Basic EntomologyBy: Bob GaraThe Insect Orders: YouShould Know ThemWhen You See ‘EmHi, Bob, it’s a beetle!Overall GoalRemember the Phylum Arthropoda: even spiders are arthropods1. Jointed appendages2. Body composed of somites3. Exoskeleton4. Dorsal heart5. Ventral nervous systemAll are arthropod classesSea-spidersHorseshoe crabsMitesTicksMillipedesCentipedesMany other classes tooPycnogonidaMerostomataArachnidaArachnidaDiplopodaChilopoda ClassesThe insects belong to the Class, InsectaInsects: The class Insecta• Three body regions-head- thorax- abdomen• One pr. antennae• Adults; winged• Three pr. legsBesides these basic insectan characteristics, I’m going to discuss: molting, metamorphosis, the mouth, the wings, the digestive system, and other stuff.1st, a new word: “molting” shedding old exoskeleton2nd, a new word: “instar” the insect between molts.(1) molting(2) instars ofthe Psylla1st2nd3rd 4thAdultEggSince all arthropods, including the insects, have a hardexoskeleton they have to changeit in order to grow. This processis called MOLTING.CicadamoltingThis is moltingMetamorphosis – “change in form”No metamorphosisIncompletemetamorphosisCommonsilverfishJumpingbristletail(found in theforest)The silver fish: order, Thysanura, has no metamorphosis.Mayflies (order Ephemeroptera) have incomplete metamorphosisGradual metamorphosisComplete metamorphosisThe PupaThe plant hoppers, orderHemiptera, has gradualmetamorphosis.Eggs Maggot The pupa! AdultComplete Metamorphosis!!Function beginning feeding reconstruction reprod.growing transformationOther nit grub chrysalis imagonames maggot pupariumcaterpillar cocoonEgg Larva Pupa AdultCharacter- inactive active inactive active noistics helpless growth!Some terms associated with complete metamorphosisChewing mouthpartsGrasshopper, order: Orthopteraocelliantennaecompoundeyesclypeuslabrummandiblepeeking outpalpsMouthLabrumMaxillaMandibleLabiumTonguePalpPalpSome dentistryMandibleMaxillaAgain, the chewing mouth partsLabrumPalpsLook at the variations found in the chewing mouth partsFierce predators: Tiger beetlesAnother fierce predator: Dragon fliesAdultNymphCalculates: speed anddirection of the preyAdultThe last thingthe prey sees!Mouth parts: Piercing-sucking(order Hemiptera – the bugs)MandibleMaxillaPiercing-sucking mouth partsof the HemipteraMore detail ofpiercing-suckingmouth parts of theHemipteraMore, piercing-suckingmode of feeding.Insect legsWhat’s so great about having6 legs?Legs on groundLegs off groundGuts of a larvaDigestion ininsects• Digestion• Circulation• Nervous systemOk, enough already,tell ‘em about the insectOrders!Within the class Insecta there are about 20 insect orders. Of these 20 I’ll introduce you to a few of them – of these few, you will identify 5 of them:1. Hemiptera – the bugs2. Coleoptera – the beetles3. Lepidoptera – the moths and butterflies4. Hymenoptera – the wasps, ants and sawflies and horntails5. Diptera – the fliesCollembola: the springtails.• Variable in form, wingless, no metamorphosis, chewing mouthparts• Have a “glue pot” on 1stabdominal segment• Have a jumping organ, furcula• Furcula held down by a latch called a tenaculum• The word “cola” is Latin for glueGluepotCollembolans are important!• live in the forest litter• 1ststep in decomposition• operate:- chip-up leaf particles- increases surface area- greater feeding groundfor fungi and bacteria- mix organic particlesinto mineral soil- fecal matter adds tosoil fertilitySome studies:• 7% of ingested litter matter was ingested, 93% egested as fecal pellets;• fecal pellets: increase surface area, aeration, pH, water holdingcapacity;• in 9 months, 60% of litter processed by earthworms, mites etc.; the restby collembolansThysanura: the silverfish, fire brats & bristle tails• no metamorphosis, chewing mouthparts• no wings, scales onbody, 3-tails, fast movements• skinny legs – fast!• Importance:- domesticated- live under baseboards,stoves, sinks, cabinets,books etc.• huge pest in libraries• family Machilidae live in litterwith collembolans and important in mineral cyclingHere’s some trivia that only entomologists could love:• fossil insect• flight• all insects have these muscles• contraction ofthese musclesallows for wing movement& flightThe Ephemeroptera (mayflies) and the Odonata (dragonflies & damselflies) are ancient remnants of the earliest flying insects.When not flying mayflies and dragonflies can’t fold their wings. They either hold them “tent-like” over their thorax or out horizontally. The wing-folding mechanisms wasn’t invented yet: the axillary sclerites.These are axillary sclerites that allowfor wing folding – most insects havethese mechanisms.Ephemeroptera*: the mayflies• ± 2,000 spp.• 2-pr. membranous wings held tent-like over body;• adults have no mouths, incomplete metamorphosis;• aquatic immatures;• 1° consumer role in the aquatic ecosystem.gills*ptera- Gr. for wingephemera- Gr. prefix for temporaryEcological role of mayflies:• shredders – headwaters of streams; •scrapers – scrape off 1° production on stones and boulders•collectors – collect fine particles as they drift down stream;• filter feeders – strain microscopic particles from the water column;• predators – few immatures arepredatorsOdonata: dragon flies and damsel flies:• adults and nymphs exquisite predators!• two pr. wings held horizontal by dragonflies and tent-like by damsel flies (but can’t fold them);• chewing mouthparts, incomplete metamorphosis;• adults are territorial and capture prey in flight;• ecological pts.- prey for birds- movement of energy from aquatic to terrestrial ecosystem- increase energy flux within aquaticecosystem ( role as generalpredators)All the rest of the insect orders have wing folding and let’s first talk about the Orthoptera.Orthoptera: grasshoppers, roaches, mantids, crickets, katydids, etc.• have chewing mouthparts, and 2pr. of wings either held straightback, like the grasshoppers, or flat along the top of their bodies;• gradual metamorphosis• most phytophagous, but some are predacious like the mantidsDermaptera: earwigs• Chewing mouth parts;• 2pr. wings, 1stpair truncate and hardened;• gradual metamorphosis• posterior – a pincher• can be pests of nurseriesIsoptera: termites:• have a caste system,