5.6-5.9 The Exocrine System Flashcards
What role does the sensilla trichodea play in the nervous system?
Touch
Which cell type is not found in adult bees?
Urate cells
What determines the release of ecdysone from prothoracic glands?
Release of brain hormone from corpora cardiaca
The organ of Johnston and how it works?
Sensing muscle tension and vibration
Acts as the honey bee’s ear
* Not visible on the outer surface.
* Many individual sensillae attached at one end to the proximal (nearest the scape) and the other
to the intersegmental of the first flagellar annulus.
* Because of their attachment across the joint of the flagellum and the pedicel, the sensillae in the
organ are able to detect vibrations of the flagellum relative to the pedicel.
What is the effect of high levels of juvenile hormone in larvae?
Maintain larval characteristics
What role does the corpora allata play in the insect endocrine system?
Produces juvenile hormone
What percentage of body weight does the fat body occupy in the larval stage?
65%
What triggers the release of sperm and mucus in drones?
Contraction of abdominal muscles
Which part of the drone’s reproductive system delivers sperm?
Ejaculatory duct
Which gland is responsible for the production of ecdysone?
Prothoracic gland
What does the hypopharyngeal gland produce in younger and older worker bees?
In younger workers, it produces an element of brood food in the form of a clear liquid. In older workers, it produces enzymes such as sucrase and glucose oxidase.
What can cause the hypopharyngeal gland to revert to food production?
Gorging on pollen
What does the mandibular gland produce in young and mature worker bees?
In young workers, it produces the white part of brood food and royal jelly. In mature workers, it issues alarm pheromones.
What is 10-HDO and its significance in young worker bees?
10-HDO (10-hydroxydec-2-enoic acid) is the principal fatty acid in brood food and acts as a preservative.
What alarm pheromone is produced by older worker bees?
Older worker bees produce 2-heptanone, which is the alarm pheromone.
What pheromones does the queen produce?
The queen produces 9-oxodec-2-enoic acid, which is a drone attractant, and 9-hydroxydec-2-enoic acid, which helps hold the swarm together.
Queen substance
What is the function of the tergite (Renner-Baumann) in bees?
The queen pheromone, emitted through queen grooming - queen substance.
- 9-oxo-2-deconic acid (attracts drone for mating)
- 9-hydroxyl-2-deconic acid (hols swarms together)
Also acts in conjunction with the pheromones produced by the mandibular glands to inhibit ovary development in workers, inhibits the production of queen cells and stabilises the court of bees once it has been formed.
What is the Nasonov gland used for?
- to attract other bees when flying in a swarm
- marking the entrance to the hive
- marking sources of forage.
What are the components of the scent produced by the Nasonov gland?
The scent includes terpenic alcohols:
Geraniol, Nerol, and (E,E)-Farnesol
as well as terpenic aldehydes:
(E)-Citral and (Z)-Citral
What is the function of the sting scent gland?
It produces alarm pheromones that attract bees to the sting site and elicits a sting response in other bees.
What are the main components that elicit a stinging response?
Alarm pheromone, (Z)-11 Eicosen-1-ol attracts
bees to sting site and stabilises Isopentyl which along with 2-heptanone elicits stinging responseattracts foragers to the site and Isopentyl acetate elicits stinging around the same spot.
What is the primary component of venom?
Mellitin, which makes up 50% of the dry weight of the venom.
What are the major components of bee venom?
Mellitin, Phospholipase A, Hyaluronidase, Acid phosphatase, and Allergen C.
What is the purpose of the sting alkaline (Dufour) gland?
It is assumed to lubricate the sting mechanism, neutralize remaining acid, and in queens, provide a protective coating to eggs.
Where is the post cerebral gland located and what is its function?
A salivary gland located behind the brain, it secretes saliva directly into outlet ducts.
What is unique about the thoracic gland?
It develops from the silk gland in larvae and has a reservoir.
footprints
Where are the Arnhart (tarsal) glands located?
In the 5th tarsome of each leg of the worker bee.
What is the role of the Arnhart glands?
Found on the 5th tarsomere of each leg of Q and W. Produce foot print odour. Essential for
surpressing q cell production (cells above q excluder).
