Transcript Diversity of Aquatic Insects

Diversity of Aquatic Insects
Insecta
• 26-32 orders – depending upon classification scheme
• found on every continent except...maybe Antarctica
– Collembola recently found in subterranean lakes in Antarctica
• 10 orders with aquatic representatives
• other orders with taxa associated with water bodies (margin dwellers like
some grasshoppers, hymenoptera parasitize aquatics, etc.
• special needs and adaptations of aquatic insects
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respiration: intake of dissolved oxygen
tolerance or intolerance of pollutants
feeding (some play role in breakdown of detritus)
mating (swarming behavior, pheromones, egg laying)
dispersal
Aquatic Insect Orders
Order: Ephemeroptera* (mayflies)
Order: Odonata* (dragonflies, damselflies)
Order: Plecoptera* (stoneflies)
Order: Hemiptera (true bugs)
Order: Megaloptera* (dobsonflies, alderflies)
Order: Neuroptera (spongillaflies)
Order: Trichoptera* (caddisflies)
Order: Lepidoptera (moths)
Order: Coleoptera (beetles)
Order: Diptera (true flies)
* entire order is aquatic – with some caveats!
Hemimetabolous
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definition: incomplete metamorphosis
nymphs resemble adults (just smaller)
egg  nymph  adult
thought to be more primitive type of
development
Ephemeroptera, Odonata, Plecoptera, Hemiptera
some use hemimetabolous to apply just to
Ephemeroptera, Odonata and Plecoptera and use
the term naiad for the nymphs
then Hemiptera would be described as being
paurometabolous
growing use of the word “larva” in place of the
word “nymph” or “naiad”
Holometabolous
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definition: complete metamorphosis
egg  larva  pupa  adult
larvae do not resemble adults
many structures broken down and reorganized
during the pupal stage
• Megaloptera, Neuroptera, Trichoptera,
Lepidoptera, Coleoptera, Diptera
• holometabolous insects outnumber
hemimetabolous insects 10:1 worldwide
• holometabolous metamorphosis reduces
intraspecific competition?
Hilsenhoff Biotic Index
Biotic Index
Water Quality
Degree of Organic Pollution
0.00-3.50
Excellent
No apparent organic pollution
3.51-4.50
Very good
Possible slight organic pollution
4.51-5.50
Good
5.51-6.50
Fair
6.51-7.50
Fairly poor
7.51-8.50
Poor
8.51-10.00
Very poor
Some organic pollution
Fairly significant organic pollution
Significant organic pollution
Very significant organic pollution
Severe organic pollution
1929-2011
Collembola (5-10), c-g
Ephemeroptera (mayflies)
• 21 families, 631 spp. in
North America
• 11 families in CA
• primitive insects (wings
don’t flex, held upright)
• hemimetabolous—with an
interesting modification
• nymphs aquatic, adults
terrestrial
• occur in streams, temporary
streams, lakes and vernal
pools
• some species have many
nymphal instars (i.e. >30)
• many are good swimmers
(i.e. important part of the
drift)
• nymphs can be difficult to
identify to species
• nymphs are good indicators
of pollution
– even though metals are
sequestered in exoskeletons
which are shed frequently
– sensitive to increased
temperature, low dissolved
oxygen, etc.
