Work Flashcards
How many segments are insects made up of?
21 (7 head, 3 thorax, 8-11 abdominal segments)
What was the most primitive mouthparts in insects?
Mandibulate
Why did chewing mouthparts (mandibulate mouthparts) evolve first?
There was no smaller insects to suck the blood out of or flowering plants
How do plague locusts feed? (These form plagues)
Taste with feet and then move head move to eat if happy
What happens to the labrium while the insect is eating?
Goes up and down
Which head segments are the labrum, maxillae, mandibles and labium in?
Labrum: 1st
Maxillae: 5th
Mandibles: 4th
Labium: 6th
What is the arrangement of head and mouthparts in hypognathous insects?
Head vertical
Mouthparts vertical
Give examples of insects with hypognathous headparts
. Grasshoppers
. Locusts
What is the arrangement of head and mouthparts in prognathous insects?
Head horizontal Mouthparts anterior (stock forward)
Give examples of insects with prognathous mouthparts
Many beetles
Earwigs
What is the arrangement of head and mouthparts of Opisthognathous insects?
Head vertical
Mouthparts posterior
Give examples of insects that have opisthognathous mouthparts
Aphids
Cicadas
Leafhoppers
(Usually a sign they are blood suckers)
How many wings and legs do locusts have?
4 wings, 6 legs
What are the things insects can have modified back legs for?
. Jumping
. Sensors on legs so it can taste what it is standing in
. Can sense pressure or stress
Locusta tarsi have 3 segments. What is on each segment? What can the tarsi do?
1-2 soft pads with pulvilli underneath and two claws separates by an aerolium. Tarsi have sensillae on them to measure pressure and stress, to taste the substrate
Give the veins in an insects wing in order (front to back)
Costa, subcosta, radius, media, cubitus, anal
How can we use wings to determine species?
Other than the anal vein they can all be more or less subdivided
How can you use wing veins to determine bees and wasps?
They have added cross veins
What are the pigmented spots some insects have on their wings called?
Pterostigma
What do butterflies/ moths and caddies-flies have on their wings that we can use to determine them?
Scales or hairs covering wings
What do wing veins do?
Veins help hold wings up in flight
Tell wings where to fold
What do haltere do?
Help flies balance
Describe how the characteristics of the pleuritic
Flexible
Membranous
Describe the characteristics of the aorta for non-muscular insects
Flimsy for any insect that is hardly muscular at all
Where does the nerve cord run?
Runs ventrally, runs between ganglia and nerves
What is an adaption of the haemocoel?
Can extend and expand a lot for eggs and food
Which segments are important in wing development?
Tergite, pleurite and sternite segments
What are the names of the 6 head segments in order?
Labral, antennal, intercalary, mandibular, maxillary, labial (and eye)
What are the 3 segments in the thorax called?
Prothorax, mesothorax and metathorax
When is segmentation clearest?
During development
What are the segment polarity genes present in the brain/ rest of body that we use to determine where one segment of the brain starts and the other finishes?
. Engrailed
. Ventral nervous system defective
How many divisions of the brain are there?
4
How do we know where the segments are in the brain?
Because the borders are marked by segment polarity genes
D/V patterning genes
What does apterygo mean?
No wings
What does terygo mean?
Wings
Describe apterygota features and give an example of one species
Have no wings Not ‘true’ insects Earliest fossil insects 300m years ago Most primitive Silverfish
Give the features of exopterygota
True insects
Externally developing wings
Young often resemble adults
What is pterygota? Which are the 2 groups?
Origin of wings
Split into 1. Mayflies 2. Odonata (dragonflies)
What are the features of the group endopterygota?
Develop wings internally
Have complete metamorphoses
Most advanced insects
Most recently evolved
Give examples of species in the group endopterygota
Wasps, bees, flies and butterflies
What are the advantages of external covering?
. Enhanced leverage for muscular movements
. Protective covering of muscles and internal organs
. Restriction of moisture loss in terrestrial habitats (deserts)
. Ability to produce both rigid jointed appendages for walking, jumping or capturing prey and membranous, foldable sheets for flying, lenses fit compound eyes
. Covering for compound eyes
What are the disadvantages of external covering?
. Vulnerability during the moulting process
. Restrictions in terms of large size and weight mainly due to the inability of oxygen to each metabolically active tissues in very large insects
(Cuticle restricts oxygen diffusion so needs trachea)
(Have to moult to grow)
How does the heart pump blood in insects?