Foragers leave a foot print odour on flowers they visit. Lasting for 4 hours at 25oC and 4 days at 5oC
What are the components of wax production according to Downing (1961)?
16% hydrocarbons
31% straight-chain monohydric alcohols
3% diols
31% acids
13% hydroxyl acids
6% other substances
What is the composition of wax according to MBBKA 2009?
70% esters
1% alcohols
10% acids
13% hydrocarbons
What is the location of the hypopharyngeal gland?
Front of head on each side behind compound eyes
Where is the mandibular gland located?
Head - Above mandibles
Where are the tergite glands (renner-Baumann) located?
On the free edges of abdominal tergites A3-5 of queens
What is the structure and location of the Nasonov gland?
A light brown band accross the abdomen
Exposed on the dorsal surface of the 7th abdominal segment when the bee flexes its abdomen.
A pale thin strip on the intersegmental membrane between the terga of A6 and A7
It consists of glandular cells which secrete pheromone through c. 600 ducts (or tiny pores) into a groove between the 6th and 7th tergite.
The glandular cells are beneath this canal.
Where is the sting scent gland found?
The glands are believed to be located on the inner surface of the quadrate plates on the abdomen.
The pheromone is a powerful alarm pheromone the main chemical being isophentyl acetate which inhibits foraging and scenting.
Where is the sting alkaline (Dufour) located?
Sting Chamber
What is the location of the post cerebal gland?
Behind brain
Where is the thoracic located?
In the thorax
Where are the wax glands located?
Sternites A4-7
What do YOUNG worker mandibular glands produce?
Brood food and royal jelly, which contains 10 hydroxyl-2-deconic acid (10 HDA), the principal fatty acid in brood food and royal jelly that acts as a preservative.
What do MATURE worker mandibular glands produce?
Alarm pheromone, specifically 2-heptanone, which is issued by guard bees to ward off robbers and initiate a stinging response from other bees.
What do QUEEN mandibular glands produce?
Pheromones used in mating and as part of the queen substance, which inhibits the building of queen cells and the development of workers’ ovaries while attracting workers to the queen.
Main components include 9-oxo-2-deconic acid (attracts drones for mating) and 9-hydroxyl-2-deconic acid (holds swarms together).
Mandibular Glands - how they work
The lumen (centre space) of the gland acts as a resevoir under pressure. The outlet is oval in shape and can be opened and closed allowing the secretion to be released as required. The secretion runs down a groove in the mandible.
Queen Mandibular gland - structural differences
Much larger in the queen. It produces a pheromone, known as “queen mandibular pheromone (QMP)”, which plays a crucial role in regulating the behaviour and development of worker bees within the colony, essentially maintaining social order by inhibiting ovary development in workers and influencing colony functions like queen rearing and foraging activity.
Queen Hypopharyngeal gland - structural differences
In queen is vestigial or very small and non-functional compared to worker bees.
It produces minimal to no secretions as the queen does not need to produce royal jelly to feed larvae, which is the primary function of the hypopharyngeal gland in worker bees.
Exocrine glands in drones
Either underdeveloped or missing completely with the exception of mandibular gland which is still smaller than in the queen or worker and produces pheromones that attract virgin queens to the DCA during mating flights
Structure and location of poison gland
- In the posterior part of the abdomen.
- At the end of each long tubule a glandular enlargement secretes venom which passes into the tubules.
- Before entering the poison sac these tubules combine into a common duct.
- This duct joins the anterior end of the poison sac.
- Here the venom is stored until required.
Pork, Ham And Perhaps Mustard + Hummus
Chemical composition of the poison gland secretion
- Phospholipase A (Breaks down cell membrane, causes pain)
- Hyaluronidase (Hydrolyzes connective tissue; opens up passages between cells for other components)
- Acid phosphatase (Involved in allergic reaction, possibly nausea)
- Mellitin (Breakdown membrane of blood and mast cells (mast cells are a form of white cell which have a role in the immune system). Histamine and serotonin released by mast cells lowers blood pressure and respiration
- Histamine (Itching, pain)
Post 3 Snacks Very Peculiar Dancing
Structural elements of the sting
- Three plates (per lancet) which along with muscles drive the associated lancet and valve to the bulb
- The shaft comprising the lancets and a stylet which expands into the bulb via an umbrella valve for each lancet, the valve opens when the lancet is extended and closes when it is removed from the victim
- Venom sac which holds the venom and is connected to the bulb
- Poison glands (acid glands) which secrete the venom into the sac
- Dufour gland (alkaline gland) which opens to the sting chamber to lubricate the stylet and to possibly neutralise any leaked venom
Before stinging the bee positions itself perpendicular to the victim by contracting ventral sclerites
and extending dorsal sclerites.
