Term
| Define Homoeostasis and list 3 behavioural and 5 physiological adaptions |
|
Definition
Behavioural:
-Seeking humid environments
-Night vs Day activity
-Shade seeking
Physiological
-Waterproofing
-Respiratory adaptions ie. open/close spiracles
-Flight, increases water content by metabolic water production
-Dehydration tolerance
-Excretion in Malphigian tubules and water reabsorption in rectum |
|
|
Term
| What are malphigian tubules? |
|
Definition
| Malphigian tubules are long blind-ended tubes floating in the haemolymph. They are derived from the hindgut and sit at the mid-hind gut junction. They take up water, salt, and metabolic waste from the haemolymph and deliver it into the hind gut for excretion/ reabsorbtion |
|
|
Term
| Describe how urine is produced? |
|
Definition
| Fluid is transferred from the haemolymph to the malphigian tubules by active transport of potassium (K+). Fluid is reabsorbed in the hindgut/rectum and nitrogoneous waste and excess water is excreted. |
|
|
Term
| What is 'the honeycomb border' and what is it's function? |
|
Definition
| Cells that make up the distal end of the Malphigian tubules. Consist of tightly packed microvillae and are the main secretory cell of the tubules. Sodium (Na) and potassium (K+) actively pumped accross the membranes and water and 'urate' follows accross the osmotic gradient |
|
|
Term
| What is 'the Brush border' and what is it's function? |
|
Definition
| Cells that make up the proximal end of the MT. Have widely dispersed microvillae and a greater proportion of mitochondria in the basal membrane, suggesting more ative transport occurs here. K+ actively pumped into haemolymph drawing out water and concentrating the uric acid. |
|
|
Term
| How does Rhodnius sp. maintain water content? |
|
Definition
| Feeding stimulates the production of a haemolymph borne 'diuretic' hormone that stimulates the production of urine and inhibits the absorption of water by the proximal end of MT or rectum. |
|
|
Term
| What is a 'rectal pad' and what is it's function? |
|
Definition
| Lines the rectum, and functions in the reabsorbtion of water into the hemocoel. Active ion transport facilitates the osmotic movement of H2O. Ions are recycled from the intercellular spaces back into the rectal pad cells. [image] |
|
|
Term
| What is the 'cryptonephridial system' and what is it's function? |
|
Definition
| Its an arrangement of the distal MT in close association with the rectum surrounded by a perinephric membrane. Ions are actively pumped into the MT lumen and water follows, resulting in very dry faeces. |
|
|
Term
| What are the four types of Mechanoreceptors? |
|
Definition
-Hair-types seen externally ie. Sensilla chaetica
-Dome-types seen externally ie. Campaniform sensilla
-Attached to the epidermis of cuticle ie. Scolopodia
-Multipolar stretch receptors |
|
|
Term
| What is the difference between a phasic and a tonic nerve response? |
|
Definition
Phasic nerve response is when impuleses are sent only with initial bending of the hair in the socket. With continued deflection, the signals stop. This is used is touch sense to inform the insect of 'new' interactions
Tonic response is when AP are sent as long as the hair is deflected. THis is used in proprioception. |
|
|
Term
| How is a nerve receptor formed? |
|
Definition
| The sensory nueron in surrounded by several accessory cells. The inner thecogen cell secretes the dendrite sheath and the outer tormogen cell secretes the socket before withdrawing to leave a lymph chamber behind. |
|
|
Term
| How can socket based mechanoreceptors be modified, and for what purpose? |
|
Definition
| Some can only bent in one direction so that only a certain movement will trigger a response eg. Raster in cane beetles (collection of setae near the anus) |
|
|
Term
| How is movement in the joints detected? |
|
Definition
| Hair plates located at the coxal joints of the insect monitor body position (proprioception) |
|
|
Term
| What is the campiform sensilla, what is is it's function? |
|
Definition
| It is a mechanoreceptor that occurs on mouthparts, basal segments of antennae, near wing veins and on ovipositors. Anywhere where the cuticle is stretched. It is a small dome in an area of cuticle usually oval in shape. A sensory nerve ending is joined with the cuticle dome and responds to the movement/ stretching of the dome. |
|
|
Term
| What is the scolopodium, what is it's function? |
|
Definition