Back and forth
What are the 4 (5) layers of the cuticle in insects?
Wax layer, epicuticle, exocuticle, endocuticle and epidermis
What does the wax layer on the cuticle do?
Waterproofs- secreted by epidermal cells
What does the epicuticle lack?
Chitin
Describe the exocuticle layer in the cuticle
Sclerotized chitin stuff, 10-15% water
Describe the endocuticle layer of the cuticle
Unsclerotized chitin layer (means it’s not hard), 50% water
What is the bulk of the cuticle made up of?
Chitin microfibrils
What is the structure of chitin made from?
Chain of poly-glucosamine
Which layers of the cuticle are sclerotized (tanned)? What happens in this process?
The exocuticle- hardens after moulting and darkens in colour (harder=darker)
Sclerotized chitin is insoluble and rigid which helps during tanning. What gives it these features?
. Chitin is linked to a protein matrix giving tensile strength
. Particular amino acid residues of the protein matrix are cross-linked by phenolic bridges, linking is achieved by quinine tanning leading to dark brown cuticular colouration
Softer cuticle is not sclerotized which allows for what?
Expansion of the insect
How is the cuticle formed?
Chitin fibres rap around each other to make them stronger
Then laid in a sheet
Each sheet is offset a little from the other. Each is turned a little relative to the other- making them very tough
Makes a helical structure
Would do cuticular protuberances do?
Give info about stress to the insect
What is the developmental (or growth) in insects that have immature stages called largae, have a pupal stage called?
Holometabolous endopterygote
Explain holometabolous endopterygote
Developmental or growth in insects where they have immature stags called larvae, have a pupal stage
Give example of insects that shown holometabolous endopterygote development
Butterflies and flies
What is the developmental or growth stage in insects where there is an immature stage called nymphs called?
Hemimetabolous extopterygote
Explain hemimetabolous extopterygote development in insects, in which species is it shown?
Immature stage called nymphs. Locusts and cockroaches
What is the type of developmental or growth called in insects when they undergo gradual or no metamorphosis?
Ametabolous apterygote
Explain ametabolous apterygote development in insects. Give an example of a species that shows this type of development
Undergoing gradual or no metamorphosis. Silverfish
What is metamorphosis controlled by?
Interaction between neuropeptidss, ecdysteriods and especially juvenile hormone titres in the insect
How is metamorphosis controlled?
The balance in juvenile hormone titres (JH) secretion from the brain can change developmental patterns from hemimetabolous to holometabolous depending on when JH secretion is stopped in the life cycle
What is the detaching of the old cuticle from the epidermis called?
Apolysis
What is the shedding of the old cuticle called?
Ecdysis
What do ametabolous insects do?
Keep moulting until they die (although don’t always keep growing), and in their final mount they become reproductively mature and are termed adults
What are some examples of ametabolous development?
Collembola, diplurans, and apterygote insects
What are the characteristics that define the super class Hexapoda/ class (order) Hymenoptera?
Paired wings, eusociality, abdomen waist
Describe springtails- also give the superclass and order they belong to
. Very abundant in soil
. Eyes are clusters of 8 ocelli
. Biting mouthparts in pockets (so cant we them )
. 6 legs
. not close to insects as they have their own origin
Superclass: Hexapoda
Order:Collembola
Describe the features of dragonflies and damselflies and give there order and class
. Biting mouthparts, large elongate bodies, huge eyes, minute antennae
. Primitive wing species- one of the first we know if (paleoptera)
. Two pairs of glassy wings with many cross-veins
. Two sub orders; anisoptera (dragonflies) and zygoptera (damselflies)
Describe the features of dragonflies and give their order and sub-order
. Forewings narrower than hindwings . Wings broad at base . Wings held outspread at rest . Eyes close, often touching . Heavily built . Nymphs have rectal gills- inside rectum . Often have wide abdomens Order: Odonata Sub-order: Anisoptera
What are the characteristics of damselflies and which order and sub-order do they belong to?
. Fore and hindwings similar . Wings are stalked . Wings held vertical at rest . Eyes separated . Slender bodies . Nymphs have caudal gills (have stocking out of back end) . Heavily used in research Order: Odonata Sub-order: zygoptera
What are the characteristics of earwigs and which class and order do they belong to?
