Diversity of Aquatic Insects Insecta 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 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 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 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 IndexWater QualityDegree of Organic Pollution ExcellentNo apparent organic pollution Very goodPossible slight organic pollution GoodSome organic pollution FairFairly significant organic pollution Fairly poorSignificant organic pollution PoorVery significant organic pollution Very poorSevere organic pollution Collembola (5-10), c-g Ephemeroptera (mayflies) 21 families, 631 spp. in North America 11 families in CA primitive insects (wings dont flex, held upright) hemimetabolouswith 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) 12 families, >400 spp. in North America 10 families in CA primitive, wings dont 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 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, dont 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 toe- biters 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) 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 arent built until the last larval instar; 1 st -4 th 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) 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