Biology 320 Invertebrate Zoology Fall 2005 Chapter 21 – Phylum Arthropoda, Superclass Hexapoda.
-
date post
22-Dec-2015 -
Category
Documents
-
view
258 -
download
2
Transcript of Biology 320 Invertebrate Zoology Fall 2005 Chapter 21 – Phylum Arthropoda, Superclass Hexapoda.
Biology 320Biology 320Invertebrate ZoologyInvertebrate ZoologyFall 2005Fall 2005
Chapter 21 – Phylum Arthropoda, Chapter 21 – Phylum Arthropoda,
Superclass HexapodaSuperclass Hexapoda
Class InsectaClass Insecta
Majority of all animalsMajority of all animals
1,000,000 described species1,000,000 described species Estimated 10 to 30 million undescribedEstimated 10 to 30 million undescribed
Do not live in oceans, with the Do not live in oceans, with the exception of a few intertidal speciesexception of a few intertidal species
Well adapted for terrestrial existenceWell adapted for terrestrial existence 2 – 250 Malpighian tubules2 – 250 Malpighian tubules Many other adaptations and behaviorsMany other adaptations and behaviors
Holometabolus (indirect) development Holometabolus (indirect) development has led to success on land by has led to success on land by promoting resource partitioningpromoting resource partitioning Largest insect orders (Lepidoptera, Largest insect orders (Lepidoptera,
Hymenooptera, and Diptera) exhibit indirect Hymenooptera, and Diptera) exhibit indirect developmentdevelopment
Insect flight allows for:Insect flight allows for: DispersalDispersal Predator escapePredator escape Access to food and optimum Access to food and optimum
habitathabitat
Many have interesting Many have interesting coevolutionary relationships coevolutionary relationships with flowering plantswith flowering plants
Some are vectors of Some are vectors of diseasedisease
Herbivory by insects does Herbivory by insects does large amounts of damage to large amounts of damage to cropscrops
Body FormBody Form
Three tagmataThree tagmata
HeadHead Two compound eyesTwo compound eyes Three unpaired ocelliThree unpaired ocelli One pair of antennaeOne pair of antennae Preoral cavity with complex Preoral cavity with complex
mouthpartsmouthparts
ThoraxThorax Three pairs of legsThree pairs of legs
ForelegsForelegs Middle legsMiddle legs Hind legsHind legs
Thorax cont…Thorax cont… Two pairs of wings in most Two pairs of wings in most
adults, while juveniles have adults, while juveniles have wing padswing pads
Some only have one pairSome only have one pair Some lack altogetherSome lack altogether Some only possess wings Some only possess wings
during reproductive periodsduring reproductive periods
AbdomenAbdomen Typically 9 – 11 segmentsTypically 9 – 11 segments Female gonopore on Female gonopore on
segment 8segment 8 Male gonopore on segment 9Male gonopore on segment 9 Some have sensory Some have sensory
appendages called cerci on appendages called cerci on last segmentlast segment
Wings and FlightWings and Flight
Wings composed of two sheets Wings composed of two sheets of epidermis covered with cuticleof epidermis covered with cuticle
Sclerotized areas called veins Sclerotized areas called veins offer supportoffer support HollowHollow House tracheae, nerves, and House tracheae, nerves, and
bloodblood
Permanently outstretched wings Permanently outstretched wings is a primitive traitis a primitive trait
The evolution of wing folding has The evolution of wing folding has allowed insects to exploit allowed insects to exploit microhabitats where outstretched microhabitats where outstretched wings would be a handicap wings would be a handicap
Flight muscles fill most of the thoraxFlight muscles fill most of the thorax Striated fibers with huge mitochondria, and profuse tracheal innervation (to Striated fibers with huge mitochondria, and profuse tracheal innervation (to
meet high oxygen demand)meet high oxygen demand)
Wings move up, down, forwards, and backwardsWings move up, down, forwards, and backwards Wing angles are frequently changedWing angles are frequently changed
Insects are probably the most skilled flyersInsects are probably the most skilled flyers Houseflies can outperform any birdHouseflies can outperform any bird
Can turn in the distance of one body lengthCan turn in the distance of one body length Can fly upside downCan fly upside down
Hummingbird moths and botflies can fly 25 mphHummingbird moths and botflies can fly 25 mph
Display positive phototaxis, and often fly into lampsDisplay positive phototaxis, and often fly into lamps
NutritionNutrition
Diverse nutritional Diverse nutritional strategies, and thus strategies, and thus diversity in mouthpart diversity in mouthpart structure and functionstructure and function