. Elongate and flattened . Prognathous (head faces forward with mouth at front of head) . Antennae short . Legs shot . Leathery forewings . Cerci modified as forceps . Female will look after eggs over winter and see any predators off Class: insects Order: Dermoptera
Give examples of species in the order Orthoptera (class insecta)
Grasshoppers
Locusts
Katydids
Crickets
What are the 2 sub-groups in the Oder Orthoptera?
. Ensifera (katydids wetas and crickets)
. Caelifera (grasshoppers and locusts)
Describe the characteristics of heel walkers and what class and order they are in
. Cylindrical bodies . Hypognathous . Long antennae . Large eyes . Adults lack wings (apterous) . Small cerci in females, prominent in males Class: insecta Order: Mantophasmatodea
What are the characteristics of Mantids and what class and order do they belong. Go into detail about one example
. Highly adapted bodies . Mobile triangular head, large eyes . Narrow thorax . Prothoracic legs are raptorial for hunting . Leathery slender forewings . Often predators . Eat males after sex if hungry . Preying mantus’s - have sterio vision, hide as leaves and flowers, wait for prey to walk past and then strike. Can extend legs 2.5cm
What are the characteristics of Mantids and what class and order do they belong. Go into detail about one example
. Highly adapted bodies . Mobile triangular head, large eyes . Narrow thorax . Prothoracic legs are raptorial for hunting . Leathery slender forewings . Often predators . Eat males after sex if hungry . Preying mantus’s - have sterio vision, hide as leaves and flowers, wait for prey to walk past and then strike. Can extend legs 2.5cm
What are the characteristics of cockroaches and which class and order do they belong to?
. Depressed bodies- because they live in condensed areas . Long cursorial legs . Leathery forewings . Membranous hindwings . Prothorax large, May cover head . Omnivorous Class: insecta Order: Blattodea
Give the characteristics of termites and which class and order they belong to
. Soft bodied . Biting mouthparts . Colonial and eusocial . Polymorphic- castes (king and queen, soldiers, workers) Class: insecta Order: Blattodea (Isoptera)
Describe the features of the class insecta order Hemiptera (bugs) adults
Adults:
. Antennae slender with 4-5 segments
. Proboscis 3-4 segmented, opisthognathous, no palps
. Pronotum usually large, trapezoidal or rounded
. Triangular scutellhm present behind pronotum (back)
. Front wings with basal half leathery and apical half membranous (hemelytra). Wings lie flat on the back at rest, forming an ‘X’
. Tarsi 2- or 3- segmented
. Opisthognathous, with piercing mouthparts l, no palps
. Liquid feeders- sap, blood juice, haemolymph
Describe the features of the class insecta order Hemiptera (bugs) juveniles
Juveniles/ immatures:
. Structurally similar to adults but lacking wings
What are the 5 sub-orders of the class insecta order Hemiptera?
. Heteroptera (true bugs)
. Coleorrhncha (moss bugs)
. Cicadamorpha (cicadas l, leafhoppers, spittle bugs)
. Fulgoromorpha (plant hoppers)
. Sternorrhyncha (aphids, jumping plant live, scale insects and whiteflies)
Give the class and order of beetle and the characteristics of this group
Class: insecta
Order: Coleoptera
. Often sturdy and compact, heavily sclerotised
. Mandibulate chewing mouthparts
. Forewings modified into rigid elytra (hard cases for actual flying wings)
. Larvae with thoracic legs
What are the 4 sub-orders of the class insecta order Coleoptera?
. Adephaga (green tiger beetle)
. Polyphage >90% of species (ladybirds, dung beetle)
. Archostemata
. Myxophaga
What are the characteristics of the class insecta order strepsiptera?
. Endoparasites of Hemiptera and Hymenoptera
. Male has large head, bulging eyes, reduced forewings, mobile
. Female has similar appearance to a larva
. Each eye lens has an individual retina-different to others
What are the characteristics of true flies? What is the class and order they belong to?
. Mesothoracic wings only- hindwings are modified into halteres
. Mouthparts vary from non-functional to sucking to piercing and sucking
. Larvae are apodous (no feet, maggots!
Class insecta
Order Diptera
What are the two sub-orders of the order Diptera?
. Nematocera (more primitive)
. And Brachycera
What are the characteristics of crane flies, mosquitoes gnats and midges? What order and sub-order are they in?
