Final Flashcards
What are the two types of movement of gases within the tracheal system
a) diffusion
b) active ventillation
how does diffusion work during resting and during activity?
resting: distal parts of tracheoles are filled with liquid (not air)
activity: osmotic pressure of hemolymph increases (metabolic waste builds up) -> liquid is withdrawn from capillary tracheoles and oxygen is brought closer to tissue cells. as metabolic waste is oxidized and removed, osmotic pressure decreases = capillary force draws liquid back into tracheoles
describe active ventillation
contracting longitudinal and dorsal-ventral muscles flatten and telescope segments causing an increase in hemolymph pressure, air sacs collapse = active respiration
when muscles relax, decrease in hemolymph pressure = air sacs expand = inspiration
it is unidirectional rather than tidal.
e.g. first 4 spiracles are inspiratory, remainder are expiratory
what is the main idea of active ventillation
increase and decrease of volume in tracheal system
what are the two types of gas exchange in aquatic insects
- O2 from air
- O2 from water
what are the 2 challenges from getting oxygen from the air in gas exchange in aquatic insects
- potential water entry into trachea when submerged
- overcome surface tension at air-water interface
what are 6 solutions that aquatic insects have for overcoming the challenges of getting oxygen from the water
a) water repellent structures around spiracles
b) posterior spiracle(s) positioned on an extendable siphon
c) air sacs (extra-tracheal)
d) oxygen from tissue in aquatic plants
e) plastron respiration (plastron = film of gas)
f) oxygen obtained from water (spiracles are nonfunctional)
what are two water repellent structures around spiracles
- glands secreting oily substances
- hydrofuge hairs
what do extra-tracheal air sacs do in aquatic insects
- carry air bubble when diving
- spiracles open into air bubble
what are the challenges of extra tracheal air sacs in aquatic insects
- buoyancy: air bubble wants to rise to the surface. insect must swim down or get a grip on substrate (brime fly)
how do aquatic insects get oxygen from tissue in aquatic plants
spiracle at the tip of a sharp pointed abdominal siphon is pushed into oxygen-containing tissue of aquatic plants
how does plastron respiration take place
through specialized structures (close hair pile)
how do aquatic insects get oxygen from water
gills = site of gas exchange
what are the purposes of the alimentary canal and associated glands (5)
- lubricate
- store
- digest
- absorb food nutrients
- expel remains
when are alimentary canals long and short
long: herbivorous insects
short: carnivorous insects
what are the 6 types of feeding habits in insects
- green plant feeders
- fungi feeders (leaf cutter ants)
- predators
- saprophagous
- parasites
- parasitoids
what are the 3 types of green plant feeders
- monophagous - feeding on one plant species (cotton boll creevil)
- oligophagous - only feeds on a few species of plant (cabbage butterfly)
- polyphagous - many plant species are fed on (gypsy moth larvae)
what are 6 things that plant selection is based on
a) olfactory cues
b) visual cues (shape, colour)
c) random encounter
d) contact chemoreception
e) Infrared (western conifer seed bug)
f) degree of linearly polarized light (cabbage butterfly)
what is the degree of linearly polarized light
the amount of light that is polarized as a percentage of all light = degree of linear polarization (DoLP)
what are phagostimulants and phagodeterrents and when do you find them
phagostimulants: a natural food component that induces sustained feeding/a synthetic compound added to bait in order to attract insects
phagodeterrents: deterrence of an insect from eating something
found in contact chemoreception
what are the 2 types of predator feeding
a) active search
b) ambush
what are the 4 types of ambush feeding
- ambush with a device to enhance the probability of capturing prey (ant lion larvae)
- ambush with camouflage (assassin bugs)
- aggressive mimicry (mantids resemble flowers to capture prey, caterpillars resembling twigs)
- ambush with attraction of prey (bola spiders)
what do saprophagous insects feed on
dead or decaying plant/feces material (dung beetles, cockroaches, carrion beetles)
what is the difference between parasites and parasitoids
