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
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
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)
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
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
Circular hole
