Module 7 - Pollination and Beekeeping Flashcards
1
Q
What is pollination?
A
Pollination
- An important component in the life cycle and sexual reproduction of seed-producing plants
- It involves the transfer or pollen, a powdery or grainy substance which contains male gametes, to female reproductive organs on another flower, or the same flower, in order for the gametes to fuse in the process of fertilization
- The most common type of mutualistic interaction btw insects and plants
2
Q
Why must plants be pollinated?
A
Plants must be pollinated in order to produce fruit and seeds, and this is often aided by insects specialize to do just that.
3
Q
What are insects and other animals that facilitate pollination called?
A
Pollinators
4
Q
What is the type of pollination performed specifically by insects called?
A
Entomophily
- While many plants can be pollinated by other means, such as wind or rain, targeted pollination by insects is often more efficient for the plants, and some species rely on this type of pollination
5
Q
In the world of ancient seed-producing plants, how did pollination primarily occur? Where does this still occur today?
A
Pollination primarily occurred by wind and water. This still occurs in many GYMNOSPERMS today, primitive seed producing plants that appeared in the fossil record ~380 million years ago, long before flowering plants evolved.
6
Q
Because wind is unpredictable, gymnosperms, such as conifer, cycads, and gingko trees must do what?
A
They must produce vast quantities of pollen to increase the likelihood that their pollen reaches a conspecific.
- While most gymnosperms rely on wind for pollination, entomophily can occur in some cases, although it is often accidental
7
Q
After gymnosperms evolved, what appeared in the fossil record and what did they do?
A
Soon after gymnosperms evolved, BEETLES appeared in the fossil record, and inadvertently pollinated some of these plants while they fed on gymnosperm pollen.
- Beetles were likely some of the first animal pollinators, and may have paved the way for the evolution of the complicated reproductive systems we see in flowering plants today
8
Q
What were likely some of the first animal pollinators?
A
Beetles
9
Q
What are flowering plant called? What complex reproductive organ does pollination involve?
A
Flowering plants are known as: ANGIOSPERMS
Pollination involves complex reproductive organs: FLOWERS
- ANTHERS: the male reproductive structures of flowers which produce pollen grains. This pollen is released/transferred to the female reproductive structures of a flower.
- STIGMA: the female reproductive structures of flowers. Pollen lands on the stigma to ultimately reach the ovaries. Once pollen grains reach the stigma of the same species, the pollen structures extend to form a pollen tube. The pollen tube provides a path for sperm and extends down into the ovary of the flower that bears the egg.
- OVARY: the part of the flower that bears the eggs. Here the male and female gametes fuse to form a zygote. Each zygote will become a seed after it’s packaged together with food and a protective coating, and so each seed must be pollinated and fertilized independtly.
10
Q
Why was animal pollination a revolutionary development?
A
It was a revolutionary development in the coevolution of insects and plants because it is more targeted and efficient than wind pollination.
11
Q
Why is animal pollination than wind pollination/ why do plants that employ animal pollinators not need to produce as much pollen?
A
This is because pollinators travel specifically towards flowers, navigating a complex environment and honing in on these reproductive structures, and so the pollen is more likely to reach the ovaries of a conspecific.
12
Q
Insect pollination helped drive the evolution of specialized what? What did the structures evolve to do?
A
Specialized reproductive structures, flowers, which evolved to produce a sugary substance called nectar to attract these pollinators nectar.
13
Q
What is the emergence of angiosperms, ~160 million years ago, closely tied with?
A
The diversification of pollinating insects, like the Lepidoptera.
14
Q
How did the flowers of early angiosperms look different than they do today?
A
- They were shallow and cup shaped, so that unspecialized pollinators, such as beetles, could easily access the nectar.
- Over time, specialist insect pollinators such as bees, butterflies, moths, and many flies began to evolve, and flowers diversified with them.
15
Q
What adaptations did pollinators evolve to access nectar more easily?
A
- long tubular proboscis seen in Lepidoptera
- long hairs to aid in the transfer of pollen
- some insects have specialized structures to carry pollen
16
Q
Why are only adult insects pollinators?
A
They can easily access flowers by flight
17
Q
Animal pollination is a ________ interaction
A
Mutualistic
- The plants benefit from targeted pollination that reduces pollen waste. And it facilitates pollination in habitats that lack wind.
