1. Why Study Terrestrial Arthropods?
Apods more species richness than any other phylum ( hyper diverse)
Apods consistent up to 80% of all animal life
About 1 million described species. Various studies say 3-5 while others studies say about 80million species
To compare 50,000 vertebrate species. That is Fish, reptiles, birds and mammals make up 50,000 total described species

2. Why Study Terrestrial Arthropods?
Key players in terrestrial ecosystems. Found in basically all terrestrial region/habitat except Polar Regions.
Dominate abundance ( # of individuals) and biomass
Pollination, most flowering plants depend on animals for pollination and most pollinators are insects.

3. Pollination
Insect pollinators are responsible for 1/3 of food in the grocery store.

4. Pollination
Many of the fruit that you take for granted require insect pollination: Apple, Pears, Japanese Plums, and Cherries. Includes Nuts as well.

5. Why Study Terrestrial Arthropods?
Plant herbivores = phytophagous (plant feeding) insects. Controls plant overgrowth
Detritivores = important in decomposition of organic material ( dead stuff)
Returns nutrients back to system

6. Why Study Terrestrial Arthropods?
Prey items – important to essentially all terrestrial food web.
Parasites of most vertebrates and majority of arthropods themselves have arthropod parasites

7. Impacts on human welfare
Negative impacts
Vectors for disease ( transmission of west Nile virus and many others)
Parasites on humans ( fleas, mites, ticks)
Dangerous allergies and venoms
Cause medical problems
Crop loss ( phytophagous insects)
Invasive species ( Argentine Ants) cause the loss of other species

8. Parasites on humans

9. Impacts on human welfare
Positive Impacts
Ecosystem services
Processes of decomposition
Nutrient cycle
Pollinators
Bio Control – use natural predators or parasites to control pests.
Important to the health of terrestrial ecosystems
Nutrition yum!

10. Impacts on human welfare
Positive Impacts
Intrinsic molecules
Silks
Venoms
Anti microbial
Forensics – forensic entomology - Use changes in insects’ ecology and life cycle to help solve crime.
See video

11. Insect Classification
3 Key Insect Characteristics
3 body segments (Head, thorax, abdomen)
3 pair of legs
1 pair antenna
Wings present sometimes reduced or absent

12. Subphylum Insecta

13. Key to Insect Dominance
We will look at the following topics to answer the question above
Factors that promote speciation
Ecological divergence

14. Key to Insect Dominance
1. Evolution of wings
Utilize new or scarce resources
E.g. flowers, most pollinators fly
Dispersal to new habitat
Escape unfavorable environment

15. Key to Insect Dominance
2. Complex metamorphosis
Immature stages morphologically different from adults and therefore utilize different resources and habitats this reduces competition with in species (ecologically divergent and lineage persistence

16. Key to Insect Dominance
3. Short generation time
Novel genetic variations arise per generation basis
Most insects have many generations per unit of time which equals lots of genetic variations
Genetic Variation is the stuff of evolutions
Most insects live less than a year.

17. Key to Insect Dominance
Diversification of Mouthparts
Allow for a variety of food sources (predation, herbivory, etc.. . .)

18. Key to Insect Dominance
Terrestrial Reproduction
Dessicant resistant eggs help sustain insect populations despite changing environments

19. Insect Diversity
More described species of insects than all other animal species combined
Subphylum Uniramia is made up of five classes (1st 4 are collectively called Myriapods):
Class Diplopoda
Class Chilopoda
Class Pauropoda
Class Symphyla
Class Hexapoda

20. Insect Diversity Class Diplopoda – Millipedes
10 to 100 trunk segments fused together = two pairs of appendages, ganglia, etc
Feed on decaying plant materials; some suck on plant juices; few are carnivorous
Adaptations include rolling into balls and chemical repellants; lack waxy cuticle
Reproduction occurs via sperm transport to females using gonopods/spermatophores; eggs are fertilized, laid and hatched.

21. Insect Diversity Class Chilopoda – Centipedes
15 or more trunk segments; single pair of legs; last pair used for sensory info
Most are predaceous
Adaptations include poison claws (maxillipeds) which spew venom. Most
Reproduction occurs via spermatophores involving courtship displays; similar to millipedes.

22. Insect Diversity Class Pauropoda and Symphyla
Pauropods have a soft body and thin exoskeleton
They have 11 segments and live in leaf litter
Symphylans have 12 leg-bearing segments, no eyes, and they resemble centipedes. Most symphylans feed on detritus, but a few are vegetable and flower pests.

23. Class Hexapoda (Insecta)
Three Tagmata

24. Class Hexapoda (Insecta)
External Structure and Locomotion
The thorax is divided into the prothorax, mesothorax, and metathorax.
Legs are attached to each thoracic segment; wings, if present, are attached to the thorax.
Spiracles are located on both the thorax and abdomen.
The abdomen has reproductive structures for copulation and oviposition.

