Transcript Other arthropods…

Soil Critter Talk
Dr. Andrew Moldenke
Dept. of Botany
Oregon State University
Special thanks to Dr. Moldenke for presentation notes provided during
the 2009 HJ Andrews LTER summer workshop.
Three thin-sectioned soils
Note: 70-80% of all
arthropod species
in the world live in
the soil (terrestrial
ecosystems)
Note: Between the
top and bottom
layers of leaves
have been eaten by
turtle mites
Note: Small white
areas are micropores
for storing water;
large white areas are
macropores for
storing Oxygen and
air
Note: Really large
dark blobs are
earthworm poop
Thin-section clear cut soil
Note: Clear cut soil
will have little
water holding
capacity; not only
are you changing
the vegetation but
how the
ecosystem
functions
Thin section mature forest soil
Note: Forest (old
growth) soil poop
will have a
surface area is
infinitely greater
Question: Why
is the size and
density of bug
poop important?
Answer : Bacteria
and fungi will feed on
the surface of the
arthropod poop and
release nutrients.
The more poop, the
more surface area of
the poop, the more
bacteria will feed on
the poop and release
more nutrients.
I have shown that species richness of soil
arthropods is SOOO large that anyone
can take a sample of forest litter (dead
leaves) and soil from anywhere in the
approximately 3,000 hectare Andrews
Forest LTER--and then, after identifying the arthropods,
I can tell you…
•
•
•
•
•
•
•
•
•
what month of the year it was
altitude
soil moisture
plant community
slope face
under which species of tree
how old the forest trees are
how long since the last fire
how far from the nearest trunk
All that information (and more!)
simply in a list of the relative
abundance of the species
Creatures that live in the soil are very sensitive
to abiotic and biotic factors
therefore excellent for use as biological
indicators.
They have fantastic potential as indicators for
determining human impacts on soil ecosystem
function and for soil health.
species/m2
individuals/m2
250
350,000
pasture
30-60
100,000
row agriculture
5-10
2 - 20,000
forest
Note: Each and every shovelful of forest dirt has 250 species per square
meter or 350K individuals. As soil is impacted more (pasture,
agriculture…) the number of species decline.
Indicators of change in the productive potential of
soil is great but I want to talk about 2 other
things today.
1. Biodiversity for its own sake. We never bother
to take the time to look at these organisms, but
they are some of the most fascinating animals
around!
WOW! FANTASTIC!
2. They don’t just passively indicate “soil health”
they are key players in the cycle of plant growth
and soil nutrients themselves.
B.P.G.T.
Many mites
EACH and EVERY SHOVEL of forest dirt =
all pictures that follow
250 spp/m2
350,000 indivs/m2
120,000 little legs (Andy’s foot)
70-80% of all arthropods in
most terrestrial ecosystems
15,000 species in Oregon
So, who cares?
Why study bugs in soil?
What do they do?
they eat and they poop
1
2
Question: Which bugs are discussed here?
Answer: Mites, springtails, and other arthropods
Mites….
Odontodamaeus
Mites….
Oppiella
Mites….
Epidamaeus
Mites….
Long-legged near Damaeus
Mites….
Galumna open
Mites….
Galumna closed
Note: Defense mechanisms
Hands and legs fold in and doors close in
Mites….
Pterochthonius
Mites….
Hermanniella
Rearing mites
Small/large turtle mites
Note: Turtle
mites are
smaller than
an eyelash
Mites….
Oribatid chelicerae
Mycorrhizae
Note: In this example, the tree feeds the fungi sugar (Carbon) and the fungi feeds the
tree N, P…. the root underneath carries water, nothing gets in unless regulated by fungi
Mycorrhiza under the
Electron Microscope
Springtails…
Notes: If
attacked,
the tail
drops and
launches
the bug
easily a
meter.
Springtails
deep in the
soil are
blind.
Isotoma
Diagrammatic springtail (Collembola)
Springtails…
Onychiurus
Onychiurus
Onychiurus, high magnification
Other
arthropods…
Note: Flight
apparatus is
like a bird
feather. ( A
little rod with
hairs).
