Midterm 1 Flashcards
Approximately how many insect species are known today?
~1.5 million
How many insect species may exist? Why might we not know all of them?
20-30 million, hard to find them all as they may be living deep in the rainforests
Where in the world are insects? Where is the only habitat that insects aren’t found?
insects have global distribution. can only not be found in the oceans
Why are insects so successful, abundant, and diverse?
because of their life history, small size, exoskeleton, metamorphosis, adaptability, wings
What about their life history makes insects successful?
high reproductive rate, short generation time. aphid may leave 10^100 descendents
What about their small size makes insects successful?
fit into diverse niches, need little food compared to other large animals, solar powered (solar energy warms them and is converted into energy)
What about their exoskeleton makes insects successful?
it is light, flexible, minimizes water loss, provides large area for internal muscle attachment, carries appendages
What about metamorphosis makes insects successful?
young and adults have different shapes and forms - allows them to specialize, larvae = feeding machines, everything designed for feeding, adults = task is for reproduction, allows to inhabit different environments - dragonflies = larvae lives in water, adults live in terrestrial environments
What about adaptability makes insects successful?
many offspring, result allows for genetic variation = rapid adaptation to environmental changes
What about wings makes insects successful?
99.9% of flying organisms are insects, dispersal and migration, mate seeking (male follows concentration gradient of females using wings), food and host location (foraging) - mosquitos flies to host using cues from host to mature eggs
What are insect roles and their relation to humans?
pollination, commercial products, biological control, insects as scavengers, insects as a food source, insects in scientific research, insects as pests
Pollination
- worth 19B in USA
- orchard fruit (apple, pear, cherry)
- many berries (strawberry, raspberry, blackberry)
- vegetables (cucumber, pepper, tomato)
Commercial products
- honey
- beeswax
- candles
- silk (silkworm)
- sex pheromone
- dyes
types of biological control
- insect vs. insect
- insect vs. plant
what is an example of insect vs. insect biological control?
cottony cushion scale: citrus pest from australia to north america.
predator = ladybird beetle. brought to north america to take care of pest
what is an example of insect vs. plants biological control?
alligator weed: aquatic plant from south america. impeding boat traffic and killing fish. predator = flea beetle. brought to control weed
insects as scavengers
feed on decomposing organic matter
- wood borers (typically beetles and fungi)
- recycle dead trees into soil
carrion feeders
- blow flies (maggots), carrion beetles, skin beetles
- vertebrates that die release - s - s - which attracts female blowflies to lay eggs
- used in forensic entomology
define maggot therapy
using maggots to eat dead skin/muscle in an infected wound in order to not have to amputate
insects as a food source
- insects for vertebrates (birds, fish, mammals, bats, reptiles, amphibians)
- insects for invertebrates
insects in scientific research
- genetics = vinegar flies (fruit flies)
- bioindicators = can use insects to gage whether an ecosystem is healthy
insects as pests
- attack cultivated plants (codling moth, mountain pine beetle)
- promote plant disease (provide entrance for pathogens, transmit pathogens)
- infest stored products (wood: termites, carpenter ants | fabric: clothes moths, dermeshed beetle | food: grain and rice weevil, flour moth
- attack humans and other animals (sting and bite: biting flies, bees, wasps) live on vertebrates (chewing lice, fleas, bed bugs)
- transmit diseases
define mechanical and biological vectors
mechanical: pick up diseases/pathogens on the outside of their body and transfers them onto other organisms through physical contact (typhoid fever, cholera)
biological: living organism that transfers pathogen inside themselves from one host to another (malaria, plasmodium)
define metazoa
many cells organized into organelles and tissues
define deuterostomes
“second mouth”, blastopore -> anus, new mouth forms
define protostomes
“first mouth”, blastopore -> mouth
define onycophora
rare, in the tropics, bilateral symmetry, segmented body, appendages, simple eyes, antennae
define arthropoda
arthro = jointed, poda = leg/foot
bilateral symmetry, segmented body - organized into regions = tagmata, specialized and jointed appendages, paired and ganglionated nerve cords, chitinous exoskeleton, open circulatory system
define chelicerata
2 tagmata - 1: cephalothorax (head/thorax), 2: abdomen
simple eyes, mouthparts: chelicera, no antenna, 8 legs = ticks, mites, spiders, scorpions, horseshoe crabs
define entognathous
having inner mouth parts, mouthparts are concealed within pouch, simple eyes, thin and pale cuticles
3 orders: 1) protura, 2) deplura, 3) collembola (springtails)
define ectognathus
having outer mouth parts
2 orders: 1) thysanura (silverfish), 2) microcoryphia (jumping bristletails)
define neoptera
new winged insects, 2 wings/1 pair, haltera needed for balance (diptera)
define paleoptera
old/ancient wings, less efficient flyers, simple and ancestral wing articulation & wing musculature
2 orders: 1) odanota 2) ephomeroptera (mayflies)
define endopterygota
wings develop internally in holometabolous insects, metabolism = change, holo = complete, wings are ony in adult stage.
