Parasites

Question 1

Egg laying on plants

Answer 1

Affects plant physically by destroying epithelium of leaf. Breaking up of epithelium produces VOCs (volatile organic compounds)

Question 2

Wasps

Answer 2

Females lay eggs inside caterpillar

Question 3

Ticks

Answer 3

Prefer smell of sick hedgehog faeces (sick hedgehogs have higher ticks). If already weak, hedgehog less likely to be able to remove them (through scratching etc). Active compound in faeces of sick hedgehogs = indole, attractive to ticks

Question 4

Nematodes

Answer 4

Different odours from different prey induce specific responses from parasitic nematode. Infest insects (not so keen on C elegans)

Question 5

P cinerella flies

Answer 5

Parasitic, lay larvae on snail faeces next to snail trail. Larvae can then track down the snail by following mucus and parasitise it.

Question 6

Hosts fight back

Answer 6

Drosophila larvae attacked by parasitoid wasps.
Larvae will avoid smell of wasps and females avoid when ovipositing.
Two OSNs respond to three components of wasp odour with specific glomeruli and projection neurons.

Can inhibit avoidance by paralysing these OSNs with temperature shift and activate avoidance with optogenetics.

Only respond to SPECIES SPECIFIC odours

Question 7

Drosophila lay eggs on

Answer 7

Citrus. Key compound is limonene, detected by specific OSN.

Parasitoids don’t like citrus.

Question 8

Hyperparasites

Answer 8

Parasitoid: wasp lay eggs in caterpillers and locates them using chem cues produced by the caterpillars eating leaves.

Hyperparasitoid: detect caterpillars that have been parasitised. Salivary glands produce secretion affected by parasitoid’s sting, including venom and a symbiotic polydnavirus.

Question 9

Phoresis

Answer 9

“Hitching a ride”
Oil beetles are nest parasites of solitary bees. Beetle larvae attach to male bee and transfer to female during mating. Female goes to nest.

Larvae “appear” similar to female bees via chemical signals.

Question 10

Kleptoparasites

Answer 10

Chemical camouflage

Silverfish lives with southeast asian army ant

Question 11

Social parasites

Answer 11

P sulcifer wasps are a social parasite. Search out host nests of other wasp species and expel or kill resident alpha. Parasite takes over as alpha, strokes nest with gaster, licks other wasps and is accepted by others. Makes nest rear own offspring.

Prior to usurpation, parasite has simple CHC profile with peak of 9,15-DNC. Within 90 mins of usurpation, this decreases, start to have profile much more similar to host. Within three days, still have DNC but much lower, blurred profile with that of host nest.

Other CHCs can stimulate aggression between nest mates and parasites.