Download Nov. 19

Ants, Wasps, & Bees
Announcements
• Speaking Today: Amanda Meadows
• Speaking Next Tuesday: Elizabeth
Andrews
• QUIZ NEXT TUESDAY OVER
CHAPTERS 25, 26, 21, 24
New Spider Threat in N America
• Tegenaria agrestis, Hobo
Spider
• Introduced from Europe to
Seattle in 1930’s
• Moved into homes
• Bite is similar to brown
recluse
• Now responsible for more
necrotic envenomations in
US than any other sp.
Spiders & MRSA
• MRSA = methicillin-resistant Staphylococcus
aureus
• Community-Acquired has been associated with
spiders
• Association is two-fold
– Transmission of MRSA via spider bites
– Misdiagnosis of MRSA as spider bites
• Misdiagnosis has been largely corrected by
including MRSA screen as part of the spider bite
diagnostic protocol. Example
– Educational effort continues in the medical community
Other effects: Urticating Hairs
• Barbed hairs on the
abdomen of many New
World tarantulas
• Used as a defense,
territorial marker.
• Commonly encountered
by pet owners when they
clean tarantula cages
• Nonvenomous but some
people have allergies.
Order Hymenoptera: Ants,
Bees, & Wasps
• Relatively recent evolutionary origin
• Generally the most beneficial group of insects to
man
– Useful products (e.g. honey)
– Biological control
• Members have the most advanced
communication, learning, and vision
• Most of the social insects in this group
– Including specializations for social defense
– Most attacks on humans are colony defense actions
Medical significance of this group is
in its sting
•
•
•
•
Stingers are modified ovipositors so only females sting
Most stinging females are not reproductive
Stinger itself can be a problem but mostly it’s the venom
Hymenopteran families of most medical significance are:
– Ants
• Formicidae – Social
– Solitary Wasps
• Mutilidae – Velvet ants; Cow Killers
– Social Wasps
• Vespidae – Yellow Jackets; Hornets; Paper Wasps
– Social Bees
• Apidae – Honey bees; Bumble Bees
Hymenopteran Stinger
Source
Wasp Stinger
Hymenopteran venoms
• Depending on the size/species one sting is
generally 0.01 – 0.15 mg venom
– Typical Human LD50 is ~100 mg
• Most are chemically similar to snake venom and
can be deactivated with ethanol
– Neurotoxins and agents to assist them
– In vertebrates, neurotoxins cause temporary pain, the
other agents cause real damage
• Often contain non-toxic components
– Pheromones (trail marking, alarm, marking)
Example: Apitoxin (Honeybee)
Name
%
Function
Melitten
52
Apamin
15 - 20
Cortisol production; neurotoxin
Phospholipase A2
(A1 in wasps)
10 - 12
Cell-lytic; decreases blood pressure;
anticoagulant; prostoglandin stimulant
Hyaluronidase
Protease Inhibitors
Dopamine &
noradrenalin
Histamine
1-3
2
1-2
0.5 - 2
Anti-inflammatory agent; induces of cortisol
production; cell-lytic.
Dilates capillaries speeding inflammatory spread
Prevents Inactivation of other constituents
Increases pulse rate
Allergic response
Reactions to Hymenopteran Stings
• Immediate localized reaction or swelling (non-allergic
responses)
– Mild: erythema, swelling, and transient pain at the sting site that
subsides within a few hours
– More Severe: may involve an entire extremity. Swelling of the
airway, tongue etc can occur.
• Systemic toxic response from multiple stings
– Mild: Hives
– More Severe: vomiting, dizziness, confusion, rash, general
weakness, shortness of breath and wheezing, and chest pain
• Systemic allergic reactions - rare
– May occur from an initial sting or may be acquired
– anaphylactic shock, difficulty in breathing, and death within 30
minutes
Example Symptoms
Adult
Onset
Allergy
Bee sting hives on arm
from a sting on leg
Paper wasp sting
near eye
Ants
• ~10,000 spp world wide only a few are
medically important
• Ant “venom” varies dramatically across
species, most are non-toxic to vertebrates.
• Medically important species
– Fire ants
– Bull-dog ant
Fire Ants
• Solenopsis spp.
• S. invicta, Red Imported Fire
Ant (RIFA) the most important
• Introduced into US in the
1930’s, now in most of SE
US.
– Have had many ecological
ramifications. Ex. here
• Sting 15 – 25 million/year in
US
• Cause $750 million damage
in Agriculture/year
Bulldog Ants
• Ants in the genus, Myrmecia.
M. pilosula is the “Jack Jumper”.
• Australia & Tasmania (Jack
Jumpers).
• In Tasmania, they cause more
deaths than spiders, wasps,
snakes & sharks combined.
• Generate anaphylactic shock in
high incidence. Life-threatening
reactions in 1-2% of cases.
• Antivenom stocks maintained
throughout their range.
Jack Jumper
Solitary Wasps
• Velvet ants, several
spp.
• Nest parasites of
ground-nesting bees
& wasps
• Very painful sting
• Yellowjackets, hornets
& paper wasps
• Yellowjackets are the
important group.
Social Wasps
– Large, annual nests
– Aggressively defended
by workers
– Often in situations with
human contact.
• Baldfaced hornets are
actually yellow jackets
which act like hornets.
Bald faced hornet
(right) & nest (above)
Above: Western Yellow Jacket
Above: European hornet
Hornets vs Wasps
Character
Hornets
Wasps
Genus
Vespa
Nest Habitat
Above ground,
tree hollows
1
Dolichovespula,
Vespula
Below ground,
wall voids
~12 important
Spp in N.
America
Bees
• Insects in the unranked
taxon, Anthophila,
several families
• 20,000 spp most of
which are harmless
• A group that switched
from predation to
feeding on nectar &
pollen
• Co-evolved with
flowers.
• Few are agressive
Africanized Bees
• Hybrids of the
European honey bee
and the African honey
bee (different
subspecies)
• Originally imported to
Brazil to increase
honey production
• Defends hive more
aggressively
• Kill 1 – 2 people/year
in US
Animated map of spread
Probable Eventual Distribution of
Africanized Bees
First Aid
• Topical steroid cream (hydrocortisone),
• Cream containing aloe vera.
• Fire ant creams:
– regular toothpaste.
– Solution of half bleach and half water applied
immediately to the area can reduce the pain,
itching and, perhaps, pustule formation.
• Oral medicines: antihistamines.
Medical Use of Hymenoptera
• Ant head sutures
– Uses soldier ant heads
– Used for at least 3,000
years
• Bee venom therapy
– 1980 FDA licensed its use
for desensitation
– Now >500 human and
veterinary applications
– American Apitherapy
Society