Orders: lepidoptera, diptera, coleoptera, hymenoptera
define mandibulata
2-3 tagmata, compound eyes, distinct mouthparts = mandibles, maxillae, labium, antennae
define insecta
3 tagmata, 1) head with mandibulate mouthparts 2) thorax with 3 pairs of legs (wings) 3) abdomen
appeared ~400 million years ago
define myriapoda
many legs, millipedes, 2 pairs of legs per segment
scientific name = diplopoda
define apterygota
a = no/not, pteryx = wings
wingless insects
define exopterygota
wings develop externally in hemimetabolous insects = half change (nymphs resemble adults)
define orthopteroids
mandibulate mouth parts ‘chewing types’, large vanal (anal) lobe
orders: orthoptera, blatteria, dermapteria, isoptera,
define hemipteroid
haustellate mouthparts (piercing/sucking types), small vanal lobe
orders: hemiptera, thysanoptera
define necromones
death recognition signals, important for insects to know if nest mate died because it may have a disease that could spread
what are MNCs
- median neurosecretory cells
- release tropic hormones
- have different names based on final destinations
What are 2 types of MNCs
1: prothoracotropic hormone: prothorax (final destination)
2: allotropic hormone: corpora allata
what is CC
- corpus cardiacum
- store and release hormones from the median neurosecretory cells
- no hormones produced here
- distribution function
what is CA
- corpus allata
- produce and release juvenile hormones
what is PG
- produces and releases ecdyson (moulting hormone)
what is the sequence of events for moulting?
- distension in abdomen and neural feedback to brain telling brain that the old suit is too tight, we need to fix it
- MNCs release prothoracotropic hormone into the CC which liberate the hormone into the hemolympth
- the hormone activates PG
- PG produces the moulting hormone ecdyson
- ecdyson activates specific genes which produce mRNA
- mRNA encodes the synthesis of tissue associated with moulting (chitin)
what is the role of JH?
- needed for well-being of the insect
- plays role in development, metamorphosis and reproduction
why is there generally less JH in an insect while it is growing?
because CA are not growing at the same rate as insect growth so there is less JH release
what happens at each of the JH concentrations? (low, intermediate, high)
low: pupa to adult moult is initiated by ecdyson
intermediate: larva to pupa moult occurs in JH is intermediate relative to ecdyson
high: larva to larva moult initiated by ecdyson
what is an insect that exploits the JH production and how do they do it?
- wasp injects eggs into a caterpillar
- eggs hatch and eat the caterpillars food
- larva release JH so the caterpillar doesn’t become a pupa
- larva keep eating caterpillars food
- larva release paralyzing hormone and leave the caterpillar when they’re done
how can humans utilize JH?
livestock production facilities:
- many flies found near livestock
- reproduce and feed of cattle or in feces
- this takes energy from and hurts the cow
- farmers add JH to cows feed which is released in feces
- flies lay eggs in feces but larva never grow into flies
mosquito control:
- mosquito develop in water
- add JH to water, mosquito larva never grow into mosquitos
- adding JH effects all other organisms
what are the 3 major layers of the integument
1) basement membrane: non-cellular
2) epidermal layer: one cell thick, expands during cuticular synthesis, dermal gland cells
3) cuticle
what are the two components of the procuticle?
endocuticle: ‘plywood’ structure, provides flexibility and strength
exocuticle: pigmented, chitinous, sclerotized (tanned and hardened)
what are the two components in the cuticle?
epicuticle, procuticle
what is the procuticle made of?
- 25-50% chitin
- proteins
- resilin
- lipids
- enzymes
- calcium carbonate
- waxes
what is in the chitin of the procuticle?
polysaccaride - acetylglucosamine, glucosamine
adjacent chains of chitin are held together by hydrogen bonds to form microfibrils
how is the protein in the procuticle composed? (eg. arthropodin)
in exocuticle - the athropodin becomes cross-linked via acetyldopamine quinone, product = sclerotin
sclerotin + chitinous microfibils form a rigid 3D structure. process referred to as sclerotization = cuticle becomes harder and darker
what is resilin
- rubber like material
- elastic
- found at joints and between segments (allows movement between body segments)
what are the 4 major layers of the epicuticle?
- inner cuticle: main function = wound repair
- outer cuticle (cuticulin): main function = inextensible (sets limits to growth)
- wax layer: prevents water loss, conserves water if insect lives in dry environment, made of long chain hydrocarbons (25-32 long)
- cement layer: main function: protects underlying wax layer. referred to as metabolic dust bin
what is important about the cement layer?
reservoir for contact pheromones
- intraspecific communication signal benefiting the producer and receiver: stops insects from mating with those of other species
reservoir for contact kairomones
- interspecific signal that benefits the receiver (parasitoid wasp checks kairomones before injecting eggs)
layer resists biological and physical penetration
where do you find primary segmentation vs secondary segmentation?
primary: in larvae with thin and flexible cuticle (caterpillar, maggot)
secondary: beetles, etc. each secondary segment has 4 sclerites: tergum, sternum, pleuron x2
if the external components are called pit and suture, what are the internal?
spike and phragma
what is a monocondylic joint?
one articulatory surface, one point of attachment (ball and socket) - antenna
what is a dicondylic joint?
two articulatory surfaces, operates like a hinge - femur, tibia, mandible
what are two outgrowths of integuments?
hair, scales
what are a) sensory hairs, b) sensillae?
a) mechanoreceptors
b) chemoreceptors
what are physical colours?