Mandibulate mouthpartsMandibulate mouthparts Grasshoppers and antsGrasshoppers and ants Large jaws for cutting and Large jaws for cutting and
chewingchewing Found in many herbivores Found in many herbivores
and carnivoresand carnivores
Sucking mouthpartsSucking mouthparts Butterflies and mothsButterflies and moths Suck nectar and fruit juices with a Suck nectar and fruit juices with a
long proboscis formed from maxillaelong proboscis formed from maxillae Rolled and coiled when not feedingRolled and coiled when not feeding Diet is N and Na deficient so they Diet is N and Na deficient so they
drink other types of liquids (mud drink other types of liquids (mud puddles, carrion, animal wastes, puddles, carrion, animal wastes, etc.) to supplementetc.) to supplement
Piercing mouthpartsPiercing mouthparts Aphids drink plant juicesAphids drink plant juices Female mosquitoes require a blood Female mosquitoes require a blood
meal to produce eggsmeal to produce eggs Stylet pierces preyStylet pierces prey
Has a salivary channel and a food Has a salivary channel and a food channelchannel
Proteins in saliva produce itching Proteins in saliva produce itching associated with mosquito bitesassociated with mosquito bites
Surrounding structures support Surrounding structures support styletstylet
Sponging mouthpartsSponging mouthparts Nonbiting fliesNonbiting flies Enlarged labium is used Enlarged labium is used
to absorb liquidsto absorb liquids Liquefy food with Liquefy food with
enzymesenzymes
Digestive systemDigestive system Salivary glands produce Salivary glands produce
many types of secretionsmany types of secretions Pectinase for breaking Pectinase for breaking
down plant cell wallsdown plant cell walls Typical secretionsTypical secretions Some have silk glands in Some have silk glands in
place of salivary glandsplace of salivary glands Used for making Used for making
cocoonscocoons
Digestive system cont…Digestive system cont… Peritrophic membranePeritrophic membrane
Protects non-cuticularized midgutProtects non-cuticularized midgut Partitions areas where digestive enzymes functionPartitions areas where digestive enzymes function
Membrane is perforated, so some enzymes pass through Membrane is perforated, so some enzymes pass through membrane and act on food bolusmembrane and act on food bolus
Hydrolyzed biomolecules pass from bolus side to lumen Hydrolyzed biomolecules pass from bolus side to lumen sideside
Additional enzymes facilitate further digestionAdditional enzymes facilitate further digestion
Midgut has two to six gastric cecaMidgut has two to six gastric ceca
Hemocoel contains a fat body that synthesizes Hemocoel contains a fat body that synthesizes and stores biomoleculesand stores biomolecules
Hemal SystemHemal System
Not many vesselsNot many vessels
Accessory hearts pump blood to important Accessory hearts pump blood to important structures (antennae, mouthparts, legs, structures (antennae, mouthparts, legs, wings, cerci, etc.)wings, cerci, etc.) Located at bases of extremitiesLocated at bases of extremities
Many insects can survive subfreezing Many insects can survive subfreezing temperatures (-30temperatures (-30°C)°C) Compounds in blood, such as glycerol, function as Compounds in blood, such as glycerol, function as
antifreezeantifreeze
Respiratory SystemRespiratory System Elaborate tracheal systemElaborate tracheal system
Branch and diverge into a network Branch and diverge into a network of smaller and smaller tubesof smaller and smaller tubes
Smallest tubes are called Smallest tubes are called tracheoles (make direct contact tracheoles (make direct contact with cells)with cells)
10 pairs of spiracles10 pairs of spiracles Two pairs on thoraxTwo pairs on thorax
Spiracles can be closed, which Spiracles can be closed, which prevents:prevents: Water lossWater loss Dust from enteringDust from entering Parasites from enteringParasites from entering
Cartilagenous support rings Cartilagenous support rings
Sensory OrgansSensory Organs
Most are derived from setae and Most are derived from setae and are associated with appendagesare associated with appendages Tarsi of many have gustatory (taste) Tarsi of many have gustatory (taste)
or tactile (touch) receptorsor tactile (touch) receptors Flies taste food by walking on itFlies taste food by walking on it
EyesEyes Form color images in someForm color images in some Some (especially pollinators) are Some (especially pollinators) are
sensitive to UV lightsensitive to UV light
