The members of this class have ___ mouth parts, however, bases of the mouthparts lie outside the ___.
- ectognathous (having exterior mouthparts
- head capsule
Pterogotes ?
- winged insects
Apterogotes?
- wingless insects
These are the most abundant of all arthropods. Fossil record indicates what about this class of arthropods?What is present among modern insects?
- they are a stable group
- continued evolution is present among modern insects.
They play a major role in __ and ___ roles with humans, and also play critical ____roles.
- medical, economic
- ecological
_____ mouth parts (retracted within the head) and often ___ pairs of wings on the ____ region of the body are present in organisms of this class.
- Ectognathous
- 2
- thoracic
Larger insects are ____.
- tropical
They are found in nearly all habitats except where?
- the sea
They are common in ____, ____, and ___. (water environments)
- freshwater, brackish water and salt marshes
They are abundant in __, ___ and can be found in ___ and in ___. (terrestrial environments)
-soils, forest canopies, deserts, wastelands
Most animals and plants have insects as parasites ___and __..
- internally
- externally
What two things makes them widely distributed ?
- small size
- wings
They have well protected ___ which can withstand ___ conditions and are readily ____.
- eggs
- rigorous
- dispersed
Wide variety of ___ and ____ adaptations gains them access to every possible niche.
- structural
- behavioural
Most structural adaptations are present in their ___, ___, ___,___, and ___.
- wings, legs, antennae, mouthparts, alimentary canal
They have a hard protective ___ well adapted to life in desert regions. It holds in ___ which is key for survival in dry environments.
- exoskeleton
- water
The exoskeleton is composed of what?
- complex plates or sclerites connected by hinge joints
What attached to sclerites allow for precise movements.
- muscles
Rigidity is due to ____ and not ____. It allows for ___ which is a necessity for flight.
- scleroproteins, not mineral matter
- - lighter body weight
They are more homogenous in ___ than the variable crustaceans.
- tagmatization (specialized grouping of body segments into functional units)
Head:
- It is usually equipped with a pair of ?
- It also has __ pair of antennae which varies greatly in what? (3)
- The mouthpart consists of what? (4)
- large compound eyes
- one
L> functioning in touch, taste and hearing - Labrum
- Pair of mandibles
- Pair of maxillae
- Labium
Thorax:
- Consists of the ___, ___ and ___.
- Each section has a pair of what?
- prothorax, mesothorax, metathorax
- legs
Wings:
- If two pair are present ? (location)
L> They consists of a __membrane
L> Veins serve what function with wings?Pattern function as well?
- mesothorax and metathorax
- double
- strengthen wing
- vein pattern is used to identify insect taxas
Legs:
- Walking legs end in what? (2)
- Hindlegs of grasshoppers and crickets are enlarged for what purpose?
- Mole crickets have front legs adapted for what?
- Forelegs of praying mantis allow it to do what?
- Honeybees have leg adaptations for?
- terminal pads and claws
- jumping
- burrowing in the ground
- allow it to grasp prey
- collecting pollen
Abdomen :
- how many segments?
- Larval and nymphal forms may have what that may be lacking in adult forms
- External ___ usually at the __ of the abdomen.
- 9 to 11
- abdominal appendages
- genitalia, end
Variations in Body Form:
- Land beetles are __ and __.
- Aquatic beetles are ___.
- Cockroaches are __ and live in __.
- Antennae vary widely from __ to __, __ to __.
- thick, shielded
- streamlined
- flat, crevices
- long, short
- plumed, knobbed
Locomotion: Walking
- Insects usually walk using the __ and __ leg on one side and the __ leg on the opposite side in alteration with the reverse. This provides what?
- A water strider has _____ that do not break the surface water tension.
- 1st, last, middle, stability
- non-wetting footpads
Power of Flight:
- Insect wings are not ____ with bird and flying mammal wings.
- Insect wings are outgrowths of the __ from the ___ and __ segments.
- Recent fossil evidence suggests insects may have evolved fully functional wings over __ years ago.
- homologous
- cuticle, mesothoracic and metathoracic
- 400 million
Most flying insects have __ pairs of wings but order Diptera have how many?
- 2
- 1
Halteres are what kind of wings?
- reduced wings that provide the fly with balance during flight
Non-reproductive ants and termites are __.
wingless
Lice and fleas have what ?
lost wings
Modifications of wings:
- wings for flight are?
- The thick and horny front wings of beetles are?
- Butterflies have wings covered in what?
- Caddisflies have wings covered in what?
- thin and membranous
- protection
- scales
- hair
Flight muscles of insects:
- Direct flight muscles attach to the wing how?
- Indirect flight muscles are different how?
- The wing is hinged on a __ that forms a __.