Sometimes referred to as a 'chordotonal organ', they are clustered together into complex hearing organs in some insects (ie. Johnston's organ in mosquitoes)
The thecogen (scolopale cell) envelopes the nerve cell and a cap sits on the top. Displacement of the cap and movement of the scolopale cell triggers an action potential |
|
|
Term
| Subgenual organ what is it? What important function does it have? |
|
Definition
| Internal organ comprised of 10-40 scolopidia and located in the proximal part of the tibia. (Absent in Coleoptera and Diptera) Clusters of sensory nuerons attach to the cuticle and respond to substrate variations, (50-8kHz depending on species) important for the detection of predators |
|
|
Term
| What comprises the johnston's organ? |
|
Definition
| Consists of groups of scolopodia arranged in the pedicel of the anntennae of Diptera. Best known in the male mosquito, detects the wing beat frequency of females. |
|
|
Term
|
Definition
| True ears are called 'Tympanal organs' and comprise of a thin cuticular membrane backed by an air sac so it can vibrate freely with changes in air pressure. 1-1000 scolopodia are attached to the centre or adjacent to the membrane. They appear in a variety of positions on the insect body. |
|
|
Term
| How do noctuid moths avoid predators? |
|
Definition
| Two scolopodia are present in the tympanal organ and each responds in a different way. A1 is phasic and requires bursts of sound to keep it activate, it responds to distant sound. A2 responds |
|
|
Term
| What is a stretch receptor? How does it work? |
|
Definition
| It is a nerve cell with multiple nerve endings. 'Multipolar' nueron. Nessercary to monitor swelling of reproductive organs, mouthparts and wings. Principle method of sensing stretch in soft-bodied larvae. Firing in a tonic pattern proportional to the amount of stretching |
|
|
Term
| What is the sensilla chaetica? |
|
Definition
| Setae or spines used for touch only, is made up of a socket and hair that moves sending an action potential. |
|
|
Term
| List 5 different types of olfactory sensilla |
|
Definition
- Basiconic sensilla (pegs)
- Capitate sensilla (Bulbous or club shaped pegs)
- Coeloconic sensilla (Pegs sunk into pits)
- Ampulaceal sensilla (Pegs sunk into deep pits)
- Placoid sensilla (Plate like disks)
- Trichoid sensilla (Tapering hair-like structures) |
|
|
Term
| How does an olfactory sensillum function? |
|
Definition
The cuticular walls of the sensilla are perforated with many pores in which molecules can enter and make contact with the dendrites.
The odour molecule is carried by a transport protein to the binding sites on the receptor and an action potential can be triggered. |
|
|
Term
| How do gustatory sensilla function? |
|
Definition
| they have a single pore at the tip, larger than those in olfactory sensilla. A porous plug plug may fill the hole. These are located on the palps, mothparts and the legs and tarsi |
|
|
Term
| What is an example of a humidity receptor? How does it work? |
|
Definition
| The coelocapitular sensilla in bees, sensillum capitula in cockroaches and styloconic sensilla in the silkmoth respond to humidity in the air. they have no pores, and respond to temperature as well as humidity. |
|
|
Term
| How can densities of sensilla vary? |
|
Definition
| Different requirements of insects in various stages selects for the optimal amount of sensilla for function and conservation of energy and resources. Differences are found between juvenile and adult stages, male and females etc. |
|
|
Term
| How does the odour molecule reach the dendrite inside the sensillum? |
|
Definition
| Once inside the lumen of the sensilla, the molecule binds to Odour Binding Proteins (OBPS) which are thought to protect the molecule from degredation by enzymes. The OBP transports the molecule to dendrite receptors which when linked opens ion sodium/potassium ion channels. Afterwards the odour molecule is broken down by enzymes. |
|
|
Term
| What are the 5 dendrite receptor types? |
|
Definition
- Olfactory receptors (Ors) respond to volatile compounds, food odours and chemical components. They weave across the dendrite membrane
- Gustatory receptors (Grs) respond to sugar, caffeine and carbon dioxide and weave across the membrane.
- Ionotropic receptors (IRs) respond to volatile amines, carboxylic acids and food odours and have an irregular pattern across the membrane
- Transient receptor potential (TRP) channel family respond to Humidity and isothiocyanates (as found in wasabi) and have the same irregular shape of IRs.