Mayfly Life Cycle
• nymphs swim to surface and subadult emerges
(subimago)
• subimago is winged and sexually mature – unique
among insects
• subimagos fly to vegetation, spend a day before
molting to adults
• adults live few hours to few days (fragile, do not feed)
• swarming common; sexes often swarm separately at
first
• swarms in Great Lakes large enough to appear on
Doppler Radar
• females oviposit by landing on water surface and dying
• masses of dying mayflies can cause road closures, car
accidents
• mayflies are important to fly fishing
Ephemeroptera
• Segmented legs w/ 1 tarsal
claw
• Abdominal gills
• 2 cerci and 1 terminal
filament
– Terminal filament often
short
• Body completely scleritized
Ephemeroptera
• Suborder Schistonota
– Minnow-Like Mayflies
• Ameletus (0)
c-g
• Isonychia (2)
c-f
• Baetis (4-6)
c-g
Ephemeroptera
• Suborder Schistonota
– Flatheaded Mayflies
• Epeorus (0) scr
Ephemeroptera
• Suborder Schistonota
– Pronggills
• Leptophlebia (4)
c-g
– Burrowers
• Ephemera (2)
c-g
Ephemeroptera
• Suborder Pannota
– Crawlers
• Ephemerella (0-1) c-g
– Squaregills
• Caenis (6-7) c-g
– Shellbacks
• Baetisca (3-4) c-g
Odonata (dragonflies & damselflies)
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12 families, >400 spp. in North America
10 families in CA
primitive, wings don’t flex
all nymphs aquatic; ~1/3 stream dwellers, rest lentic
nymphs large and predatory (often top predators)
characteristic labial scoop (extendable and prehensile)
coloration highly variable within a species, depends on habitat and
food
not good indicators of water quality
long life cycles, 1-4 years with 11-12 instars
adults are aerial predators and beneficial
adult males set up and defend breeding territories (can identify
species by flight pattern)
adults can be identified on the wing – insect equivalent of bird
watching
most nymphs can be identified to species (if mature and intact)
two extant suborders
Odonata
Zygoptera
• 5 families in North America,
3 in CA
• caudal lamellae present
Anisoptera
• 7 families in North America,
all 7 in CA
• nymphs move by crawling
or jet propulsion
Odonata
• Zygoptera (Damselflies)
– Broadwinged damselfly
• Calopteryx (6) prd
– Spreadwinged damselfly
• Lestes (6) prd
Odonata
• Aeshnoid Dragonflies
– Graybacks, Clubtails, & Darners
• Aeshna (3-5) prd
Odonata
• Biddies or Spiketails
– Cordulegaster (3) prd
Odonata
• Skimmers
– Epitheca (2-5)
prd
– Sympetrum prd
(2 or 9 family)
Plecoptera (stoneflies)
• 9 families, > 600 spp. in
North America
• all 9 families in CA
• hemimetabolous
• nymphs aquatic, adults
terrestrial
• important part of fish diets
• often top predators
• Segmented legs w/ 2 tarsal
claws
• Thoracic gills
• 2 cerci No terminal filament
• Body completely sclerotized
Plecoptera life cycle
• nymphs crawl out of water to molt (ecdysis)
• adults live a few days to maybe two weeks
• females deposit fertilized eggs by briefly touching
abdomen to water, spraying eggs over the water
or even crawling into the water to deposit eggs
on substrate
• recent studies have shown that eggs will diapause
up to 3-4 years before hatching
• some large spp. take 2-3 years to complete
development (Pteronarcyidae)
• crawlers; poor swimmers, don’t drift much
Plecoptera
• Winter and Spring Stoneflies
– Broadbacks (e.g. Taeniopteryx, 2) shr
– Slender Winter Stoneflies (e.g. Capnia, 1-3) shr)
Plecoptera
• Summer Stoneflies
– Giant Stoneflies
• Pteronarcys (0) shr
– Common Stoneflies
• Perla (0-4) prd
Hemiptera (true bugs)
• 16 aquatic families in North
America
• all 16 families in CA
• piercing sucking mouthparts
• predators or sapsuckers
• sold as fish food or even as
human delicacies
• hemimetabolous
• wings are called hemelytra
– leathery, half
membranous
– some taxa apterous, i.e.
without wings
• some taxa can inflict painful
bites, hence the name “toebiters”
Hemiptera, prd
• Backswimmers (Notonectids)
– Buenoa
– Notonecta
Hemiptera, prd
• Water Scorpions (e.g. Nepa)
• Giant Water Bugs (e.g. Lethocerus)
Hemiptera, prd
• Water Boatman (Corixids – e.g. Sigara, 3-5)
• Water Striders (e.g. Gerris)
Megaloptera (dobsonflies & alderflies)
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2 families in North America
both families in CA
holometabolous
pupate terrestrially
Megaloptera, prd
• Alderflies (e.g. Sialis, 4)
• Dobsonflies (e.g. Corydalus, 4)
Neuroptera (spongillaflies)
• 2 genera
• larvae associated with freshwater sponges
Neuroptera, prd
• Spongillaflies (e.g. Climacea)
– (5)
Trichoptera (caddisflies)
• 26 families, >1400 spp. in North America
• 19 families in CA
• adults can mostly be identified to species, although the
literature is scattered
• larvae for most genera cannot be identified to species at
present- “underwater architects”
• three suborders based on how they live
– Rhyacophiloidea (Spicipalpia) – free living, purse cased or
saddle cased
– Hydropsychoidea (Annulipalpia) – net spinners
– Limnephiloidea (Integripalpia) – tubecase makers
• cases often distinctive enough to identify individuals to genus
• hypermetamorphosis – in Hydroptilidae purse cases aren’t
built until the last larval instar; 1st -4th instars free living
Trichoptera
• holometabolous
• closely related to
Lepidoptera – adults have
hairs, not scales
• larvae for all but a few spp.