- The pollinators have access to nectar as a CHO rich nutrient source, and protein and other nutrients in pollen
18
Q
Why are specialist pollinators advantageous for the plant?
A
Decreases the chances of pollen being carried to the wrong species of plants, or being lost to the environment
- many pollinators are generalist who visit a wide range of plant species while specialists have refined tastes and specialize only on certain species
- ex. of a specialist pollinator is Darwin’s hawk moth
19
Q
What is an important cue for day-flying insect pollinators?
A
Flower colouration
- alluring to the pollinator
- make the flower stand out from its surrounds so they are easy to locate
- some have NECTAR GUIDES
20
Q
What are nectar guides? Why are they important?
A
Some flower have nectar guides on their petals; markings that direct pollinators to the nectaries at the bases of flowers
This reduces the time spent by foraging pollinators in finding the nectar source on the flower, since it is clearly marked.
- Many insects can see UV light, and nectar guides often reflect UV light to make the flowers even more apparent to pollinators
21
Q
Nectar guides and colouration are 2 important cues used by insect pollinators? What is a 3rd cue used?
A
Scent; helps them locate and identify flowers
- flowers give off a strong aroma intended to lure in pollinators
- scent is especially important cue for nocturnal insects, allowing them to forage in low light condition or in habitats with poor visibility
22
Q
What do some necrophagous insects pollinate? What cues attract them?
A
Corpse flowers
- use colouration, scent, and even heat to mimic carrion and trick the insects into pollinating the flower
23
Q
Corpse flowers are not the only examples of plants that deceive pollinators. What is another?
A
Species or orchids
- the male tricks the pollinating insect into thinking the flower is a female pollinator
- orchids achieve this mimicry through a combo of morphology and chemistry that make them look and smell like a female insect ready to mate
- A male will attempt to mate with the flower and pick up a packet of pollen in doing so. The pollen packet will be transferred to another flowers as he tries to mate with another orchid of that species.
24
Q
What is a common symptom of heavily modified landscapes?
A
Decrease in BIODIVERSITY
- pollinators in particular face a variety of threats associated with human activiteis
25
What is a key driver of habitat loss to pollinators?
The growth and spread of agriculture and industrial development
- these types of land use reduce floral diversity and abundance, making habitats less suitable for pollinator foraging; a population can only flourish so long as a food source is in good supply; the monocultures that dominate the ag landscape fail to provide pollinators with the diversity of nectar and pollen required to reach optimal fitness
- a pollinator that only feeds on one type of flower will be deprived of essential nutrients
26
What do monocultures that dominate an agricultural landscape fail to provide pollinators with?
The diversity of nectar and pollen required to reach optimal fitness
27
What are neonicotinoids?
- a type of systemic insecticide that has come under recent scrutiny for its detrimental effects on pollinators; the systemic chemicals are transported and stored in the rest of the plant tissues, poisoning herbivorous insects when they feed on plant tissues
- neonicotinoids can also be present in the nectar and pollen of the crop plant; as pollinators feed they receive a dose of the toxic chemicals; the dosage is not usually enough to dill pollinators but may produce subtle sublethal effects
- popular worldwide because of their effectiveness at controlling insect pest while being safe for vertebrates
28
How is global crop production affected by pollinators?
Global crop production, is increased with the activity of pollinators, and in some cases completely dependent on it.
- pollination is done by both managed and wild pollinators
29
What are the most common managed pollinators?
Honey bees
- important components of many cropping systems, and are essential to the cultivation of crops producing key agricultural products
- while they make great pollinators, they were originally kept for their wax and honey production
30
For a long time, honey bees were the stars of the pollinator world. It wasn't until the late 20th century that a need for another type of managed pollinator arose in commercial greenhouses. What were they?
- Bees in the genus Bombus, commonly called bumble bees, were domesticated; today 5 species are reared commercially
- Bumble bees produce only small quantities of honey so they are managed for pollination services
- Unlike other pollinators, bumble bees are able to pollinate flowers of tomatoes and sweet peppers because of their unique foraging behaviours.
31
How do bumblebees pollinate?
- Upon finding a flower, bumblebees rapidly contract their flight muscles, vibrating the flowers and shaking loose the pollen in a way that only a strong breeze could replicate
- This unique behaviour is called BUZZ POLLINATION and is a necessity for greenhouse tomatoes and peppers bc wind pollination is not available indoors
32
In addition to buzz pollination, why are bumble bees also the pollinator-of-choice in greenhouses?