parasites feed off of their host (lice and fleas), parasitoids kill their hosts
what are the 3 types of unusual reproduction and post fertilization development
- parthenogenesis
- polyembryony
- viviparity
what are the 3 types of parthgenogenesis
- haplo-diploidy
- ameiotic
- meiotic
describe haplo-diploidy
parthenogenesis - oocytes undergo normal meiosis, fertilized eggs develop into daughters and unfertilized eggs develop into sons (hymenoptera, thysanoptera)
describe ameiotic
parthenogenesis - all offspring have identical genetic constitution as mother; all daughters (aphids)
describe meiotic
parthenogenesis - meiosis occurs but fusion of nuclei restores the diploid number of chromosomes, all daughters (some lepidoptera and orthoptera)
what are 2 possible advantages of parthenogenesis
- rapid mode of reproduction
- at low population density (when males are rare) the female genotype will survive
what is 1 disadvantage of parthenogenesis and 1 possible solution
- genotype in successive generations remains constant = adaptations to changing environments are slow
solution - one or more parthenogenic generations are followed by a sexual generation (aphids)
what is polyembryony
development of several offspring (larvae) from one egg. occurs in some parasitic wasps
what are the 2 types of viviparity
a) ovoviviparity
b) larviparity
describe ovoviviparity
oviparity - eggs are retained by mother just prior to hatching (tachinid flies)
describe larviparity
oviparity - gives birth to a larva or nymph, in viviparous diptera vagina is enlarged to form a uterus, reduced number of offspring but each with a better chance of survival (tse tse fly)
list the 8 leg specializations and what adaptations are present
a) running: femur, tibia and tarsus are very long to cover distance (cockroach)
b) jumping: femur thick with strong muscles and tibia is elongated (crickets, grasshoppers)
c) grasping: extended reach for grasping prey, tibia and femur fitted with spines (preying mantis)
d) swimming: coxa, trochanter, femer and tibia are paddle-like (water beetles)
e) pollen collection: tibia rows of hair ‘corbicula’ = pollen basket
f) legs for hearing (grasshoppers)
g) legs for courtship (damselflies)
h) legs for digging: shortened legs, fore legs short and flat, serrated edge helps to dig
name 2 structures used to grasp substrate
- claws
- adhesive structures
what are the 2 major theories of wing evolution and which one is most accepted
- tracheal gill theory
- para-notal process theory (most accepted)
describe the para-notal process theory
paranotum: lateral expansion of the notum
‘wings arose as lateral expansions (processes) of the thoracic
what is the evidence that supports the pro-notal process theory
-paranotal processes in cockroach fossils have venation similar to wing venation of living cockroaches
- 2 pairs of lobes (-> wings) beating together cause drag and turbulence
what are 6 adaptations that are pertinent to 2 pairs of wings
- reverse wing beat (odonata)
- hindwings reduced (hymenoptera)
- hindwings absent or modified - halteres (diptera)
- front wings are absent - halteres (strepsiptera)
- forewings are hardened and not used in flight (coleoptera)
- coupling of wings
what are the 3 types of wing coupling
a) frenate coupling: a frenulum (well developed hair) engages with frenulum hook
b) jugate coupling: jugum clips onto the hindwing
c) hamuli coupling: hooks (hamuli) along costa margin of hindwing catch into fold of forewing
what are 2 adaptations pertinent to each wing
- reduction of wing venation. wing veins may contain nerves, trachea, hemolymph
- reduction in pleating
what are the 3 articulations between thorax and wings
- anterior notal process articulates with axillary sclerite 1, AS1 also articulates with subcosta and AS2
- posterior notal process articulates with axillary sclerite 3, AS3 also articulates with AS2 and anal veins
- pleural wing process articulates with AS2
what two muscle groups are involved in moving the wings and what do they do
a) indirect flight muscles - move wing up and down
b) direct flight muscles - move wing forward, backward, twist wings
what muscles are involved in indirect flight muscles
- dorsal longitudinal muscles
- tergosternal muscles
what muscles are involved in direct flight muscles
wing extensor and depressor muscles
describe the process of moving the wings up and down