- how light is reflected on the insects surface
- colour produced by interference colours
what are interference colours?
- often produced by laminated surfaces
- changing the angle of the surface relative to observer is equivalent to altering the distance between lamina (a different wavelength is reinforced, change of colour relative to angle of viewing = iridescence)
what are pigmentary colours?
a) biosynthetic pigments (produces its own pigment)
b) ingested pigments - caratinoids (orange)
why is colour important?
camouflage/concealment, mate attraction, advertisement, visual mimicry, thermoregulation
what might colour be advertising?
poisonous, bad tasting, stings/bites
how do insects use visual mimicry?
- appear as other insects
- mimic predator eyes
- mimic objects (leaf, stick, thorn)
- mimic structures of the environment
how does thermoregulation work?
dark colours: absorb heat/solar radiation, cold environments
light colours: able to reflect heat (hot environment)
what is molting and what does it allow?
- shedding of old cuticle and growing a new one
- allows for: growth, repair, metamorphosis
what are the two stages of molting?
1) apolysis: separation of old cuticle, exuvial place -> forms when cuticle separates from epidermis
2) ecdysis: shedding of old cuticle
what are the primary function of the head and appendages?
- sensory perception
- neural integration
- food gathering
head is commonly composed of various segments:
prostomium and 6 metameres (segments)
what 3 things does each segment in the head have?
- neuromere
- coelomic sac (independent body cavity)
- appendages
appendages can be:
- embryonic (not visible)
- antenna
- mandibles
- maxillae
- labium
what are the two types of eyes?
1) ocelli - not always present, often 3, measures light intensity, helps maintain circadian rhythm
2) compound eyes - used for vision, perceives images, colour, motion, composed of facets (ommatidia)
what are ommatidia?
each ommatidium sees one part, and all together all of the ommatidia see the entire image
what do antennas measure?
- tactile stimuli
- odour
- contact chemoreceptors (physical contact necessary)
- hygro receptors (humidity)
- temperature
- air speed
- sound receptor
explain sexual dimorphism in antenna
female antenna are more simple (pheromone producing sex), male antenna are plumose (pheromone sensing sex)
describe 1) endognathous and 2) ectognathous mouth parts
1) mouth parts are concealed in some kind of pouch (soil dwellers)
2) mouth parts always visible
what are the ways mouthparts are organized?
- according to visibility
- according to orientation of MPs relative to the head
- according to the function of the MPs
how might the mouthparts be orientated relative to the head and what are they called?
1) hypognathous: MPs point down (grasshopper)
2) prognathous: MPs point forward (predatory beetle)
3) opisthorhynchous: MPs slope forward, primarily when insect is moving forward, not when sucking
what are the mouthparts according to function?
- mandibulate: chewing type
- haustellate: sucking/piercing/sponging
what are characteristics of mandibulate MPs?
heavily sclerotized mandibles, dicondylic joints, strong muscles that move the mandible
what are characteristics of piercing MPs?
- 6 piercing stylets
- labrum (food canal)
- mandibles 2
- maxillae 2
- hypopharynx (salivary gland)
- labium (serves as a sheath for stylets, folds up as stylets overtissue)
what are characteristics of siphoning MPs?
- highly modified
- proboscis made up of 2 galaea forming a highly elongated tube
- except for pulp, rest of MPs absent or reduced
- pumping hemolymph into tube leads to extension
what are characteristics of sponging MPs?
- sponge up liquids
- proboscis is divisible into: basal rostrum, median and flexible haustellum, 2 apical labella (each labellum has transerve grooves along which liquid is drawn into oral aperature
what are the characteristics of chewing/lapping MPs?
- combination of haustellate and mandibulate, need the combination for housing
- if food is easily accessible then the glossae, labial pulps, galeae form a composite tube which liquid is drawn up
- if food is combined in a narrow nectery, only the glossae are used to obtain it
what mechanisms create the suction to draw up liquid?
1) cibarial pump: cibarium = pre oral cavity, as dilator muscle of cibarium contracts -> cibarium extends -> suction
2) pharangeal pump: as dilator muscle of the pharynx contracts -> pharynx extends -> suction
3) special suction causing movements of MPs (eg. hoverfly larva) - dragonflies = labium evolved into prey catching mask that is rapidly protruded
what are the 3 major sections of the thorax and what is the purpose of the thorax?
1) prothorax
2) mesothorax
3) metathorax
locomotion
where are the wings located?
meso and meta thorax
how is the head attached to the prothorax?
the cervix
what are the 3 sections of thoracic segment? what is between them?
1) notum - dorsal
2) pleuron - lateral (x2)
3) sternum (ventral)
resilin is between them
what can be found internally where there is a suture?
a ridge or phragma to which muscles attach
