Lecture 15 Flashcards
describe the feeding method of specialized interactions insects & plants have
feed on plant & use it as protection
galls
lay eggs in tissue of plants & manipulates tissue of plant to grow nutritive & protective tissue around the eggs
describe the evolutionary history of insect-plant interactions
Insects were present at or before the origin of vascular plants
The two most significant radiations in insect diversity coincide with the evolution of:
seed plants
flowering plants
what did the evolution of flowering plants result in?
largest radiation of insect diversity
when were most of the insect orders created?
during the evolution of see plants
coevolution leads to the evolution of _____ _____
novel traits
Describe the cycle of coevolution
- Plant evolves new chemical defense: temporarily free from herbivory
- Radiation of new, but related plant species
- Insect evolves ability to overcome plant defenses: is temporarily free from competition
- Radiation of new but related insect species
- Cycle continues over evolutionary time
the assoc b/w Brassica plants & Pierid butterflies was a result of?
coevolution
describe the coevolution Brassica plants & Pierid butterflies
- A Brassica species evolved defenses to avoid insect attack (glucosinolates)
- Radiation of plants
- A Pierid butterfly species evolved counter defenses to plants containing glucosinolates
- Radiation of new Pierid species that could feed on plants containing glucosinolates
what are the 2 main categories of plant defenses?
constitutive defenses
induced defenses
constitutive defenses
always present & expressed
E is continually put into the defenses of this plant whether they are under attack or not
induced defenses
only synthesized/produced in response to herbivory (injury)
Invest E only when attacked
what are the categories used to categorize plant defenses?
constitutive defenses
induced defenses
mechanical defenses
chemical defenses
what are mechanical defenses used in plants?
Waxy epidermal cuticles
Leaf toughness
Seed coats
Spines, prickles, thorns
Bark
Trichomes - hairs, scales & grandular (exude substances)
pitching out
pitching out
trunk of the tree is a highly-pressurized tube, when a hole is made there is pinch & resin to close it
when it is an effective defense for plants to use pitching out?
when insects lay eggs &/or feed
what type of plants use glandular defense?
carnivorous plants
primary metabolites include:
AAs, sugars, nucleotides & lipids
primary metabolites function in _____ & _____
growth & reproduction
what is an ex of primary metabolites used in chemical defenses?
high sugar content – make the fruit less susceptible to herbivory, many insects prefer to feed on other parts of the plant (increases fitness b/c they need seeds)
what are the 2 grps of chemical defenses in plants?
primary metabolites
secondary metabolites
primary metabolites are found ________
whereas,
secondary metabolites are found ______
throughout the plant kingdom
in related grps of species (shared common ancestry)
secondary metabolites
Often co-opted metabolism by-products
what are the modes of action in secondary metabolite defenses?
Feeding & oviposition deterrents
Toxicants
Antimicrobial activity
Attractants (smell, colour, taste) for pollinators & parasitoids
what are exs of defensive chemicals produced by plants?
Gluccosinolates are only present in Brassicaceae
Nicotine in tobacco
Tannins in tea & many other pants
Salicylic acid (Aspirin) in willow bark
Caffeine, morphine, cocaine, cannabinoids, myrcene
what is the role of limonene in interspecific communication?
distasteful to herbivores causing them to stop feeding
what is the role of menthol in interspecific communication?
warns herbivores that the plant is toxic to them before feeding commences
is limonene volatile?
no, non-volatile
is menthol volatile?
yes
phytoecdysones
secondary metabolites
plant steroids similar to insect molting hormones
can interfere with molting when ingested
semiochemicals
chemical communication
volatile
allelochemicals
facilitate interspecies communication
allomones
Produce negative response in insects
Repellents, deterrents & toxins
kairomone
Benefits the recipient
Harms the emitter
describe the chemical defense of caterpillars
produces volatile secondary metabolites that are detected by other insects
how they function depends on the indiv that detects it
indirect defense (idk if OT)
plant makes use of a third party to defend itself, using secondary plant metabolites to call for assistance
what are the morphological adaptations seen in insects? (2)
Ex: acorn weevil – larvae feed on seeds of acorns, have specialized mouthparts that can grind through the acron to deposit eggs
Ex: horntails –feed on bark of tree, deposit eggs to pierce through bark to deposit eggs where they can feed
what are the behavioural adaptations seen in insects?
Eat parts of leaves to avoid or limit production of defensive compounds
Chew a ring of tissue, cuts off the ability of plants to transport metabolites for defense
what is an ex of a behavioural adaptation seen in caterpillars?
trenching – seen in leaves with caterpillars
behavioural adaptations used by plants lead to the production of what?
secondary metabolites
what are exs of biological conditioning seen in insects?
Ex: inoculation of plant with fungi (& bacteria or both) to alter/suppress plant defenses or improve plant nutrition for offspring
Mycangium – structure on body adapted to transport spores of symbiotic fungi
exs of detoxification enzymes
the parsnip webworm can metabolize furanocoumarins & neutralize plant defenses
saliva - Injected into plant tissues to reduce production of or break down induced secondary compounds (ex: corn earworm caterpillars feeding on tobacco plants)
sequestration
Storage of toxic/distasteful secondary plant metabolites in tissues (of insects)
become distasteful & poisonous to predators
what insects sequester cardenolides? (3)
turnip sawfly
milkweed bug
monarch butterfly
what adaptation to overcome plant defenses is accompanied with aposematic colouration?
sequestration
substitution of an NA has enabled insects to do once? How many times did this happen?
genetic resistance enabling insects to feed on plants containing cardenolide poisons
occurred 4 diff times leadingto4 diff orders
what is an adaptation to overcome plant defenses that occurs at a pop level response?
mass attack
describe the mass attack of bark beetles & mountain pine beetles
females need to bore through bark to deposit eggs, when this occurs, the holes they bore fills up with sticky material, the beetles can get stuck in it & die
When the female finds a suitable tree she produces an aggregation pheromone to induce beetles to go into the tree, many beetles start going into the tree
Limited amount of pitch the tree can produce (sticky material)
Have a high enough number of beetles to go into the tree & lay eggs
The number of beetles are higher than the amount of pitch the tree can produce to kill them all
Once in the tree, produce antiaggregation pheromone to indicate that the tree if full
