Entomology Midterm #2 Flashcards
Lectures 8-13
what is the main toxic element produced from amino acid metabolism?
nitrogen
what are the three methods of packing nitrogen?
ammonium, urea, uric acid
what are the disadvantages of the ammonium method of oxygen packing?
very toxic, requires a lot of water to rid the body of this waste
what two methods of oxygen packing are relatively non-toxic?
urea and uric acid
what are Malpighian tubules?
the “kidney” of insects
what do malpighian tubules look like?
long, thin tubules (2-200) that wave freely in haemolymph
what is the function of Malpighian tubules?
filter and remove wastes (especially nitrogenous products), and absorption of amino acids, salt, and water
where do Malpighian tubules empty their secretions?
into the gut at midgut-hindgut junction
what is the end product of breakdown in malpighian tubules?
ammonia
in most terrestrial insects what is ammonia converted into?
uric acid (insoluble and crystallized out easily)
how does uric acid move out of haemolymph into Malpighian tubules?
passive diffusion (down its concentration gradient)
what does the lining in Malpighian tubules do?
protects rectal cells from relatively large amounts of toxic material in faces
where are the anal lobes/ anal papillae located in mosquitos?
rear end of the larva
what is the function of anal lobes/ anal papillae?
absorb salt
how do the size of anal lobes vary?
based on the concentration of salt in the rearing medium
when is metabolic water produced?
when sugars are broken down into energy, carbon dioxide, and water
what are the three different feeding strategies?
phytothagnous - plant eating
saprophagnous - dead or decaying organic matter
carnivorous - meat eating
what are some physical defences that provide challenges to digestion?
hooks, spines, trichomes, tough leaves
what are the three types of challenges when it comes to digestion?
chemical, physical, low nitrogen levels or low nitrogen/ water levels
what problems do sap feeding insects face when ingesting huge amounts of water?
overloads digestive systems, dilutes enzymes, dilutes haemolymph
what do fat bodies consist of?
loose aggregation of cells invested in connective tissue
what are fat bodies concerned with?
fat metabolism and metabolism of sugars and proteins
what type of regulation are fat bodies involved in?
hormone regulation
what are the four functions of fat bodies?
- metabolism of carbohydrate, lipids and proteins
- regulation of blood sugar
- synthesis of haemolymph proteins
- storage os fats, proteins, and glycogen
what is the trachea?
a ventilation system where air enters the body through spiracles and are carried through the body by increasingly fine branching structures to within 3-4 cells of all parts of the body
what amount of spiracles are present through out an insects body?
max of 2 pairs in thorax and max of 8 pairs in abdominal segments
how is air carried through the body by spiracles?
by increasingly fine branching structures to within 3-4 cells of all parts of the body
what is insect blood not involved with
gas transport
what does diffusion account for
gaseous requirements of tissues in most insects at rest
how does the insect pump air when at activity or when it is simply larger in size?
pumps air in and out through tracheal system by collapsing and expanding air sacs
how are tracheae formed?
invagination of the ectoderm and are thus lined with cuticle
what is the first region that is supplied with oxygen?
head region
where are spiracles that supply wing muscles?
isolated from rest of body
what is an advantage to spiracles that supply wing muscles being isolated?
large amounts of Co2 produced in flight are largely confined to the thorax
what is the spiracular entrance lined with?
hairs to keep dust out
why are spiracles generally kept shut for short amounts of time?
to prevent water loss
what is opening of spiracles controlled by?
CO2 production in haemolymphs
when do spiracles become more resistant to opening?
if water levels are low
when are cuticular linings of trachea shed?
after each moult
immediately after a moult, what are there spiracles filled with?
water. later replaced by gas (gas does not enter through spiracles)
how does a cuticle change
changes from hydrophilic to hydrophobic as it becomes tanned
what is forced out when cuticle changes from hydrophilic to hydrophobic
water
what is the tympanic organ generally backed by
air sacs
how is sound produced through the tympanic organ?
allows vibration of organ which produces sound
how do aquatic insects obtain air?
get it from the air (when they resurface) or from dissolved air in the water
how is air held underwater in diving beetles?
under elytra
what is a plastron?
a permanent bubble which is a film of thin air on outside of body held by specialized hairs
plastron function?
permanent interface between water and air, acts like a grill
what are gills?
leaf0like structures of very thin cuticle with a network of tracheoles
what is pudding in butterflies (male specifically)?
sipping moisture from mud puddles to take in salts and minerals
what do male butterflies do with the extra salts and minerals obtained from pudding?
incorporates them into their sperm
what are ganglion?
bundles of neurons from which peripheral nerves run to sense organs, muscle system, internal organs, and secretory glands
what makes up an insects brain?
fused ganglia
how many ganglia are in each body section?
