## 1 Introduction  
Honeybees are an important and fascinating species for humans, with regards to their complex social structure, honey production, and pollination of cultivated crops. Honeybees in temperate climates gain specific physiologic characteristics throughout the seasons to adapt for overwintering [1, 2, 3, 4]. Overwintering honeybees show an increased life span [5, 6] as well as a larger fat body for better storage of nutrients, such as lipids and proteins, required to respond to the great energy expenditure throughout the winter, from the vibration of their wings to regulating the temperature within the hive [7, 8, 9, 10, 1].  
The increased honeybee mortality rate has become a worrying issue in the last three decades for both the scientific and general population. A Colony Losses Monitoring (COLOSS) survey showed a winter beehive loss rate around 20-25% in Europe [11]. InCanada, the beehive loss rate even reached 45.5% in the winter of 2022, corresponding to the highest recorded loss since 2007 [12]. This phenomenon is reported to be caused by several factors, most particularly by the parasite _V. destructor_[12; 13]. Varroa is thus a great threat for _Apis mellifera_ in temperate areas [14].  
Varroa has a life cycle that follows that of the honeybee's [15]: the female varroa produces eggs within the honeycomb where the bee pupae grow, causing a weakening of the emerging honeybee [16]. The varroa mother and daughters continue to feed on the adult honeybee, further weakening the bearer [16]. Varroa can also transfer viruses to developing and adult bees when feeding, thus spreading and intensifying viral loads [15; 16; 17; 18]. Evidence of mite contribution in viral transmission (vector role) is clearly demonstrated for deformed wing virus (DWV), acute bee paralysis virus (ABPV), cashmere honeybee virus (KBV), and Israeli acute paralysis virus (IAPV) [15; 16; 17; 18] (Table A1).  
Varroa feeds on the hemolymph and the fat body of the honeybees [19], an organ playing a key role in honeybee overwintering [1] and in metabolic functions such as growth, neural control, immunity, detoxification, and nutrient storage [20; 21].  
Since varroa infestations lead to altered metabolism and reserve mobilization, sugar concentrations in hemolymph might fluctuate directly from parasite consumption or indirectly from parasitic stress and co-infections [22]. Glucose and trehalose, which are produced in the fat body, are the main energy substrates for honeybees during their flight and their thermoregulation [20; 23].  
Varroa is also known to affect the immune system of the honeybee by decreasing expression of immune genes such as _apidaccin_[16; 24; 25] and by decreasing hemocyte counts and melanin synthesis, both playing key roles in immunity [16; 26]. Therefore, the susceptibility to opportunistic agents is likely to increase in Varroa-infested honeybees. As a matter of fact, some researchers showed that _Serratia marcescens_, a commensal bacterium from the gut, can induce bacteremia with varroasis [27]. [PERSON] et al. even isolated a cytotoxic strain (Ss1) of _S. marcescens_ in the hemolymph of dying, infested, and overwintering honeybees as well as in varroa mites [27; 28].  
Diagnostic techniques are currently lacking to evaluate the physiologic and biological impacts of varroa on honeybees. An innovative way to improve knowledge would be to adapt diagnostic techniques commonly used in veterinary medicine (i.e., biochemistry, glucometer, RT-PCR, bacteriology) to monitor the health status of honeybees and, consequently, help beekeepers prevent winter losses and better manage the beehives.  
The objective of this study was to determine the impact of varroa infestation on the sugar concentrations in honeybee hemolymph over time and on the presence of concomitant viral and bacterial infections.