Ptiliid beetle
forewing
Other
arthropods…
Notes:
1) In all soils
2) Important in
nutrient cycling
3) No common names
for them
4) Evolutionally they
lost their antenna,
false antenna as first
set of legs
Summary: When
putting together
foodwebs, all these
bugs so far have been
fungivores
Protura
Other
arthropods…
Enchytraeid
Other
arthropods…
Suctobelbella – bacterial-feeder
Other
arthropods…
Cydnidae – Burrowing bug
Other
arthropods…
Symphyla
Other
arthropods…
Cicindelid immature
Other
arthropods…
Gamasid
Other
arthropods…
Uropodid
Uropodid - facial view
Other
arthropods…
Polyaspidid
Note: Strings of wax
secreted from the
analogous of sweat
glands
Mites…
Cyta
Notes:
1)Predacious mite
2) Dumped out of
helicopters on
caterpillars (biocontrol)
Onychiurus being eaten by Labidostoma
Symphylan being eaten by Pergamasus
Note: Worst
vegetative pest
in the
Williamette
Valley
Pergamasus feeding
(high magnification)
Notes:
1) There is a mite
hitching a ride on
the Pergamasus
(feeding)…
2) Bacterial and
fungal spores
also catching
rides if we looked
closer, so they
make the
environment
homogenous…
(always moving
everyone in the
environment
around)
Pseudoscorpion
Note: Poison gland in
tip of claw released
on prey
Chthoniid pseudoscorpion
Pseudoscorpion, facial view
Taracus – Skunk-spider (Opilionida)
Notes:
1) Probably 400
species of
spiders in OR
soil
2) The largest
the same size of
a period on the
printed page
Sclerobunus – skunk-spider
Native scorpion with young
Spider webs
Spider fangs
Callobius
Pardosa
Micro-spider, male
Antrodiaetus
Cicindela
Omus
Staphylinidae
Lithobiidae
Geophilid
Centipede fangs
Notes:
1) All are
predators….ants
are the worst
predators because
they work as
individuals and as a
colony
2) Specialist
predators eat 1 or 2
species
3) Generalists eat
many types of
species
Ant head
Snail-feeding beetle
Snail-feeder, immature
Taracus - Opilionid
Note: Devices
for butchering
a snail
Glowworm eating millipede
Note:
Glowworm
catches a
millipede and
cuts segments
off one by one
and sucks
insides out
Millipede segments
Diapriid wasp – Diptera parasite
Note: You
could collect
50-100 species
of unnamed
parasitic wasps
Rhododendron decomposition
Millipede jaws
Notes:
1)Millipedes are
the big shredders
in this system
2) Molars crush
dead leaf-filter
through sieve,
grind large
pieces again
Schematic of millipede jaw
Harpaphe mating swarm
Leaf skeletonization
Isopod
Pen-knife mite
Note: Really
important
shredders
Pen-knife mite, closed
Note: When a
predator comes
they totally
close up in a
ball and it takes
an hour for a
predator to
crack open
Collohmannia nymphs
Leaf skeletonized by Collohmannia
Bacteria eaten by fungus
Note: Fungus dissolves bacteria by secreting a substance in 30 minutes
Soil and Plant Growth
Microbial biomass
(bacteria, fungi)
(nutrient
immobilization)
In the short-term (minutes to years) the USEFUL
nutrient content of soils is basically equivalent to
the amount of nutrient incorporated into living
microbial tissue.
(Most nutrients in mineral soil are long-term resources)
Soil and Plant Growth
Microbial biomass
(bacteria, fungi)
(nutrient
immobilization)
Microbes grow by producing exoenzymes that
decompose the organic (+) material in the soil
more bacteria
more decomposition
Soil and Plant Growth
Microbial biomass
(bacteria, fungi)
(nutrient
immobilization)
Nutrient availability in dead/decaying organic
matter is limited by surface area for exoenzyme attack
“shredding” increases surface area; therefore shredding
animals (like millipedes) indirectly regulate rate of
decomposition and microbial growth (example: 450x)
plant biomass
Human Connection :
Think of it this way…
the reason you chew
your food is to increase
its surface area, which
increases the nutrients
the bacteria can
uptake.
Your intestines grab
whole bacteria, kill
them and dump their
remains in your
bloodstream. Humans
are basically
bacteriavores like
arthropods are.
Soil and Plant Growth
Microbial biomass
(bacteria, fungi)
(nutrient
immobilization)
?
shredders
roots are completely
passive for
nutrient uptake
Soil and Plant Growth
Microbial biomass
(bacteria, fungi)
(nutrient
immobilization)
shredders
(surface area)
nearly all nutrients mineralized by
microbivory are assimilated by the
remaining microbes.
Question: If we
were interested in
finding soil
nutrients do we
look at
fungi/bacteria?
Answer: Yes
bug poop
(nutrient
mineralization)
Protozoa,
Nematoda,
Arthropoda
nutrient uptake
Surface area (microbes)
surface area (roots)
Positive Feedback Loop: More bacteria>>More enzymes>>More bacteria>>More enzymes
Plants only can assimilate nutrients released in the rhizophere
Anderson Millipede soil mineralization
Notes:
1)Took soil from oak forest, sterilized it,
reconstructed soil horizons in flower pots,
reinnoculated fungi, bacteria and protozoa,
NO bugs.
2) Flower pot>>adds H2O>>trickles to
bottom>>tests for N.
3) Then adds shredder (millipede)…LOTS
more N.
4) Adds baby oak tree (No difference).
5) Repeats study and baby oak tree. No
difference. Baby oak tree used N from
millipede feces for growth.
6) WHOLE POINT: All of the nutrients that are
ultimately incorporated in to the growing
plants, have to go through the digestive
system of the shredder.
7) Unless you are dumping fertilizers the only
way nutrients will help plants is bug poop.
When you double the N content, the growth of
the oak tree is tenfold.
Onion cultivation