- Amiloride-sensitive degenerin/epithelial Na+ channels (DEG/ENaC) respond to salts (Na) and have a larger loop inside of the dendrite. |
|
|
Term
| How do insects regulate their feeding patterns? |
|
Definition
Intake of sugars or specific feeding can stimulate the production of hormones in the haemolymph that act on the receptiveness of specific sensory nuerons.
For example, a grasshopper that was fed on a high protein diet would be far more responsive to sugars and carbohydrates and vise versa.
ORNS in mosquitoes sensitive to host chemical lactic acid are tuned down after a blood meal. |
|
|
Term
| What are the five-types of odour induced orientation? |
|
Definition
- Ortho-kinesis
- Klino-kinesis
- Klino-taxis
- Tropo-taxis
- Anemotaxis
[image] |
|
|
Term
| What is the aim-and-shoot strategy? |
|
Definition
| An insect in contact with a substrate can detect the direction of wind using mechanoreceptors. If an odour activates take-off, the insect can maintain an upwind setting so long as the surrounding visual cues remain informative. If the odour stimulus is lost, the insect lands and waits until it re-contacts with the stimulus. Tsetse flies use this strategy. |
|
|
Term
TRUE or FALSE
An insect in flight cannot gauge wind direction using mechanoreceptors. |
|
Definition
|
|
Term
| Give a simple explanation of how memories are formed. |
|
Definition
| The CNS released octopamine and dopamine when sensory stimuli are associated with a reward or punishment. These brain chemicals can modify neural activity within the mushroom body, strengthening or weakening the connections between active/inactive cells. |
|
|
Term
| What do insects utilise vision for? |
|
Definition
| Finding mates, identifying rivals, detecting moving prey, finding suitable oviposition sites, and maintaining circadian rhythmns. |
|
|
Term
| What are the three primary types of eye structures? |
|
Definition
Compound eyes- which are paired structures (normally on either side of the head) composed of many units called ommatidia. Ommatidia are cartridges composed of cuticle, support cells, photoreceptors (cells which detect light and pigment cells)
Ocelli- are single-lens eyes often located on the top of the head (where there are normally three near each other).
Stemmata- are also single-lens eyes which are often found in holometabolous larvae on the sides of the head. |
|
|
Term
| What is the apposition eye? |
|
Definition
| Arrangement of the ommatidia in which the photoreceptors make up most of the ommatidia. The photoreceptors form a cartridge of cells including the pigment cells extending from the basal lamina to the crytalline cone. Pigment cells surround the photoreceptors and block light from straying outside of each cartridge of cells. Therefore, an image is divided into the different views of the facets of the eye. This is usually seen in light adapted insects. [image] |
|
|
Term
| What is the superposition eye? |
|
Definition
| Coleoptera and lepodoptera have superposition eyes. photoreceptors are located close to the basal lamina. Image is not divided, so more photons reach the receptors. Gathers more light, helpful for nocturnal insects. [image] |
|
|
Term
| How can the photoreceptors be arranged for different conditions? |
|
Definition
The rhabdom can be more or less tightly packed to allow more light through.
