Lecture 15 The sting slides by xuyuzhu


									the sting....
OUCH! What is that arthropod
      doing to me?!

        • Bites
        • Jabs
        • Stings
Spiders bite,
not sting, and can
inject venoms
                                Loxosceles reclusa

Related species that lives in
non-urban desert habitat

                                   Brown Recluse
Centipedes bite, can
inject venoms, but do
this with modified legs
Some insects bite
and inject various
salivary products
and this can be
very painful.
The Corsair Assassin Bug
Rasahus biguttatus
Scorpions do inject
venom by a stinger on
their tail

Like many insects, the ovipositors
Are used to insert the egg into plant
The sting is modified female genitalia. No males sting.
However, there is pseudo-sting behaviors.
Evolution of the sting has
proceeded from a
“plant saw” to an “injections
system” to a “weapon”.

                          Insects that
                          really sting!
The sting is modified female genitalia. No males
sting. However, there is pseudo-sting behaviors
in some wasps.

 ♂                                     ♀

Cicada hunters and the male pseudo-sting
Imported Fire Ants
Insects like the fire ant put a lot of energy into defense.
Imported Fire Ants

Many individuals
from the colony
Some ants sting others (formicines)
bite and spray formic acid
• Bullet Ant: reputed to be one of the world’s
  most painful insect stings (New World
• Bulldog Ant: Right up there on the pain
  scale (Australia)
Bee lancets are
barbed and wasp/ant
lancets are smooth or
much smoother.
Why bees rip out the sting....
Haplo-diploidy sex determination as in
         many Hymenoptera
                 A    BC    queen

                      AB    AC      or queens
drones   B       C
 Death of the honeybee defending
            her hive….
• Probably evolved in response to mammals
  feeding on the honey and bees
• The sting is not ripped out when bees
  sting other bees, etc.
• Alarm pheromone directs the attack
• Some workers are super-sisters, e.g.
  share more than 50% of their genes due to
  haplo-diploidy (but this is imperfect)
     What to do if AHB attack…
• RUN, yes really RUN!
• Cover your face to protect your eyes and other sensitive
  areas as long as it doesn’t keep you from running or
  causes you to run into things
• Do not swat at or squash bees, it only makes them
  “angry”, i.e. more alarm pheromone is produced
• Keep running until you can get into shelter or cover
• Encourage other still under attack to run more and faster
• Remove stings by scraping not pinching
• If stung more than 15 times and feel ill or if you think you
  have an allergy to bee venom call 911
• 10 stings per pound of body weight is usually non-lethal
             The venom and its actions
   1. neurotoxic (paralysis
of the nervous system),
   2. hemorrhagic
(increase in the
permeability of the blood
   3. hemolytic (destruction
of red blood cells).
   4. Allergic reactions-the
body's reaction to proteins
and histamines (producing
its own histamines)
Components ( a few of them)
 1. Histamines
 2. Proteins
 3. Non- proteinaceous substances
   -Many others
Why all these compounds that are
bioactive (not strictly pain-inducing)
          for vertebrates?
• Fooling the predator
• Teach the predator
• Association of aposematic signals
The Corsair Assassin Bug
Rasahus biguttatus

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