Parasitoids - Guest Lecture

Question 1

What is a parasitoid

Answer 1

A parasitoid results from the interspecific relationships that have a direct trophic interaction that has one host that they exploit and always kill

Question 2

What are the three main characteristics of parasitoids

Answer 2

1. they use only one host for their entire larval development
2. larva always kills its host
3. are only parasitic as larva only (the adult is free living)

Question 3

Explain types of species and numbers that make up parasitoid biodiversity

Answer 3

many are wasps/hymenoptera (100,000), flies/diptera (10,000), few beetles/coleoptera (400), rare mantidflies (52), rare moths (32).

Question 4

What are the five ways that parasitoids can locate their hosts

Answer 4

1. olfactory cues (hairs increases receptors, smell saliva and plant)
2. visual cues (eyes)
3. tactile cues (antenna are also feeders)
4. gustative/taste (bottom of feet sensors or bottom of abdomen, can sting without injecting)
5. auditory cues (sounds)

Question 5

Explain solitary vs. gregarious parasitoids

Answer 5

solitary = typically lay one egg per host
gregarious = lay multiple eggs per host

Question 6

Explain ectoparasitoid vs. endoparasitoid

Answer 6

ecto = parasitoids attached on the outside of hosts
endo = parasitoids attaching on the inside of hosts

Question 7

Explain koinobiont vs. idiobiont parasitoids

Answer 7

Koinobiont = allow the host to continue its development while feeding upon it
idiobiont = prevent further development of the host after initially immobilizing it

Question 8

Explain primary parasitoids, hyperparasitoids, and hyper-hyper parasitoids

Answer 8

primary parasitoids = have the simplest parasitic relationship, involving two organisms, the host and the parasitoid
hyper parasitoids = are parasites of parasites, where they specialize in parasitizing insects that themselves are parasitic on others

Question 9

Explain how stage of host attacking changes with life histories

Answer 9

few attack adults (because fast, hard to move), egg-larval (lay eggs in eggs-grow in larvae-and kill larvae), larval-pupal (lay eggs into larvae-grows into pupae- kills pupae)

Question 10

Explain specialists vs. generalists of life histories

Answer 10

specialist = has few closely related host species
generalists = has many host species, at least from different genera

Question 11

Using the life cycle of Cotesia Vanessae as an example, what happens if all goes well for the host vs. for the parasitoid

Answer 11

good for host = the host encapsulates the parasitoid eggs and larvae in the host’s hemocytes and they suffocate the eggs
good for parasitoid = can inject viruses along with the eggs to destroy host immune system cells and also prevent the host from pupating (hormonal properties) and replace host immune defenses (antibiotic properties)

Question 12

What are the two physiological modifications of hosts that parasitoids can cause with examples

Answer 12

1. modification of the host’s behaviour (ex. a bug turns its host into a body guard)
2. modification of the host development (species induces their hosts to have a supernumerary molt)