What do insects do for a living? - University of San Diego Home Pages

What do insects do for a
living?
Insect Ecology
Food chains
•  All insects interact
Tertiary consumer
with other organisms
as part of the food
Secondary consumer
chain.
Primary consumer
Producers or
Decomposers
•  What kinds of
insects are found at
each of these
levels?
Tertiary consumer
Secondary consumer
Primary consumer
Producers or
Decomposers
•  Which of these are
likely to be found as
ground-dwelling
insects?
Tertiary consumer
Secondary consumer
Primary consumer
Producers or
Decomposers
Where are they found and
what are they doing?
Common habits
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Detritivores and saprophages
Rhizophagous insects
Predators and ground-nesting insects
Decaying wood
Coprophages
Necrophages
Fungivores
Common
adaptations
•  Wing
modifications
–  Protection
–  Brachypterous
–  Apterous
–  Deciduous
Apterous
Common
adaptations
•  Leg modifications
–  Cursorial
–  Saltatory
–  Fossorial
Fossorial
Detritivores & Saprophages
•  Activity much like that of
earthworms.
•  Bulk-feeders.
•  Lots of throughput and
lots of feces.
•  Important in structuring
and aerating soils.
•  Mostly Collembola,
certain termites, some
beetle larvae.
Rhizophagous
•  Probably very
important in
ecosystems.
–  50-90% of plant
biomass below
ground.
•  Can substantially
damage plants.
Metamorphosis
•  Often rhizophagous
nymphs or larvae
and phytophagous
adults.
Predators & Ground-nesters
Decaying Wood
•  Usually associated
with fungi
–  What else is there?
•  Numerous taxa
–  Wood wasps, bark
beetles, ambrosia
beetles, scavenger
beetles, silken
fungus beetles,
dance flies, termites,
cockroaches.
Associations with fungi
•  Most have
specialized
structures for
carrying fungal
spores:
mycangia.
•  Why are most
attracted to forest
fires:
pyrophilous.
Sirex wood wasp
Coprophages
•  What are these?
•  What are they
feeding on?
•  Why is this such a
good lifestyle?
•  First colonization
usually dung flies.
•  ~45 independent
origins of viviparity.
Why?
Coprophages
•  These can get to
nuisance levels.
•  Dung dispersers
therefore provide an
important ecosystem
service.
•  Almost always
Scarabaeidae
Necrophages
•  Often a very similar
lifestyle to
coprophages.
•  Often very closely
related.
•  Most other origins of
viviparity here.
Necrophages
•  Often distinct
succession.
•  Very useful for forensic
entomology.
•  Most initial colonizers
are Diptera.
•  Later are Coleoptera.
•  Dried are more
Coleoptera (e.g.
Dermestidae)
•  Final stages are tineid
larvae (keratin)
Fungivores
•  The true
decomposers are
fungi.
•  There is a whole
guild of insects
that specialize on
these.