Term
Define the term integument
~Cuticle & Exoskeleton~ |
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Definition
The cuticle, as well as he layer of cells below the cuticle known as the epidermis.
Culticle can be broken into endo and exocuticle (procuticle), with an epicuticle overlaying. |
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Term
What is the culticle in insects composed of?
~Cuticle & Exoskeleton~ |
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Definition
| Chitin microfibrils - Chitin being unbranched polysaccharide amino sugars. Typically sheet-like arrangements are seen within the microfibrils - linked together by a protein matrix |
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Term
What are the functions of the cuticle (External)
~Cuticle & Exoskeleton~ |
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Definition
Colouration
Protective covering
Antibiotic properties
Tools for cutting etc
Sensory |
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Term
What are the functions of the cuticle (Internal)
~Cuticle & Exoskeleton~ |
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Definition
Insulation
Muscle attachment sites (Apodeme?)
Flexibility
Organ support |
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Term
What is the dermal gland and pore canal used for?
~Cuticle & Exoskeleton~ |
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Definition
Secretions onto the surface - dermal gland
Secreting waxy coatings - Pore canal (much smaller) |
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Term
Why is the cuticle typically in a lamellate formation?
~Cuticle & Exoskeleton~ |
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Definition
| Microvilli producting chtin, move around within the epidermis, and as such each layer is oriented in a different direction (approximately spiral) - improves structural benefit |
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Term
What is the function of wax on the surface of the epicuticle?
~Cuticle & Exoskeleton~ |
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Definition
Water rention and resistance
Removal of hydrocarbons - taste cues - important for reproduction - produced by oenocytes and dermal glands |
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Term
What is tanning in insects?
~Cuticle & Exoskeleton~ |
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Definition
| Process by which the culticle becomes further sclerotized by use of proteins. These protein chains form bridges excluding water, and inducing drying (water insoluble). - only in exocuticle |
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Term
What is the use of melanin and how is it created?
~Cuticle & Exoskeleton~ |
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Definition
Made from excess dopemine used in the process of sclerotization.
Useful as an antibiotic layer, as well as UV photon shielding. |
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Term
Why may an insect not require sclerotization in the cuticle?
~Cuticle & Exoseleton~ |
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Definition
Typically to increase the amount of movement available eg some larvae and intersegment regions (eg between leg sections)
Honey pot ants, scale insects, plant feeding larvae, and diptera abdomens are examples of this. Honey pot ants intersegmental regions are able to strech the membranes in their abdomen in order for greater honey carriage. |
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Term
For instances where the cuticle needs to be tougher than other regions (eg chewing mouthparts, ovipositors), what differences can be seen?)
~Cuticle & Exoskelton~ |
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Definition
Incorperation of metals such as zinc, iron, manganese. Will always co-occur with halogens such as chlorine and/or bromine.
This can be seen in leaf cutter ants and termites especially.
In some instances, complete mineralization may also be seen such as muscid fly larvae, in order to avoid parasitism. |
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Term
What are the functions and properties of resilin in the cuticle?
~Cuticle & Exoskeleton~ |
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Definition
Highly hydrated protein used in the joints and tendons of most insects.
It has been artificially created though genetic modification of Drosophile genes to be resilin coding in bacteria.
Particularly prominent at dragonfly wing muscle sites, and flea legs (plural arch, located internally in the metathorax). |
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Term
What are interference colours and pigmentation colours and how do they differ?
~Cuticle & Exoskeleton~ |
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Definition
Light waves interfering with one another as they bounce off the cuticle shape (particularly in fine striated patterns or grating eg lepidoptera).
Pigmentation colours however are a chemical present in the cuticle which will absorb or reflect a particular wavelength, giving colour. Omatidia on the eyes may have pigmentation. |
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Term
What is light scattering and how does it work?
~Cuticle & Exoskeleton~ |
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Definition
A creation of colour through the interaction of the roughness of a cuticle, to the wavelength of light put onto the cuticle.
Eg large irregularities provide white colour (large wavelgnths reflected), whereas small provide blue colour (reflecting only small wavelengths). |
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Term
Within the cuticle, what are restricting factors in relation to size?