Reproductive SystemReproductive System Gonochoric with internal fertilizationGonochoric with internal fertilization
Female systemFemale system Two ovaries produce eggs with a waterproof capsuleTwo ovaries produce eggs with a waterproof capsule Two oviducts converge and empty into a vaginaTwo oviducts converge and empty into a vagina Oviduct opens on segment 8Oviduct opens on segment 8 Tubular ovipositor for depositing eggs in appropriate substratum (i.e. Tubular ovipositor for depositing eggs in appropriate substratum (i.e.
soil, wood, plant, animal, etc.)soil, wood, plant, animal, etc.) Ovipositor is modified to form a sting with poison glands in some Ovipositor is modified to form a sting with poison glands in some
Hymenopteran females Hymenopteran females
Male systemMale system Two testes with sperm ductsTwo testes with sperm ducts
Accessory glandsAccessory glands
Median ejaculatory ductMedian ejaculatory duct
Penis is extensible / Penis is extensible / retractableretractable Everts through gonopore on Everts through gonopore on
segment 9segment 9 Releases spermatophore or Releases spermatophore or
spermsperm Sperm plug (mating plug)Sperm plug (mating plug)
May have claspers for holding May have claspers for holding female during copulationfemale during copulation
Sperm enter egg through a Sperm enter egg through a micropyle in egg capsulemicropyle in egg capsule
Insect DevelopmentInsect Development
Under hormonal controlUnder hormonal control
Three main stages:Three main stages: EggEgg
JuvenileJuvenile Many instars separated by Many instars separated by
moltsmolts Main role is to feed and growMain role is to feed and grow
AdultAdult Technically termed an imagoTechnically termed an imago Sexually mature with functional Sexually mature with functional
wingswings May / may not continue to moltMay / may not continue to molt Main role is dispersal and Main role is dispersal and
reproductionreproduction
Direct DevelopmentDirect Development
Three main typesThree main types
Paurometabolous Paurometabolous development is the only development is the only type we will discusstype we will discuss Grasshopper, cockroaches, Grasshopper, cockroaches,
etc.etc. Juveniles are morphologically Juveniles are morphologically
similar to adultssimilar to adults Adults don’t moltAdults don’t molt Does not promote resource Does not promote resource
partitioningpartitioning Adults and nymphs in Adults and nymphs in
competition with one anothercompetition with one another
Indirect DevelopmentIndirect Development Holometabolus developmentHolometabolus development
Hymenopterans, flies, beetles, and LepidopteransHymenopterans, flies, beetles, and Lepidopterans
Juveniles (larvae) are wormlike, and called grubs, maggots, or Juveniles (larvae) are wormlike, and called grubs, maggots, or caterpillarscaterpillars
Many larval instarsMany larval instars
Pupa phase between last instar and imagoPupa phase between last instar and imago Undergoes metamorphosisUndergoes metamorphosis
Imago has wings and looks nothing like juvenileImago has wings and looks nothing like juvenile Different mouthparts, and therefore they feed on different types of Different mouthparts, and therefore they feed on different types of
foodsfoods
Promotes resource partitioningPromotes resource partitioning
CoevolutionCoevolution Definition - evolution of plants and insects in response to Definition - evolution of plants and insects in response to
one anotherone another
Plants and insects are vital to each otherPlants and insects are vital to each other Plants provide food (nectar, pollen, and plant tissues) and shelter Plants provide food (nectar, pollen, and plant tissues) and shelter
to insectsto insects Insects pollinate plantsInsects pollinate plants
Bees, wasps, butterflies and Bees, wasps, butterflies and moths are the primary insect moths are the primary insect pollinatorspollinators
Insects pollinate 70% of all Insects pollinate 70% of all flowering plantsflowering plants
Plants adapt to make Plants adapt to make improvements that minimize improvements that minimize costs to both organisms, and costs to both organisms, and maximize efficiency of pollination maximize efficiency of pollination processprocess Characteristic colors, odors, and Characteristic colors, odors, and
nectars to attract insectsnectars to attract insects Guide marks and UV-sensitive Guide marks and UV-sensitive
patterns on flowerspatterns on flowers Time that flowers bloom Time that flowers bloom
coincides with periods of insect coincides with periods of insect activityactivity
Coevolution in response to Coevolution in response to herbivoryherbivory
