Hypopharyngeal Gland Activity in Task-Specific Workers Under Brood and Broodless Conditions in Apis Cerana Indica (Fab.)

Abstract

A b s t r a c t The hypopharyngeal gland (HPG) is the principal organ of protein synthesis in honey bees. It is involved in larval rearing. We examined the fresh head weight, HPG acini diameter, and HPG protein content in worker bees engaged in different tasks and under brood and broodless conditions. Scanning electron microscopy revealed that the HPG acini diameter of worker bees was related to their task. The highest HPG volume was found in nurse bees, and the volume regressed when the task changed from guarding to foraging. The fresh head weight was positively correlated with HPG acini diameter. Although, there was no positive correlation between HPG acini diameter and protein concentration, the glandular protein concentration increased progressively in nurse bees and declined in guard and forager bees. Histochemistry revealed similar results. Despite displaying significantly larger glands, guard bee protein secretion was similar to that of the foragers. Brooding had a significant effect on HPG activity. Only worker bees from the colony with an intact brood showed elevated rates of protein synthesis; thus, it is possible that a signal was emitted by the brood, which stimulated protein synthesis in the HPG. However, the size of the HPG was similar in both brood and broodless conditions.

Combined effect of pollen quality and thiamethoxam on hypopharyngeal gland development and protein content in Apis mellifera

“…Our results confirm the positive effect of a high-protein diet on HPG size for bees sampled the 8th day, which corresponds to the age of maximum development of HPGs in worker bees (Al-Ghamdi et al 2011;Lass and Crailsheim 1996). On the 12th day, bees showed smaller acini than bees sampled at day 8, confirming the age-dependent development of HPGs, with acini that reach the maximum size around 6-8 days, in correspondence to the nursing task carried out in the hive (Deseyn and Billen 2005;Rahman et al 2014). The decrease in acini size observed in 12-day-old bees was no longer influenced by the diet quality.…”

“…The chronic exposure to thiamethoxam determined a general decrease in head proteins, which was consistent with the variations in acini size, even though at day 8 the protein concentration did not adequately reflect the dose-dependent effect which was observed for HPG acini. As evidenced by Rahman et al (2014), the protein concentration may not always be correlated with the HPG size, probably because of the above-mentioned differential pattern of protein expression over the life of a bee. To that purpose, it might be also interesting to evaluate the changes in bee head protein composition in response to different stressors.…”

Field-relevant doses of the systemic insecticide fipronil and fungicide pyraclostrobin impair mandibular and hypopharyngeal glands in nurse honeybees (Apis mellifera)

“…Specifically, we examined secretory-cell height and reservoir volume of the mandibular glands as well as acini size and number in the hypopharyngeal glands. Cell height of the mandibular glands is a main indicator of development and secretory activity of these glands 38 , 52 , whereas acini size in hypopharyngeal glands indicates activity and the amount of royal jelly secreted 36 , 38 , 40 , 53 , 54 .…”

Effect of season and behavioral activity on the hypopharyngeal glands of three honey bee Apis mellifera L. races under stressful climatic conditions of central Saudi Arabia

“…Each gland consists of small oval bodies (acini) that are linked to axial or terminal secretory ducts. HPGs become fully developed in young workers (6-13 days old) with large functional secreting acini (Lass and Crailsheim 1996;Rahman et al 2014). However, these glands degenerate when the bee initiates foraging behavior outside the colony (Robinson 1992).…”