- when the dorsal ventral/tergosternal muscles contract, the notum is pulled down, notal processes are down in relation to the pleural process = wing elevation
- when the dorsal longitudinal muscles contract, insect shortens, notum is raised, notal processes are up in relation to the pleural process = wing depression
name 4 head glands and what they do
- labial glands: cocoon spinning (caterpillars), net spinning (caddisfly larvae)
- mandibular gland: pheromone production, induce retinue behaviour (queen honey bee)
- maxillary glands: lubrication of mouthparts, may produce toxins (some neuroptera)
- pharyngeal glands: produce brood food which feeds young larvae, may play a part in caste determination (hymenoptera)
what is retinue behaviour
- occurs in queen honeybee, pheromone secreted from mandibular glands
- queen produces pheromone, worker bees are attracted to pheromones, some bees lick queen to get pheromones and then spread them through the hive
how is the foregut formed
ragination of integument, lined with cuticle (intima)
what is the foregut differentiated into
a) pharynx
b) esophagus
c) crop (food storage), diverticulum (found in blood feeding insects - bed bugs)
d) proventriculus (serves as a grinder)
e) proventricular valve - stomodeal (regulates passage of food between foregut and midgut
what is the midgut
ventriculus, of endodermal origin = no cuticular lining
what are the parts of the midgut
a) lined by a thin, permeable, paritrophic membrane that prevents mechanical damage to midgut cells and limits abrasion
b) epithelial layer: secretes enzymes for digestion, absorbs products of digestion
c) gastric caeca: increases secretion and digestive surface
describe the midgut in aphids
- 3 sections
- 1st and 3rd rut contact each other: area of contact = filler chamber
- plant sap passes from 1st ventriculus directly to 3rd ventriculus
- excess fluid released from anus as honeydew
describe the hind gut
- proctodaeum
- cuticle lined: replaced during molting
what are the regions of the hindgut
a) pylorus: pyloric valve, regulates movement of material from midgut to hindgut
b) intestine: ileum (anterior), colon (posterior)
c) rectum: terminal structure, opens externally through the anus, rectal pads, important in the reabsorption of water, salts, amino acids
what about the digestive system allows beetles and termites to eat wood
ileum = houses microbes (bacteria and protozoa) that digest wood
what are the 4 modes of sperm transfer
- direct transfer: internal fertilization (much like invertebrates) - bark beetle
- indirect transfer (with use of a spermatophore)
- direct transfer with a spermatophore (lepidoptera)
- haemocoelic insemination
describe haemocoelic insemination
- male perforates females abdomen at weak point and injects sperm directly into body cavity. some sperm is digested and provides nutrients, some sperm migrates to ovaries where fertilization takes place
- occurs in bed bugs
what are the 3 types of insect growth (postembryonic development)
- ametabolous development
- hemimetabolous development
- holometabolous development
describe ametabolous development
immatures are the same as adults except for size and underdeveloped gonads (apaterous insects)
describe hemimetabolous development
larvae/nymphs resemble adults but are smaller and lack functional wings and genitalia (hemiptera)
describe holometabolous development
striking change between larvae and adults. larvae = feeding machine, pupa = body rearranges for next task, adult = disperse and/or reproduce (hoverfly)
describe the mode of action for olfactory in insects
- odor molecules (pheromones) enter through pore opening in hair
- receptor protein in dendrite membrane interacts with pheromone
- receptor membrane depolarizes generating an electrical potential (=receptor potential)
- information transferred via primary axon to CNA = behavioural response
which insect has an interaction between olfactory and gustatory receptors
hover fly
which insect has a combination between chemoreceptors and sound receptors
pocodot moth
what is photoreception and what components are involved
- detection of light energy through photosensory structures
1. ocelli
2. stemmata (lateral ocelli in larval insects)
3. compound eyes
what are 7 things that all photosensory organs detect
- forms
- patterns
- movement
- distance
- photoperiod
- UV and visible light (<400nm, >400nm)