The rooms are often too cramped for the large populations that make up honey bee colonies
33
In addition to bumble bees, and honey bees, what other bees are employed for pollination?
Leafcutter bees
- solitary, do not live in colonies
- will happily use human-made nesting sites
- pollinate alfalfa more efficiently than honey bees which also sometimes nectar rob
34
What makes mason bees fantastic pollinators of tree fruits?
Managed as pollinators of fruit trees?
- only visit flowers a short distance from the nesting site, and have a strong preference for flowers of fruit trees, which makes it easy to direct the bees to the target crop and allocate energy to crop pollination
- also have a short flight period during the year = easy to apply insecticides when they are not active
- peak activity coincides with the flowering period of fruit trees
35
What were the first species of bee to be domesticated?
Honey bees
- humans have been exploiting honey bees for millennia, harvesting honey and wax
- simple to domesticate bc they nest in natural cavities in the wild, which predisposes them to accept human-made hives
- their plentiful products and nesting habits have promoted a long history of APICULTURE
36
What is apiculture?
Beekeeping
37
What is the importance of apiculture?
1. Products: honey, pollen, royal jelly, beeswax
2. Ecosystem services in the form of pollination
- they are generalist foragers so they will forage on a wide variety of flowers
38
What is the first species of bee to be domesticated? What are 4 traits?
Apis mellifera (European honey bee)
- adapted to nest in natural cavities, which makes it an easy transition to move the bees into humanmade hives
- great generalist pollinators, allowing them to pollinate a wide variety of cultivated and wild plants
- produce large quantities of honey making them profitable
- able to regulate the temperature of their colony, which allow s the entire colony to overwinter, even in cold climates (produce heat by vibrating their thoracic muscles without vibrating the wings)
39
How did the Africanized Honey Bees come to be?
African honey bees (Apis mellifera scutellata) also farmed for their honey; adapted for a tropical climate, and are more resistant to certain pathogens and parasites; European honey bees cannot survive as long in the tropics and will produce less honey in tropical regions.
They were imported to increase regional honey production but escaped and interbred with European varieties = Africanised honey bee (an aggressively defensive hybrid).
- can enter and take over European honey bee hives
- aggressive towards humans, pursuing attackers further; earning them the nickname "killer bees"
40
Asiatic honey bee (Apis cerana)
- smaller than the European honey bee
- kept in hives across their native habitat in Asia
- smaller hives and less honey than their European relatives, but are kept because they can tolerate low temps and are more resistant to parasitic mite infestations
41
Apis dorsata (giant honey bee)
- nests out in the open, with their colonies clinging from the underside of rock faces or branches of tall trees
- more aggressive than the European honey bees, adaptation to their exposed nesting habits
- produce a lot of honey but are difficult to domesticate because they don't nest in natural cavities
42
Apis florea
- small species of honey bee from which honey is harvested in Southern Asia, where they are important wild pollinators
- exposed nesting habits so not domesticated
- do not produce very much honey in each hive but still provide valuable income to families of bee-hunters
- unique defensive technique to ward off foraging ants; bees will coat the tree branch on either side with sticky propolis (beeswax and saliva) which will trap any anys
43
What is one of the factors that made honey bees great candidates for domestication?
They live in large colonies that are eusocial
44
What is eusociality? What are the 3 traits
A highly organized social structure characterized by 3 traits. For a society to be considered eusocial, it must have:
1. Cooperative brood care whereby individuals care for offspring that are not their own
2. An overlap of generations in which offspring assist the reproductive(s) with colony tasks
3. A CASTE system whereby the colony is primarily composed of individuals that do not reproduce, and only one or a few reproductive individuals
45
Why are altruistic behaviours a key component of eusocial societies?
Since individuals care for offspring that they did not produce
- most members of eusocial societies display the extreme altruistic behaviour of foregoing reproduction to assist the reproductive caste of the colony instead
- altruistic behaviour more likely to arise if individuals in the colony are closely related; due to haplodiploidy, this is the case in the eusocial Hymenoptera
46
What is haplodiploidy?
The mechanism of sex determination that occurs in all members of the Hymenoptera, as well as a few other animals
- Males develop from unfertilized eggs and are haploid, while females develop from fertilized eggs and are diploid
47
What is an interesting consequence of haplodiploidy for males?