- Insects cause the ___ with indirect muscles that pull the _____ downward.
- Dragonflies and cockroaches contract direct muscles to pull the wing ___.
- Bees, wasps and flies arch the ___ to cause the downstroke ___.
- Beetles and grasshoppers use a combination of what to move wings?
- directly
- alter the shape of the thorax to cause wing movement
- pleural process, fulcrum
- upstroke, tergum (thickened dorsal plate on each segment)
- downward
- tergum, indirectly
- direct and indirect muscles
What is Synchronous muscle control?
- uses a single volley of nerve impulses to stimulate a wing stroke.
What is Asynchronous muscle control?
- stretch antagonistic muscle and cause wing to contract in response. It requires occasional nervous stimulation.
Potential energy can be stored in what?
- resilient tissues
Wing thrust:
- Direct flight muscles
- Fast flight
- alter the angle of wings to twist leading edge to provide thrust
- requires long, narrow wings and a strong tilt, as in dragonflies and horse flies.
The digestion system is comprised of what three things?
- Foregut, Midgut and Hindgut
What is the Foregut?
- what makes it up
- function?
- Mouth with salivary glands, esophagus, crop and gizzard.
- some digestion but no absorption, occurs in crop as salivary enzymes mix with food.
- gizzard grinds good before it enters the midgut
Midgut?
- Primary site of digestion and absorption
- ceca may increase digestive and absorptive area
Hindgut??
- primarily a site for water absorption
Most insects feed on plant ____ or ___ are what type of food acquirer?
- tissues, juices
- herbivorous or phytophagous
Many caterpillars are specialized in what way with acquiring food?
- specialized to eat only certain species of plants
Some ants and termites cultivate what for food?
- fungus gardens
Most beetles and other insect larvae eat what? What are they classified as?
- dead animals
- saprophagus
Many species are parasitic as ___ and or ____.
- adults
- larvae
What is hyperparasitism?
- parasitic insects having parasites
Parasitoids live inside a host and eventually do what?
- kill the host
- this is important in pest control
What forms a tube to pierce tissues of animals or plants?
- sucking mouthparts
Houseflies and blowflies have what kind of mouthparts?
- sponging mouthparts
- soft lobes at the tip absorb food
What can biting mouth parts do?
- seize and crush food
What kind of heart is found in insects? location? What does it move/where?
- tubular heart
- pericardial cavity
- moves hemolymph forward through dorsal aorta
What kind of heartbeat is present in insects?
- peristaltic wave
What helps move hemolymph to the legs and wings?
- accessory pulsatile organs
What is hemolymph composed of?What does it not function in?
- plasma and amebocytes
- does not function in oxygen transport in most insects
In what kind(s) of insects does hemoglobin function in the transport of oxygen?
- some insects, particularly aquatic immature in low oxygen environments.
What dilemma are terrestrial animals faced with in regards to gas exchange?
- exchanging gases while preventing water loss
Describe the tracheal system!
- network of thin walled tubes that branch throughout the insect body
- spiracles open to the tracheal trunks
- valves on the spiracle reduce water loss and may serve as a dust filter.
What are tracheae composed of?
- single layer of cells lined with cuticle that is shed at each molt
What is the function of spiral thickenings of the cuticle on the trachea?
- prevents it from collapsing
What are tracheoles?
-trachea branch out into these fluid filled tubules that reach individual body cells.
The trachea system provides gas transport without the use of what?
- oxygen carrying pigments
What do mosquito larvae use to snorkel surface air?
- short breathing tubes
Describe a run through of how the trachea system works?(2)
- contractions of muscles in the jaw or limbs increases pressure inside the exoskeleton causing the contraction of tracheae for exhalation.
- Muscular movements may assist in moving air in and out of air sacs.
- In very small insects gases are transported how?
- What about in aquatic insect nymphs?
- simple diffusion
- tracheal gills or rectal gills
Excretion and Water Balance:
Insects and spiders utilize ___ in conjunction with ___.
- malpighian tubules
- rectal glands
Malpighian tubules vary in number but join between the ___ and ___.
- mid gut and hind gut
Blind ends of the malpighian tubules float freely in the_____ bathed in____.
- hemocoel
- hemolymph
What is actively secreted into the malpighian tubules? What about the other solutes?
- potassium
- they follow the gradient
What is the main waste product of insects?
- uric acid
- flows across at upper end that is mildly alkaline in the malpighian tubule
In the lower end of the malpighian tubule potassium combines with what to be reabsorbed?
- CO2
Rectal glands reabsorb what three things?
- chloride, sodium and water
- wastes pass out the body
The nervous system of insect resembles the ns of what other group in arthropods? What is the similarity?
- crustaceans, fusion of ganglia
Sense organs:
- Many insects have ___ sensory perception.
