Do insects feel pain?

[Patrick Foley]

Ken,

Insects certainly can detect and respond to heat. Not only can some 
thermoregulate individually (for example Bernd Heinrich's bumblebees, an 
example that postdates Snodgrass) but some ants and of course honey bees 
thermoregulate their nest and hives very precisely.

As we have all agreed from the start of this discussion, there is plenty 
of evidence that insects _behave_ differently than mammals when damaged. 
My contention is that this behavioral difference is probably due to the 
experience created by the integration of the incoming information in the 
Central Nervous System rather than due to fundamental differences in the 
receptor cells. I agree that the presence in vertebrates of specialized 
nerve fibers for transmitting serious body damage stimuli may make a 
difference that changes the experience of 'pain' qualitatively. But it 
is not absolutely convincing difference, since it is well known that 
insects, crustaceans and even mollusks will behave sometimes in a way 
that appears 'frantic' and 'panic-stricken'. And it is also true that 
vertebrates (including myself upon breaking a leg) often go into some 
state of 'shock' in which pain is experienced very differently than is 
normal for a vertebrate. This state of shock is partly mediated by 
endorphins. Insects also have opioid endorphins, that play possibly 
similar roles (Nunez et al 1998. Alarm pheromone induces sress analgesia 
via an opioid system in the Honeybee. Physiology and Behavior 63: 
75-80). It is, of course, hard to know whether an opiated bee feels 
'calmer' and less 'panic-stricken'. We see the creatures as little 
robots, while we convince ourselves that we are 'aware'. I am not trying 
to belabor the philosophy of all this, but the original question was 
ultimately aimed at tricky epistemological problems. Or maybe it was 
just about whether insect neurobiologists have adopted the term 
'nociceptor'. If so, my bad.

Patrick
patfoley at csus.edu

Kenelm W Philip wrote:

>Doug Yanega appears to have answered this question--but it might
>be worth adding the following quote from Snodgrass (Principles of
>Insect Morphology, 1935): "Insects are not known to have any
>specific organs for the perception of temperature, though they are
>highly responsive to temperature changes, nor are they known to
>have pain receptors or proprioceptors other than the terminal
>endings of sensory nerve fibers on the skin, muscles, and other
>tissues." (p. 512).
>
>As regards insects' ability to 'show very little outward sign of
>distress' after serious injury, consider the male praying mantis
>who continues to copulate after the female removes his head.
>This has nothing to do with pain, of course--since one can't feel
>pain without one's head--but it does indicate that insects work in
>very different ways than vertebrates...
>
>Like Doug, I have had a situation in which my ability to feel pain
>in a localized area was destroyed (for some time). This was the
>consequence of removing a wisdom tooth--a nerve was scraped
>resulting in my total inability to feel pain in part of my lower lip.
>I could feel pressure, but not pain. (I referred to this as 'iatrogenic
>leprosy'). Fortunately, this condition did not last more than a
>few months, since I was continually biting my lip by accident.
>A vague feeling of pressure was not enough to prompt me to
>instantly stop a bite.
>
>		Ken Philip
>
>
>
> 
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