19 Flashcards
Many ways to eat a plant? 4•
•Insect herbivores
•Parasitic Herbivores
•Mammalian herbivores
•Some omnivore
Mammalian herbivores tend to be?
Generalists (polyphagous)
Insect herbivores are mostly?
Highly specialized (monophagous)
About what percent of insects feed on only at most 3 plants?
> 90%
Important ecological and evolutionary causes of host specialization?
Interactions drive traits of both to specialization and sometimes coevolution.
!!What can host specialization eventually lead to? 3•
•Plant defense
•Herbivore counterdefense
Resistance traits?
A trait in a plant that reduces the preference or performance of herbivores.
Deterrence?
A trait which inhibits feeding or oviposition when present in a place where herbivores would, in its absence, feed or oviposit.
Physical deterrents?
Any sort of deterrence that occurs morphologically, such as thorns.
!!Chemical deterrents?
Any sort of chemical deterrences in the surface of the leaf, such as phenolics and oxidative enzymes that create a sticky surface for aphids.
Trichome terpenes deterrent?
Aphids reared on accessions with terpenes in trichomes have reduced longevity and fecundity.
Terpenes are?
Carbon based compounds that create a bitter taste and have anti-fungal properties.
Chemotypes with terpenes reduce what?
Aphid landing preference.
Why don’t all plants have trichomes?
•Energetic costs
•Water lost
•Ecological costs: repel benefits
Two big types of trichomes?
Sticky and velvety.
How many genes decide what trichomes does the plants make?
One gene
The sticky trichomes have what chemical?
Acylsugar
Acylsugars?
They are sticky and smelly sugars that are very lipophilic (may desiccate herbivore membranes).
Toxins interfere what type of metabolism?
Primary
!How does nicotine enter the nervous system of caterpillars?
Their saliva is basic in base: R-N = lipophilic.
Because of their lipophilic properties, they will not bind with the mouth membranes. They thus pass thought to hemolymphs, which is acidic in acid: R-NH = water soluble. They then move to the ganglia and into the blood stream.
Counterdefense from caterpillars?
Halitosis. They are able to detoxify nicotine and let it all out. But some of that nicotine is taken into the hemolymph and then since the hemolymph is moving all through the body, it interacts with the spiracles of the body. Some of that nicotine is excreted out of the body of the caterpillar. If a predatory spider comes that is not able to handle the nicotine, the caterpillar can defend itself using the plant’s defenses.
