Salivary Glands of the Honey Bee
Scientific Beekeeping
Scientific Beekeeping
info@scientificbeekeeping.co.uk
This information is based on an article that appeared in the Scottish Beekeeper Magazine in 2017
written by Margaret Thomas NDB.
written by Margaret Thomas NDB.
Image 1 : Saggital Section of the Head and Thorax of a Worker Bee
Salivary Glands help with the digestion of food. In the honey bee there are two paired salivary glands, One pair in the head and one pair in the thorax. Each gland is made up of a number of smaller units.
The paired glands in the head are the postcerebral salivary glands (PCSG), sometimes refererred to as "Head Glands". The pair in the thorax are the thoracic salivary glands (TSG) which lie ventrally in the anterior part of the thorax.
The numerous small bodies of the TSG appear like a bunches of bananas and secrete into a duct meeting the duct of the PCSGs. The bodies of the PCSGs appear somewhat like clover leaves. The PCSG and TSG discharged their secretions onto the root of the proboscis in the salivarium, within the mouth where they come into contact with food. These secretions are known to breakdown solids such as sugar, fondant or solid honey by the action of enzymes..
The salivary glands have been found to contain invertase, glucose oxidase and amylase. In a recent analysis the PCSGs were found to contain more aldolase and acetyl-CoA acyltransferase 2 than the TSGs.
In addition the Hypophargeal Glands (HPGs) of older workers also produce similar enzymes which assist in the breakdown of food. In the older house bee, once it is involved in receiving and ripening nectar from foragers, the glands decrease in size and produce enzymes which are added to the nectar as it passes from the mouth through the oesophagus and into the crop. There are sensory receptors that trigger the secretion of these enzymes. Once the bee becomes a forager these enzymes continue to be added and are important in the inversion of sucrose to glucose and fructose. This enzyme is known as invertase. Another enzyme, glucose oxidase, acts on glucose forming gluconic acid, one of the acids found in honey. Part of this chemical breakdown also forms hydrogen peroxide which protects the nectar from micro-organisms. This is one of many reasons for using honey as a dressing. Diastase, is an enzyme which catalyses the breakdown of starch into maltose. Diastase is also produced by the hypopharyngeal gland.
The paired glands in the head are the postcerebral salivary glands (PCSG), sometimes refererred to as "Head Glands". The pair in the thorax are the thoracic salivary glands (TSG) which lie ventrally in the anterior part of the thorax.
The numerous small bodies of the TSG appear like a bunches of bananas and secrete into a duct meeting the duct of the PCSGs. The bodies of the PCSGs appear somewhat like clover leaves. The PCSG and TSG discharged their secretions onto the root of the proboscis in the salivarium, within the mouth where they come into contact with food. These secretions are known to breakdown solids such as sugar, fondant or solid honey by the action of enzymes..
The salivary glands have been found to contain invertase, glucose oxidase and amylase. In a recent analysis the PCSGs were found to contain more aldolase and acetyl-CoA acyltransferase 2 than the TSGs.
In addition the Hypophargeal Glands (HPGs) of older workers also produce similar enzymes which assist in the breakdown of food. In the older house bee, once it is involved in receiving and ripening nectar from foragers, the glands decrease in size and produce enzymes which are added to the nectar as it passes from the mouth through the oesophagus and into the crop. There are sensory receptors that trigger the secretion of these enzymes. Once the bee becomes a forager these enzymes continue to be added and are important in the inversion of sucrose to glucose and fructose. This enzyme is known as invertase. Another enzyme, glucose oxidase, acts on glucose forming gluconic acid, one of the acids found in honey. Part of this chemical breakdown also forms hydrogen peroxide which protects the nectar from micro-organisms. This is one of many reasons for using honey as a dressing. Diastase, is an enzyme which catalyses the breakdown of starch into maltose. Diastase is also produced by the hypopharyngeal gland.
Glucose oxidase & Diastase, more specifically Amylase
Sucrase, more specifically Invertase
Sucrase, more specifically Invertase