~Cuticle & Exoskeleton~ |
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Definition
| Limitation of size through the exoskeleton being disproportionately larger, the larger the insect is. |
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Term
Describe the trachael system in relation to the cuticle
~Cuticle & Exoskeleton~ |
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Definition
| The foregut, hindgut, and part of the reproductive system and respiratory system are all cuticle lined for structural support. Tissues with high metabolic activity will have a much higher tracheal activity. Tracheols will run between individual cell in order to provide oxygen. Spiracles are also chitin based - filters for dust or water from getting into the trachea. |
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Term
What are narrowarrays and how do they work?
~Cuticle & Exoskeleton~ |
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Definition
A narrowarray is a section of bumbs, so close together that light has no reflectance upon it (Btw 200nm and 300nm). This creates a continuous gradient of light channeled to a certain area, or away. Moths are flies are able to use the light onto their eyes more efficient, whereas some cicada wings can become essentially invisible at night.
Water also effects the ability of surfaces to be wet, forming balls rather than spreading out (lotus effect). This can then be used in cleaning practices, removing dirt particles, or as a water hydrophobic property, used in flight, or to stand on water. |
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Term
What are gland I cells?
~Glands &Secretions~ |
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Definition
Epidermal cells with the outter plasma membrane folded into microvilli. Secretion passes through canals between the microvilli and gland cell.
Typically released as pheramones.
Frequently clustered to form the gland. |
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Term
What are gland II cells?
~Glands & Secretions~ |
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Definition
Cells derived from epidermal cells, however do not connect to the cuticle, nor have a duct. These cells include the oenocytes - which are released on the abdomen wall as hydrocarbons, to eventually become a waxy layer.
It is believed that lipophorins carries the hydrocarbons through the hemolymph to be released through the cuticle elsewhere. |
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Term
What are Gland III cells?
~Glands & Secretions~ |
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Definition
They are the cells of a more complex "Unit" called "A class III dermal gland". Typically multicellular, with at least one cell set as a canal cell for transportation.
There is also an end apparatus responsible found in the cavity of the secreting cell for sorting secretions. Will also have microvilli where the secretion is released. |
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Term
In what respect are dermal glands important in a female's reproductive system?
~Glands & Secretions~ |
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Definition
Often females will have a spermatheca used in storing sperm, in which this organ will be sclerotized. And posterior to this, there is a pair of accessory glands capable of secreting a glub-like substance which either binds the eggs to themselves, or the substrate (colleterial gland).
In some cases similar accessory glands are capable of producing silk, and as such are a modification of this simple premise. Whereas in bees and wasps, this accessory gland has been modified in all but the queen to secret toxic chemicals. |
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Term
What are metaplural glands?
~Glands & Secretion~ |
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Definition
| Glands found on an atrium of ants. At the base of a hair, each gland can be found. Gives some indication that dermal glands may have originated through sensory organs. |
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Term
What is a functional definition of silk?
~Silks~ |
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Definition
| Protein fibres spun by a number of arthropod lineages. Refers to the process of making an insoluble filament from an aqueous protein solution. |
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Term
What are labial gland silks?
~Labial silks~ |
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Definition
| They are glands which produce saliva for lubrication, and enzymatic functions upon food, however some have been modified to produce silk (Eg all lepidoptera, and glowworms; Arachnocampa) or venoms. |
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Term
What modification do lacewings have in terms of their colleterial glands?
~Other silks~ |
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Definition
| A modification which allows a silk substance to be excreted when laying eggs, forming a stalk like egg. |
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Term
What two factors drive gas exchange in insects?
~The Tracheal System~ |
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Definition
1. Passive diffusion of oxygen in the atmosphere directly into the muscles
2. Connective ventilation |
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Term
Describe diffusion and convection
~The Tracheal System~ |
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Definition
Diffusion: Kinetic movement of molecules from high to low concentrations - how gasses move from dead-ended tracheols across membranes
Convection: The bulk movement of molecules from high to low pressure - movement of large quantities of gasses over large distances |
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Term
What system of ordering does the insect respiratory (tracheal) system use?
~The Tracheal System~ |
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Definition
Spiracles - The opening allowing gas to pass through into the respiratory system (Can be opened or closed depending on what is required). Typically have hairs in the atrium to pretend bust and mites.
Trachea - The initial terminal after the spiracle opening. They are paired and run elongate along the insect. Responsible for the movement of gasses within the system. Using contraction and expansion, are able to drastically increase the efficiency in which gasses are channeled through opening and closing the spiracles.
