Week 2 - Evolution and Insect Products Flashcards
Insect Evolution: Key Points
- Natural Selection
- Importance of Paleoentomology
- Evolutionary Time frames
- Important Events
Importance of DNA
DNA is the “ladder of life”, can change on a continuous basis, adapting to new environments
Charles Darwin
- Defined our current understanding of species evolution and natural selection
- British, lived in 1800’s
- Interested in botany and entomology
- Wrote “The Origin of Species” 1859
Alfred Russell Wallace
- Independently concluded that evolution happens through natural selection
- British, lived in 1800’s
- Interested in botany and entomology
Definition of Natural Selection (Darwin)
The principle by which each slight variation, if useful, is preserved.
Evolution via Natural Selection
- “Survival of the Fittest”
- “survival” = getting your genes into the next generation
- “fittest” = those who are able to get their genes into the next generation
Natural Selection: Selective Pressure
Forces (usually environmental change) that select in favor of individuals best suited to survive the change, and against those who are not able to.
Natural Selection: Differential Reproduction (the 5 Principles of Natural Selection: Natality, Variability, Survivorship, Heritability, Time)
- Natality - more individuals are born into a generation than will survive and reproduce
- Variability - there is variation between individuals in any given population
- Survivorship - individuals with certain characteristics have a better chance of surviving and passing along their genes
- Heritability - some of the characteristics responsible for differential reproduction are genetically mediated
- Time - enormous amount of time are involved in evolutionary change
Paleoentomology
- Bugs don’t make good fossils; only about 1% of Class Insecta has a fossil record
- Best-preserved insect fossils are in ambers
- Fossils show 55 extinct orders of insects
- Fossils can be used to trace insect evolution
Paleoentomology: Phylogeny
A “family tree” based on morphological and structural similarities between groups, establishing an ancestral lineage, providing an understanding of how all living things are connected.
Time Frames (micro-evolution, speciation, macro-evolution)
- Micro-evolution - changes in populations over decades
- Speciation - changes that result in new species over hundreds of thousands of years
- Macro-evolution - major changes in phylogenetic patterns over long time scales (millions of years) and broad geographic regions
Important Events (8 major periods in earth evolution)
- Earth - 4.5 billion years old
- Precambrian era (prokaryotes) - 3.1 bya
- Cambrian era (metazoans) - 600 mya; first abundant fossils
- Silurian Period - 425 mya; invasion of land by arthropods
- Devonian Period - 400 mya; first true insects
- Carboniferous Period - 345 mya; first great radiation of insects
- Cretaceous Period - 135 mya; second great radiation of insects
- Tertiary Period - 63 mya; dominance of land by mammals, birds, and insects
- Quaternary Period - 2 mya; first Homo
Important Events: When/how insects evolved
- Evolved from the Annelids (worms)
- Evolved 400 mya
- Devonian Period
Oldest Insect orders
- Apterygotes (wingless)
- Thysanura (bristle tails and silverfish)
- Collembola (spring tails)
Most Advanced Insect Orders
- Coleoptera - 250,000 species
- Lepidoptera - 120,000 species
- Hymenoptera - 89,000 species
- Diptera - 78,000 species
Important Events: Big 4 (origin, wings, flexion, metamorphosis)
- Origin of insects - 400 mya
- Wings (paleopterous) - 350 mya
- Wing flexion/folding (neopterous) - 300 mya
- Complete metamorphosis - 290 mya
Insect Products: Key Concepts
What are the following, and who makes them?
- Sericulture by moths
- Lac by scale insects
- Paper and Ink by wasps
Instar
a developmental stage of arthropods (like insects), between each molt until maturity is reached
Filature
process of drawing fibers into threads, esp the process of reeling raw silk from cocoons
Sericulture: who makes
- Made by Giant Silkworm moth family
- Silkworm moths from Order Lepidoptera
- The “commercialized” silkworm moth species is Bombyx mori (native of Asia)
Sericulture: definition and origin
- The propagation of silkworm moths and their host plants.
* Started in China about 4000 years ago, spread to Japan about 2100 years ago, and Europe about 1500 years ago
Sericulture: process
- Adults mate
- Females lay eggs on paper
- Instar larvae feed on mulberry leaves
- Mature larvae spin cocoons
- The cocoons then undergo filature
- End product is silk
Lac: what is it, and origin
- A resin produced in flaky layers or shells, and used to make varnish, phonographic records, insulation, and other things.