- Most sense organs are ______ and located in the ____.
- Different organs respond to what four things?
- keen
- microscopic, body wall
- mechanical, auditory, chemical, visual and other stimuli
Sense organs :
- Mechanoreceptors ??
- what kind of stimuli do they detect/ what detects them
- distributed where?
- react to touch, pressure, vibration etc. are detected by sensilla
L> may be a single hair like seta or a complex organ.
L> distributed widely over antennae, legs and body
Sense organs : - Auditory Reception L> what two kinds are there? L> What three groups of insecta is one specialized to? L> organs in the leg can do what?
- Sensitive setae (hair like sensilla) or tympanal organs detect airborne sounds.
- Tympanal organs occur in Orthoptera, Hemiptera and Lepidoptera.
- Organs in legs can detect vibrations of substrate
Sense organs :
- Chemoreceptors
L> usually are bundles of what?located where?
L> may be located on what three parts of an insect?
L> What four things do chemoreceptors mediate?
- usually bundles of sensory cell processes located in sensory pits
- may occur on mouthparts, antennae and legs
- some insects can detect odors several km away
- Feeding, mating, habitat selection and host parasite relationships
Sense organs :
- Visual reception
L> what are the two types of eyes?
L> From honeybee studies what was learned about ocelli’s function?
L>Compound eyes may contain thousands of what?Also describe these structures!
L>Describe an insects sight line and imaging
- simple and compound eyes
- ocelli monitor light intensity but do NOT form images.
- thousands of ommatidia- structures similar to that of crustaceans
- sight can be simultaneously in almost all directions therefore the image is myopic and fuzzy.
In most animals how many senses are dominant?
- 1 or 2
Flying insects have higher ______ rate. A bee can distinguish ____ but cannot detect shades of __.
- higher flicker fusion rate L> distinguish 200-300 flashes per second aka can see very slight movements L> ultraviolet L> red
Other senses:
- Insects are very sensitive to what?
- What are they also very keen at detecting? (3)
- temperature, cells in their antennae and legs are especially sensitive
- humidity, proprioception, gravity and other physical properties
Arthropods muscles are what?
- cross striated
Strength of muscle is related to its _____ area
- cross sectional
What type of muscle is very proficient at storing a lot of energy?
ex?
- elastic muscles…
- a flea can jump 100 times its length by storing energy in an elastic resilin protein.
Reproduction:
- Parthenogenesis occurs in what orders?
- What type of reproduction is considered norm for insects?
- hemiptera and hymenoptera
- sexual reproduction is norm
Whats the low down on sexual attraction with Insects?
- moths
- fireflies
- other methods used by various insects (3)
- female moths secrete pheromones to attract males from a great distance
- fireflies uses flashes of light to detect mates
- some insects use sounds, colour signals and other courtship behaviours.
Is fertilization usually internal or external?
- internal
Sperm may be released ____ or via?
- directly
- packaged into spermatophores
Spermatophores are a result of what? Are they transferred only with copulation?
- result of an evolutionary transition from marine to terrestrial existence
- can be transferred via copulation or without
- Females may only mate once in their life time. Why?
- Females also have options when it comes to laying eggs, what are they??
- store sperm to fertilize eggs throughout her life
- they can lay a few eggs and care for their young or lay huge numbers
Why must Butterflies and moths lay eggs on a host plant?
- this is so the caterpillars can survive (food source ?)
Whats the low down with wasps and laying their eggs?
- they have to locate a very specific species that is the only host to their young for them to lay eggs in.
With respect to metamorphosis and growth most insects change form after doing what?
- hatching from an egg
What is an instar?
- stage between molts
When do insects develop wings?
- in their last stage of growth/metamorphosis
What are the three types of metamorphosis ?
- Ametabolous (Direct ) development
- Hemimetabolous ( gradual) metamorphosis
- Holometabolous (complete) metamorphosis
Ametabolous Development ?
- stages?
- what kind of insects ?
- ex?
- stages are egg-juveniles-adult
- wingless insects
- EX: silverfish and spring tails have young smilar to adults except in size and sexual maturation
Hemimetabolous Metamorphosis
- ex?
- what kind of metamorphosis is this?
- what are the bud like growths?
- stages?
- gradual metamorphosis
- young are called nymphs
- bud like growths in early instars show where the adult wings will eventually develop
- stages: egg-nymph-adult
- ex: grasshoppers, cicades, mantids, true bugs, mayflies and dragon flies
Holometabolous Metamorphosis
- common or uncommon?
- what does this do to physiology of the stages?
- environment comparison of larvae and adults?