Tracheols -Directly take or give gasses to muscles. Done through passive diffusion. |
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Term
Why is diffusion inefficient?
~The Tracheal System~ |
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Definition
Movement from a concentration gradient is slow due to the fact that there is no positive pressure on the molecules. As such, diffusion is slow, especially with the minuscule diameter of the trachea, and long distances. A fluid filled tracheal system would be even slower. (Rule of squares)
Therefore this is only efficient over minuscule distances. |
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Term
What is convective airflow?
~The Tracheal System~ |
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Definition
| A process known as auto-ventilation is typical in flying insects, where the activity of the flight muscles causes expansion and collapse or air sacs causing convective airflow. |
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Term
How can the pattern of closing and opening the spiracle in terms of oxygen intake and CO2 depositing be measured?
~Patterns of Respiratory Gas Exchange~ |
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Definition
Flow through respirometry.
Place animal in an enclosed space and measure the emergent O2 and CO2 from the other side.
Eg Continuous (High metabolic rate needed) vs Cyclic (at rest) vs Discontinuous DGC (independently evolving; low energy?) |
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Term
What is the Hygric hypothesis in terms of DGCs?
~Patterns of Respiratory Gas Exchange~ |
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Definition
| The hypothesis that DGCs evolved as a way of reducing water vapor loss that must accompany gasses. As such, the longer the spiracles are closed for, the lesser the water loss. This should show that insects living in arid areas are more likely to have this adaption, however this has not been found as of yet. |
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Term
What is the Cthonic hypothesis in terms of DGCs?
~Patterns of Respiratory Gas Exchange~ |
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Definition
| Its the hypothesis that states that DGCs evolved in response to environments with either low oxygen levels or high carbon dioxide levels. This then creates a greater concentration gradient to enhance gas exchange. This would imply that underground species would exhibit this, as many ants do, however this is not consistent. |
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Term
What is the Oxidative Damage hypothesis in terms of DGCs?
~Patterns of Respiratory Gas Exchange~ |
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Definition
| This is the hypothesis that states that DGCs reduce the overall exposure to oxygen, and therefore the reactiveness of oxygen. As such the breath holding and flutter phase could act to reduce tissue exposure to oxygen. |
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Term
What is the Emergent Property hypothesis in terms of DGCs?
~Patterns of Respiratory Gas Exchange~ |
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Definition
| The hypothesis that states that DGCs occur through reflexive response in gas levels. This therefore is a non adaptive trait. |
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Term
What type of circulatory system do insects use?
~Circulation~ |
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Definition
| Insects use an open circulatory system which entails the inner body cavities filled with circulating haemolymph. |
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Term
What is the function of the dorsal vessel?
~Circulation~ |
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Definition
It is a segmentally arranged tissue, with the abdominal end being considered the "heart" and the head/thorax being considered the "aorta".
Composed of single layer myocardial cells in a spiral arrangement.
It provides directional flow of haemolymph through pressure, however some pulsatile organs (bases of appendages) assist this. |
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Term
What are ostial valves used for?
~Circulation~ |
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Definition
| Slit-like openings found in the wall of dorsal vessels also with sentimental distributions. Divided between incurrent and excurrent ostia. Excurrently are generally for passive flow with non-contractile openings. |
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Term
How do the ventral and dorsal diaphragms control contraction?
~Circulation~ |
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Definition
They contract using a thin layer of muscle which is able to actively used.
The dorsal is located beneath the dorsal vessel. Whilst the ventral is located immediately above the central nerve cord. |
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Term
What do alary muscles do?
~Circulation~ |
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Definition
| Small, fan shaped muscles, which allows blood to flow into the pericardium from the perivisceral cavity and then into the heart. This process is neurally invoked, however not in line with the heart. |
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Term
What is the route taken by hemolymph entering the dorsal vessel?
~Circulation~ |
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Definition
| Enters through incurrent ostia or aorta; with the heart beat proceeding in a wave from posterior to anterior (peristaltic) |
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Term
What are the functions of haemolymph?
~Circulation~ |
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Definition
Nutrient transportation from gut to tissue and fat body to tissue
Storage of metabolites, water, proteins etc
Distribution of hormones
Thermoregulation
REVIEW "CIRCULATION SECTION FOR SPECIFIITIES ON HEART DIRECTIONAL FLOW ETC" |
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Term
What are the 5 different types of metamorphosis, and define?