. Many jointed antennae . Antennae >6 flagellomeres . Modified mouthparts in adults . Eucephalous larvae . Imported vectors of mammalian disease . Abdomen becomes red as it fills up with blood Order Diptera Sub-order: nematocera
What are the 6 infraorders of the order Diptera sub-order Brachycera?
Asilomorpha Muscomorpha Stratiomyomorpha Tabanomorpha Vermileonomorpha Xylophagomorpha
What are the characteristics of the order Diptera sub-order Brachycera?
. Stout bodies . 3-segmented antennae (<7 flagellomeres) with terminal bristle (arista) . Mandibles can be adapted into blades . Often predacious . Acephalous larvae
Give an example of a species and a characteristic of the sub-order Brachycera infraorder Tabanomorph
. Tsetse fly
. Carry infected blood from one animal to another
what are the characteristics of fleas and which class and order do they belong to?
. Very small 1-2mm long, laterally compresses, apterous
. Ectoparasites
. Piercing and sucking mouthparts with no mandibles
. Apodous larvae with head capsule
What are the characteristics of butterflies and moths and which class and order are they in?
. Hypognathous, with coiled proboscis
. Multi-segmented antennae
. Distinctive larval stage (caterpillar) with sclerotised bead and abd. Prolegs
What are the 4 sub-order did the class insecta order Lepidoptera?
. Glossata (98% of order, includes all that have a coilable proboscis)
. Micropterigoidea
. Agathiphagoidea
. Heterobathmiodea
What are the super-families in the class insecta order Lepidoptera sub-order glossata
. Noctuoidea (owlet moths)
. Sphingidae (hawk moths)
. Geometroidea (geometric moths include swallow tails)
. Papilionoidea (geometric moths include swallow tails)
. Hesperioidea (skipper butterflies)
. Hedyloidea (butterfly moths)
What are the characteristics of bees, ants and wasps? Which class and order do they belong to?
. Waist formed from last thoracic and first abdominal segment (mesosoma)
. Mouthparts mandibulate to sucking and chewing
. Usually long, multi-segmented antennae
. Simple venation on wings
Class: insecta
Order: Hymenoptera
What are the two sub-orders of the class Insecta order Hymenoptera?
. Symphysis (wood wasps and sawflies)
. Apocrita (wasps, bees and ants)
What is the sub-order Apocrita divided into?
Aculeata
Parasitica
What are the characteristics of wood wasps and sawflies? What class, order, sub-order do they belong to?
. Unwaisted wasps
. Phytophagous larvae with abdomen prolegs
. Saw-like ovipositor
What are the characteristics of parasitoid (parasitica) wasps? What class, order, sub-order are they in?
Minute in size, slender bodies, distinct waist
. Endo- or ectoderm- parasites of other insects
. Ichneumonids are parasitoids of Lepidoptera
Class: insecta
Order: Hymenoptera
Sub-order: apocrita
Parasitica
What are the characteristics of bees, ants and stinging wasps (Aculeata) and which class, order and sub-order do they belong to?
. Distinctive waist . Social families, but also many non-social families Class: Insecta Order: Hymenoptera Sub-order: apocrita Aculeata
What are the fore and hind gut lined with. What is the midgut lined with?
. Cuticle- protective layer (when moulds will come out because it moulds all its cuticle)
. Thin peritrophic membrane for protection
What happens to the guy in insects with a short lifespan?
Simplified to a tube
What cant insects synthesise that they have to get from their diet or from microorganisms because they cannot synthesis them themselves that are very important?
Sterols (for moulting hormone)
Carotenoids (used in visual pigments)
What is the purpose of saliva?
Lubricates the mouthparts (so they don’t get stuck), and May contain digestive enzymes or anticoagulants
Describe the foregut
Begins at the mouth, and includes the pharynx, oesophagus, crop (storage organ) and proventriculus a grinding organ in dorm insects which can provide a valve controlling the entry of food into the midgut
Describe the midgut in its simplest form
The main site of digestion and absorption of my. In its simplest form it is a tube from which bling sacs branch
Describe the midgut in a blood sucking insect e.g. Diptera and Hemiptera
The blood meal is held in a specialised portion of the midgut where no digestion occurs (“stomach”). Portions of the meal are then passed down through the digestive and absorptive mid and post parts of the midgut, some being completely digested and defecated before some even enters the digestive midgut