Pigment concentration in the pigment cells can vary: more pigment in light adapted inscets and less in dark
Nocturnal insects can hace a structure at the base of the ommatidia called the tapetum that reflects photons to increase sensitivity. |
|
|
Term
TRUE OR FALSE
All of the ommatidia in a single compound eye are identical |
|
Definition
FALSE
Insects often have high and low resolution areas in the eye. High resolution areas have a very low interommatidial angle whilst the rest of the eye has a lower resolution at a higher ommatidial angle. |
|
|
Term
| How is light converted into a nueral signal? |
|
Definition
| The phototransduction mechanism is a series of reactions, where a molecule, retinal, changes shape with the introduction of light. This conformational change is then translated into enzymatic changes. These enzymatic changes induce a G-protein cascade, leading to the opening of channels and depolarization (or excitation) of the photoreceptors |
|
|
Term
|
Definition
| A single-lense eye normally located on the top of the head. The focus depth of ocelli indicates that they don't form images but can detect changes in light and poosibily changes in horizon. |
|
|
Term
|
Definition
Stemmata are also single-lens eyes which are often found in holometabolous larvae on the sides of the head
Stemmata are also thought to be poorly developed for image formation, but can be used to detect light. |
|
|
Term
| What are the four functions of vision? |
|
Definition
- Detection of polarised light patterns
- Detecting movement of surroundings
- Detecting colour
- Detecting patterns in a visual scene |
|
|
Term
| How is the insect eye optimised for sensing polarized light? |
|
Definition
| Alignment of the rhabdom (microvillae) in the photoreceptor captures only the photons in the same longitudinal direction as the microvillae. This ensures that polarized light moving in the direction of the microvilli is captured by the photoreceptors. |
|
|
Term
| What are the different modes of vision? |
|
Definition
Wild field motion- detection of the world moving around you as you move in the environment
Small field motion- tracking of small objects in the world |
|
|
Term
| How do insects see colour? |
|
Definition
| In general can see from UV to green wavelengths, some can't see yellow or red. Although some butterflies can see from UV to red. |
|
|
Term
| Describe the 'black box' of the insect nueral system |
|
Definition
|
|
Term
| What is the basal condition of the nueral system? |
|
Definition
| The basal CNS system comprises of a bundle of fused ganglia that makes up the brain and a ganglia for each segment of the thorax and abdomen. The ganglia in the thorax are responsible for the locomotion of the insect and connected internuerons maintain synchronisation of limbs. The abdominal ganglia process mechanosensory information and homeostatic functions. |
|
|
Term
| What is the subesophageal ganglion? |
|
Definition
| Is closely associated with the brain and lies underneath the beginning of the gut. Contains key structures for neurohormones and is a major interfcte between the body and the brain. |
|
|
Term
| What structures is the brain divided into? |
|
Definition
From anterior to posterior in the head:
1. Protocerebrum
2. Deutocerebrum
3. Tritocerebrum
4. subesophageal ganglion
They are all relatively fused in most insects. |
|
|
Term
| What are the functions of the different brain areas? |
|
Definition
1. Protocerebrum - Visual input from eyes and ocelli, and major central brain structures and mushroom bodies
2. Deutocerebrum- Antennal inputs and processing
3. Tritocerebrum- nerve connections to the labrum of the insect and gustatory inputs |
|
|
Term
| What structures make up the protocerebrum? |
|
Definition
|
|
Term
| What is a neuromodulator? |
|
Definition
Neuromodulators generally have a slow effect on the postsynaptic cell and induce long-term changes in the cell through second messenger systems and changes in protein expression patterns of the cell
Neuromodulators can cause the target cells to increase or decrease general activity, change synaptic strength, or change the entire dynamics of the network. Important in learning and memory.
ie. Dopamine, seratonin, octopamine in the CNS |
|
|
Term
| How are photoreceptors in a single ommatidium seperated? |
|
Definition
- Photoreceptors 1-6 are often green-sensitive and output to the lamina, which are also considered to feed into the motion detection pathway
- Photoreceptors 7-8 (9) are often UV or blue sensitive and send their outputs to the medulla and input to the colour and processing pathway
Lamina then sends inputs into the medulla |
|
|
Term
| How is the visual system laid out? |
|
Definition
Retina --> lamina --> medulla --> lobula complex --> central brain
The system is layered within the visual system, but it is also retinotopic, in that the world outside is represented on the retina in a spatial array, with each ommatidial cartridge represented in columns in the lamina, the medulla, and, sometimes, in the lobula complex |
|
|
Term
| How does motion detection work? |
|
Definition
Motion processing involves detecting when objects are moving in the environment.