~Growth and Metamorphosis~ |
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Definition
Ametaboly:Progressive growth through moults - no metamorphosis
Hemimetaboly: Immatures resemble adults; Wings and genitalia appear in final moult; No quiescent pupal instar;
Holometaboly:External wing rudiments not seen until pupal instar; pupa between imago and larvae
Neometaboly: Holometabolous, but not monophyletic
Prometaboly: Hemimetaboly, other than 2 winged stages rather than 1 |
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Term
What is Dyar's rule?
~Growth and Metamorphosis~ |
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Definition
The ratio in instars for a given feature is constant, eg 1.4:1 for head capsule width in caterpillars. As such growth is exponential.
Growth against this is known as allometric.
This process is cellular through mitosis - with cell division occurring after apolysis. |
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Term
What is endoreplication?
~Growth and Metamorphosis~ |
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Definition
Cell growth without replication, however the chromosomes are still replicated.
Typical of metabolically active cells. Eg salivatory gland cells
Gives rise to polytene chromosomes - die at metamorphosis |
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Term
What advantages does hemi / holometaboly provide?
~Growth and Metamorphosis~ |
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Definition
Reduction of wing rudiments means less vulnerability.
Predetermined final instar - though does have energy and time losses, as well as being more vulnerable during ecdysis.
Moulting with fully formed wings can be difficult.
Allows further adaptions to prevail without concerns about moulting. |
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Term
What changes have been made between hemi and holomeboly?
~Growth and Metamorphosis~ |
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Definition
Wing development restricted to to very latest instars.
The pupa also evolved as a intermediate phase to allow external growth of wings - particularly with the use of imaginal discs. |
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Term
What are imaginal discs, And how do they change during metamorphosis?
~Growth and Metamorphosis~ |
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Definition
A sac-like epithelial structure found inside the larva of insects that undergo metamorphosis. The larval tissues degenerate, and the imaginal discs become the external features.
Cells change from cuboid to sqamous chape; Contraction of the peripodial membrane when changing |
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Term
What is primordia?
~Growth and Metamorphosis~ |
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Definition
| Less extreme versions of imaginal discs seen in lepidoptera. Particular to larval antennae and leg formation. |
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Term
What are the differences between the circulatory system and the nervous system?
~Insect hormones~ |
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Definition
Slower
Single effectors (rather than nerve network)
Accumulation before distribution
Coordination of physiological responses
Nervous system runs circulatory system
(through neurohormones and specialized neurohormonal organs and onto endocrine glands) |
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Term
Describe the process of a neurohormone
~Insect hormones~ |
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Definition
| Neurons -> Neurosecretory cells -> Neurohemal organ -> Neurohormones -> Feedback to neurons (+/-) OR target cell (+/-) OR endocrine gland -> Hormone -> Feedback to neurons OR target cell |
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Term
What are two of the main endocrine glands?
~Insect hormones~ |
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Definition
Prothoracic glands (ecdysteroids)
Corpora allata (Juvenile hormones) |
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Term
What are the properties of lipid hormones?
~Insect hormones~ |
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Definition
Able to pass through cell membranes and manipulatate DNA - transcription regulation
Ecdysone - steroid
Juvinile hormone - terpenoid
Originally found through manipulation of salivary gland cells in drosophila ecdysteroids (polytene cells) |
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Term
Describe the properties of polypeptides
~Insect hormones~ |
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Definition
Typically produced by neurosecretory cells
Bind to receptors in cell membrane
Requires a coupling molecule to move to the receptor
Includes second messengers of cAMP and cGMP
Includes Eclosion hormone and prothoracicotropic hormone |
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Term
What are brain neurosecretory cells?
~Insect hormones~ |
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Definition
Large neurons that produce peptides rather than neurotrasmitters
Typically clustered |
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Term
What are the functions of the corpora cardica?
~Insect hormones~ |
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Definition
Neurohemal organ for brain neurosensory cells
Intrinsic neurosecretory cells
Typically located next to the heart |
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Term
What is the function of the corpora allata?
~Insect hormones~ |
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Definition
Glands innervated from the brain through the corpora cardiaca
Glands synthesize JH |
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Term
What are prothoracic glands?