They have a sort of "exposed" genome in which all alleles, including recessive ones, are expressed because there is only one copy of each. Since there are no other alleles to mask recessive phenotypes, any deleterious genes are expressed in males and would be weeded out of the population
48
What is an interesting consequence of haplodiploidy in females? As such, why can haplodiploidy help promote altruistic behaviour among relatives, which in turn can lead to a eusocial lifestyle?
It results in a high degree of relatedness between sisters born from the same father.
- Female offspring of the queen bee, receive half of their genome from each parent. Her father is haploid so contributes his entire genome, while the queen contributes half of her diploid genome. Since sisters all receive the same genes from father, they immediately share 50% of their genes; likely closer to 75% since they are likely to share genes from the mother as well.
- Important when considering how an individual bee allocates energy towards reproduction. In order to maximize the amount of her genes being passed on, it would be more beneficial for the bee to help her mother produce more sisters than to produce her own offspring (she is more closely related to a full sister than her own offspring)
49
What are the 2 female castes in honey bee colonies? What is the male castes?
Females: workers and a reproductive queen bee
Males: drones
50
Honey Bee Castes: Workers
- What do they do?
- Carry out all the laborious tasks that keep the colony functioning; foraging duties, brood care, and defend the hive from attackers
- Typically do not reproduce; any eggs laid will be unfertilized and inevitably turn into a male
51
What are the most populous members of a honey bee colony?
Workers
52
Honey Bee Castes: Workers
- Life cycle
The life cycle of a worker bee involves many responsibilities that change as the bee ages.
- After growing through her larval stages and pupating in a sealed cell, an adult worker bee uses her mandibles to break through the cell and emerge
- Starts her adult life as a nurse bee who's tasks revolve around colony maintenance; keep the hive tidy, feed developing larvae, build honeycomb, attend the queen bee
- As they age, some workers may become guards, defending the colony and monitoring the entrance for intruders. When resources are scarce, guards may need to guard the colony from foreign bee invaders. If resources are not scarce guards will welcome a foreign bee.
- Approximately 21 days into the adult life of a worker bee, workers that aren't guarding the nest may leave to take on foraging duties.
53
Nursing bees care for the queen and her offspring by providing them with nutritious food. What are they referred to as?
Her brood
54
What is royal jelly?
Background: Adult worker bees provide themselves with food produced from nectar transferred btw bees until much of the water has evaporated, thickening it into honey. Pollen and nectar are also converted into food for the larvae by mandibular glands in the heads of the worker bees. Workers mix fermented pollen (bee bread) with honey to produce larval food (worker jelly) which is supplemented with mandibular gland secretions.
Royal jelly: fed to larvae destined to become queens, is produced exclusively from the mandibular glands of workers.
- All larvae receive royal jelly for the first 3 days of life; after 3 days, larvae intended to become workers are fed worker jelly while queen larvae continue to be fed royal jelly
- Nurse bees do all of this feeding
55
How do worker bees communicate?
Using alarm pheromones, cooperating to sting attackers en masse in order to protect the valuable brood and honey
56
In order to navigate to distant food source what do forager honey bees use?
1. visual landmarks
2. position of the sun
57
Honey Bee Castes: Queen
- The only reproductive active member of the hive
- New queens are reared in special queen cells where they are provided with royal jelly as they grow.
- Construction of queen cells is normally inhibited by the queen, but this inhibition grows weaker as the queen gets older or weaker or if the colony becomes overcrowded. In these situations, workers will begin to rear queen larvae to replace a dying queen or to enable the colony to split.
- Once an adult queen bee emerges from her cell, she will feed and leave the hive in search of mates, which tend to congregate in certain areas
- She may take up to 15 mating flights (nuptial flights) attracting males using pheromones. Only individuals that keep up with her will be able to mate; queens mate in mid-air with multiple males = POLYANDRY. This increases the diversity of genes in her offspring and provide her with enough sperm to allow her to fertilize eggs for the remainder of her life.
58
What is polyandry? What does it increase the likelihood of?
Queens mate in mid-air and will mate with multiple males during their nuptial flights. This polyandry increases the likelihood that she will mate with drones from other colonies, increasing the diversity of genes in her offspring.
59
How does the queen bees morphology reflect her different tasks?
1. Large abdomens with fully developed ovaries: to produce and store large numbers of eggs, as well as a functional spermatheca to store sperm.