DISS 9-ODA and 9HODA
Composition of tergite gland secretions
- During mating attracts drones
- Incites populatory behaviour
- Supress ovary development in workers
- Stimulate retinue behaviour in workers.
Structure of hypopharyngeal gland
The glands one on each side, of the workers head, each having it own duct and connected to the
hypopharyngeal plate. Look like bunches of grapes
The two connections are on the underside of the plate and the secretions runs down the upper side and collects in the labial base.
The secretion is led to the larvae the bees using its mandibles to direct the brood food into the cell.
Each gland consists of 100’s of pear shaped acinis each with a short duct connecting to the main
axial duct.
They are no apparent opening or closing valves on these glands but it is being suggested that the movement of the hypopharyngeal plate could kink the duct and stop the flow.
The size of the gland depends on the duties and it is at its largest where the bee is a few days old working as a
nurse bee.
The glands produce a clear liquid (protein) which combines with secretions from the
mandibular glands and is known as brood food or royal jelly.
Later these glands shrink and are the source of invertase in the foraging bee.
Larval food composition
- White, produced by the mandibular gland
- Clear, produced by the hypopharyngeal gland
- Yellow, from pollen
Composition of feed: - Queen larva (Royal Jelly)
o First three days mostly white
o Last two days ratio white to clear 1:1 - Worker (Brood Food)
o white:clear:yellow in ratio 2:9:3 average
Points to note:
- queen is fed 10 times volume of worker, queen “swims” in royal jelly, worker fed as needed
- larva up to 3 days old transferred between cell types and hence feed change will mature to appropriate caste i.e. queen cell produces queen, worker produces worker.
- Larva transferred 3-4 days old will mature to appropriate caste but may exhibit traits of other caste e.g. pollen baskets on queen.
- Sugar composition in royal jelly is 34% and in brood food 12% for first three days. Brood
food rises to 47% after 3 days with addition of honey to mixture. Sugar stimulates to consume more.
- Higher levels of Juvenile Hormone in larva triggers queen development, royal jelly stimulates JH production by the early development of the endocrine system
Royal jelly composition
- 67% water,
- 12.5% crude protein, including small amounts of many
different amino acids, - 11% simple sugars (monosaccharides),
also including a relatively high amount (5%) of fatty acids. The main acid is the 10-hydroxy-2-decenoic acid (10-HDA) (about 2 - 3%). - It also contains many trace minerals, some enzymes, antibacterial and antibiotic
components, pantothenic acid (vitamin B5), pyridoxine ( vitamin B6) and trace amounts of vitamin
C,[2] but none of the fat-soluble vitamins, A, D, E, and K.
Brood food composition
- 15-25% protein,
- 30-60% sugars,
- lipids decline in volume with age of larva
- unprocessed pollen also added.
What is the definition of a pheromone?
Pheromones are substances which are
secretred to the outside by an individual and received by a second individual of the same species
in which they release a specific reaction which may be behavioural, developmental or
physiological.
Mandibular - Facts
- Largest in the queen. Smallest in the drone. One gland on each side of the head above the
mandibles. - In the worker when on nurse duties produces 10 hydroxyl-2-deconic acid (10 HDA) which is the
principal fatty acid in brood food and royal jelly and acts as a preservative. - When worker bees start foraging it produces 2-heptanone which is an alarm pheromone.
- In the queen it produces queen substance:
- 9-oxo-2-deconic acid (9ODA), which attracts drones in mating.
- 9-hydroxyl-2-decaonic acid (9HDA), which holds swarms together.
- Inside the hive queen substance inhibits the production of queen cells, inhibits the development
of workers’ ovaries and attracts workers to the queen.