~Insect hormones~ |
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Definition
Production of ecdysteroids
Ecdysone is released as it is created, as opposed to stored
Not found in adults
Typical of secretory cells |
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Term
What is the function of Prothoracicotropic hormone
~Insect hormones~ |
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Definition
| Released from brain, accumulates in CA, prompts the prothoracic glands to release ecdysone |
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Term
What is the function and properties of ecdysone?
~Insect hormones~ |
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Definition
Released from prothoracic gland targets the epidermis to initiate moulting
I. apolysis
II.enzyme secretion
III. digestion and reabsorption
Prohormone, converted into 20-hydroxyecdysone by fat body and epidermal cells. |
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Term
What is the function of eclosion hormones?
~Insect hormones~ |
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Definition
Released from brain (a neuropeptide) through corpora cardiaca and targets the CNS to produce eclosion (or ecdysis) behaviour, often timed according to circadian rhythm of eclosion in adult silkmoths, without brain becomes free rhythm.
Typically associated with time of the day for release. |
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Term
What is the function of ecdysis triggering hormones?
~Insect hormones~ |
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Definition
Released from peripheral nerve cells associated with the trachea near the spiracles. Trigger the onset of ecdysis
behaviour.
Previously assumed for role to also have included Eclosion hormone, however is now known to be be stimulated by EH, which then acts on the CNS.
This also results in a positive feedback where:
Ecdysteriod levels drop triggering low VM activity -> EH released -> ETH released acts on terminal abdominal ganglion -> preecdysis -> ETH acts on VM cells -> EH release triggered |
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Term
What is the function of Bursicon?
~Insect hormones~ |
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Definition
Released from neurosecretory cells of thoracic and abdominal neuromeres; Targets epidermis to produce
sclerotization and melanization of the cuticle |
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Term
What is the function of JH (Juvenile hormone)?
~Insect hormones~ |
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Definition
| Secreted by endocrine cells of the corpora allata, widespread targets, maintains juvenile stage |
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Term
What is the function of diuretic hormones?
~Insect hormones~ |
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Definition
In Rhodnius, stretch receptors in
abdomen monitor abdominal distension
following gluttonous meal, leads to
increase in urine production. Proximal
portions of abdominal nerves are the
neurohemal organs for DH
Antidiuretic hormones have the
opposite effect |
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Term
What is the function of Proctolin?
~Insect hormones~ |
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Definition
Neuropeptide (pentapeptide) both a
neurotransmitter and neurohormone;
Induces generalised muscle
contractions in the gut;
Also neuromuscular junction
neurotransmitter |
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Term
What is the function of Cardioactive
peptides?
~Insect hormones~ |
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Definition
| Released from perivisceral organs |
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Term
What are the functions of the Embryonic diapause?
~Insect hormones~ |
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Definition
Bombyx females produce diapause
hormone from cells in SOG that acts
on eggs while still in ovary, causing
them to arrest after oviposition.
Late stage diapause: stimuli detected
by the embryo itself |
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Term
What are the functions of the Diapause?
~Insect hormones~ |
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Definition
Arrested development as an
adaptation to adverse conditions that
has evolved as an adaptation in
anticipation of adverse conditions
rather than a response to their onset
(torpor). Usually involves some
stimulus indicative of impending
onset. |
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Term
What are the functions of the Ovarian hormone
(ecdysone)?
~Insect hormones~ |
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Definition
Released by ovaries and
targets fat body where
vitellogenin is released for egg
production |
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Term
What is the function of JH (Juvenile hormone)2?
~Insect hormones~ |
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Definition
From the corpora allata targets
accessory glands of the
reproductive system to
coordinate production and
secretion; JH also targets
follicle cells to enable them to
utilise vitellogenin |
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Term
What is the function of Mating inhibition hormone?
~Insect hormones~ |
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Definition
Male accessory glands targets
female CNS to make female
refractory |
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Term
What is the function of the Oviposition initiation hormone?
~Insect hormones~ |
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Definition
Targets the oviduct to initiate
oviposition |
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Term
What is the function and meaning of a polyphenic trait?
~Polyphenism~ |
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Definition
Multiple phenotypes arising from a single genotype variant.
Distinct forms can develop in response to some internal or environmental cue.
Different from polymorphism due to not being heritable genetic differences.
