W10: Invertebrate Physiology (Physiology Of Smell: Insect Olfaction & Defence) [Dr. Blair] Flashcards
Olfaction?
= the detection of chemicals that influence the physiology & behaviour of insects (pheromones).
Pheromones?
= scent produced that signals the same species to perform a behaviour.
Thing to note about pheromones?
They DON’T influence the behaviour/physiology of another species.
Areas that insects can smell from? (3)
- Antennae.
- Mouth parts.
- Legs.
Antennae attributes? (3)
- Located on the head of the insect.
- Main receptors for sensory perception.
- Have sensilla.
Mouth parts & Legs?
For gustatory reception.
Types of sensilla? (2)
- Sensilla on antennae.
- Sensilla of mouthparts/legs.
Sensilla on antennae?
= peg-like structures where olfaction occurs.
Sensilla on mouthparts/legs?
= peg-like structures where gustatory olfaction occurs.
Pathway of pheromones/odours through sensilla? (3)
Pheromones/Odours eneter the pores of sensilla
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Odours excite the nerves upon entering pores
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ORN senses this and signals it to the brain (deutocerebrum).
ORN stands for?
Olfactory Receptor Neuron.
How are pheromones produced?
Pheromones are produced by specialised exocrine glands, located in different parts depending on the species & type of pheromone.
Variety of pheromones?
Not only used in mating.
Types of pheromones? (2)
- Volatile pheromones.
- Non-volatile pheromones.
Volatile pheromones attributes? (3)
- Released into the air & travel long distances.
- Detected by antennae.
- Mating/alarm responses.
Non-volatile pheromones attributes? (3)
- Deposited on surfaces & detected through direct contact.
- Detected by legs, mouthparts & antennae.
- Marking trails.
Egs of Volatile pheromones? (2)
- Creatonotos gangis (male antennae are designed to detect attract females).
- Aggregation in insects (as pheromones are spread in the air).
Eg of Non-volatile pheromones?
Ants
- Social insects mark paths to food & pheromones are continuously reinforced by members (active).
Insect aggregation?
= when conspecifics gather in one location, often for feeding or mating.
When is insect aggregation problematic?
When it causes locust swarms.
Locust swarms attributes? (3)
- Caused by a period of drought followed by sudden, heavy rainfall.
- Disadvantageous for farmers as it caused crop damage.
- High population density causes solitary species to be gregarious due to the aggregation pheromone (4VA).
Alarm/Defence pheromones?
= social insects release alarm pheromones when threatened as a defensive response to enable large numbers to confront the threat.
Bees VS Hornets?
Release alarm pheromones so that large numbers of bees smother the hornet intruders.
Beyond pheromones, what other ways are odour molecules detected? (2)
- Volatile organic compounds (VOCs) in plants.
- Specific odours in predators.
Chemotaxis in which organs? (2)
- Antennae.
- Gustatory (mouthparts & legs).
Egs of VOCs? (2)
- Mosquitoes.
- “Smelling’ predators.
Mosquitoes attributes? (2)
- Track you through your C02 concentrations & skin odours.
- Repellants actually “hide” you form their radar.
“Smelling” predators attributes? (2)
- VOCs from the predators & their excrement.
- Causes a physiological/behavioural response.
Types of insect defences? (4)
- Physical.
- Chemical.
- Behavioural.
- Ecological.
Physical defences?
= body structure adjustments.
Egs of Physical defences? (3)
- Spines (makes you harder to eat).
- Mimicry.
- Camouflage.
Chemical defences?
= produce toxins/venoms.
Egs of chemical defences? (2)
- Venoms (stings/bites).
- Aposematism.
Watch Out For the following? (7)
- Bullet ants.
- German wasps.
- Honeybees.
- Velvet ants.
- Paper wasps.
- Rove beetles.
- Blister beetles.
Egs of Behavioural defences? (4)
- Startle displays.
- Thanatosis (playing dead).
- Autotomy (removal of limbs).
- Run away.
Egs of insects that partake in Autotomy? (3)
- Lizards.
- Stick insects.
- Spiders.
Ecological defences?
= symbiotic relationships.
Egs of Ecological defence? (2)
- Ants & “Acacias”.
- Ants & Aphids.
Super summary? (3)
- The antennae (antennae, sensilla, brain, gustatory sensilla).
- Olfaction (pheromones, various pheromones, VOCs).
- Defence (variable defence responses, underpinned by physiology).