- polarized light
describe compound eyes
- each eye is comprised of photosensilla = ommatidia
describe the shape of facets when few ommatidia are present vs many in a compound eye
few: facets are round and separated by a cuticle
many: facets are hexagonal (most efficient use of space)
what are the 4 components that each ommatidium consists of
a) an optical, light gathering (diotropic) part
b) sensory receptor part, perceiving radiation and transforming it into electrical energy
c) optical part
d) sensory part
describe the optical part of the ommatidium
- cuticular (corneal) lens that is transparent, colourless, biconvex
- crystalline cone
- primary pigment cells (corneal)
describe the sensory part of the ommatidium
- 7-8 elongate cells/reticular cells/primary sense cells
- each reticular cell lacks a dendrite, instead, the margin nearest the ommatidial axis forms a rhabdomere, all rhabdomeres combined form the rhabdome
- rhabdome contains visual pigments (e.g. retinal aldehyde of vitamin A)
- tapetum
what is the mode of action for the tapetum
- light is absorbed by pigment molecules in rhabdome
- molecular structure of the pigment molecule is altered
- energy is released resulting in a receptor potential (can be measured in electroretinograms)
the abdomen is made up of
11 metameres
each abdominal metamere has: (3)
- dorsal sclerite (tergum)
- ventral sclerite (sternum)
- spiracles
what are gonopores
genital openings on the genital segments 8 and 9
where are post genital segments
abdominal segments 10-11
what are male and female external genitalia
female: ovipositor (evolved from appendages (gonopods) of segments 8 and 9
male: penis (aedeagus) evolved from appendages of 9th abdominal segments
what are the 7 special appendages of the abdomen
- cerci: in wingless and hemi-metabolous insects
- styli
- furcula
- collophore
- prolegs (pseudopods/larvapods)
- gills in aquatic insects
- cornicle
purpose of cerci
plays a role in copulation (earwigs)
purpose of styli
raise abdomen off the ground during locomotion (silverfish)
describe furcula
is turned forward and held in position by a retinaculum (collembola)
describe collophore
add appendage - unsure of function (collembola)
function of prolegs
support the abdomen (caterpillars)
function of gills
respiration, can be internal or external
function of cornicle
secrete alarm pheromone (E-B-farnesene), level of concentration fluctuates depending on whether there is a predator or not (aphids)
2 things that make insect circulatory system different from vertebrates
- open, non-vascularized system
- insect hemolymph combines the vertebrate blood and lymph system
what is the composition of the hemolymph
- water (50-90%), most abundant
- inorganics (sodium, potassium, phosphate, bicarbonate, magnesium)
- waste products (uric acid)
- organic acids (fatty acids, citric acids, amino acids)
- carbohydrates (alpha-trehalose (dissacharide) - most important sugar in insects)
- lipids
- proteins
- gases (CO2, O2)
- hemocytes (cellular fraction of hemolymph)
- no pigments - is translucent
what are the 6 functions of hemolymph
- transport of nutrients to cells and removal of waste
- storage (fat body)
- protection (primarily carried out by hemocytes)
- hormone transport
- thermoregulation
- hydraulic medium (helps to get rid of old cuticle during molting, also used during eclosion)
what is a hemocyte and what do they do (4)
- component of insect immune system
1. phagocytosis/endocytosis: ingest foreign particles (FP’s) such as microbes (viruses, bacteria, fungi, protozoa)
2. encapsulation - if a foreign particle is too large (like nematode) to be ingested it becomes surrounded by layers of hemocytes
3. detoxification of poisons - plant defense mechanism: plants are coming up with poisons to poison insects, but insects find ways to detoxify posions. the poison the insects ingest is sequestered and safely set aside to later be used as a defense
4. coagulation - plug small wounds
what is eclosion
the emergence of an adult from a pupa or a larva from an egg
what is ptilinum
eversible bladder at front of the head in flies, used for eclosion from puparium
what are the components of saliva
- carbohydrates (digesting - amylase and invertase)
- protein/fat (digesting - proteases and lipase)
- no enzymes but anticoagulants (mosquitoes)
- pectinase in aphids
- toxins (venoms) - paralyze or kill prey e.g assassin bugs or rubber flies
