Exam 1 Review Flashcards
What is entomology
The study of insects!
Its a subdiscipline of biology
Why is Entomology important
genetics, ecology, evolution, behavior, agriculture, medicine, biomechanics, biodiversity, conservation, evolutionary biology, soldier, crop consultant, epidemiologist
Why Study Insects?
-Incredibly diverse
-Extremely abundant
-Important in ecosystem functioning
-Important to humans
-Model organisms for research
Insect Diversity
-10-30 million animals = over ½ of all animals on earth
-⅓ of all animals are beetles
-Even exist in Antarctica
-Found on every continent
-For every 1 human there are 200 million insects
-40 million insects per acre of land
-400 pounds of insects per acre
Why are insects important in the functioning of ecosystems?
-Play a massive role in every ecosystem except benthic environments like the ocean
-Critical to food webs because they are food source for many species
-They are important decomposers that breaks down organic matter, bury dung, and feed on carrion (insects that remove dung are good bc it stops as much of nuisance pests like flies and gets rid of dung from farmed animals)
-Pollination by wild bugs (not controlled honeybees)
-Pest control by beneficial insects like ladybugs, dragonflies, and parasitoid wasps that feel on pest caterpillars (biological control)
-Wildlife nutrition (also supports many species aka sport and commercial fishing, wildlife watching, and small game)
-When thinking of only dung removal, pest control, pollination by wild bugs, and wildlife nutrition it adds up to be $57 billion in the us economy (doesn’t include silk from silk moths or honey or crops from honeybees)
Insects & Disease
-Most dangerous animals in the world
-Disease: malaria, chickungunya, yellow fever, west nile, zika virus, dengue fever
-Malaria = 2-3 million per year
-Not just a problem for developing nations
-Aedes aegypti and aedes albopictus = are spreading disease
Why are insects extensively studied?
-Small
-Cheap and easy to rear in mass numbers
-Have quick generation times
-Simple and easy to manipulate in studies
-We share a common ancestor
-Share 75% of genes related to diseases
-Flies have insulinand insulin receptors so they help with diabetes
-Have 3 chromosomes and are genetically simple
-Fruit flies have taught us:
-Inheritance
-Development
-Biological clocks
-Aging
-X rays and mutagenics
-Pain
-Molecular techniques
What is an Insects Body Structure?
-All arthropods have segmented bodies and paired, jointed appendages
-The body is grouped into 3 functional regions
-Head - used for feeding and sensory organs (sensing)
-Thorax - used for locomotion (where legs attach to body)
-Abdomen - contains the internal organs and external genitalia
How do insects breath?
-They have an open circulatory system aka their blood (hemolymph) is pumped through their heart (dorsal vessel) and then just bathes the organs in their body cavity (hemocoel)
-The oxygen then enters through openings in the exoskeleton called spiracles
-These spiracles are connected to
tubes inside the insect’s body
called trachea that carry oxygen
throughout the insect’s body
Insect Eyes
-Compound eyes (many ommatidia that are filled with photoreceptor cells)
-Form images
-Low resolution
-The large orbs that we see (like
dragonflies)
-Simple eyes (ocelli)
-light/dark sensors
-Little eyes (there are 3) perceive
the light and dark
Insect Antennae
-Incredibly diverse in form and function
-Have chemoreceptors
-Which are used for taste, smell,
and the sense of pheromones
-Have mechanoreceptors
-Which are used to sense
movement, touch, pressure, and
vibrations (aka hear)
Insect Mouth Parts
-Mandibulates = chewing
-Sucking =
-Siphoning
-Sponging
-Lapping
-Piercing-sucking
-Mandibulate mouthparts for chewing
-They chew from side to side
-Mandibles are like knives and
slice the food
-Ancestral insect mouth (first
insects) = mandibulate
mouthparts
-Mandibles can be used by
herbivores, carnivores, filter-
feeding
-Sucking mouthparts
-Siphoning mouthparts =
-Lepidoptera (moths and
butterflies)
-Coiled proboscis when not in
use, when in use uncoiled and
then pumped using muscles
-Sponging mouthparts = diptera (flies)
-Have a little sponge on end of
mouth
-Can easily spread disease bc of
the sponge’s warm and moist
environment
-Lapping Mouthparts = some Hymenoptera (ex honeybees)
-Its like a tongue! They use it to
lap up their food
-Many bees have mandibles too
for cutting open flowers
-Piercing-sucking mouthparts = Hemiptera (cicadas, aphids) & some Diptera (mosquitos)