Plants have evolved a suite of Plants have evolved a suite of defenses against insect herbivorydefenses against insect herbivory
Mechanical – spines, bristles, and Mechanical – spines, bristles, and hairshairs
Chemical – nicotine, caffeine, Chemical – nicotine, caffeine, cyanide, and tanninscyanide, and tannins
In turn, insects develop counter In turn, insects develop counter offensesoffenses
Enzymes that detoxify protected Enzymes that detoxify protected tissuestissues
These insects specialize on These insects specialize on plants they can detoxify, and plants they can detoxify, and have little competitionhave little competition
Defensive chemicals may Defensive chemicals may become attractantsbecome attractants
Arms race continuesArms race continues
GallsGalls
Another interesting aspect of insect-Another interesting aspect of insect-plant relationships is gall formationplant relationships is gall formation
Many herbivorous insects cause Many herbivorous insects cause plants to form gallsplants to form galls Swollen portion of plant tissue Swollen portion of plant tissue
containing eggs or larvaecontaining eggs or larvae Forms in response to compounds Forms in response to compounds
secreted by ovipositing female and secreted by ovipositing female and larvaelarvae
Gall shape is characteristic of the Gall shape is characteristic of the insect that laid eggsinsect that laid eggs
Gall protects larvae, larvae feed on Gall protects larvae, larvae feed on gall tissue; eventually emergegall tissue; eventually emerge
ParasitismParasitism Fleas, lice and biting flies are Fleas, lice and biting flies are
parasiticparasitic
Usually only one life phase is Usually only one life phase is parasiticparasitic
Human botfly (Human botfly (DermatobiaDermatobia)) Captures a mosquito or biting flyCaptures a mosquito or biting fly Deposits eggs on the captured fly Deposits eggs on the captured fly
and releasesand releases Recently captured insect bites a Recently captured insect bites a
human or other animalhuman or other animal Egg falls into woundEgg falls into wound Grub develops in a cavity called a Grub develops in a cavity called a
warblewarble Molts several timesMolts several times Crawls to surface, falls to ground and Crawls to surface, falls to ground and
pupatespupates
ParasitoidismParasitoidism
Insects that parasitize larger Insects that parasitize larger insectsinsects
Typically deposit eggs in or Typically deposit eggs in or on host using an ovipositoron host using an ovipositor
Eggs hatch and consume Eggs hatch and consume hosthost
Very commonVery common It has been hypothesized that It has been hypothesized that
each insect species has a each insect species has a parasitoidparasitoid
Parasitoids are important for Parasitoids are important for controlling insect populationscontrolling insect populations
Example 1: Example 1: Wasp secretes chemical that Wasp secretes chemical that
causes worker ants to fight each causes worker ants to fight each otherother
While ants fight, wasp enters While ants fight, wasp enters nest and oviposits on larvaenest and oviposits on larvae
Example 2:Example 2: ApantelesApanteles (wasp) oviposits in (wasp) oviposits in ManducaManduca (Sphinx moth) larvae (Sphinx moth) larvae
Up to 500 larvae can grow inside Up to 500 larvae can grow inside caterpillarcaterpillar
Rupture body wall and form Rupture body wall and form cocoon on surfacecocoon on surface
CommunicationCommunication Pheromones Pheromones
Chemicals used for:Chemicals used for: Attracting potential matesAttracting potential mates Marking territories and trailsMarking territories and trails Locating and removing dead Locating and removing dead
individuals from colonyindividuals from colony DefenseDefense Warning conspecifics of Warning conspecifics of
dangerdanger Locating foodLocating food
Usually dispersed by windUsually dispersed by wind
Effective in very small Effective in very small quantitiesquantities
FlashingFlashing FirefliesFireflies Species-specific flashing patternSpecies-specific flashing pattern Some female fireflies mimic Some female fireflies mimic
flashing patterns of other speciesflashing patterns of other species Attracts male of a different Attracts male of a different
speciesspecies Female preys upon maleFemale preys upon male
SoundSound Stridulation is produced by wings Stridulation is produced by wings
and leg filesand leg files Other types of sound produced Other types of sound produced
by wing beating, forcing air from by wing beating, forcing air from tracheae, etc.tracheae, etc.
