Entomology 2 notes.oo3

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1 Entomology 2 notes.oo3 Entomology 2: Insect Diversity/Taxonomy 1 Entomology: Insect Diversity and Taxonomy Matthew J. Grieshop MSU Department of Entomology 2 The Importance of Insect Identification Insects are incredibly diverse creatures and perform in a variety of roles in agroecosystems. Thus, knowing what insect we are observing is critically important. Is it "harmful" or "beneficial"? Does it need to be managed? How can we manage it? 3 Insects in Agroecosystems Insects consume 14% of the worlds crops Insects also pollinate Insects vector diseases Insects breakdown waste materials Insects feed other organisms 4 Taxonomy vs. Systematics Taxonomy is the science of naming organisms based on accepted criteria Typically insect names are in latin Also names typically have some meaning that pertains to traits that Systematics is the science of classifying organisms by their phylogeny Phylogeny: a hierarchal structure by which every organism is related to other organisms "tree of life" Systematics (and thus taxonomy) are changing all the time due to the discovery of new evolutionary linkages among insects. 5 Insect Taxonomy/ID Basics Do the adults look like the juveniles? Does it have wings? How many, How are they shaped? What kind of mouthparts? What kind of legs? 6 Insect Identification Within Class Insecta insects are divided into two Subclasses Apterygota: Ancestrally without wings Pterygota: Ancestrally with wings Subclass Pterygota is further divided into two Divisions Exopterygota: Simple body change during development Endopterygota: complex body change during development 7 Identification to order Ordinal identification for insects is generally simple

2 Orders are broad and contain insects that fulfill many ecological roles Example: Coleoptera: Beetles Pests/Herbivores: Colorado Potato Beetle Predators: Carabidae (ground beetles) Detritovors: Scarabidae (Dung Beetles) However, identification to order will often allow further identification by someone with more training 8 10 Insect Orders Apterygota Collembola Pterygota Exopterygota Odonata Orthoptera Dermaptera Isoptera Heteroptera (Hemiptera/Homoptera) Endopterygota Lepidoptera Coleoptera Hymenoptera Diptera 9 Collembola (Spring Tails) Some place Collembola in Superclass hexapoda outside of Insecta Extremely important in soil food webs and common in compost piles Very rarely pests Soft bodied, require moisture Have a Furcula and Retinaculum used for jumping. Species that live deeper in the soil lack these structures. 10 Odonata (Dragon and Damsel Flies) Chewing mouthparts Predacious as both nymphs and adults Direct flight Aquatic nymphs Labrum modified into a "grabber" like in alien suborder: Anisoptera dragon flies Wings don't fold; broadly attached to thorax Typically larger Larvae with internal gills (inside anus) Suborder: Zygoptera damsel flies Wings held rooflike at rest: Narrowly attached to thorax Typically smaller

3 Larva with external gills 11 Orthoptera Grasshoppers, Crickets, Mantids, Cockroaches Chewing mouthparts Tegmina 12 Families Acrididae, Tettigoniidae, and Gryllacrididae contain pests Family Mantidae contains praying mantids (beneficials) Family Blattidae contains cockroaches Important in forest ecosystems as detritivors only a few pestiferous species 13 Dermaptera (Earwigs) Omnivorous Have tegmina (1st wings) Most are flightless Chewing mouthparts Can be important predators (e.g. codling moth pupae) Also important detritivors Can also damage crops when in high numbers 14 Isoptera (termites) Social insects Exhibit caste system Workers, Reproductives, Soldiers Break down cellulose through mutualism with protozoans and bacteria Trophalaxis maintains social structure and transmits symbionts from one generation to the next. 15 Formosan Subterranean Termite (Coptotermes formosanus) Very serious pest in the Southeast Tunnels into concrete and wood Can destroy a house in a matter of years 16 Hemiptera (True bugs and aphids) True bugs/aphids Flying insects: 4 wings Piercing Sucking mouthparts Heteroptera: longer mouthparts, wings held flat Homoptera; shorter mouthparts, wings held rooflike Many with Hemielytra 17 Most Homoptera are plant feeders Many are pests: Aphids Have a complicated life cycle Are often vectors of viruses (e.g. Soybean aphid and soybean mosaic virus) 18 Heteroptera Many are omnivorous or predatory Reduviidae (assasin bugs)

4 Predatory. Rhodnius is the vector for chagas disease a protozoan parasite of mammals. Pentatomidae (Stink bugs) Omnivorous 19 Lepidoptera (Moths, Butterflies, and Skippers) Largely herbivorous with a few exceptions Larvae have chewing mouthparts Adults have siphoning mouthparts or non functional mouthparts Larva are called caterpillars and have prolegs on their abdomen 20 Tomato Hornworm (Manduca sexta) Sphingidae: caterpillar feeds on solanaceous plants Pupates in the soil Defoliates plants and can feed on fruit 21 Coleoptera (Beetles) The most diverse order of insects (and therefore any animal) 250,000 described species More than 100 families Chewing mouthparts on both larva and adult stages Forewings modified into elytra Sclerotized wing coverings Provide additional physical and desiccation protection 22 Hymenoptera (Sawflies, Wasps, Bees, Ants) The second most diverse Order Hymenoptera have chewing or lapping mouthparts Can be solitary or social Mostly beneficial Two Suborders 23 Symphyta (Sawflies) Lack a propodium broadly joined thorax and abdomen Trochanters are two segmented Almost all are herbivores and several are serious pests Wheat Stem Sawfly (Cephus cinctus) 24 Apocrita (Wasps, Bees, Ants) Adults have a propodium comprised of the last thoracic metamere and first abdominal metamere. "Thread waist" Most Apocrita are parasitic and attack other insects or arthropods. Propodium allows ovipositor to be brought to bear in a variety of angles Bees and ants are social Bees are important pollinators Ants can be beneficial or pestilent 25 Cotesia congregata Tobacco Hornworm parasite

5 Adult parasitoid lays eggs inside larva Eggs hatch and keep larva from metamorphosing Larva emerge, spin cocoons and fly off Moth larva does not complete life cycle but continues to feed on plants 26 Yellow Citrus Ant (Oecophylla smaragdina) Important biological control agent in Chinese citrus systems Used "tree bridges" to link ant nests Ant nests stored and fed overwinter or kept on intercropped pommelo trees 27 Invasive Fire ant (Solenopsis invicta) South American in origin Has been spreading North in the US Also present in Asia and Austrailia Rapacious consumer kills other insects as well as vertebrates Has value as a biological control agent in some annual systems Kills pollinators important to perennial systems 28 Diptera (True Flies) Diptera are perhaps the most negatively important order of insects Very diverse and elaborate mouthparts Sopping Piercing Sucking Mixtures of the two "Two Wings" Hindwings altered into halteres Provide flight stability Three broad groups of flies 29 Nematocera "Thread Anntena Flies" Nine segmented long antennae Usually aquatic, includes mosquitoes (Culicidae), craneflies (Tipulidae), and Midges (Chironomidae) Mosquitoes are responsible for more human deaths than any creature by vectoring important pathogens Malaria, Yellow Fever, Typhus, Dengue 30 Brachycera "Shortened Antenna Flies" Shortened antennae (Clavate) usually three segments maggots with sclerotized heads Horse flies are one example (Tabanidae) 31 Cyclorrhapha "Circular Seamed Flies" Shortened antennae like Brachycera Refers to how the adult fly ecloses out of the

6 Circular hole House flies (Muscidae)