P. (2019). The year of the honey bee (Apis mellifera L.) with respect to its physiology and immunity: A search for biochemical markers of longevity. Insects, 10(8), 244. https://doi.org/10.3390/insects10080244

Kunc, M., Dobeš, P., Ward, R., Lee, S., Čegan, R., Dostálková, S., Holušová, K., Hurychová, J., Eliáš, S., Pinďáková, E., Čukanová, E., Prodělalová, J., Petřivalský, M., Danihlík, J., Havlík, J., Hobza, R., Kavanagh, K., & Hyršl, P. (2022). Omics-based analysis of honey bee (Apis mellifera) response to Varroa parasitisation and associated factors reveals changes impairing winter bee generation. Insect Biochemistry and Molecular Biology, 103877. https://doi.org/10.1016/j.ibmb.2022.103877

Lee, S., Kalčic, F., Duarte, I., Titěra, D., Kamler, M., Mrna, P., Hyršl, P., Danihlík, J., Dobeš, P., Kunc, M., Pudło, A., & Havlík, J. (2022). ¹H NMR profiling of honey bee bodies revealed metabolic differences between summer and winter bees. Insects, 13(2), 193. https://doi.org/10.3390/insects13020193

Mattila, H. R., & Otis, G. W. (2007). Manipulating pollen supply in honey bee colonies during the fall does not affect the performance of winter bees. The Canadian Entomologist, 139(4), 554–563. https://doi.org/10.4039/n06-032

Quinlan, G. M., Döke, M. A., Ortiz-Alvarado, Y., Rodriguez-Gomez, N., Koru, Y., & Underwood, R. M. (2023). Carbohydrate nutrition associated with health of overwintering honey bees. Journal of Insect Science, 23. https://doi.org/10.1093/jisesa/iead084

Ricigliano, V. A., Mott, B. M., Floyd, A. S., Copeland, D. C., Carroll, M. J., & Anderson, K. E. (2018). Honey bees overwintering in a southern climate: Longitudinal effects of nutrition and queen age on colony-level molecular physiology and performance. Scientific Reports, 8, 10475. https://doi.org/10.1038/s41598-018-28732-z

Smoliński, S., Langowska, A., & Glazaczow, A. (2021). Raised seasonal temperatures reinforce autumn Varroa destructor infestation in honey bee colonies. Scientific Reports, 11, 22256. https://doi.org/10.1038/s41598-021-01369-1

Steinmann, N., Corona, M., Neumann, P., & Dainat, B. (2015). Overwintering is associated with reduced expression of immune genes and higher susceptibility to virus infection in honey bees. PLoS ONE, 10(6), e0129956. https://doi.org/10.1371/journal.pone.0129956

Topal, E., Mărgăoan, R., Bay, V., Takma, Ç., Yücel, B., Oskay, D., Düz, G., Acar, S., & Kösoğlu, M. (2022). The effect of supplementary feeding with different pollens in autumn on colony development under natural environment and in vitro lifespan of honey bees. Insects, 13(7), 588. https://doi.org/10.3390/insects13070588

Van Dooremalen, C., Gerritsen, L., Cornelissen, B., Van Der Steen, J. J. M., Van Langevelde, F., & Blacquière, T. (2012). Winter survival of individual honey bees and honey bee colonies depends on level of Varroa destructor infestation. PLoS ONE, 7(4), e36285. https://doi.org/10.1371/journal.pone.0036285