Term
| what is the difference between microparasites, macroparasites? |
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Definition
| microparasites are unicelluar with rapid within-host replication while macroparasites are multicellualr and often complete development with out of host stages. |
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Term
| give some examples of microparasites, macroparasites. |
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Definition
microparasites: viruses, bacteria, fungi, protozoa
macroparasites: nematodes (worms), mites (ectoparasites), parasitoids. |
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Term
| what is unique about the nematode infection *Steinernema carpocapsae* |
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Definition
| works with another pathogen, a bacteria that kills the fly before the nematodes takes over. |
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Term
| what are parasitoids? what is an example of one? |
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Definition
parasitoids are half parasite, half predator.
• Wasps injects eggs into caterpillar. Larvae eat way out. they eat judiciously, saving organs for last and then the host dies and larvae emerge. |
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Term
| describe the history of invertebrate pathology |
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Definition
• 2700 B.C. Silkworm diseases first recorded in China and Honeybee diseases discovered
• Mid 1800s Efforts to catalog insect pathogens
• 1980s – present Ecology of insect diseases
• the current focus is on
o pest insects and biological control
o regulating disease in beneficial insects |
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Term
| what are the five unique features of insect parasites? |
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Definition
1. Mode of invasion typically oral or via cuticle (some vertical)
2. Dying hosts climb to an elevated location
3. Abiotic environment important to the spread and persistence of disease
. No lasting host immunity (no “recovered class”)
o significant because makes modeling much easier
5. Parasites that accumulate in the external environment can be considered as a separate class - there is an ‘infectious particle’ class in the SI model |
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Term
| what is summit disease syndrome? |
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Definition
| infected insects climb to the top of something to die. (behavioral modification by the pathogen that facilitates the spread of the disease) |
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Term
| what are the three corners of the disease triangle? |
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Definition
| environment, pathogen, susceptible hosts |
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Term
| in the study of flies infected with *Entomophthora muscae* what determined transmission? |
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Definition
| abiotic factors determined transmission, not density. |
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Term
| what implication does no recovered class in insect parasites have for modeling? |
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Definition
| no R class. makes modeling much simpler. |
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Term
| why are insect pathogens so lethal? compare this with STDs in humans. |
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Definition
| life cycles of insects so short that pathogens need to be really virulent to reproduce and spread in a manner that get's their seed out before their host dies. |
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Term
| diagram the SI model for insect pathogens and write out the compartmentalized equations? |
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Definition
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Term
| under what conditions can the insect pathogen regulate the host population? |
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Definition
| when transmission (Beta) is high and pathogen induced death rate (alpha) is greater than the regular birth - death rate. |
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Term
| what conditions are required, in the case of an insect pathogen, for the population to cycle? |
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Definition
| population cycles when the pathogen death rate (mu) is small and the pathogen induced death rate (alpha) is relative to natural mortality (d) |
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Term
| name three forest pathogen caterpillars (lepidoptera) |
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Definition
| gypsy moth, spruce budworm, forest tent caterpillar. |
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Term
| describe long term fluctuations in caterpillar pathogen density. |
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Definition
| The populations of all the caterpillars shown above cycle. The cycles vary in period from 5-15 years (time between peak abundance) |
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Term
Describe the Gypsy Moth *Lymantria dispar*
when was it introduced and when was the record outbreak? what happened during this outbreak? where is it located? in what direction is it expanding? what is it's cycle length? what can this be attributed to? |
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Definition
• Introduced in 1869
• 1981 record outbreak
• Defoliated 12.9 million acres
• Range still expanding to south and west
• Past cycles of 8-12 years possible due to NPV (nuclear polyhedrosis virus, see next) |
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Term
| what is NPV? how is it used? |
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Definition
nuclear polyhedrosis virus (NPV)
• introduced by humans to kill pathogenic caterpillars like the gypsy moth when they take over forests and defoliate everything. |
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Term
| describe Dwyer and Elkinton's 1993 study on NPV and gypsy moth abundance. what did they find? |
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Definition
| found that NOV can regular gypsy moth abundance and that increasing the pathogen decay rate shortens the time between cycles. |
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Term
| what is *Bacillus thuringiensis*? |
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Definition
| soil pathogen lethal to many insects. used as a biocontrol agent (like NPV) |
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Term
| diagram the life cycle of *bacillus thuringiensis* |
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Definition
| free spore crystals are activated in the insect gut to produce a toxin. |
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