Parasitism Flashcards
Hairworm lifecycle
- cricket drinks infested water
- larva enter the crickets body and feeds on its tissue, growing into an adult
- Cricket jumps into the water and drowns, hairworm eemerges and mates.
How do enslaver parasites manipulate the behavior of their host?
Hairworms alter concentration of three amino acids in the host cricket (ultimate mechanism)
Taurine
a neurotransmitter in insects and regulates the sense of thirst
Symbionts
Organisms that live on or inside other organisms
Are some symbionts mutualists?
yes
parasite’s function
consumes the tissue or body fluids of an organism on which it lives
Pathogen
parasites that cause disease
Do parasites typically harm but do not immediately kill the organisms they eat?
Yes
True or false: Parasites feed on many species but host species do not have multiple parasite species.
False: Parasites typically feed on only or or a few host species, but host species have multiple parasite species
Macroparasites
large species such as arthropods and worms
Microparasites
microscopic, such as bacteria
Ectoparasites
live on the outer body surface of the host
Endoparasites
Lives inside their host within cells or tissues or alimentary canal
Mistletoe
hemiparasitic
Hemiparasitic
they get water and nutrients from the host but also photosynthesize.
Holoparasite
parasite that does not photosynthesize on its own
Advantages of being an endoparasite
safe from external environment
ease of feeding
safer from natural enemies
Disadvantages of being an endoparasite
Vulnerability to the hosts immune system
Advantages of being an exctoparasite
Ease of dispersal
safe from hosts immune system
Disadvantages of being and exctoparasite
Vulnerability to natural enemies
exposure to external environment
feeding more difficult
Coevolution
populations of two interacting species each in response to selection imposed by the other.
What factors of host health can parasites reduce?
Survival
growth
reproduction
What parameters would we need to know in order to understand population growth of a pathogen?
How infectious it is
How many people are immune to it
how many people hav been effected
Symbol for : host population divided into susceptible individuals
S
Symbol for : infected individuals
I
Symbol for recovered and immune individuals
R
Threshold density equation
dI/dt= BetaSI-mI
SI stands for
Probability of infected individuals encountering susceptible individuals
Beta
stands for the transmission coefficient
What is the transmission coefficient?
How effectively the disease spreads
dI/dt>0
Disease is growing
When will disease grow?
dI/dt>0
When will a disease establish and spread?
when the number of susceptible individuals exceeds threshold density (ST= m/ beta)
ST stands for
the number of individuals necessary for disease to spread- less than that is a safe population size.
What can raise the threshold number: (ST)
Public health measures.
What does climate change effect?
Distribution of diseases
What are water temps correlated with?
Increased disease in coral reefs, shellfish, and amphibians
leishmaniasis
flesh-eating bacteria