The way some neurons work is to detect changes in light across neighboring cartridges and integrate it, finally responding when things move in one direction or another |
|
|
Term
| Polarized light processing? |
|
Definition
| Polarized light information enters via the photoreceptors, goes through the medulla into a portion of the lobula and projects into the central brain. |
|
|
Term
| What is chromatic opponency? |
|
Definition
| Colours can trigger excitatory or inhibitory responses and can amplify eachother or cancel out. |
|
|
Term
| How do insects process olfactory information? |
|
Definition
| When odorants bind to receptor proteins and produce a response in the ofactory receptors (ORN), it travels along the ORNs which form bundles along the antennal nerve and enter the brain at the antennal lobe. They then project to structures called glomeruli. They send signals to projection nuerons (PNS) which project to the lateral horn, into the lateral protocerebrum and to the mushroom bodies. |
|
|
Term
| What is the difference between asynchronous and synchronous muscles? |
|
Definition
Synchronous muscles require constant stimulaton from the nervous system to contract. Seen in muscles used for walking and direct flight
Asynchronous muscles only require a few nueral inputs to initiate contraction and maintain, and the muscles may oscillate long after the time of neural input. Seen in indirect flight muscles. |
|
|
Term
| Describe the components of the insect leg musculature |
|
Definition
Adductor: pulls limbs away from the body
Abductor: pulls limbs toward the body
Rotator: rotates the limb around a joint
Levator: flexes the parts of the joint upward
Depressor: extends the parts of the joint downward
Extensor: extends the joint
Flexor: extends the joint |
|
|
Term
| What types of sensilla can be found on the legs? |
|
Definition
| Small peg-like sensilla, sensory hairs, campaniform sensilla and mechanosensory inputs all over to detect strain, pressure and leg position. |
|
|
Term
| What is the difference between indirect and direct flight muscles? |
|
Definition
The indirect-flight muscles connect from the coxa or base of thorax to the underside of the top of the thorax and are not directly connected to the wing sclerites. Have longitudinal muscles for manourvering of wings.
The direct mucles are connected from the base of the coxa or abdomen to the wing schlerites and have two mucles for each wing for up and down movements. |
|
|
Term
| What types of sensory organs are found on the wings? |
|
Definition
| Campaniform sensilla and setae are there to detect deflections of the wings. |
|
|
Term
| What are the halteres? What is their function? |
|
Definition
| Modified pair of hind wings in the order Diptera and function as stabilising gyroscopes and detect accelerations of the yaw axis. They beat at the same frequency as the wings providing fast feedback on position of the fly. |
|
|
Term
| How do insects take flight? |
|
Definition
In taking off, flies push down their middle legs (the mesothoracic leg).
The mesothoracic leg moving down then shifts the thoracic sclerites, resulting in the wings lifting up.
As the wings lift up, the flight musculature is engaged, resulting in the beginning of flight. |
|
|
Term
| Where is learning known to occur? |
|
Definition
| Antennal lobes, mushroom bodies and the central complex |
|
|
Term
| What are the different types of memory> |
|
Definition
| Short term, mid-term, and long term memory. There is also anesthesia resistant memory |
|
|
Term
| How does learning happen at the synaptic level? |
|
Definition
1.Number of neurotransmitters released can increase or decrease
2. Number of post-synaptic receptors can increase/decrease
3. cells can also increase or decrease the number of synapses connecting them |
|
|
Term
| What are the three main phases of memory? |
|
Definition
1. Acquisition
2. Consolidation
3. Retrieval |
|
|
Term
| What organs make up the male reproductive system? |
|
Definition
| Paired testes, paired vas deferens (may be dialated to form a storage organ for spermatozoa), accessory glands, and ejaculatory duct muscularised to form a pump, and an aedagus (penis) |
|
|
Term
| What organs make up the female reproductive system? |
|
Definition
| Terminal filaments where oocytes are formed, ovarioles where maturation of eggs, spermatheca; storage for sperm after mating, bursa copulatrix- a muscular expansion that is the site of egg fertilisation and coating of female accesory gland secretions, accessory glands, gonopore, genital chamber. |
|
|
Term
|
Definition
| nurse cells produced in the terminal filaments |
|
|
Term
| What is the vitelllarium? |
|
Definition
| large part of the ovariole in which oocytes grow by deposition of yolk in a process called vitellogenesis |
|
|
Term
|
Definition
| The germarium at the distal end of the ovariole contains female germ cells (oogonia), which undergo mitotic division and become primary oocytes, oocytes pass down the ovariole wrapped by follicle cells and then undergo vitellogenesis in the vitellarium. |
|
|
Term
| List the three types of ovarioles and the differences |
|
Definition
1. Panoistic- no trophocytes (seen in primitive insects)
2. Telotrophic - the trophocytes in the distal end of the ovariole remain in contact with the oocyte through long tubes (nutritive cords) that carry nutrient into the oocyte. Found in Hemiptera and some Coleoptera
3. Polytrophic- Trophocytes are enclosed in the follicle and intimately associated with the oocyte. Found in most holometabolous species. |
|
|
Term
| When does oocyte reabsorbion occur? |
|
Definition
| In adverse conditions, proteins and lipids dissappear from the oocyte and are reabsorbed into the haemolymph. |
|
|
Term
| What are the 5 phases of oviposition and mating? |
|
Definition
1. Approach to attractants
2. Searching and settling
3. Preparation for egg laying
4. The act of oviposition
5. Post oviposition stage |
|
|
Term
| Describe Pheromones, allomones and kairomones? |
|
Definition
Pheromones are intraspecific signalling and include alarm, sex and attractant pheromones. Allomones and Kairomones and interspecific.