- after several larval instars occurs what happens
- complete metamorphosis (about 88% insects go this route)
- separates the physiology of larval growth, pupal differentiation and adult reproduction
- larva and adults often live in completely different environments (no competition)
-after several larval instars the mouth or butterfly becomes a pupa inside a cocoon or chrysallis
L> they often pass the winter in this stage
-final molt occurs and the adult emerges in the spring
-stages: egg-larva-pupa-adult
What is Diapause?
L> Winter version?
L> summer version?
- period of dormancy in the annual life cycle that is independent of conditions.
- Hibernation
- Estivation
Diapause:
- stages this occurs in?
- what controls it?
- at any stage an insect may experience this to survive adverse conditions
- internally controlled but may be triggered by environmental cues such as day length.
Diapause:
when does it occur?
-It always occurs at the end of an active growth cycle - insect is than ready for another molt.
Diapause:
-what does it stop
- once this occurs many larvae do not develop beyond it until late spring in spite of the mild temperature.
What are three very prominent defence mechanisms ?
- protective colouration, warning colouration and mimicary
Repulsive smells and tastes are common among what groups for defence purposes?
- stink bugs etc
What does the monarch caterpillar specifically have?
- poisonous substance that it acquires from its food plant known as milkweed.
The bombardier beetle has what defence ability?
-irritating chemicals
Behaviour and Communication:
- responses to stimuli are governed by what?
- most behaviours are made up of what?
- is most behaviour innate/ is learning involved?
- responses to the environment are governed by the physiological state of the animal and its nerve pathways
- many behaviours are complex sequences of responses
- most behaviour is innate but some involve simple learning.
Pheromones, what the heck are they?
L> what are they used for? (4)
- chemicals secreted by one individual to affect the behaviour another
- attract opposite sex, trigger aggregation, fend off aggression and mark trails
what do bees, wasps and ants use pheromones for as a defence mechanism?
- to identify nestmates and signal an alarm if strangers enter the nest.
How can pheromones be used in a practical way to monitor insect populations?
- can be used to trap them
Sound Production and Reception:
- what three things is sound production used for?
- ex: crickets
- ex: male cicada
- warning devices, advertisement of territory and courtship
- chirp for courtship and aggression
- vibrates paired membranes on abdomen to attract females
Tactile Communication:
- involves a variety of techniques such as? (4)
- ex: beetles, flies and springtails use what?
- ex: female fireflies
- tapping, stroking, grasping, and antennae touching
- bioluminescence
- mimic another species flash patterns to attract males and then eat them
Social Behaviour:
- what two kinds of social groups are there? Characteristics?
- what group is caste differentiation common among?
- some social communities are temporary and uncoordinated but some are highly organized and depend on chemical and tactile communication
- caste differentiation is common in most organized social groups.
Dead animals are rapidly consumed by what??
- fly maggots
Insects are critical components of most what?
- food chains; and an important food source for many fish and birds.
-Harmful insects eat and destroy ___ and ___.
- plants and fruits
- this requires substantial money for insect control
What are some examples of harmful insect forest pests? (3)
- bark beetles, spruce budworms, gypsy moth
Insects also destroy what other three things?
- food, clothing and property
Medically important insects include what?
- vectors for disease agents
How many in percent of all arthropod species are parasites or micropredators?
- 10%
Warble and bot flies attack what?
- humans and domestic livestock
Malaria is carried by what?
- Anopheles mosquitos , this is the most common major world disease
Yellow fever and lymphatic filariasis are also __borne.
- mosquito
Fleas carry what disease?
- Plague
Lice carry what disease?
- typhus fever?
What is the name of the newest viral plague that is carried by mosquitos?
- West Nile Virus
Broad Spectrum insecticides? What do they do?
- they damage beneficial insect populations along with targeted pests
What can be an issue with some chemical pesticides ?
- they can persist in the environment and accumulate as they move up the food chain
Some strains of insects have evolved a resistance to what?
- common insecticides
What are some biological controls for insects?
- natural agents, including diseases, to suppress an insect population
What is Bacillus thuringiensis?
- a bacterium that controls lepidopteran pests
- gene coding for the B.t. toxin has been introduced to other bacteria and transferred to crop plants.
Some viruses and fungi are used as what?
- economical pesticides
Natural predators or parasites of insect pests can be beneficial in pest control how?
- they can be raised and released to control pests
What is a method of eradicating insect species that only mate once?
- releasing sterile males
Pheromones can ___ pests and ____ may play a role in disrupting the life cycle.
- monitor, hormones
What is integrated pest management?
- combined use of all possible, practical techniques listed above, to reduce reliance on chemical insecticides
What kind of fly is essential in Forensic Entomology?
- Blowfly
L> they can tell how long the body has been dead via the life stages of the blow fly present on the body. ( 3 larval stages, pupa and adult)