Social InsectsSocial Insects Isopterans (termites) and Isopterans (termites) and
Hymenopterans (bees, wasps, and ants)Hymenopterans (bees, wasps, and ants)
All groups share several characteristicsAll groups share several characteristics One queen that mates with other fertile One queen that mates with other fertile
individuals (drones)individuals (drones) Physical labor is carried out by sterile Physical labor is carried out by sterile
individualsindividuals Caring for juvenilesCaring for juveniles ForagingForaging SoldiersSoldiers
No individual can exist independent of No individual can exist independent of colonycolony
No individual can be accepted into a No individual can be accepted into a colony other than its owncolony other than its own
However, some ants raid nests of other However, some ants raid nests of other species, kidnap pupae, raise juveniles, species, kidnap pupae, raise juveniles, and force them to work as slavesand force them to work as slaves
Characteristics…Characteristics… Caste systemCaste system
Individuals with different morphologiesIndividuals with different morphologies Have different dutiesHave different duties Examples: soldiers, workers, and dronesExamples: soldiers, workers, and drones
Ants and termites usually inhabit Ants and termites usually inhabit elaborate colonies with many elaborate colonies with many tunnels, chambers, entrances and tunnels, chambers, entrances and exitsexits Army ants are an exceptionArmy ants are an exception Leaf cutter ants have chambers for Leaf cutter ants have chambers for
growing fungusgrowing fungus
Colony formationColony formation In bees, new queens are produced In bees, new queens are produced
when larvae eat a substance known as when larvae eat a substance known as “royal jelly” that is produced by the “royal jelly” that is produced by the hypopharyngeal glands of nursery hypopharyngeal glands of nursery workersworkers
Queen usually takes part in nuptial flight Queen usually takes part in nuptial flight in order to start new colonyin order to start new colony
In bees 20,000 to 60,000 individuals will In bees 20,000 to 60,000 individuals will swarm and search for a new colony swarm and search for a new colony locationlocation
DiversityDiversity
There are around 30 insect There are around 30 insect ordersorders We will We will brieflybriefly cover 14 cover 14
Order OdonataOrder Odonata Dragonflies and damselfliesDragonflies and damselflies Voracious predators found near Voracious predators found near
waterwater Nymphs are aquaticNymphs are aquatic Dragonflies are heavy bodied with Dragonflies are heavy bodied with
outstretched wingsoutstretched wings Damselflies are more slender and Damselflies are more slender and
delicate, with wings held over delicate, with wings held over abdomen while at restabdomen while at rest
Order OrthopteraOrder Orthoptera Grasshoppers, crickets, and Grasshoppers, crickets, and
katydidskatydids Large insects with large Large insects with large
compound eyescompound eyes Large hind legs for jumpingLarge hind legs for jumping Stridulating and auditory Stridulating and auditory
organsorgans HerbivoresHerbivores
Order PhasmidaOrder Phasmida Walking sticksWalking sticks Mimic sticks or vegetationMimic sticks or vegetation Elongate and cylindrical Elongate and cylindrical
bodiesbodies Usually lack wingsUsually lack wings Some up to 30cm longSome up to 30cm long
Order DermapteraOrder Dermaptera EarwigsEarwigs Nocturnal and omnivorousNocturnal and omnivorous Elongate bodyElongate body Large pincer-like cerci Large pincer-like cerci