-Used by plant eaters to bypass
the plants natural defenses
-Used by blood eaters to pierce
the skin and reach blood
vessels
-When either of ^ those do it they
end up injecting something into
the host which can cause disease
spreading
Thorax - Locomotion (wings&legs)
-Thorax contains musculature for
wings and legs
-Has 3 segments
-Prothorax (1st part)
-Mesothroax (2nd part)
-Metathroax (3rd part)
-Legs = one pair on each segment
-Wings (if present) = on meso &
meta thorax
Kinds of Leg Modifications
-Raptorial = prey capture
-Saltatorial = jumping (crickets and grasshoppers)
-Prehensile = grasping/clinging
-Fossorial = digging (mole crickets)
-Natatorial = swimming
-Cursorial = running
Abdomen - digestion and reproduction
-Usually the largest part of the body
-Contains the internal organs for digestion, excretion (of waste), and reproduction
-External genitalia include the copulatory organs
-Some of the abdomen (at the end) have stingers, which originally were reproductive organs (laying eggs) that have been modified for this purpose (only females can have stingers)
-Ex = bees and ants bc they have
queens that lay all the eggs
Body Modifications
-Can be used for camouflage
-Can be used as weapons (ex = horns on beetle heads for fighting)
-Leafhoppers = have unique prothorax modifications that can be used to camouflage and sometimes are ejectable so if they are attacked by a predator they can leave it behind and hopefully escape
Insect Development
-Metamorphosis = change in form
-Molting = when insects ditch the outside layer of their bodies (exoskeleton) so they can grow larger and develop
-Instar - the insect itself between molts
-Insects can have multiple
-Ex = 1st instar, 2nd instar, 3rd
instar
-The number of larval instars
varies among insects
-Molting - the process of shedding of the exoskeleton
-Stadium - the length of time between molts
Types of Insect Development
-Ametabolous development -without metamorphosis
-Start out as eggs
-Become “young”
-And then become adults
-Only thing that really changes
after hatching is their size, they
don’t really change form
-Can continue to molt even after
becoming adults
-ex = silverfish
-Hemimetabolous development - gradual metamorphosis
-Most = begin as individuals
without wings and reproductive
organs to adults with wings and
reproductive organs
-Look similar but not the exact
same & have new body mods
-Normally 3 stages
-Eggs
-Nymphs
-Adult
-ex = grasshoppers, cicadas,
praying mantis
-Holometabolous development - complete metamorphosis
-Normally 4 stages
-Egg
-Larva
-Pupa (when they are in
coccoons)
-Adult
-Looks very different from larva
to pupa to adult (no
resemblance)
-Normally fill different niches
-Ex = ants, bees, wasps, beetles,
butterflies
Exoskeleton Functions
-Exterior protection to internal structures and organs
-It provides support for muscle attachment (internally)
-Forms the wings
-Lines the trachea and parts of the gut
-Serves as a food reserve during times of starvation
-Is a barrier to pathogens and stops water loss
-Give the insect its distinct color, shape, hair, scales, etc
-Is essential for adaptive coloration (and or camouflage) and mate recognition
What is the Exoskeleton Made of?
-Proteins and chitin
-Chitin = carbohydrate (long chain)
-Chitin fibers is interwoven with the protein matrix
-The hardness of the exoskeleton
-The hardness of the cuticle depends on the degree to which proteins are crosslined in a process called sclerotization
-Ex = larval cuticle is soft and flexible bc there is less cross-linking and less sclerotized BUT adult cuticle can be very hard bc there is extensive cross-linking and its more sclerotized
The major layers of the exoskeleton (most internal -> most external)
-Epidermis = the living layer that produces materials to make the other layers
-Endocuticle = the outer part that progressively hardened to add thickness to exocuticle; may be digested and reabsorbed during times of starvation
-Exocuticle = gives hardness to cuticle
-Epicuticle = waterproofing
The molting process in chronological order
-Apolysis - separation of the cuticle from the epidermis
-Secretion - new cuticle materials laid down beneath old cuticle
-Degradation - breakdown of the old endocuticle
-Ecdysis - shedding of old exocuticle
Hormal Control of Molting
-Hormone - a substance that is produced by one tissue and transported to another tissue where it produces a specific response
-Endocrine Gland - glands that secrete hormones directly into the blood
-Endocrinology - study of hormones and their effects