- Process developed by Maya and Aztec
Lac: what makes it
- Made by scale insects, Order Homoptera, Family Coccidae
- 2000 species
- Have a phytophageous life style (“sap tappers”)
Lac: scale insects of economic importance
- LAC scale
- Cactus scale (for Cochineal dye)
- Kermes scale (for Kermes dye)
Lac: about the Cochineal (from cactus scale)
- Females are wingless, males are winged
- Feed on cactus
- Native to S America and Mexico
Lac: how it is made
- Females produce carminic acid as defense, extracted from bodies and eggs
- Cochineal extract - raw coloring made from crushed insects
- Carmine - purified coloring made by boiling the crushed insects with solvents
- Used to color food, makeup, cloth, wool, paint, ink
- 155,000 insects used to make one kg of dye
Paper and ink: wasps
- Order Hymenoptera, Family Vespidae
- Social wasps: yellow jackets and hornets
- Evolved about 70 mya
Paper and ink: nests
- Made out of cellulose, similar to paper
Paper origin
- Developed in China about 1800 years ago
- 800’s in Arab world
- Moorish Spain - 1150 AD
- England - 1590 AD
Ink
- Produced from oak galls
Galls
- Physical growth by a plant in response to an insect laying eggs in the plant tissue, in this case a wasp of Genus Cynips gallae-tinctoriae
- Oak leaves develop galls from gall wasp
Products of the Hive: Key Points
- History of Beekeeping
- Modern Apiculture (removable frames, bee space)
- Honeybee Products (honey, beeswax, pollen, venom, royal jelly, pollination services)
History of Beekeeping
- Prehistoric man collected honey
- Oldest apiculture records are Egyptian
- Honeybees were brought to Western Hemisphere in 1622
- Before 1853, hives used were called “skep” hives, the cone-shaped/”wound” hives; harvest was destructive and inefficient
Primary bee specie
- Apis mellifera
- 2 biotypes used: European and African
- 27 subspecies in the world
Apiculture
The management of honeybees
Modern Apiculture
- Began 1853 with publication of “The Hive and the Honeybee” by L.L. Langstroth, considered the “father” of modern beekeeping
- Established bee space, top-opening hives, and removable frames
Bee Space
Between 1/4” and 3/8”; too much space and they attach combs to the walls, too little, and they don’t create combs
Honey: constitution
About 17% water, 82.5% sugar (glucose, fructose, maltose, sucrose), .5% protein/vitamins/minerals
Honey: how it’s produced
- Produced from plant nectar, mostly from flowers.
- Nectar comes from phloem sap, a dilute solution of sucrose
- For bees to make the honey, the nectar is dehydrated and undergoes enzymatic “inversion”, breaking sucrose down into glucose and fructose
Honey: uses
- First sweetener
- First alcoholic beverage (mead)
- US produces 200 million pounds per year (2 billion lbs worldwide)
- US consumption: 1 lb/person/yr (Germany = 4)
- Also used in pharmacy and cosmetics
Beeswax: uses
- Cosmetics
- Candles
- Beekeeping uses
Beeswax: how it’s produced
- Comes from 4 pairs of sub-dermal glands underneath abdomen of worker bees.
- Produced when bees 10-18 days old
- Produced as small, translucent flakes
Beeswax: components
Over 300 identified individual components
Royal jelly: definition
Glandular secretions of young worker bees (4-10 days old) by hypopharyngeal gland in the head, used as food for larval bees.
Royal jelly: composition
- 66% water
- 14% protein
- 14% carbohydrates
- 5% lipids
Bee venom: uses and composition
- Used to desensitize people who work with bees
* Mixture of proteins and peptides
Pollen: definition and uses
- Plant male gametophyte (reproductive structure that carries sperm)
- Direct food source for older larvae
- Indirect food source for royal jelly
Pollen: composition
- Protein: up to 28%
- Lipid: up to 20% (usually <5%)
- Sterols, sugars, starches, minerals, vitamins
Pollination Services
- Greatest economic value of beekeeping
* US: $15 billion/year
