Insect Anatomy and Physiology

1 3/17/20171Dr. Jonathan L. LarsonExtension entomologistInsect Anatomy and PhysiologyWhat is an Insect ?GrossDestructiveStrangeBeautifulF ascinatingBut, where do they fit into the larger Animal kingdom? How do they work? Arthropoda: A phylum of animals more commonly known as arthropodsMost of life on Earth is a member of phylum Arthropoda!Insects are one of the representative classes within ArthropodaEukaryotaChordataMammaliaPrima tesHominidaeHomosapiensAnimaliaOoh, rainbowDomainKingdomPhylumClassOrderFami lyGenusSpeciesEukaryotaArthropodaInsecta HymenopteraApidaeApismeliferaAnimaliaDom ainKingdomPhylumClassOrderFamilyGenusSpe ciesArthropods descended from marine worms of Cambrian era (~500 million years ago)3/17/20172 Once upon a , the ancestor to arthropodsPrecursor to insects?

2 Onychophora Articulated appendages Mouthparts May be early ancestor or sister groupVelvet Worm First known land animalPneumodesmusnewmaniArthropodaInsec taCrustaceaMandiblesCheliceraArachnidsMy riapodaMerostomataUniting traits of arthropodsGreek ; rthron: meaning joint ; pous(podos): meaningfoot1. All arthropods have jointed appendagesFirst is hidden in the name Arthropoda 3/17/201732. All arthropods have bilateral symmetry3. Arthropods have segmented bodies4. Arthropods have an exoskeleton, a waxy cuticle over whole body A suit of armor provides protection from attack or injury, Muscles attach directly to the body wall, stops fluid loss ArthropodaInsectaCrustaceaMandiblesCheli ceraArachnidsMyriapodaMerostomataArthrop ods with chelicera lack jaws, chelicera can chop food/inject venomThe end result of feeding can be a crunched up ball or a hollow bodyMerostomata(Thigh mouth): Sea scorpions and horseshoe crabsAll have book gills, 6 pairs of appendages, and a pair of compound eyes 3/17/20174 Only extant members of merostomataare the horseshoe crabsHave been around for 450 million years, are considered living fossilsArachnida (Spider).

3 All arachnidsScorpionesAcariAraneaScorpions, ticks , mites, spiders, : 2 body segments, no antennae, 4 pairs of legsAll other arthropods have mandiblesbyfir0002 Myriapoda(Many legs): Centipedes and their cousins the millipedesCommon traits: 1 pair of antennae, 1 pair of legs per body segment, flat bodies, venomous jawsCommon traits: 1 pair of antennae, 2 pairs of legs per body segment, round bodies, decomposersMillipedesCentipedesCrustacea (Hard shelled ones): Crayfish, lobsters, shrimp, etc. Common traits:2 body segments, 2 pairs of antennae, 5-7 pairs of legs, swimmerets or gills3/17/20175 Insecta(Cut into sections): All of the insectsCommon traits:3 body segments, 1 pair of antennae, 3 pairs of legsPhotos by Alex Wild: looking wildly different, these are all insects!

4 !Most biodiverse group on Earth: There are more than 1 million species identifiedPossibly upwards of 30 million species in existenceDaly (1978) Just let me fasten these together, then we can get to build a bug!We will remove some of the mystery of insectsUnderstanding Insect Anatomy helps with identification and pest management strategiesTa-da!3/17/20176 Insects have 3 distinct body sectionsThe Head: Serves as the center for sensory input from sensory organsRhett StuartAlso houses the Insect s largest ganglionSome have ocelli, or simple eyes. These perceive light and darkInsects have one pair of compound eyesJJ HarrisonMade up of many facets that create a composite imageCompound eyes detect movement, make Insect nearsighted Insects also perceive color differently than us3/17/20177 All insects come with a pair of antennae, located on headAntennae are for smelling, touching, and even hearingAntennae can tell the Insect they are touching something delicious to eat Or, could help them orient towards a food sourceAntennae also detect pheromones (a hormone that affects fellow individuals)