Order IsopteraOrder Isoptera TermitesTermites Soft bodied and pale in colorSoft bodied and pale in color Build large mounds or nests in Build large mounds or nests in
treestrees Can infest buildingsCan infest buildings Have endosymbiotic microbes Have endosymbiotic microbes
that produce cellulasethat produce cellulase
Order MantodeaOrder Mantodea MantidsMantids Large and slow movingLarge and slow moving Cryptic colorationCryptic coloration Ambush predators with Ambush predators with
raptorial forelegsraptorial forelegs Large eyes on a freely Large eyes on a freely
movable headmovable head
Order BlattariaOrder Blattaria CockroachesCockroaches Fast runnersFast runners NocturnalNocturnal OmnivorousOmnivorous Endosymbionts similar to Endosymbionts similar to
those of termitesthose of termites
Order PhthirapteraOrder Phthiraptera LiceLice Ectoparasites of mammals and birdsEctoparasites of mammals and birds Prehensile legs for clinging to hair or Prehensile legs for clinging to hair or
feathersfeathers WinglessWingless All life stages are spent on hostAll life stages are spent on host Host to host physical contact is Host to host physical contact is
required for transmissionrequired for transmission
Order HemipteraOrder Hemiptera True bugsTrue bugs Stink bugs, water striders, aphids, and Stink bugs, water striders, aphids, and
cicadascicadas Sucking mouthparts for ingestion of Sucking mouthparts for ingestion of
liquidsliquids Herbivory is of economic significanceHerbivory is of economic significance Some are vectors of plant or animal Some are vectors of plant or animal
diseasedisease
Order ColeopteraOrder Coleoptera BeetlesBeetles Largest order at Largest order at
approximately 600,000 approximately 600,000 speciesspecies
Extremely sclerotizedExtremely sclerotized Forewings are called elytraForewings are called elytra
Most are herbivores, but Most are herbivores, but ladybird beetles are ladybird beetles are carnivorouscarnivorous
Order HymenopteraOrder Hymenoptera Ants, wasps and beesAnts, wasps and bees Chewing mouthpartsChewing mouthparts Most have wings, but worker Most have wings, but worker
ants lackants lack In females, ovipositor may be In females, ovipositor may be
a stinga sting Maggot-like larvaeMaggot-like larvae
Order LepidopteraOrder Lepidoptera Butterflies and mothsButterflies and moths Adults have a coiled proboscisAdults have a coiled proboscis Drink nectar and fruit juicesDrink nectar and fruit juices Larvae are herbivorous caterpillarsLarvae are herbivorous caterpillars Cocoon or chrysalis is constructed Cocoon or chrysalis is constructed
for pupa phasefor pupa phase
Order SiphonapteraOrder Siphonaptera FleasFleas Small and winglessSmall and wingless Laterally compressedLaterally compressed Ectoparasites of mammals and Ectoparasites of mammals and
birdsbirds Excellent jumpersExcellent jumpers Larvae aren’t parasiticLarvae aren’t parasitic Some are vectors of disease like Some are vectors of disease like
bubonic plaguebubonic plague
Order DipteraOrder Diptera True fliesTrue flies Mosquitoes, houseflies, Mosquitoes, houseflies,
gnats, and cranefliesgnats, and craneflies Large compound eyesLarge compound eyes Feed on animal or plant Feed on animal or plant
fluidsfluids Some are vectors of Some are vectors of
diseasedisease Eggs deposited in wet Eggs deposited in wet
substrata such as flesh, substrata such as flesh, fruit, or waterfruit, or water
Larvae called maggotsLarvae called maggots