BIOL3046 Lecture Notes - Lecture 21: Toxoplasma Gondii, Nicotine, Cordyceps
5 Jul 2018
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Animal Behaviour BIOL3046 460381099
Lecture 21: Parasitism.
A symbiotic relationship, non-mutual, needs a host, parasitic or free-living stages.
Hyperparasites, can have up to 7 levels.
1. Classic parasites: endoparasites, ectoparasites
2. Parastoids: develop inside, then emerge as free living.
3. Brood parasites.
1. Classic parasites:
20% of species are parasites. Are there any individuals without parasites? The host can be
seen as an ecosystem. Parasite life cycle depends on the needs. Example: Plagiorhynchus,
the effs are in the intestines of infected birds, they are then shed with feces. Terrestrial
isopod eats the feces, and the eggs hatch within the isopod.
Parasites influence host appearance and behaviour.
Parasites aim to maximise reproductive output: Uses host resources to benefit its own
fitness. Divert hosts to benefit parasites: sterilisation and growth. Make resources more
available to the parasite, feeding or protection. Example: Adult wasp will put eggs into
caterpillar, then the eggs hatch and eat the caterpillar inside out. Or, the larvae emerge and
a few remain inside. These inside, dictate the behaviour of the host and makes it protect the
emerged larvae.
Emerald cockroach wasp, selects victim and stings it causing temporary paralysis. The
second sting involves injection directly into the sub-oesophageal ganglion. It can never walk
on its own free will anymore. It can be pushed, so it is taken to a whole where eggs will be
injected into it. Cockroach is still alive, until newly hatched grub eats it alive.
Parasites aim to maximise the likelihood of transmission: Some parasites seek out a
definitely host, whereas some manipulate the actions of their hosts to get to where they
need to be. Example: Malaria, plasmodium manipulates mosquito by reducing risky feeding,
interferes with blood drinking and tinkers with the chemo sense of the mosquito.
Nematomorphs, grows inside cricket, then needs to get to water to grow to next stage. The
worm then comes out of the cricket, and host can survive this. Ant brainjacker is the
Document Summary
A symbiotic relationship, non-mutual, needs a host, parasitic or free-living stages. Hyperparasites, can have up to 7 levels: classic parasites: endoparasites, ectoparasites, parastoids: develop inside, then emerge as free living, brood parasites, classic parasites: The host can be seen as an ecosystem. Example: plagiorhynchus, the effs are in the intestines of infected birds, they are then shed with feces. Terrestrial isopod eats the feces, and the eggs hatch within the isopod. Parasites aim to maximise reproductive output: uses host resources to benefit its own fitness. Divert hosts to benefit parasites: sterilisation and growth. Make resources more available to the parasite, feeding or protection. Example: adult wasp will put eggs into caterpillar, then the eggs hatch and eat the caterpillar inside out. Or, the larvae emerge and a few remain inside. These inside, dictate the behaviour of the host and makes it protect the emerged larvae. Emerald cockroach wasp, selects victim and stings it causing temporary paralysis.
