Honey bees preferentially consume freshly-stored pollen

Abstract

Honey bees (Apis mellifera) collect and store both honey and pollen in preserved forms. Pollen storage involves the addition of honey or nectar and oral secretions to pollen granules. It is controversial whether the duration of pollen storage alters the palatability or nutritive value of the pollen storage medium. We examined how bees utilize different-aged stored pollen during an extended pollen flow. The deposition of pollen into wax cells and subsequent consumption were monitored daily on 18 brood frames from 6 colonies over an 8d observation period. Despite a greater abundance of older stored pollen cells on brood frames, bees showed a marked preference for the consumption of freshly-stored pollen. Two to four day-old pollen cell contents were significantly more likely to be consumed, while pollen cell contents more than seven days old were eaten at much lower rates. Similar experiments that controlled for cell abundance and spatial effects using cage assays yielded the same result. One day-old stored pollen was consumed approximately three times more often than 10d-old stored pollen, and two times more often than 5d-old stored pollen. These consumption preferences for freshly-stored pollen occurred despite a lack of clear developmental advantages. Young adult workers reared for 7 days on 1d-, 5d-, or 10d-old stored pollen showed no difference in body mass, stored pollen consumption, hindgut fecal material accumulation, or hypopharyngeal gland (HPG) protein titers, suggesting that different-aged pollen stores did not vary in their nutritional value to adult bees. These findings are inconsistent with the hypothesis promoting a period of microbially-mediated, “beebread maturation” that results in greater palatability or nutritive value for aged pollen stores. Rather, stored pollen that is not eaten in the first few days accumulates as excess stores preserved in a less preferred, but nutritionally-similar state.

Landscape factors influencing honey bee colony behavior in Southern California commercial apiaries

“…A recent study found that among 6 geographically disparate apiaries in the US, 79 different pesticides and metabolites were observed, with up to 10 distinct modes of action 27 . While wax and honey can last for many months or even years, bees prefer pollen <72 h old 28 , so it would more likely reflect the hive's recent environment than wax or honey. In both August and October, beebread samples from the AG sites had more compounds (13.3 and 11.8, respectively) than either those in CA (11 and 5.8, respectively) or MT landscapes (7 and 8, respectively).…”

Quantifying the effects of pollen nutrition on honey bee queen egg laying with a new laboratory system

“…These glands produce the proteinaceous secretions that nurse bees use to provision members of the hive including developing larvae and the queen [25,35,36]. Bee bread is made by mixing pollen, honey, and honey bee salivary secretions that contain bacteria commonly found in the honey bee digestive track [37–39]. Cage studies have shown that while honey bees can survive and develop their HPGs and other tissues when fed artificial sources of protein, consuming bee bread results in the most developed HPGs [40,41].…”

The impact of pollen consumption on honey bee (Apis mellifera) digestive physiology and carbohydrate metabolism

“…Stored pollen harbors very few bacteria and can be considered a preservation environment evolved to minimize microbial growth and prevent spoilage (Anderson et al., ). Moreover, honey bees prefer to consume freshly collected pollen (Carroll et al., ). Glucose and leucine are absorbed in the anterior two‐thirds of the midgut, suggesting that host digestion concludes in this region (Crailsheim, a, ).…”