2. Lack pollen baskets on their legs and have shorter probosci: since the queen does not forage for pollen and nectar
3. Glands: many glands present in worker bees are atrophied in queens, but other glands take their place and produce compounds important in maintaining colony fxns
4. Smaller barbs on their stinger: allow the queen to sting vertebrates multiple times; primarily used on rival queens that may show up in the colony when she becomes old or sickly. When a new queen emerges she will use her stinger to kill the other virgin queens in their cells; if 2 queens emerge at the same time they must have a deathmatch.
60
Honey Bee Castes: Drones
- What are they, what is their purpose?
- Drones are male honey bees, which hatch from unfertilized eggs and are haploid; although not technically considered a "castes", drones have completely different fxn than female bees
- ONLY purpose in life is to mate with a queen on her nuptial flight; do not forage and have no stingers = do not contribute to maintenance and defense
- Queens have some control over the number of drones in a colony since they choose the number of fertilized and unfertilized eggs that are laid; the number of drones will usually be low until the mating season.
61
Honey Bee Castes: Drones
- What adaptations do they have that help them find and secure a mate?
1. Exceptionally large eyes: to spot a queen during her nuptial flight
2. Large wings and flight muscles: to keep up with her
3. Antennae: that have olfactory receptors highly sensitive to the queen's sex pheromone
4. No stinger: do not contribute to the defense of the nest
5. Lack pollen baskets and have a short proboscis; rely on nestmates for food
62
What happens to honey bee drones during mating season?
- They leave or are dragged out of the nest and not allowed to return
- Any drones remaining in the colony will be evacuated prior to winter since the colony needs to conserve resources
- Once they've left the nest, they congregate int he air in specific locations that may be used by honey bees year after year
- Release a pheromone blend to attract virgin queens to the congregations, and are attracted to the queen's own pheromone blend
- Die after they have mated because their endophallus (the sperm transferring organ) lodges in the queens repro track and breaks off the male leaving a large hole in his abdomen = a temp plug in the queen to keep the sperm in; once removed another drone can mate the queen.
63
How is the sex of honey bees (and other hymenopterans) determined?
By the number of sets of chromosomes in the organism
64
How is caste differentiation determined?
By the nutritional components in the food provided to developing larvae
- While the cells for queen larvae are quite different from worker cells, the eggs laid in these 2 cell types are exactly the same; it is the food supplied to the larvae in these cells that causes them to become workers or queens
- First 3 days: royal jelly to all developing larvae; continues to be provided thereon to larvae in queen cells and are fed a larger quantity
- On the 4th day: worker larvae fed worker jelly = bee bread + honey + mandibular gland secretions
ON THE 4TH DAY, THE CASTE OF A DEVELOPING HONEY BEE IS ESTABLISHED.
65
What do the differences in worker jelly and royal jelly affect?
Affect the levels of juvenile hormone in developing larvae
- Higher levels of JH found in developing queens which is associated with the development of ovaries
- By the end of larval development, the quantities of JH in worker queen larvae fall to the same level in preparation for metamorphosis
66
What adaptations for foraging do honey bees have?
1. Specialized CHEWING AND LAPPING MOUTHPARTS with the mandibles retaining their chewing fxn and a labium modified into a tongue-like structure
- "tongue" is an extendable proboscis that laps up nectar and is covered in contact chemoreceptors that allow the bee to taste its food source
- mandibles used to build, maintain, and defend hives as well as manipulate food or wax, and nectar rob
2. Excellent vision to efficiently locate flowers
- see a wide range of colours and their vision extends into the ultraviolet range, enabling the to see the nectar guides on flowers
- can detect polarized light which helps them navigate the enviro in foggy conditions; important since honey bees use the position of the sun as a guide
67
What is the pollen basket?
Honey bees, as well as some bumble bees, have additional pollen collecting structures on their hind tibiae = the pollen baskets. These are covered in velcro-like hairs to which pollen can be packed for easy transport.
- When a bee visits flowers, she fills her crop, called a honey stomach, with nectar, as she packs pollen into her pollen baskets.
68
How is honey produced?
1. When a bee visits flowers, she fills her crop, called a honey stomach, with nectar, as she packs pollen into her pollen baskets. Within the honey stomach, digestive enzymes begin to break down the complex sugars into simple monosaccharides.
2. Within the hive, bees regurgitate nectar to each other so each bee can add more digestive enzymes to help break down the nectar. This is then deposited into a cell and the workers will fan the nectar with their wings to help evaporate remain moisture before capping and sealing the cell with wax. This give honey a low water content, which combined with its acidic nature makes honey inhospitable to fungi and bacteria so it can remain edible for centuries.
