What is AMP?
Adenosine monophosphate (derived from ATP) is an important intracellular chemical messenger
What are semiochemicals?
Chemicals used for communication
What is the most well-known semiochemical?
Pheromones
What are pheromones?
Volatile substances that influence behaviour or development of other members of the same species
Do insects use pheromones?
Yes! Pheromones are the predominat means of communication among insects (especially social insects)
How are pheromones usually distributed?
Pheromones are usually air bourne (travelling slowly)
What is the first type of pheromone used in insects
Sex Pheromones
What are the two types of sex pheromones?
Sex attraction pheromones (used for arousal and produced by only one sex) and courtship pheromones (employed prior to mating)
Which gender usually produces sex attraction pheromone?
Usually the female does to arouse the male
How can courtship pheromones be manipulated?
Can be used for pest control or prey capture
What is the second type of insect pheromone?
Trail pheromones
What are trail pheromones?
Short-lived pheromones used to lay down an odour trial for members to follow (not species specific). They can be detected at very low concentrations
What is the third type of insect pheromone?
Alarm Pheromones
What are alarm pheromones?
Used by very social insects. Volatile, non-persistent compounds that are readily dispersed. Attract aggressive workers for attack and defense
What is the fourth type of insect pheromone?
Aggregation pheromones
What are aggregation pheromones?
Causes both sexes of an insect to swarm and gather towards the source of the pheromone.
What are the applications of aggregation pheromones?
Added protection against predators, using a scarce food source, bringing together of members of the same species, increased mating opportunity, and hibernation
What is the fifth type of insect pheromone?
Spacing Pheromones
What are spacing pheromones?
Pheromones that work contrary to aggregation pheromones. Encourages spacing out of colonies
What is the sixth type of insect pheromone?
Individual and group recognition
What are recognition pheromones?
Used to identify if an insect belongs to their specific colony
What is the seventh type of insect pheromone (last one)?
Caste determination
What are caste determination pheromones?
Polymorphism accompanied by a difference in a behaviour
What are other types of semiochemicals?
Allomones, synomones, and kairomone
What are allomones?
provide an advantage to the producer by modifying the behaviour of the receiver
(Defense repellant chemicals)
What are synomones?
Chemicals the benefit both producer and receiver
(chemicals released when a plant is damaged)
What are kairomones?
benefit the receiver but create a disadvantage to the producer
(pines produce terpenes that fail to deter pine beetles)
What are some facts about Mammalian pheromones?
Help maintain behaviour and reproduction, released via urine feces or outaneous glands, elict both behavioural and endocrine responses, and are thought to act singly or in combination
What are the two types of mammalian pheromones
- Primer pheromones (slow response may elicit future behavior)
- Releaser pheromones (rapid behaviour response)
How are pheromones in mammals received?
Via the vomeronasal organ (located between nose and mouth and not seen in primates)
What can male rat urine cause in female rats?
Hastening puberty in females (via primer pheromone)
How are pheromones present in rams?
Pheromones in ram wool, wax, and urine can stimulate ovulation
What is the “ram effect”
Ewes and rams separated from each other for 6 weeks and at least 2 km away to keep ovulation from occurring
Why is the ram effect used?
To intensify the ovulation when the ewes and rams are brought in contact
Can sex pheromones in rams still work even without testes?
Yes
How do bucks (goats) use pheromones to get does?
They pee on their front legs and chest and emit a scent from scent glands below horns during normal mating season (fall)
How do does (goats) respond when they smell a “buck jar”?
Wag their tail rapidly
What is boar taint sensitivity?
steroids (androstenone) stored in fat tissues of boars after sexual maturity onset puberty (ovarian activity after parturition) in heifers
Does BTS still work with a boar with no testes?
Yes
What did Martha Mcclintock (Harvard) discover about women?
Women living in same dorm gradually developed synchronous menstrual cycles
What evidence is there that human pheromones exist?
- underarm secretions had a calming effect on women
- women experienced a surge of luteinizing hormone (triggering sex drive + ovulation)
- Ovulation may be linked to odours that attract men to women
What has declined over the past 150 years?
Puberty age
What is allelopathy?
chemical competition caused by one higher plant on another in the natural environment
What are some characteristics of allelopathic substances?
plant secondary compounds, and they are usually volatile terpenes or phenolic compounds
Why may allelopathic substances and toxins arise?