Allomones - The sender benefits
Kairomones - The receiver benefits |
|
|
Term
| What are Pheromone biosynthesis activating neuropeptides? |
|
Definition
| PBANs are produced by the nuerosecretory cells of the subesophageal ganglion and stored in the corpora cardiaca. Released into haemolymph under circadian control and act dircetly on pheromone glands, stimulating pheromone stimulus in females. |
|
|
Term
| What are cuticular hydrocarbons? |
|
Definition
| They are present on all surfaces of insects and play important roles in waterproofing and communication. Roles in communication are relatively unknown. |
|
|
Term
| What two orders are capable of bioluminence? |
|
Definition
Diptera - genus Arachnocampa and Orfelia
Coleoptera - Fireflies, railroad worms and click beetles |
|
|
Term
| How is bioluminence produced in adult beetles? |
|
Definition
| The cuticle in the posterior abdominal segments is visible and contain an array of symmetrically packed, modified fat body cells that are the light emitting cells (photocytes) they are innervated by nuerons that release octopamine. |
|
|
Term
| How does bioluminescence occur in glow worms? |
|
Definition
| A reaction involing the protein luciferin, the enzyme luciferase and ATP in the presence of oxygen. Regulation of BL appears to be under nueral control and suggests that the default state is to bioluminesce and is turned off in daylight or under stressful conditions. Octopamine is thought to be involved in teh expression. |
|
|
Term
| What are the five types of thermoregulation? |
|
Definition
Homeothermy- Body temperature is relatively constant and independent of ambient temperature. The term is usually applied to birds and mammals.
Poikilothermy- Body temperature is variable and dependent on ambient temperature.
Endothermy- Heat that determines body temperature is produced by the animal's own energy metabolism. The only continuously endothermic terrestrial animals are birds and mammals.
Ectothermy- Heat that determines body temperature is acquired from the environment by radiation, convection, or conduction.
Heterothermy- Endothermic part of the time and ectothermic part of the time. |
|
|
Term
| What are the three zones of growth in the testes? |
|
Definition
- Zone of growth: primary speratogonia divide via mitotic divisions and increase in size to form spermatocytes
- Zone of maturation and reduction: Spermatocytes divide meiotically to form spermatids
- Zone of transformation: speriogenesis occurs (spermatids mature into mature spermatazoa) |
|
|
Term
TRUE OR FALSE
Sperm are filamentous and the head is not very prominent |
|
Definition
TRUE
Spermatozoa are usually filamentous. 300µm to over 1 mm in length. Head and tail are approximately same diameter, unlike most mammalian sperm. Sperm head is occupied by the nucleus, acrosome and mitochondrial derivative. |
|
|
Term
| What are some functions of the male accessory gland secretions? |
|
Definition
- Activation of spermatazoa
- Spermatophore formation
- Release of a mating inhibition factor
- Accelerate oocyte formation
- Provide nutrition for female
- Small peptides that can affect female via nervous system eg. Receptiveness to males, oviposition-stimulating etc. |
|
|
Term
| What are the possible roles of the bursa copulatrix |
|
Definition
- Receiving the aedagus and male secretions
- Site of egg fertilisation
- coating of accessory gland secretions |
|
|
Term
| What role does the spermethecal accessory gland play? |
|
Definition
| Aids in the filling of the spermatheca and provides nutrient to the sperm. |
|
|
Term
| What is the function of the Ectadenia and Mesadenia? |
|
Definition
| Ectadenia opens into the ejaculatory duct and the mesadenia opens from the testis to the vase deferens |
|
|
Term
| Whats an example of cuticular hydrocarbon? |
|
Definition
| in many flies, sex pheromones are distributed in the waxes of the cuticle and are detected by taste on contact |
|
|
Term
|
Definition
| Special scales often on wings that are specialised to carry scent. Release of pheromones. |
|
|
Term
| What is an example of an oviposition pheromone? |
|
Definition
|
|
Term
| What are some examples of alarm pheromones? |
|
Definition
- many aphid species release alarm pheromone from droplets secreted from tube-like structures called cornicles on their dorsal posterior
- Hymenoptera release alarm pheromones from their sting chamber. Isopentyl acetate is the main component of the pheromone |
|
|
Term
| Describe the evolutionary origin of bioluminescence |
|
Definition
| They are evolutionarily derived from the abdominal fat bodies. Initially evolved for an aposematic function, it was co-opted for sexual attraction and used in conjunction with pheromones. Now they don't use pheromones in sexual attraction and just light although it is still thought to have an aposematic function. Seen in conjunction with a 'switch' in the temporal niche |