3 in head, 5 in body
what are thoracic ganglia important for?
movement
what are abdominal ganglia important for?
digestion, excretion, and reproduction
what is a neurosecretory function?
secretion of hormones which initiate events like moulting, sexual maturation, and diapause
how do muscles contract?
ganglia send signals through nerve cells causing them to contract
how many neurons does an insect brain have?
~200,000
what are dendrites?
cell bodies where nuclei are located
what are ganglia formed from?
aggregated neurons that come together to form ganglia
what forms nerves?
bundles of axons
what are action potentials?
nerve impulses that are conducted along axons
how can Neve impulses be enhanced or suppressed?
by regular inputs received from dendrites
what does it mean when insect neurons are unipolar?
the neurons have only single axonal projections
what neurons are bipolar and multipolar?
bipolar = some sensory neurons
multipolar = neurons in brain and stretch receptors
what are the three types of neurons?
unipolar, bipolar, multipolar
what are unipolar neurons? and what do they stimulate?
have only one structure that extends away from the cell body. stimulates muscles or glands
what do bipolar neurons do?
receive signals from photoreceptor cells that are sensitive to light and transmits the signals to ganglion cells which take them to the brain
(photoreceptor cell signal -> bipolar neuron -> ganglion cells -> brain)
what do multipolar neurons do and what is their structure?
may be found between sclerites to detect “stretching”. many extensions but only one axion
what are afferent (sensory) neurons? and what is their function?
dendrites associated with sense organs or receptors.
function: carry info to CNS
what type of neurons are afferent neurons?
bipolar or multipolar
what are efferent (motor) neurons?
unipolar cells which conduct signals away from the CNS and stimulate muscle and glandular responses
what are interneurons (association) neurons?
unipolar cells (with several branching axons) that conduct signals within the CNS
where do individual neurons connect?
synapses
what is the process of synaptic transmission?
1) nerve impulse reaches synapse
2) chemical messenger released
3) neurotransmitter diffusion across synapse
4) potential membrane potential change in dendrites of one or more connecting neurons
what are the two types of postsynaptic neurons?
excitatory and inhibitory
what are the four neurotransmitters?
acetylcholine, 5-hydroxytryptamine, dopamine, noradrenaline
what do neurotransmitters do?
transmit nerve impulses and stimulate muscle contractions
what is the only “solid: organ in the insect body?
ganglia
where isn haemolymph not present?
inside the ganglia
where do nutrients and wastes diffuse across?
a sheath that covers the ganglia
what does the central nervous system consist of?
paired ganglia connected to each other along a ventral nerve cord
what does the ventral nerve cord consist of?
paired segmental ganglia running along the ventral midline of the thorax and abdomen
what is the protocerebrum associated with?
vision, ganglia innervate the compound eyes and ocelli
what does the deutocerebrum do?
processes sensory information collected by antennae
what are the two things the tritocerebrum does?
1) innervation of the labrum and integrates sensory inputs from photo and deutocerebrums.
2) links brain and stomatodeal nervous system that controls internal organs
what does the protocerebrum have?
large lobes associated with the eyes
what are optic lobes?
link between the receptor surfaces of the compound eyes and the brain
what function do antennal lobes have?
receive input from millions of olfactory receptors and integrate taste and smell info
what are mushroom bodies?
“higher” centres in the insect brain, where learning, memory, and integration occur
what do neurosecretory cells do?
produce peptide hormones that regulate endocrine and homeostatic functions in insects
what do corpora cardiaca and corpora allata do?
both secrete hormones. corpora allata produces juvenile hormone
what does the subesophageal region consist of?
fused neural elements from three primitive body segments that merges with the head to form mouthparts
what 6 things does the subesophageal region innervate?
mandibles, maxillae, labium, hypopharynx, salivary glands, and neck muscles
what is the stomatogastric (stomatodeal) visceral nervous system associated with?
brain, salivary glands, and foregut
what is another name fro the visceral nervous system (VNS)?
sympathetic nervous system
what is the ventral VNS associated with?
ventral nerve cord
what is the caudal VNS associated with?
posterior segments of abdomen
what does the stomatogastric (stomatodeal) VNS innervate?
innervates internal organs
what does the hypocerebral ganglion innervate?
insect heart
what does the frontal ganglion innervate?