To deter herbivores
What can happen to a plant with allelopathic substances over time?
They can begin to excrete from the plant (through leaves, stems, and roots)
What environment was allelopathy first discovered in?
Desert environment with desert plants
What is a secondary application for allelopathic chemical defenses?
Used to outcompete other plants within the same environment (between different or same species)
Do black walmut trees kill things?
Yes through leachates from roots and leaves
What did thistles negatively affect?
oat plants
What did leafy spurge harm?
Flax
What harms beans?
Dipped in water with root exudates from other beans
What is Juglone?
water-soluble yellow pigment produced by green parts of the plants that kills root growth and inhibits seed germination
What are animal hormones?
Made of steroids (lipid)or peptides (protein)
Made by endocrine system and transported to site of action
What are plant hormones?
diverse chemical compounds produced in a variety of sites and transported short distances
What are some types of hormones plants use for growth and development?
- Abscisic acid (inhibits bud growth and promises bud + seed dormancy)
- Cytokinins (promotes cell division)
- Auxins (regulate cell growth and stimulate cells elongation in stems
- Gibberellins (regulate development)
- Ethylene (enhances fruit ripening and leaf senescence)
What are phytoestrogens?
Compounds that mimic estrogen when consumed. Have health benefits but also known to disrupt hormones
What kinds of plants have phytoestrogens?
soy, pomegranate, date seeds, garlic, oats, rye, coffee, sunflower, parsley, potato tubers
What happened in Holland during WWII?
Women were forced to eat tulip bulbs which ended up leading to menstrual irregularities and failures to ovulate
What are isoflavonoids?
Produced by the legume family. Used to provide the basis (skeleton) for phytoalexins (antibiotic compounds) that provide disease resistance in legumes
What are the recreational uses of psychoactive drugs? (phytochemicals)
- Simulants (create alertness)
- Hallucinogens (cognitive distortion)
- Hypnotic (induces sleep)
- Analgesics (relieves pain)
Have certain types of phytochemicals been used in religious ceremonies before?
Yes! Substances such as mescaline, muscimol, jimsonweed, shrooms, and canabis
What is another human use for phytochemicals?
Use of medicines and poisions
What is digitalin used for?
To treat heart conditions
What is bee therapy used for?
To treat arthritis
What are chemicals like morphine used for?
Pain killers
What are some examples of essential oils?
Citronella, menthol, camphor
What can essential oils be used in?
Can be used in ointments, lozenges, and other over the counter remedies
What are some properties of essential oils?
Antiseptic, anti-inflammatory, or astringent properties
What is an application for soy-derived phytoalexins?
May reduce menopausal symptoms, and prevent breast, ovarian, and prostate cancers
What is resveratrol?
Antioxidant found in the skins of grapes and some legumes.
Beleived to be responsible for cardio protective properties
Have anti-cancer anti-inflammatory, and lowers blood sugar (when tested on lab mice)
What are essential oils used for within plants?
For pest control (they are toxic)
What are some examples of essential oils being used for defense?
Cinamon is toxic (antifeedant)
Lemon is phytotoxic (pest-control)
Can essential oils be manipulated for pest control in crops?
Yes! Precocene 1 + 1 causes precocious metamorphosis
What is azadirachtin?
Chemical found in neem oil of neem trees. Used in cosmetics and skin care. Alters insect behavior (antifeedant, and interrupts metamorphosis)
What are some applications for pheromones with pest control?
Pheromone traps and mating interruptions
What has plant breeding done to make plants more resistant?
Herbivory damage, and fungal infections
How has selective breeding of certain traits negatively affected plants?
Desirable traits contribute to a tradeoff with lack of fungal resistance
How have phytoestrogens affected sheep?
In australia, lambing (newborn sheep) percentages were significantly reduced with 2 types of phytoestrogens found in the fields they grazed (genistein and formonoetin)
Can isoflavonoids be harmful to farm animals?
yES. Can cause difficult labour, infertility, lactation before its supposed to occur
How does rainfall affect legumes growth and isoflavonoid production?
Good rainfall means legumes grow rapidly and have low isoflavonoid content
Poor rainfall means legumes grow less profusely and have higher isoflavone content
How do isoflavonoids help humans?