69
Unlike other invertebrates, what is a trait unique to honey bees?
Can generate their own body heat in order to keep their colony warm during the cold winter months.
- achieved by decoupling their flight muscles from the wings so that the muscles vibrate without moving the wings
- can also be used as a defense mechanism; vibrate their thoracic muscles, and raise the temp and CO2 levels around the intruder they are smothering
70
What is swarming?
- Unlike most other bee species, a new colony of honey bees is formed by an abundance of individuals rather than a single queen
- Honey bee colonies multiply through a complex phase of the colony's life cycle called SWARMING
- swarm is made up of a mass of bees outside the hive that contains a queen
- swarm searches for a new nest site
- advantage to colony propagation with a large number of individuals is that the queen gets assistance from workers in foraging, the construction of the new nest, and the rearing of her brood.
71
When will swarming occur?
If the population of a hive gets too crowded
- in order for a swarm to form, there must be more than 1 queen in the colony, so rearing of queen larvae occurs in prep for swarming
- timing of queen rearing coincides with the formation of a swarm, and a swarm will not form until at least a few queen cells have been sealed
- queen cells are frequently constructed and destroyed during foraging season to help time the emergence of virgin queens with peak populations
- a week before swarming workers feed the queen less and being to chase her so her body weight drops
- workers prepare for swarming by engorging their crops with honey so they have reserves to survive the period of time without a hive
72
Once swarming is initiated, what happens?
- Workers leave the hive and form clusters
- A queen (usually the old one) will leave and join one of the clusters
- Once a swarm cluster has formed, scout bees fly out to search for potential sites to build a new hive; if approved the swarm follows a trail of pheromones to the location
73
Once a swarm is initiated, what happens in the old colony?
- Virgin queens typically emerge within a week following the original swarm, called a prime swarm, which contained the original queen
- Large colonies may swarm more than once in a season and all following swarms are termed after swarms; smaller and contain new queens that emerged that season
- A newly emerged queen will take her nuptial flight, after which she will form an afterswarm or stay in the colony and suppress the emergence of other queens.
74
What are the 2 primary modes of communication used by honey bees?
1. Body language in the form of dances
2. Chemical-based communication via pheromones
75
What is dance used for and where is it performed?
- Used for communication between individual bees in a colony
- Performed by worker bees on the vertical surfaces of combs, or on the outer layers of a swarm
76
What are 3 forms of dance in honey bees?
1. ROUND DANCE
- simplest type of dance used to advertise the presence of food close to the nest
- moves in a circular pattern to broadcast the presence of food nearby, and she offers some pollen and nectar from the food source to her audience; tells bees which scent to follow to find the source
- only tells other bees about the presence and type of food in the area, but not the location
2. WAGGLE DANCE
- more complicated dance used to communicate the specific direction and distance of faraway food sources
- figure-eight pattern during which the bees "waggle" their abdomens
- 2 phases: waggle phase is the straight portion in the middle of the dance, and the return phase follows 2 ring-shaped paths to return the dancer to her starting point
- waggle phase corresponds to the direction of the food at an angle relative to the sun
- length of the waggle phase tells spectators about the relative distance to the food source; report distance in terms of effort required to reach the destination
- bits of food are exchanged to allow other bees to efficiently locate the source; more rich in pollen and nectar the resource is = the more vigorously the communicating bee will waggle
3. DORSO-VENTRAL ABDOMINAL VIBRATION DANCE (DVAV)
- used to regulate foraging activities in response to seasonal food availabiliy
- may also be used to influence the emergence of new queens, or help initiate swarming behaviour
77
Some glands, such as the Nasanov's gland in the bee's abdomen or tarsal glands in the tarsi produce FOOTPRINT PHEROMONES. What are they used for?
- These pheromones are used to help bees orient to important places
- Act as beacons to guide bees to nest entrance, water sources, foraging sites, or a swam cluster
78
What are alarm pheromones?
- Another pheromone produced by worker bees from both the mandibular and abdominal glands
- released by workers when defending the hive against raiding bees or other animals
- they signal danger and elicit defensive behaviours from other higve members
79
What is an important pheromone produced by queens?