Inlcudes:
chromatic adaptation
• seasonal morphs
• castes in social insects
• phase polyphenism in locusts |
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Term
How are Chromatic Adaptation polyphenistic traits?
~Polyphenism~ |
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Definition
Green vs Brown polyphenism in Orthoptera as response to photoperiod or humidity.
JH is known to be responsible.
Takes at least a moult to recognize and respond to. |
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Term
How are phase changes polyphenistic traits?
~Polyphenism~ |
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Definition
Locusts can either be gregarious or solitary phase, and require environmental input to switch.
Olfactory, visual and tactile cues than cause an elevation of serotonin levels in the ventral nerve cord. |
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Term
What is PTTH and how is it triggered?
~Moulting~ |
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Definition
A neurosecretory polypeptide, produced by neurosecretory cells located in the brain.
Regulates the secretion of ecdysteroids by the prothoracic gland projected to the corpora cardiaca (aside for lepidoptera where it is to the corpora allata)
Activated for short periods of time to trigger a response |
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Term
What do ecdysteroids do and how?
~Moulting~ |
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Definition
Produced before and during moults.
Circulates in the haemolymph reaching all tissues. Act on epidermis for apolysis, mitosis and new cuticle secretion.
Some processes are concentration specific particular in the dropping phase eg programmed cell death, pigmentation, secretion of eclosion hormones. |
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Term
Where is the origin of JH and what are the promoters and inhibitors?
~Juvenile hormone, EH and ETH~ |
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Definition
Corpora allata is the origin of JH.
• inhibit JH production (allatostatins)
• promote JH production (allatotropins) |
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Term
What is the source of EH (eclosion hormone?)
~Juvenile hormone, EH and ETH~ |
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Definition
neuropeptide released from VM cells in brain (2 neurons per side). The neuropeptide has 62 amino acids.
Stimulation of neurosecretory neurons causes release. |
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Term
What are the two different types of dormancy, and how do they differ?
~Dormancy~ |
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Definition
Quiescence (sometimes torpor) - Dormancy due to a limiting factor, however resume normally once no longer limited
Diapause - Physiology "switched" to a dormant state adapting to impending hardship, coined "aestivation". Triggered by a cascade of gene responses. Often during pupa or embryo. |
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Term
What are cues, and what is an example?
~Dormancy~ |
|
Definition
Photoperiod is a common cue - signally for seasonal change (eg long day response). Used to trigger various responses including dormancy.
Quality and quantity of food may also be influential. |
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Term
| What is a potential sequence of requirements to cause a pupal diapause? |
|
Definition
| Genetic capacity -> no maternal diapause history -> Exposure to short day length as embryo -> Short day length as larvae -> cool temperature after pupariation -> DIAPAUSE! |
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Term
What is the role of the brain in initiating diapause?
~Dormancy~ |
|
Definition
Believed that the brain is the primary light receptor responsible for the photoperiod triggering diapause rather than the eyes or ocelli.
diapause is mainly due to
Inhibition of PTTH and ecdysteroid secretion, preventing the moult to the pupal stage. |
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Term
What is periodicity in terms of feeding, locomotion, mating etc?
~Rhythms~ |
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Definition
| Physiological properties occurring at various set intervals such as tidal, daily, lunar, annual etc. |
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Term
What are rhythms?
~Rythms~ |
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Definition
| Processes governed by biological responses, typically constant when under constant conditions. |
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Term
What are cicardian rhythms and how do they work?
~Rhythms~ |
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Definition
| Rhythms which have a periodicity of around 24 hours and is regulated by day light. However in constant darkness or light they show their free running rhythm, coming in between 22 and 27 hour cyclic periods. This is somehow temperature regulated. |
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Term
What is a Zeirgeber?
~Rhythms~ |
|
Definition
| It is a placement time in order for a rhythm to be achieved. Mosquitoes under constant light will oviposit randomly, however after a period of darkness, they will oviposit at 24 hour rhythms. |
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Term
Do glowworms provide evidence for an internal clock with their bioluminescence?
~Rhythms~ |
|
Definition
| Characteristically not exactly 24 hours. It is however light sensitive, and as such react to one another's light. |
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Term
What is a gated rhythm?
~Rhythms~ |
|
Definition
| It is a "missed window" opportunistic property, typically occurring with eclosion in drosophilla, where it will emerge on the exact same time the next day in order to maximize resources. |
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