Sensory systems & communication II Flashcards
insect vision
- ocelli
- compound eye
- superposition compound eye
- apposition compound eye
insect vision - ocelli
- on top of the head in groups of 3
- sense light levels and horizon (which way is up) when flying
insect vision - compound eye structure
- ommatidium
- rhabdom
insect vision: compound eye - ommatidium
- Each facet in the compound eye
- Pigment on sides means each ommatidium ‘sees’ only small slice of visual field
- More facets = higher resolution of vision
insect vision: compound eye - rhabdom
- Rhabdom are photoreceptors that converge to optic nerves
- the brain then constructs image from individual inputs
insect vision - superposition eye
- sacrifice resolution for increased light
- used by nocturnal insects
insect vision - apposition eye
- high resolution, but only when there is enough light
- Not used by nocturnal insects
What does an insect see?
- Insect spectrum is shifted
- Flicker-fusion rate
- see polarized light
what does an insect see? - insect spectrum
- insects see weak in red (except Lepidoptera – they see red) but strong in UV
- Implications for sexual signaling and flower design
- Insects see color AND UV – not either/or
what does an insect see? - flicker-fusion rate
- a measure of temporal resolution of vision
- Humans see ~ 60 frames per second
- insects see ~ 200-300
what does an insect see: flicker-fusion rate - why is it so fast
- flight
- Means that an insect can see and react to motion before we even notice that an object is moving
define Bioluminescence
- Light production
- Fireflies (beetles – Lampyridae): males use light signal for females (mating)
Why do insects fly to lights?
- Sky is brightest part of environment, even at night and it keep insects right-side up when flying
- But artificial lights overwhelm the night sky, insects tilt towards them, hijacks navigation ability
why do insects fly to lights? - prediction and result of experiment
- prediction: diffuse light from above should not interfere with flight bc it’s the sky
- result: This prediction is met
define Chemoreception
sense of smell
Chemoreception - where is it located
- Multi-porous sensilla
- Pore kettle
- Odorant binding proteins (OBP)
- antenna
chemoreception - multi-porous sensilla
basic sensory unit for chemoreception
chemoreception - pore kettle
- at each pore, tubules connect with dendrites
- Pores let molecules in through cuticle
chemoreception - odorant binding proteins
- they bind with chemical molecules to depolarize dendrite and it stimulates the neuron
- Specificity of OBP determines specificity of chemoreception
chemoreception - antenna
- Multi-pore sensilla are concentrated on the antenna
- Larger antennal surface area -> more sensilla -> more sensitivity to chemoreception
chemoreception - Often males have elaborated antenna. Why?
It’s most likely a species where female releases sex hormone, so males are selected to sense them
define pheromones
- Chemicals signals to influence behavior of receiver
- this is not just smelling other insect, but detecting chemical message sent by them
pheromones - typical examples
- Spacing
- Aggregation
- Alarm, especially social bees and ants
- sex pheromones
pheromones - atypical examples
- Thymine wasp and orchid
- lycaenid (Lepidoptera) caterpillars and ants