1.Reduces cancer risk (protection against tumors)
2.Improves bone health
3.Prostate protection
4.Reduce heart disease risk
5.Ease menopause symptoms (increases bone density and reduces hot flashes)
What are the major conditions for insect pheromones?
Must be present in the right concentrations and at right time during insect lifecycle for normal development
What are the two types of insect hormones?
- Insect molting hormone (ecdysone) - controls moutling of each life stage
- Insect juvenile hormone (maintains the insect in a juvenile state)
Do plants mimic insect hormones as a way of protection?
Yes! a-ecdysone produces molting and is found in yew leaves and fern rhizomes
What evidence is there that plants mimic insect hormones for protection?
- Phytoecdysones occur in ferns and gymnosperms which are free of insect predation
- The result of this hormone is that insects are sterile and die early
- Found at high concentrations
- Structural variation in phytoecdysones may help them resist inactivation
How were juvenile hormones in plants first discovered?
Czech biologist came to US to study European fire bug. Bug remained in 5th larval stage. Filter paper in experiment was made of balsam fur (only used for paper in us). Juvabione was found within the tree as a juvenile hormone
What is special about Juvabione?
Only effective against one insect family (pyrrochoridae)
Can juvenile hormones be manipulated for agriculture protection?
Yes!
What are some examples of other juvenile hormones in plants?
- Juvicunebe 2 occurs in leaves of sweet basil for protection against milkweed bugs
- Juvadecene occurs in roots of Kawakawa against milkweed bugs
- Precocene 1 + 2 in ageratum against milkweed bugs
What is a classic example of an evolution arms race?
Tobacco vs tobacco hornworm
How do phytophagous insects come to exist?
- Evolve in response to physiological obstacles.
2.Results in the diversification of tolerance to plant secondary compounds
What evidence is there for coevolution between animals and plants?
- There is an abundance of plant secondary metabolites identified (30 000 total known) (6k alkaloids and 10 k terpenes)
- The destructive potential of herbivorous insects has not prevented higher plants from dominating the earth
- Most herbivorous insects discriminate between plants in feeding
- Host plants of a given insect may share similar secondary plant compounds but be different in general morphology and antomy
- Many secondary plant compounds are highly toxic to insects
- Plants can arrive all the same solution to an ecological problem in different ways
- All angiosperms tend to have at least one type of secondary compound in major concentration
Why is it difficult to test the theory of coevolution between plants and animals?
- Occurs over millions of years
- Chemical toxicity may be subtle
- Chemical intake only need to slightly reduce insect fitness to be considered significant
- Chemicals may take other roles
- Chemicals intermediates may have no functional role
What are some insect bioassay problems?
- monophagous insects are reluctant to feed on non-host plants
- some will starve rather than accept food lacking a particular feeding stimulant
What are the two functions of plant secondary compounds?
- chemical attractants
- chemical repellents
Why may a plant that can only eat one plant become exclusively dependent on it?
New niche with no competition! Toxins become the attractant to the insect.
What are the problems with insects that can only feed on one plant?
Become dependent for feeding on the chemical attractant. This can lead it to become hooked, making it not eat the plant if the chemical is absent
What are three groups of chemicals involved in feeding behaviour of silkworms and mulberry?
- Olfactory attractants (essential oils - monoterpenes)
- Biting factors (2 sugars, 1 terpenoid, and 2 flavonoids)
- Swallowing factors (Cellulose, silicate, and phosphate)
What does monophagy of silkworm suggest?
Other plant secondary compounds may be hostile to it
What shows evidence of other chemicals harming the silkworm?
18th century silkworm production moved to new rearing houses made of bald cypress. Inhibited larval growth. Volatile chemical impact nutrition.
What is the most studied glucosinolate?
Sinigrin (releases allyl isothiocyanote in metabolism)
What is sinigrin generally known to be?
Anti-feedant
What is sinigrin to cabbage butterfilies?
positive feeding stimulus
What shows the cabbage butterflies are addicted to sinigrin?
They would rather die then not eat it (larvae) and they ate 20% more with it added to diet
How does sinigrin aid in oviposition?
Females lay eggs near plants containing sinigrin
Where can tannins be found?
leaves of woody plants
How and what do tannins deter?
Higher animals, birds, reptiles, and some insects deterred from astringent taste
What do humans use tannins for?