5 Pheromones differ from sight or sound signals as they travel slowly, do not fade quickly, and are effective over a long rangeAlarmAggregationEpideictic TrailSexualAll antennae are divided into 3 partsScape, pedicel, and flagellum; will help with identification!Filiform antennae: Segments are same size, threadlike in appearance Most common type of antennaePectinate and PlumoseLots of surface areas to pick up more infoSuggestive of a combFeather-like3/17/20178 Serrate and Lamellate Saw likeFan-like, pages in bookAristateand SetaceousOnly on fliesOn fast fliersA balloon with a plumose antennaeLike a thin mustacheGeniculate aka elbowedCapitate and ClavateInsect mouthparts come in many shapes and size, can be diagnosticChewing mouth: Most commonAppears in many groups, both herbivores and predators3/17/20179 Chewing mouths lead to many different types of damage/symptomsPiercing-sucking.

6 2ndmost common, can be used on plants or on A&MNeedle like mouthparts used to siphon fluids for foodPiercing-sucking creates distinctive damage as wellPlant damageSkin damageSponging mouthparts: Must liquifyyour food firstFound mainly on fliesSiphoning mouthparts: Straw like proboscisfor liquid foodFound mainly on butterflies and mothsChewing-lapping: Used to consume both pollen and nectarWasps, bees, and few others3/17/201710 Thorax: Main purpose is for locomotion, the Insect s legs and wings are located herePurdueInsects are the only invertebrates to have evolved wingsWings are usually membranous with veins, wing folding is more advancedNot all insects have wings thoughSome have no wings at all, others only have wing pads and they don t developAll insects have 3 pairs of jointed legsThorax is a cylinder with 9 piecesPro-ThoraxMeta-ThoraxMeso-ThoraxPr o-legsMeta-legsMeso-legsWe aren t so walking motionAmbulatory Legs: Cursorial, walking, running, or simple legsMost common of all legsNC StateSaltatorialLegs: Jumping legsBuilt very similar to walking legs, difference lies in femurClasping.

7 Leg with femur and tibia formed into pincer like structureCommon in lice, used to grasp on to different surfaces. Different places, different clawsJ. M. BatesBird louse on featherHead lice on humanNatatorialLegs: Swimming legsLeg flattened into a paddle like organ, typically hairy as well3/17/201712 Fossorial Legs: Digging legsTibia or tarsi modified into scraper like organ Raptorial Legs: Grasping legsLegs are armed with opposing spines or spurs on the femur & tibiaCronodonAbdomen: The business end Externally: Tympanum, spriaclesInternally:A little bit of: cardiac, nervous, respiration, digestion Mostly: sexual reproductionExternal Anatomy : At the posterior end of the abdomen may be cerci or an ovipositorCerciOvipositorTactile organs, sort of like butt antennaeSword like egg laying device, can be defensiveTympanum.

8 The main type of hearing organ, located externally on abdomenA membrane stretched across an air sac, it is vibrated by sound similar to our ear drum3/17/201713 Insect Respiratory System: A complex of networked tubes known as a tracheal systemSpiraclesSpiracles are the valve like opening where air enters the bodySpiracleInternal Anatomy : Compared to us, the nervous system and circulatory system are reversedThe hearts in the abdomen help pump the fluid forward into the aortaInsects have an open circulatory system, this means their blood is free floating, contacting organsHemolymph: Insect blood Carry nutrients to tissues, carry away wastes, function in phagocytosisInsect blood cells that have engulfed bacterial or fungal invadersUnlike human blood, Insect blood cells lack hemoglobin and do NOT carry oxygenInsect Nervous SystemMore brains than us!

9 Have several ganglia to control particular organs3/17/201714 Ventral nerve cordTracheaeBrain The scene seen through my macro tube was quite horrifying, also because in this case, the female started eating her partner before the mating, beginning from his mouth, after immobilizing his claws, in order to leave him without that, the male, totally deprived of his head, completed the mating, while the female continued eating him Insect digestion: Insects have a complete digestive system , meaning there is a mouth and anus rather than a combined organ The abdomen contains the midgut, where most digestion occurs and the organs responsible for waste production and disposal Stomach Kidneys Colon Insect Reproductive SystemsMost insects use internal fertilization Insect Reproductive SystemsInsect Reproductive Systems3/17/201715 After mating most females will lay their eggs Depending on the Insect and its location, the eggs may hatch quickly or overwinter 2 types of development in insects, Complete and Incomplete Metamorphosis