|
|
Term
| What are the differences between wide and small field motion in wiring of the brain? |
|
Definition
| They are found in the medulla |
|
|
Term
| What is the function of the lobula plate? |
|
Definition
| The lobula plate has been found to be responsible for two portions of vision: The horizontal system, detecting front to back motion, and the vetrical system. |
|
|
Term
| How do insects navigate swarms? |
|
Definition
| The descending contralateral motion detecter cell (DCMD cell) sends input to the motor centers to allow the insect to move away from an object. |
|
|
Term
| How do the colour and motion pathways differ? |
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Definition
| The colour pathway in insects operates in the front portion of the brain whilst motion detection pathways operate in the hind portion. |
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Term
| Explain the difference between extrinsic and intrinsic muscles |
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Definition
Intrinsic: All muscle attachment sites are within the leg
Extrinsic: Have attachment points outside of the leg, such as within the thorax |
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Term
| Explain the 'tarsi reflex' phenomena |
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Definition
| Many insects have a 'tarsal reflex' where if the tarsi is touching any substrate, wing-beating stops immediately or will not be initiated |
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Term
| Explain the two different theories of light regulation in beetles. |
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Definition
Nitrous oxide based: When the light is off, mitochondria consume O2 and insuffient O2 reaches the peroxisomes to initiate a flash. After a nerve impulse (octopamine releaesed) released nitrous oxide which inhibs O2 consumption by mitochondria, enabling O2 to reach the peroxisomes and react with the luciferase/luciferin and make a 'flash' of light.
Tracheal fluid: The trachea is filled with fluid when light in not emitted, nueral stimulation leads to increase in osmotic potential of the tracheolar cell decreasing fluid levels allowing more oxygen supply to the photocytes and FLASH |
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Term
| Why does bioluminence appear to be the default state of the gloworm fly larvae? |
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Definition
| When exposed to anaesthetics causes an acute release of light even if larvae were not glowing at the time of exposure. |
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Term
| What kind of thermoregulation is seen in insects? |
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Definition
| Insects are ectothermic but can increase/decrease heat with endothermic processes such as flight, shivering or internal water regulation. |
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Term
| How does 'shivering' help an insect to warm up? |
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Definition
| “The primary mechanism is for the flight muscles—DLM and DVM—to work against each other. They fire synchronously and the wings do not flap but work is being done. Sometimes visible in the form of high frequency “whirring” of the wings” |
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Term
| How do insects 'lose' heat? |
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Definition
Tiger beetles raise their body away from the hot sand, they also fly short distances to lose heat convectively.
Some insects shunts heated haemolymph into the abdomen from where it dissipates.
Some use evaperative cooling through reguritation (bees) and thermo sensors are in the head and cause instand reguritation when heated. Requires a high water reserve.
Condensation structures in desert beetles |
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Term
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Definition
Bees have a coiled dorsal vessel in the petiole. Suggested to function as a counter-current mechanism for maintaining elevated temperatures of the thorax, preventing warming of the abdomen by haemolymph.
Cool abdominal haemolymph is pumped anteriorly through the petiole within the dorsal vessel.
Warm thoracic haemolymph is forced back through the petiole.
The presence of coils in the dorsal vessel maximises heat exchange. |
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Term
| Describe how insects survive supercooling? |
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Definition
| Ice crystals form in the haemolymph, where many supercooling insects have very high concentrations of glycerol reducing formation of ice crystals. |
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