Tanning animal hide to made leather
Why do moth larvae stop feeding on oak when tannin levels get too high?
Tannins bind to leaf proteins making it tougher and harder to digest
Why are oaks so successful?
Tannins as deterants
Why is predation usually limited for specific plants?
Few insect species feed on a particular plant`
What are adaptations of a plant of herbivores develop adaptations for grazing?
May develop a stronger toxin (more concentrated) or a second toxin. Some herbivores will not be able to adapt to this while others become more specialized
WHat is the list of complexity of chemical deterrents in different plants?
Ferns, gymnosperms, woody angiosperms, herbaceous angiosperms. More advanced species may be better protected than more primitive species
What is the general rule of thumb for plant secondary metabolites?
Every type of toxin is either a deterrent or feeding attractant (except condensed tannins)
Who demonstrated interactions between insect herbivores and coumarins (carrot family)?
Berenbaum
What are coumarins and their derivatives?
- Coumarins (found in hundreds of plant families: known to be toxic to insects and a rodenticide)
- Hydroxycoumarins (36 plant families)(phytoalexins - antibiotics (germination inhibitor))
- Furancoumarins (8 plant families) (housed in special structures in all parts of plant)(absorbs uv meaning its more toxic than hydroxycoumarins)
What are some other benefits of furanocoumarins other than for protection?
- Able to move to new geographic locations
2.Uv absorption allows plants to move to drier area and become phytotoxic - Non adapted insects are poisoned
What are the metabolic costs for insects to cope with furanocoumarins?
- Leaf rolling to avoid uv induced toxicity
- Development of an efficient detoxification system
- Insects may move to other plant families with similar plant chemistry
What are the benefits to insects who can eat furanocoumarins?
- Physiological and behavioral immunity (leaf rolling)
- Less competition
- Specialization allows some insects to tolerate furanocoumarins
When would toxins be presented in a plant be advantageous?
When the plant is vulnerable
What is an example of a toxin presented when a plant is vulnerable?
In coffee plants:
-germinated seeds have very little caffeine
-Increase concentration when the plant grows
-decrease concentration as leaves mature
-non-existent in senescent leaves
-increased levels in young fruit but decreases with age
What are animal responses to an increase of a plant toxin?
- Detoxification or metabolism (leads to adaptation)
- Sequestration of toxins (use toxin for something like warning coloration)
- Excretion (gets rid of toxin)
- Change in behaviour (feeding habits of animal may alter the plants ability to produce the desired chemical response)
How is Juglone stored/administered?
Occurs in plant in a safe, non-toxic form. Becomes active once it leaches from stems and leaves. May be in effective concentration in soil and is renewed by rainfall.
What plants are susceptible and tolerant to juglone?
Susceptible- alders, broad-leaved herbs, ericaceous shrubs
Tolerant - blackberry, smooth meadow grass
How do desert plants share?
Growth of annual plants are inhibited to ensure a share of available soil moisture (via plant secondary metabolites)
What is the Californian chaparral?
An area of low rainfall along the coast of Southern California. Shrubs inhibit surrounding herbaceous plants using terpenes.
What are shrubs and grasses found in Cali-chap?
Shurbs: purple sage, California sagebrush
Grasses: Avena, Bromus, Festuca
How are terpenes used in shrubs in Cali-chap?
-Abundant in leaves
-turned over by shrubs
-excreted in the dry surrounding soil (rain destroys them)
How is the Cali -Chap maintained?
Cyclical forest fires occuring every 25 years. Terpenes are burned. This allows herbs and grasses to dominate. Shrubs slowly return and exert their alleopathic effect (6-7 years later) soil occurs around shurbs
What do most higher plants share in common?
Resistant to microbial attack
Coexist in a symbiotic relationship with microbes without producing symptoms
What are the two types of disease resistance compounds?
Pre-infectional compounds and post-infectional compounds
What are two types of preinfectional compounds?
- Proinhibitins (metabolites reduce or hault development of pathogens)
- Inhibitins (metabolites that undergo post-infection to express full toxicity
What are two types of post-infectional compounds?
- Post-inhibitins (pre-existing inactive metabolites in healthy tissues are activated)
- Phytoalexins (metabolites that are formed following the invasion of a pathogen)