what does the female reproductive system include
a) pair of ovaries each containing ovarioles
b) 2 lateral oviducts (distal part = calyx)
c) common oviduct
d) vagina - several glands/organs connected to the vagina
e) spermatheca - functions to store sperm + spermathecal gland - secretes nutrients and facilitates sperm transport
f) accessory glands - secretion provides a protective and adhesive coating around eggs
how does the gut move food/fecal matter
peristaltic contractions
digestive enzymes are:
produced and released in response to food presence
what are 3 odd digestive enzymes
- keratinase (clothes moth larvae)
- chitinase
- beeswaxase (wax moth larvae)
describe food digestion by microbes
- microbes reside in alimentary canal of host insects = mutualistic relationship
- insect provides suitable anaerobic environment
- microbes ferment cellulose to glucose - insects are using fungal gardens within nest (leaf cutter ant)
2 types of metabolism
- anabolism: formation of more complex molecules
- catabolism: formation of simpler molecules and release of energy
what is the function of the male reproductive system
to produce, store, and deliver sperm
what does the male internal reproductive system consist of
a) paired testis (where sperm is produced)
b) paired vas deferens (duct that connects the testis and the seminal vesicle
c) paired seminal vesicle
d) ejaculatory duct (carries sperm out of the body)
e) accessory glands (add seminal fluid to carry sperm or harden sperm to form a spermatophore)
what do testis produce
flagellated haploid spermatozoa through the process of spermatogenesis
what is the purpose of the female reproductive system
- production of eggs
- reception and storage of sperm
- fertilization of eggs
- oviposition of eggs through external genitalia (ovipositor)
what does the female internal reproductive system contain
a) terminal filament (attach to dorsal body wall or dorsal diaphragm)
b) germarium (where oocytes are produced)
c) vitellarium (tone of yolk deposition process - vitellogenesis)
d) pedicel (primer pheromone, effects physiology)
what are the 5 sensory systems
- mechanoreception - tactile/sound stimuli
- chemoreception - chemical perception
- photoreception - light, visual
- hygroreception - humidity, moisture
- thermoreception - temperature
what are the different types of mechanoreceptors
- mechanosensilla
- propioreceptors
- sound receptors
describe mechanosensilla
sensory hairs of different shapes located on tarsal segments of legs, antenna, mouthparts, body surface
what are the components of mechanosensilla
a) rigid hair in a membranous socket
b) sense cell with a dendrite enclosed in a scolopale = cuticular filament
how do mechanoreceptors respond to stimuli
- hair deforms/deflects (bends)
- dendrite deforms = production of electrical potential
- mechanosensilla perceive changing stimuli
- hair distorted = nerve firing
- if hair remains distorted - nerve stops firing = response is phasic
describe proprioreceptors
provide continuous information on body posture and position. include hair plates and companiform sensilla
what are hair plates
- proprioreceptor
- perceive a constant sitimulus
- if hair remains distorted, nerve continues to fire = tonic response
what is the mode of action for companiform sensilla
(proprioreceptor)
1. dendrite is enclosed on a scolopale which is attached to a thin dome (located on legs)
2. nerve is stimulated as long as leg bears weight
3. if insect is on its back, then there is no stress on the dome = no nerve firing = activation of righting reflex (tries to get back on its feet)
what are the 2 types of sound receptors
- johnstons organ
- tympanal organ
describe johnstons organ
- suspended sensilla = scolopidia
- vibrations cause the flagellum to move in its socket = exciting inner and outer scolopidia
where is the tympanal organ present
- many adult insects
- metathorax, abdomen
what are 3 common features of the tympanal organ
- thin cuticular membrane = tympanum
- large air sacs appressed to tympanum
- scolopidia sitting on top of air sacs
mode of action of tympanal organ
- sound waves strike tympanum = results in vibration
- vibration is transferred to the air sacs
- scolopidia (sitting on top of air sacs) are excited
= sound perception
what are 2 types of chemoreception
- olfaction (smell)
- gustation (taste)
