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Flashcards in Insects Deck (32)

Why are insects successful?

Widely distributed in all available habitats- found everywhere except the poles
Insects are species-rich, numerically enormous and structurally diverse


How many species of insects are there?

6-10 million species of insects


How do insects exploit different habitats?

Diverse in shape and size and structure


What are there manner of life strategies?

Adaptable to season, rapid life cycles allow for genetic change


What are the Seven Reasons for success?

1. Metamorphosis
2. Feeding strategies
3. Sophisticated behaviour
4. Small size
5. Chitin
6. Wings
7. Life cycles


What is metamorphosis?

Sharp change in form during postembryonic development (after they have become an embryo and egg)
Separate growth from reproductive stages (more dramatically


What does metamorphosis provide?

Opportunities for surviving extremes during different phases


What are the different stages in metamorphosis?

Larvae, lymph (development, growth), final stages reproduction


What does metamorphosis allow?

Period of growth when environment won't allow it


What are feeding strategies?

The ability to exploit highly specific resources:
• Herbivores
• Predators
• Parasites
• Saprophages (scavenging decaying organic material/dead things!)
Mouthparts of insects highly specific to what they are eating


What do sensory and neuro-motor systems allow (sophisticated behaviour)?

Response to different environmental stimulus in different ways


What is the response to environmental stimuli?

Chemical stimulus and mechanical stimulus


What are the other sophisticated behaviours in insects?

Complex patterns developed
Social insects
Communication in sophisticated ways- warn prey


What are the benefits of insects being small?

Simply there is more room for small organisms than large ones in the same habitat
Can survive states of cold periods


What are the disadvantages of insects being small?

Loss of water rapidly, can only grow to a certain size based on water capacity, can lose heat rapidly


What are the consequences of there small size on surface area/volume?

Loss of water more rapid but have chitinous integument
Rapid loss of heat – temperature regulation has profound effect on biology, e.g., if cold then a state of torpor allows survival; warmer then accelerated activity shortens life span.
Flight more difficult for tiny species but wind-borne migration possible.
Power/weight ratio high- body cant support weight, because exoskeleton is shed and the new one isn’t fully hardened so insects would die if they were larger
Feeding on or within other organisms
Small animals attain maturity quickly and have short life spans (average for insects 6 months; vertebrates 5 years)- accelerate processes much better


What is chitin?

Exoskeleton of insect


What is the integument of a insect?

Complex structure made of tanned proteins, layers of hydrocarbon waxes and polysaccharides


What are the benefits of chintin?

It is physically tough, chemically resistant but plastic
The great variety of shape and form is made possible by the cuticle
Pigments are incorporated as are reflective and refractive effects
It is light enough to provide membranous materials such as for wing surfaces but is strong enough to enable jaws to cut through timber or even metal- allows flexibility


How do wings make insects successful?

Escape earthbound predators
Colonise newly created habitats quickly- flexibility
Abandon unsuitable areas
Find new food sources


How do life cycles make insects successful?

Rapidity a product of small size
Fecundity determined by selection
By comparison with mammal longevity insects have x10 more breeding cycles
Pesticides massive issue for insects- rapid life cycles allows adaptations to pesticides


What is forensic entomology?

Combines the study of insects with the science of criminal investigations


How are insects useful in post mortem?

Insects accumulate on and around the body
Become apart of evidence
Able to estimate time of death or post mortem interval (PMI) from insects present- can be used to determine whether body has moved, if drugs are involved, or if something was involved in another crime


After what time can you no longer identify time of death using body temperature?

After 72 hours, body stone cold


What arrive on a dead body first?

Flies- feed on liquefied food (blow flies and flesh flies)


What do blow flies use to detect body?

Chemical detection


What conditions do beetles prefer?

Beetles prefer drier conditions- pick of dry skin, lay eggs around it


What sequential manner do insects arrive on the body?

1. Flies (blow flies), fresh corpse, in the first 3 months after death
2. Flies (blow flies and dlesh flies), odoured corpse
3. Dermestid beetles, corpses fats are rancid, between 3-6 months after death
4. Various flies
5. Various flies and bettles, corpse ammonia fermentation stage, between 4-8 months
6. Mites, arrive on the body between 6-12 months
7. Dermestid beetles, arrive on the corpse when its completely dry, arrive between 1-3 years
8. Beetles, arrive after 3 years


What other factors can affect the body decomposition as well?

Environmental factors (i.e. temperature), how body has been deposed of (i.e. water, plastic bags)


How can insects predict or reconstruct when death was?

The table of succession are derived from past cases, experiments and observations
It may seem puzzling initially that although a succession of insect species will invade a copse this cannot be predicted
A large number of variables will affect particular case(s)
The observed succession can be used only to reconstruct and interpret past events


What can identify different species?

Number of antenna, reproduction cycle


What can closely related and superficially similar species have completely different?