25. Class Hexapoda (Insecta)
Insect Flight
Insect flight required wings, but the original function of wings may have been to protect the spiracles.
Early insects may have been gliders rather than wing flappers.
Flight required the ability to thermoregulate because the body must be kept warm to allow flight muscles to contract. Insect flight may be accomplished by direct or indirect flight mechanisms
Insects use a direct or synchronous flight

26. Class Hexapoda (Insecta)
Direct – muscle contractions move wings
Indirect – muscles change shape of thorax

27. Class Hexapoda (Insecta)
Insect Locomotion
Insect locomotion includes walking, running, jumping, or swimming, in addition to flight. When walking, insects have 3 or more legs on the ground at the same time.
Jumping insects have larger metathoracic legs; some (Fleas) use muscles to “cock” legs, storing elastic energy

28. Class Hexapoda (Insecta)
Nutrition and Digestive System
Insects feed on a diverse array of food items by biting, piercing, sucking, sponging, or chewing; their mouthparts are similarly diversified.
The digestive tract consists of a foregut, a midgut for digestion and absorption, and a long straight hindgut that may include a crop and gizzard.

29. Class Hexapoda (Insecta)
Excretory System
Malpighian tubules and the rectum accomplish excretion and resorb water.
Excretion of uric acid is advantageous for terrestrial life because of water conservation, however it is energetically costly to produce uric acid as the primary metabolic waste.

30. Class Hexapoda (Insecta)
Gas exchange
Gas exchange occurs through the tracheae that form a finely branching network that pipes air directly to cells.
Ventilation is usually aided by muscle contraction to exchange air in the tracheae.
Aquatic insects may rely on tracheae, gills, or diffusion.

31. Class Hexapoda (Insecta)
Circulatory and Temperature Regulation
Circulation is accomplished by the blood, which carries dissolved materials, but is not important in transfer of gases.
Thermoregulation is critical for flying insects; they produce a variable body temperature (heterothermy) via basking or shivering thermogenesis.
Honeybees may even cool their hives by beating their wings at the hive entrance in order to draw cooler, outside air into the hive.

32. Class Hexapoda (Insecta)
Nervous Systems
The nervous system of insects is similar to that of annelids and other arthropods.
The supraesophageal ganglion controls sensory structures of the head, and the subesophageal ganglion controls the mouthparts and excitatory functions of other body parts.
A well developed visceral nervous system also is present. Insects are capable of some learning and possess a memory for visual and olfactory cues.

33. Class Hexapoda (Insecta)
Sensory Functions
Insect sensory systems include receptors for touch, vibration, stretching, and chemicals.
Tympanic organs are found in orthopterans and some lepidopterans and function in sound reception.
Compound eyes are well developed in most adult insects, and are composed of ommatidia. The eye of an insect functions primarily in detecting movement, and can also see light waves that humans cannot; some can even detect polarized light for navigation.

34. Class Hexapoda (Insecta)
Sensory Function
Receptors for odor, mechanoreceptors, and stretch receptors are all relatively well developed—Johnson’s organs and tympanal organs sense pressure waves for hearing.
Chemoreceptors are abundant throughout the surface of the organism.
Pheromones are released by insects and function in intraspecific signaling.

35. Class Hexapoda (Insecta)
Reproduction and Development
The most primitive insects, such as silverfish, have indirect sperm transfer via a spermatophore. They develop via ametabolous metamorphosis in which the young are miniatures of the adult, and simply grow in size through stages called instars.
Some of the relatively primitive insects have hemimetabolous metamorphosis where the eggs hatch to form a nymph that goes through a species specific number of molts to gradually become an adult. Adults have wings and sex organs. In primitive aquatic insects, the larvae are called naiads and often have gills. Examples include grasshoppers, chinch bugs, dragonflies, and damselflies.

36. Class Hexapoda (Insecta)
Reproduction and Development
The third type of development is called holometabolous metamorphosis. Immatures are called larvae (caterpillars of moths and beetles). Larvae have a species specific number of molts and the final molt results in formation of a pupae. A protective case called a cocoon, a chrysalis, or a puparium may enclose and protect the pupae. During the term of pupation, all of the adult characteristics of the particular species develop. The adult insect emerges from the protective case in a process called eclosion.

37. Class Hexapoda (Insecta)
Reproduction and Development
Most insects have direct fertilization. Males often have abdominal, copulatory appendages, and females may lay eggs using an ovipositor. Use of pheromones and/or sounds to attract mates is common, and mating display behaviors are often well developed and complex. Timing of reproduction may depend upon nutrition (female mosquitoes must take blood meals), day-length, temperature, and density factors.

38. Class Hexapoda (Insecta)
Innate Behavior and Social Insects
Insects have many innate (non-learned) complex behaviors. The social insects (order Hymenoptera; the bees, ants and wasps and order Isoptera; the termites) show the most complex behaviors.
Several different castes compose the colony.
Reproductive females are the queens; sterile females are workers; males (who develop from unfertilized eggs) are drones (exception: males which are infertile in the termite colony are also workers). Pheromones released by the queen control the castes.