Download Announcements Aquatic Insects Habitats for aquatic insects

Announcements
• Insect collections due April 2
– ID to order only
• Field trips next two Mondays
– FOP
– Laguna
– Arrive by 8 am for departure and arrival at
SSU again by noon
– Wear clothes that can get damp
Reproductive system
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Dioecious- female and male
Usually reproduce sexually, and both sexes present
If asexual reproduction, males absent
Internal fertillization
Sperm stored in spermatophore
Usually eggs laid, some live birth
• For now skipping insect sensory structures
Female reproductive system
• Eggs made in ovaries
• Sperm stored in
spermatheca (up to 20
yrs)
• Copulation in genital
chamber
• Accessory glands
secrete compounds for
eggs
Aquatic Insects
• Repeated colonizations of freshwater by terrestrial
insects
• Hemimetabolous:
– Mostly aquatic
• Ephemeroptera- Mayflies
• Odonata- Anisoptera, Zygoptera
• Plecoptera- Stoneflies
– Mostly terrestrial
• Hemiptera or True Bugs
• Holometabolous, colonized water more recently
– Neuroptera and Megaloptera- Alderflies, Dobsonflies
– Trichoptera- Caddisflies (mostly aquatic)
– Lepidoptera- Butterflies & Moths
– Coleoptera- beetles
– Diptera- Flies
Male reproductive system
• Spermatozoa produced in
testes
• Sperm stored in vas
deferens
• Semen or spermatophore
transmitted during mating
through ejaculatory duct
Habitats for aquatic insects
• Lotic- flowing water
– influenced strongly by velocity of flow
• Particle size
• Substrate type
– Inputs from outside and local nutrient supplies
•Lentic- standing water
–Often strong zonation
•Limnetic zone- penetrated by light
•Profundal zone- deeper zone w/o much light
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River Continuum
• Energy inputs
• Morphology
Unusual habitats
• Temporary water bodies (e.g. vernal pools)
• Marine environments
– Intertidal habitats
• Between high and low tide
• biting flies, plant feeding insects, detritovores
– Littoral habitats
• Coastal regions with shallow water
• Some midges and beetles
– Open ocean- water striders feeding on food of
terrestrial origin
Ephemeral Water
• Seasonal rainfall
• Adaptations
Marine, Intertidal, Littoral Water
• Few truly marine insects
How do aquatics obtain oxygen?
Oxygen supplies
• Air- 200,000 ppm (20%)
• Lotic environments (15 ppm)
– Depends on O2 production/consumption by plants
– Affected by turbulence and water quality
• Lentic environments
– oxygen levels vary with temperature and salinity
– turbulence affects nutrient and oxygen distribution
• Anoxic
– no oxygen present
• Atmospheric oxygen
– Keep part of body out of water
– Carry oxygen into water
• Aqueous oxygen
– Use of open tracheal system
• Adult insects
• Immature forms
– Use of closed tracheal system
• Specialized structures for gas exchange
in water
• Often adults have open tracheal system
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Closed Tracheal System
Tracheal system
Mosquito larva
Dragonfly larva
• Gills- lamellar extensions of tracheal system
• Found in many insect orders
• Gills may be in many places
– Base of legs
– Abdomen
– End of abdomen
Mayfly larva
Mosquito larva
Open Tracheal System in flies
• Respiratory siphons near abdomen or thorax
• Different location in mosquito pupa than larva
Other air bubble gills
• Water kept away from body through ‘hairs’
or ‘mesh’
• Oxygen diffuses from water to air against
body
• Usually slow moving insects with low
oxygen demand
Open tracheal system in diving beetles
• Bubble stored beneath elytra
• Gas exchange can occur in water
Lotic Adaptations
• Flattened bodies
• Attachment through
suckers
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Lentic Adaptations
More Lotic Adaptations
• Taking advantage of surface tension of
still water
• Nets
• Cases
Water strider
Whirlgig beetle
Zonation in lentic habitats
Using insects to monitor aquatic environments
• Usefulness
– Diverse taxa to choose from, many common
– Functionally important to ecological community
– Ease of sampling many individuals without major
ethical constraints
– Ability to identify species
• Responses
– Increases of certain taxa in waters with sediment, low
oxygen, increases in temperature
– Loss of diversity with pollution and or eutrophication
Ephemeroptera
mayflies
• Wings held above
body at rest
• Antennae
inconspicuous
• Often have ‘tails’
• Found near streams
• Preserve adults and
nymphs in alcohol
Odonata
dragonflies and damselflies
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Immature stages aquatic, adults often near water
4 elongate, many-veined membranous wings
Antennae small, bristle-like
Pin adults, preserve nymphs
in alcohol
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Hemiptera
true bugs
Plecoptera
stoneflies
• Somewhat flat, drabcolored
• Wings at rest flat over
abdomen
• Long antennae
• Near streams and
rocky shores
• Adults, nymphs in
alcohol
Hemiptera
water boatman
• Diving or at surface
• Adults and immatures
both aquatic
backswimmer
creeping water bug
Coleoptera
beetles
• Live at surface or at bottom
• Generally pupate on land
• Often predatory
Left: Nepidae tails are breathing tubes
Right: Belostomatidae egg tending by males
Trichoptera
caddisflies
Diptera
flies
• Adults resemble moths,
but have long slender
antennae
• Larvae case-building
• Wings held roof-like
• Adults and larvae in
alcohol
• 1 pair of wings
• Hind wings are ‘knobs’
• Pin or point adults
• Larvae in alcohol
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Neuroptera & Megaloptera
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