EXPLOITATION: HERBIVORY AND PARASITISM

MODULE 3

Chemical Defenses

How do plants defend themselves?

Quantitative and Qualitative defenses

What are the two general types of chemical defenses

Quantitative defense is ingested in large amounts that causes indigestion and do not kill

What is Quantitative defenses?

Phenolics

Give me an example of type of animal that has a quantitative defense?

Qualitative defenses is ingested in small amounts that kills the herbivore

What is Qualitative defenses?

Alkaloids, Glycosides, and Terpenoids

Give me the three examples of animals that has Qualitative defenses

Monarch Butterfly

Give me an example of glycoside that does not typically kill

Thorns and Spines

What are examples of mechanical defenses

Masting

Producing many numbers of young for better survival

Mutualistic relations

This type of relationship increases the fitness of both parties that acts as a buffer to some challenges in the environment

Ants and Acacia Tree. The ants eat some of the parts of the plant that is secreted in which is beneficial to acacia as they stay to fight off other worse herbivores that can damage the tree more extensively. The ant gets free food for protection.

Example of Mutualistic Relationships that are Anti Herbivory

Polyphagous herbivory

Which is more important than monophagous herbivory?

Monophagous herbivore eats exclusively just one species of plant while Polyphagous eats multiple species of herbivores

Difference between monophagous and polyphagous

That mans that the herbivore is not overly selective and it will not be only eating one species and so it would not be very detrimental to the population size of that plant species because its an equal opportunity feeder. Therefore in a community structure it will be controlling the population of many species and not just one.

Why is Polyphagous more important?

15-18 percent for terrestrial plants and 51 percent for marine plants

What is the percent of plant tissue consumed by herbivores?

Biological control particularly of exotic weeds

Herbivory can be used for…

Plant nitrogen content often limits population densities of herbivores

Relationship of plant nitrogen content and population density

Plant nitrogen

What is the primary nutrient that herbivores require from their diet

Opuntia stricta

What is the scientific name of prickly pear cactus

Cactoblastis cactorum

Moth that is found to be an effective herbivoreof Opuntia stricta

The predator or biological control introduced may also be invasive and may shift its diet to native species

What could have gone wrong or what is the typical danger when you introduce a biological control for an invasive species and efficient predator is introduced

Yes as plants may be stimulated to re-grow by the attacks by herbivores. Herbivores can also shape communities.

Can herbivory be beneficial to plants?

Polyphagous herbivory controls the population of several species of plants

Give an example of herbivory shaping communities

Monophagous herbivory is important in a sense that it controls the population of the dominant species of plant thereby preventing the dominant species of plant from competitively excluding non-dominant species of plant thereby maintaining biodiversity

Give an example of monophagous herbivory shaping communities

Typically fertilizers are mono elemental therefore can lower biodiversity. By introducing a mono-nutrient fertilizers then you are promoting the growth of competitive excluder that will overtime limit the biodiversity.

What can the introduction of fertilizers do to biodiversity?

Limiting nutrient

When you introduce a particular nutrient or increase the amount of one nutrient which becomes the most important determinant of what species can survive in the ecosystem

There is no absolute definition as there are a lot of types of parasitism

What defines a parasite?

A predator kill it’s prey while a parasite live on its host but do not necessarily kill

How would you differentiate a parasite from a predator?

Around 80 percent of all organisms may be considered parasites

How prevalent is parasitism?

Ectoparasites and Endoparasites. Ectoparasites lives on the outside surface of the host while endoparasites are those who live inside the host.

What are the two types of parasites and differentiate them

Schistosoma japonicum

Give me an example of endoparasites

Leeches

Give me an example of ectoparasites

Their unusual life cycles and morphologies

What are unusual about parasites

Oncomelania sp.

What is the genus of the usually intermediate host of blood flukes?

They spend their asexual life stages in the intermediate host while their spend their sexual life stage in their primary host

What is one major difference between intermediate and primary host?

Horsehair worms and Cordyceps

What are the most common mind controlling parasites?

Cordyceps

What mind controlling parasites to ants

Horsehair worms

What mind controlling parasites to grasshoppers

Euhaplorchis californiensis

What mind controlling parasites to fish

Toxoplasma gondii

What mind controlling parasites to rats

Spring-headed worm (Acanthocephala)

What is the type and scientific name of the worm that changes the behavior of amphipods in ways that make it more likely that infected amphipods will be eaten by a suitable vertebrate host?

Plagiorhyncus

A bird that lay eggs within the intestines of infected birds and the eggs are shed with feces

Cellular defense4 reactions, Vertebrate immune responses. Grooming and Preening

How do hosts defend themselves against parasites?

Grooming and Preening

Behavioral modifications wherein the hosts defend themselves from parasites. This is a maintenance and cleaning of an animal’s body and the maintenance of the feathers by birds

density of susceptible hosts in population

Parasitism model: N

Transmission rate of disease

Parasitism model: B

Average period over which infected host remains infectious

Parasitism model: L

Rp = NBL

Rp is the number of infected host give it’s formula

disease or parasites spreads

If Rp is greater than 1 then

the parasite dies out

If Rp is lesser than 1 then

Each individual that is infected will infect one more individual

If Rp is = 1

Larger populations tend to breed more parasites or diseases and parasites will keep their hosts alive longer

Significant generalization from the parasitic model

If the virulence is high then it is most likely that the host will die therefore not be able to transmit it anymore. A transmissibility is high then it is most likely that the host will live as the effects of the disease in the body is less severe.

Why is it that a typical pathogen can’t have both transmissibility as the same time high virulence.

Parasites significantly affect the host populations, Extinctions possible from parasitism, and more long-term associations may evolve to commensalism or mutualism

How do parasites interact with their host?

Wolbachia and Drosophila

Example of commensalism in parasitism

Exponential growth by host population

What does rhNh stands for

rate of parasitism

What does P stands for in the Lotka Volterra?

Number of hosts

What does Nh stands for in the Lotka Volterra?

Number of parasites

What does Np stands for in the Lotka Volterra?