pharynx and muscles associated with swallowing
what does the recurrent nerve do?
connects frontal ganglion with a hypocerrebral ganglion. this innervates the heart corpora cardiaca, and portions of the foregut
what does various sensory neurons or receptors differ in?
receptor specificity and receptor sensitivity
what do mechanoreceptors do?
detect movements, vibrations, or other mechanical disturbances
what are examples of mechanoreceptors?
tactile receptors, prioreceptors, sound receptors
what do chemoreceptors do?
detect the presence of chemical substances in the air (smell) or on substrates (tase)
examples of chemoreceptors?
taste receptors on palms, antennal sensillia
what do photoreceptors to?
detect the presence and quality of incident light (electromagnetic radiation)
examples of photoreceptors?
compound eyes and ocelli
what are feeding stimulants in eg 1a feeding?
nutritional factors (sucrose, amino acids) and token stimuli (ATP in blood-feeders, secondary plant compounds)
what is feeding cessation in eg 1a feeding?
sensory habituation and gut stretch
what is 1b feeding?
- labium encloses “needle-like stylets”,
- large food canal + small salivary canal,
- labium does not enter skin
what is a fascicle?
outer pair of mandibles + outer pair of maxillae
what is a phagostimulant?
token stimuli (ATP in blood feeders, secondary plant compounds)
what is diptera?
true flies, aka “two-winged flies”
what does holometabolous mean?
undergo complete metamorphoisis
what is the cycle of complete metamorphosis?
egg, larve, pupa, adult
what are the three suborders of diptera?
nametocera (long-horned flies)
brachycera (short horned flies)
cyclorrhapha (circular seamed flies or aristate antennal flies)
what is vermiform (maggots)?
no legs or distinct capsule, mouthparts reduced to “mouth hooks”
what is culciform?
head capsule with chewing mouthparts
what are the 4 characteristics of diptera?
antenna, legs, wing venation, and chaeotaxy
what is chaeotaxy?
arrangement of bristles especially on head and thorax
what are larve like in suborder nematocera?
aquatic with well-developed head capsules and mandibulate mouthparts
what are pupa like in suborder nematocera?
obtect (appendages adhere to the body wall
what mouthparts do adult nematocerans have?
haustellate
what do male and female nematocerans feed on?
female: blood and sugars
male: sugars only
what are the 10 families in order diptera?
culicidae - mosquitos
simuliidae - black flies
chironomidae - non-biting midges
tipulidae - crane flies
tabanidae - horse and deer flies
asilidae - robber flies
muscidae - house flies
syrphidae - hover and flower flies
drosophilidae - fruit flies
callliphoridae - blow flies
what is haemolymph?
insect blood
what is the appearance of haemolymph?
colourless or slightly green or yellow fluid
what does haemolymph consist of?
fluid or plasma portion (90%) and a cellular portion of haemocytes and a high concentration of free amino acids
what is trehalose?
insect blood sugar
what are the 9 functions of haemolymph?
lubrication, hydraulic fluid, transportation & storage, protection, detoxification, coagulation and plasma precipitation, non-cellular protective factors, heat transfer, reflex bending
what is the ptilinum?
a vesicular organ on the front of the head of flies that aids in rupturing the pupa case
how does thermoregulation happen?
if cold: heartbeat slows so heat stays in thorax
if warm: flight muscles generate heat and heart beat increases
what type of circulatory system do insects have?
open
where do metabolic wastes go after circulatory system?
Malpighian tubules
what are Ostia
pores in the heart through which blood enters
how is blood directed anteriorly?
through peristalsis
how is blood circulated?
undulatory movement from diaphragm, accessory pulsatile structures, and visceral & body movements
where do accessory structures help pump blood to?
down into legs, wings, and antennae
what is the dorsal vessel?
functional insect heart and supported by alary muscles
what are ostioles?
pairs of holes in each segment that allow for haemolymph to be sucked into the vessel with each contraction
where is the ventral diagram located?
above the ventral nerve chord
how does the ventral diaphragm help to pump blood?
acts with thoracic pulsatile organs to pump blood anterior end to posterior end
what is another word for diaphragms?
septa
what is the function of homeopoietic organs?
serve to produce some of the homocytes and serve as phagocytosis centres
what is phagocytosis?
the process of a phagocyte cell (white blood cell) engulfing the entirety of another cell or particle
what aids in backwards flow of haemolymph?
undulations of ventral diaphragm
where is circulation fast and slow?