Nasanov - Facts
- Worker bee only.
- Situated on the dorsal surface secreting a pheromone via some 600 ducts in a groove between
the 6th and 7th tergites. Only exposed when the bee stretches its abdomen. - Pheromone used for marking and orientation, e.g. marking a new home , attracting the queen
back home after a mating flight, keeping a swarm together. - The main chemical
Tergite (Renner-Baumann) - Facts
- Only on the queen. Located on the free edges of the abdominal tergites A3, A4 and A5.
- The queen grooms herself three or four times every hour spreading her pheromones over her
exocuticle. The queen’s court pay particular attention to her abdomen and so awareness of the
queen’s presence is spread round the colony. - Composition is unknown.
Sting scent gland (Worker only) - Facts
- Believed to be located on the quadrate plates.
- Produces a powerful alarm pheromone isophentyl acetate, which inhibits foraging and scenting.
- Elicits a sting response in other bees and recruits other bees to act as guard bees.
Dufour’s Gland (Workers and queens) - Facts
- Bigger in queens.
- Part of sting apparatus.
- Reflects the fertility and fecundity o the queen or worker.
Arnhart (Queen and worker)
- Found on the 5th tarsomere of each leg. Produces footprint odour essential for suppressing
queen cell production. - Foragers leave foot print odour on flowers they visit. Last 4 hours at 25C and 4 days at 5C.
Koschevnikov (Queen only)
- Tiny cluster of cells in the sting chamber of the queen. Its main ducts open between the
overlapping spiracle and the quadrate plates - Free quotes Butler and Simpson who determined that the pheromone produced was possibly a
source of attraction to court bees, i.e an element of queen substance.
Most Tame Drones Know Tergites
Chemicals that make up queen substance
- Mandibular,
- Tarsal,
- Dufour’s,
- Koschevnikov
- Tergite glands
Where are the wax glands located in bees?
The wax glands are located inside the exoskeleton on sternites A4-A7 inclusive. Each pair of glands is situated at the front of its sternum so that the sternum of the previous segment overlaps it.
What is the composition of the cellular mass over each wax gland?
The cellular mass is composed of oenocytes and fat cells.
How many pairs of wax glands do bees have?
Bees have four pairs of wax glands.
What do the wax glands secrete?
The wax glands secrete a liquid that oxidizes into wax in the wax pockets.
What are the wax glands, mirrors, and pockets collectively known as?
They are known collectively as the ‘waistcoat pockets’.
At what temperature is wax secreted?
Wax is secreted at a temperature of 33-36°C.
How much honey is needed to produce wax?
1 lb of honey is needed to produce 5-8 lbs of wax.
At what age are wax glands best developed in worker bees?
Wax glands are best developed in worker bees that are 12-18 days old.
What do bees do after consuming honey when building combs?
Bees hang in festoons near the building site, waiting for the wax to form.
What covers the wax glands inside the exoskeleton?
The wax glands are covered with fat bodies.
What are the main constituents of wax?
The main constituents of wax are:
- Monohydric alcohols 31%
- Fatty acids 31%
- Hydrocarbons 16%
- Hydroxyl acids 13%
- Other substances 6%
- Diols 3%
What color is wax normally, and what can tint it?
Wax is normally white but can be tinted yellow by pigments from pollen.
What is the structure of the wax gland in newly emerged workers?
In newly emerged workers, the wax gland consists of flat epithelial cells.
What changes occur to the wax gland cells by day 14?
By day 14, the cells have enlarged longitudinally and are richly supplied with trachea.
What inhibits wax production?
Queenlessness inhibits wax production.
Production of wax
- The ingredients for wax are made in the oenocytes above the glands.
- The components pass to the columnar cells of the wax glands and a liquid pours into the spaces between those cells
- This then passes through the waz mirrorss which are perforated by an enourmous number of fine canals and hardens to a small transparent flake of wax, the same shape as the wax mirror.
- The flake of wax is extruded from the pocket made by the overlapping sterna.
- Several flakes of wax may build up on a single wax mirror at times.
- The bee removes the wax flakes with its hind legs.It is then passed to the mandibles via the basitarsus for manipulation into comb, cappings etc.