aquatic, most stream
dwellers (~1/8 lake
adapted)
• dominate stream biomass in
some streams
– Hydropsyche californica in
Central Valley streams
(Feather River)
– Brachycentrus spp. in
Arkansas River in Colorado
• some hatches can be so
large they contaminate
products in factories and
cause car accidents
Trichoptera
Larva
• Segmented legs
• Anal claws
• Scleritized head and thorax
• Fleshy abdomen
• Often build cases
Pupa
• Obvious developing wings
• Large crossed mandibles
• Often in modified larval
case
• Often hairy in appearance
Trichoptera
• Free-living Caddisflies
– Rhyacophila (0-1) prd
– Hydroptila (6) scr
Trichoptera
• Net Spinning Caddisflies
– Fingernail netspinners (e.g. Chimarra 2-4) c-f
– Nettube Caddis (e.g. Psychomyia, 2) c-g
Trichoptera
• Net Spinning Caddisflies
– Trumpetnet Caddis (e.g. Polycentropus, 6) prd
– Common Netspinners (e.g. Hydropsyche, 0-6) c-f
Trichoptera
• Tubecase Makers
– Humpless Case Makers (e.g. Brachycentrus, 0-1) c-f
– Northern Case Makers (e.g. Limnephilus, 3) shr
Trichoptera
• Tubecase Makers
– Lepidostomid Case Makers (e.g. Lepidostoma, 1) shr
– Strongcase Makers (e.g. Psilotreta, 0) scr
Trichoptera
• Tubecase Makers
– Snailcase Makers (e.g. Helicopsyche, 3) scr
– Longhorned Case Makers (e.g. Nectopsyche, 3) shr
Lepidoptera (moths)
• confusion about which and how many families are truly
aquatic
• Family: Pyralidae has the most recognizable aquatic forms
(e.g. Petrophila now Crambidae)
• Lepidoptera larvae are very difficult to identify without the
right literature and/or
• many aquatic Lepidoptera build cases out of macrophytes
 really need associated plant host information to make
accurate identification
Lepidoptera
Lepidoptera Larva: Petrophila sp.
• Short
segmented legs
• Abdominal
prolegs with
rings of hooks
• Sclerotized head
• Fleshy abdomen
• Long gills on
abdomen
Coleoptera (beetles)
• aquatic representatives from ~31 families in North
America
• few families entirely aquatic
• many marginal or semiaquatic taxa
• hardened forewings are called the elytra
• holometabolous
• for most families, larvae and adults have different
feeding strategies
– an exception: riffle beetles (Elmidae)
Coleoptera
Larva
• morphologically, very
diverse
• segmented legs
• variable scleritization
• never have anal claws
Adult
• most with hardened elytra
covering most of abdomen
• some with oar-like legs for
swimming
• predators, grazers or
scavengers
Coleoptera
• Crawling Water Beetles (e.g. Haliplus, 5) shr
• Predaceous Diving Beetles (e.g. Dytiscus, 5) prd
Coleoptera
• Whirligig Beetles (e.g. Gyrinus, 4) prd
• Water Scavenger Beetles (e.g. Berosus, 4) c-g
Coleoptera
• Water Pennies (e.g. Psephenus, 4) scr
• Riffle Beetles (e.g. Stenelmis, 5) scr
Diptera (true flies)
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lots of families
many difficult to key even to family
some worm-like, with few modifications
some highly adapted for specific habitats
Diptera
Larva
• Sclerotized head or head
invisible
• Rest of body fleshy
• No segmented legs (May
have prolegs)
• Worm-like
Pupa
• Variable appearance
• Wings tightly folded to the
body
• Sometimes in pupal case
• Obvious respiratory organs
Diptera
• Crane Flies (e.g. Tipula, 6) shr
• Phantom Crane Flies (e.g. Bittacomorpha, 9) c-g
Diptera
• Phantom Midges (e.g. Chaeoborus, 8) prd
• Mosquitoes c-f
– Anopheles (8)
– Aedes (8)
– Culex (8)
Diptera
• Biting Midges (Culicoides, 10) prd
• Midges
– Chironomus (9-10) c-g
– Tanytarsus (6) c-f
Diptera
• Black Flies (e.g. Simulium, 4-7) c-f
• Horse and Deer Flies (Tabanus, 5) prd
Diptera
• Rat-tailed Maggots (Eristalis, 10) c-g
• Shore Flies or Brine Flies (Ephydra, 6) shr