1. Insects
Chapter 37

2. The Insect World
Section 37.1

3. Characteristics of Insects
Three tagmata:
Head: mandibles to chew, pair of antennae for sensory
Thorax: 3 pairs of jointed legs, most have 1 or 2 pairs of wings
Abdomen: 9-11 segments

4. Head
Thorax
Abdomen

5. Exoskeleton with…
Antennae Examples:
Leg Examples:

6. Appendage examples:

7. Two types of mouthparts:
Sucking
Chewing

8. Entomology: The study of insects Person = entomologist
& other terrestrial arthropods
Person = entomologist
Classify insects into 25 orders based up:
Mouthparts
Number of wings
Type of development

9. Classification of Insects
Subphylum: Hexapoda
Class: Insecta
Common Orders:
Hemiptera
Homoptera
Isoptera
Odonata
Orthoptera
Coleoptera
Diptera
Hymenoptera
Lepidoptera
Table on
page 743

10. Success of Insects Insects live everywhere (except deep ocean)
1 million species (more than 3x all other animals!)
10 million might exist
Why so many?
Ability to fly
Escape & dispersal
Small
Short life spans
Quick adaptations

11. Insects and People Competition for food  Spread diseases 
Plague, typhoid fever, malaria
Consume clothing & carpet 
Crop pollination 
Make commercial products 
Wax, silk, honey
Recycle nutrients 
Video

12. Insect Development
Hatchling must go through several molts to reach adulthood (sexual maturity)
Metamorphosis: major developmental changes from larvae to adult
Two forms: incomplete & complete

13. Incomplete Metamorphosis
Nymph: immature form of insect that looks like adult
Only the adult can fly and is sexually mature

14. Complete Metamorphosis
Two stages of development that look drastically different
Pupa: changing from larvae to adult
Cocoon: protective covering of pupa
Chrysalis: butterfly pupa protection

15. Insect Defense Passive defense examples: Aggressive defense examples:
Camouflage
Look like plants
Aggressive defense examples:
Venomous stingers
Harmful chemicals
Warning coloration: color pattern to warn of poison

16. Mimicry
Mullerian mimicry: poisonous species mimics the coloration of another poisonous species
Bees & wasps
Batesian mimicry: harmless species mimics the coloration of a poisonous species
Monarch & viceroy butterflies

17. Grasshoppers
Subphylum Hexapoda

18. External Structures:
Head = mouthparts, antennae, simple & compound eyes
Thorax = 3 parts:
Prothorax = 1st pair walking legs
Mesothorax = 2nd pair walking legs & forewings (protective)
Metathorax = 3rd pair legs (jumping) & hindwings (flying)

19. Abdomen = upper & lower plates connected by flexible exoskeleton
Covered by waxy cuticle (prevents desiccation)

20. Video Feeding Chewing mouthparts (feed on plants)
Labrum: functions like upper lip
Labium: functions like lower lip
Mandible: tears food
Maxilla: helps hold & cut food
Video

21. Digestive Tract
Mouth  saliva (from salivary glands)  esophagus  crop (storage)  gizzard  midgut/stomach (bathed in enzymes from gastic ceca)  nutrients absorbed in hindgut/intestine  anus

22. Circulation, Respiration, & Excretion
Circulatory system:
Open
Aorta (large, dorsal vessel)
Heart (pumping organ)
Respiratory system:
Tracheae (site of air diffusion inside body)
Spiracles (openings to allow air in/out)
Excretory system:
Malpighian tubules: return most water back to hemolymph, rest leaves body via feces

23. Neural Control
CNS = brain, ventral nerve cord, & ganglia at each segment
Antennae – touch & smell
3 simple eyes – intensity of light
2 compound eyes – sight
Tympanum – sound & communication
Sensory hairs - touch

24. Reproduction Separate sexes (male & female) Sexual Reproduction:
male deposits sperm into female seminal receptacles
Eggs released from ovaries
Internal fertilization
Ovipositor: digs a hole in soil to lay eggs

26. Insect Behavior
Section 37.2

27. Communication Chemical communication via pheromones
Chemical released that affects behavior or development of other members of same species
Uses of pheromones:
Attract mates
Identify hives
Food trails
video

28. Communication Con’t…
Sound communication via chirping, buzzing, etc. (crickets, mosquitoes)
Attract females
Protect territories
Sight communication via flashes of light (fireflies)
Find mates

29. Behavior in Honeybees
Social insects: insects that live in colonies with division of labor
Innate behaviors: genetically determined
Not taught or learned
Three types of honeybees:
Worker
Drone
Queen

30. Worker Bees Sterile females
First adult week: feed honey & pollen to queen, drones, & larvae
Royal jelly
Next two weeks: secrete wax (build & repair honeycomb), remove wastes, guard hive, circulate air in hive

31. Continued… Last weeks of life: collect nectar & pollen Adaptations:
Barbed stingers for protection of hive
Mouthparts for lapping nectar
Legs with pollen packers, baskets, & pollen combs

32. Drones Males developed from unfertilized eggs
Parthenogenesis
Can travel from hive to hive
Sole function: deliver sperm to queen
succeed in mating = death
penis and associated abdominal tissues are ripped from the body at intercourse

33. Queen Bee Continuous diet of royal jelly as larvae = queen bee
Secretes pheromone “queen factor” that prevents other females developing into queens
Sole role: reproduction
Mates only once
Sperm remains inside her for 5+ years
Lays millions of eggs per year!
Video

34. The Dances of the Bees Round Waggle
Dancing performed by scout worker bees
Round dance: told workers that food was nearby but not exact location
Waggle dance: told workers that food was far away and told location
Round
Waggle

35. Altruistic Behavior
Definition: aiding other individuals at one’s own risk or expense
Kin selection: increasing the propagation of one’s own genes by helping closely related individuals reproduce
Example: worker bee stinging = death
Video