Nectar preferences in male bumblebees

Abstract

Social insect males are relatively understudied, but knowledge of their biology is increasingly important for conservation of declining groups. Bumblebees are important pollinators in temperate, sub-arctic, and Alpine regions, but many species are in decline across the globe. Agri-environment schemes have been designed to support female bumblebees, but free-living males may also need support. Male bumblebees have an energetically expensive lifestyle, and so understanding their foraging choices may provide a first step towards designing interventions to support them in the wild. Using a series of controlled laboratory choice experiments, we demonstrate that males prefer sugar concentrations of between 50 and 60% when under either simple (binary) or complex (octanary) choice conditions when presented with a broad range of sugar concentrations. When presented with concentrations within this preferred range, males exhibit a clear preference for sugar solutions of 56% w/w sucrose when solutions differ by 4%. These results suggest that males maximise their rate of energy intake, as predicted by theoretical models, rather than minimise their water consumption. In the future, male preferences for high sugar concentrations can be combined with knowledge of baseline nectar concentrations and flower phenology to maximise the value of conservation interventions for this neglected sex.

Sulfoxaflor and nutritional deficiency synergistically reduce survival and fecundity in bumblebees

“…Additionally, syrups with lower sucrose concentration resulted in lower sucrose intakes, despite higher syrup consumption rates. This confirms that workers' ability to volumetrically increase food consumption as a response to the reduced sugar content is limited by their capacity to process water, similar to the situation in males (Brown and Brown, 2020). These data emphasise the importance of nectar quality as a predictor of pesticide toxicity, hence demonstrating how the lack of harmonisation of sugar content in the treated solutions (Klinger et al, 2019) may undermine the reliability of the J o u r n a l P r e -p r o o f…”

“…Based on these findings and aiming to explore the widest possible realistic variation of nectar quality, in this study we defined low-and high-quality diets as containing 15 % w/w and 50 % w/w sucrose J o u r n a l P r e -p r o o f Journal Pre-proof respectively. Despite laboratory studies showing that bumblebees prefer slightly more concentrated nectars than % w/w (Bailes et al, 2018;Brown and Brown, 2020), we set this concentration as the upper limit of our assessment, as this value is the most commonly used across official lab and semi-field bee testing methodologies (OECD, 2017a;Oomen et al, 1992).…”

Sexual dimorphism in the proventriculus of the buff‐tailed bumblebee Bombus terrestris (L. 1758) (Hymenoptera: Apidae)

“…Conversely, male bumblebees are typically bigger and focus their efforts towards activities such as mating and dispersal (Duchateau & Marin, 1995; Dornhaus & Chittka, 2004). During the activities mentioned above bumblebees must often cover long distances, which requires a high level of energy (Brown & Brown, 2020). Therefore, they require a nutrient‐rich diet, obtained through their specialised digestive system (Pyke, 1980; Wolf et al, 1999).…”

Electrophysiological and Behavioral Responses of Apis mellifera and Bombusterrestris to Melon Flower Volatiles

“…Plant flowers regulate the interaction between pollinators and plants by releasing volatiles. Pollinators can identify volatiles of flowers according to their nutrition and reproductive needs, judge distance and location, and conduct pollen collection [7,8]. The volatile compounds of flowers have important effects on pollinator searching behavior [9,10].…”