Queen mandibular pheromone (QMP)
- constantly released by queen, although quantity drops with age
- informs the colony about the presence of a healthy queen, while simultaneously inhibiting the production of eggs in the ovaries of workers
- queen feeds QMP from her mandibular glands to her attendants, who then pass it to other workers so pheromone can be spread throughout the colony
80
Developing larvae produce pheromones as well, what do they do?
- Indicate their presence to nurse bees and stimulate pollen foraging activities
- Cells that contain brood are chemically labelled to inform nurse bees about the type of larva int he cell
81
What do scents released by empty honeycomb indicate?
If there is an abundance of empty cells intended to store honey, scent signals released by these clusters induce foraging in worker bees
82
What are several factors contributing to the decline of domesticated populations of the European honey bees?
disease, climate, habitat loss, pesticide use
83
What is a significant challenge beekeepers must deal with?
The identification and treatment of the many parasites and diseases that can appear in honey bee colonies
- international transport and large-scale breeding can increase risk of transmission of pathogens and parasites btw colonies
84
What is the bizarre condition that affects honey bee colonies, called Colony Collapse Disorder (CCD)?
- Occurs if the majority of workers abandon a hive, leaving the queen, her brood, a few nurse bees, and the food stored
- Hives cannot be sustained with small worker populations and eventually collapse
- Potential cause may be poor quality management, whereby the bees are provided poor quality food and inadequate parasite and disease control
- Another potential cause may be pesticide poisoning
- It is likely a combination of factors that stimulate abandonment of the hive
85
What is the most severe parasite of honey bees?
The mite, Varroa destructor
- external parasites that feed on the fat body
- female Varroa mite enters a brood cell before it is capped, hiding from the nurse bees, and will reproduce here
- easily spread btw colonies
- may not directly cause death in the bees they infect, the open wounds resulting from their feeding activities are susceptible to infection by pathogens
- bees infected during development will emerge with deformations, and a colony infected will become increasing unhealthy over time
- one common disease carried by these mites is deformed wing virus
86
How do tracheal mites (Acarapis woodi) impact the heath of bee colonies?
- so small they spend their lives inside the tracheae of honey bees where they pierce the tracheal wall and feed on the bee's hemolymph
- mate inside the tracheae; females emerge to disperse
- as they feed they create woods in the tracheae which can become infected and their presence affects gas exchange
- overall reduces bee activity and shorten their lifespan while high infestations can decrease foraging and honey production
87
Parasites like mites can reduce bee health and vitality, but what can cause more serious harm?
Fungi, viruses, and bacteria
- a large number of microbes can infect and colony and only detectable once the infection has reached a late stage where symptoms are clearly visible
88
What is a fungal disease that causes significant losses to honey bee colonies?
Chalkbrood disease
- caused by the fungus Ascosphaera apis
- only affects larval bees, but can be transmitted by foraging adults to nurse bees and larvae
- fungal spores enter larval food supply
- if gut flora in larva is inadequate, fungal spores germinate and kill the larva
- disease only presents itself during humid months
89
what is an example of a virus that can be extremely detrimental to the individual bees?
Wind virus
- vectored by Varroa mites
- deformations in infected bees cause them to die as pupae, or son after eclosing into adults;; bees that do survive into adulthood can't fly
90
What is a common bacterial disease that affects larval bees?
American foulbrood
- caused by the bacteria Paenibacillus larvae
- highly contagious and very destructive, killing entire honey bee colonies if untreated
- bacterium infects bee larvae when they ingest food contaminated with foulbrood spores
- spores germinate in the midgut and grow, absorbing essential nutrients from the bee host
- larvae die from starvation bc the food is absorbed by bacteria
91
In addition to the multitude of parasites and pathogens that affect European honey bees, what additional stress do these insects face?
Human-associated activities aka Modern farming
1. Reduces the diversity of flower species in the transformed landscape; monocultures do not provide bees with the diversity of pollen and nectar needed to maintain a healthy colony.
2. Heavy use of insecticides for pest control that contaminate nectar and pollen.
3. Beekeepers must also be mindful of how they manage the hives; leaving enough honey during the harvest for the colony to survive the winter.
92
How can beekeepers help ensure healthy bee populations?
1. Place hives in relatively close proximity of a diversity of flowers in order to ensure the bees have access to a variety of pollen and nectar.
2. Limit the exposure of bees to insecticides by reducing use or using species-targeted formulations. Can also be applied at times when bees are not actively foraging.