fast: dorsal vessel
slow: appendages
where does haemolymph circulate through insect wings?
anterior veins and return to thorax via anal veins
what is tidal flow?
all wing veins filling and emptying at the same time
what can hemocytes phagocytose?
viruses, bacteria, protozoa, rickettsias
what is the aorta?
the anterior portion of the dorsal vessel that does not have ostia and is slightly narrower than the heart
what is the heart?
the posterior portion of the dorsal vessel that bears alary muscle and ostia
how many Ostia are there in insects?
number of ostia varies between 2 and 12, depending on the taxon
how do insects avoid freezing?
carbohydrates and cryoprotectants (e.g., glycerol and sorbitol) lower freezing point of the hemolymph
what do the testes consist of?
a number of testicular follicles (sperm tubes), which can vary from 1 in some beetles to over 100 in locusts
what are the testes connected to?
vas deferensand paires seminal vessels and a medial ejaculatory duct
what happens to sperm after they are transferred to the female spermatheca?
undergo further changes to become functional
how is sperm passed through the ejaculatory duct?
through the aedeagus
what happens to the nutrients that are deposited by males into females?
the nutrients are reabsorbed and go towards helping mature the oocytes
what are the 4 functions of the accessory gland fluid?
- help form spermatophore
- maintains sperms
- chemical prevention for other males to impregnate female
- females store fluid in her body so accessory gland will provide nutrients to keep sperm alive
what do ovarioles produce?
oocytes (eggs)
how are eggs fertilized in some insects?
- eggs dropped down from calyx end of ovarioles into oviducts
- eggs are fertilized as they pass through genital chamber
where are oocytes contained?
germanium
how are eggs provided with yolk?
undergo division and proceed into the vitellarium
what is a yolk composed of?
proteins, lipids, carbohydrates, and RNA
what is yolk deposition called?
vitellogenesis
what are yolk proteins derived from?
female haemolymph
what is the function of accessory gland fluid in ants?
pheromones used in marking trails are produced by these glands
function of accessory glands in Hymenoptera?
produce venom which paralyzes their prey
what can cause an egg to be reabsorbed?
inadequate amount of yolk acquired or if fertilization does not occur
what are the 5 types courtship behaviour?
smell (pheromones), vision (wing colouration), hearing (Orthoptera calling), touch/ tactile
how do sex pheromones work in Lepidoptera?
secreted by females to attract potential mates. males have special plumose antennae which allow them to detect the pheromone back to its source
4 types of sound production for mating?
- grasshoppers rubbing forewings across hindwing
- katydids rubbing their wings together
- cicadas abdominal tymbal in males
- green grasshopper male rubs hind leg against wings (generates species specific song)
how does female choice happen in mating?
female eggs are more “valuable” than male contribution
how does sperm transfer happen in primitive (wingless) insects?
sperm is not directly transferred. left on ground in spermatophore for female to pick up
what is the aedeagus?
intromittent organ
what happens during intromission (insertion)?
male holds female with claspers (derived from cerci) or ninth abdominal segment)
in Odonata where does mating generally occur?
during flight
how long does copulation generally take?
few seconds to hours
what is a mating plug?
a structure that locks inside a female and ensures that male semi cannot be scraped out nor can the female mate again for a specific amount of time after
what insects form a mating plug?
mosquitos and butterflies
what insects leave “anti-aphrodesiac”?
heliconius
what insects stay with the female until she oviposits?
Odonata
what is the structure of an insect egg?
chorion exoskeleton, micropyle for sperm entry, aeropyle for O2 penetration, fertilized vie micropyle
what is oogenesis?
mitotic divisions
what does an ovipositior enable a female to do?
deposit her eggs into plant an animal tissue
what two receptors do ovipositors have?
mechanoreceptors and odour receptors
how do females in honeybees and wasps lay eggs?
egg emerges from a pore beneath the sting
what is parthenogenesis?
asexual reproduction
what is oviparous?
egg laying (abandoned) with sufficient Yolk for embryological development
what is ovoviviparous?
sufficient yolk but stays inside mother until hatched
what is viviparous?
low yolk levels, mother supplies nutrients until live birth
what is oestrus ovis?
lays 1st instar larvae into nasal cavities of sheep and goats
sex chromosomes in bisexual insects?
female: xx
male: xy or xo
what are the sex chromosomes like in Lepidoptera and trichopteran?
female: xy or xo
male: xx
how are males produced in Hymenoptera, Thysanoptera, and some Homoptera?
unfertilized eggs (produced through haplodiploidy)
