Arthropods/insects

1. Arthropods/insects • Phylum Arthropoda -Most successful phylum of animals due to diversity and numbers. • Five classes of Arthropods in Illinois: Class Chilopoda - millipedes Class Dilopoda - centipedes Class Crustacea - crustaceans Class Arachnid - spiders, mites, ticks and scorpions Class Insecta - insects (Use text chapter 28-sect 3 as a supplement) Insects have: • segmented body • jointed appendages • exoskeleton • three body parts- head, thorax, abdomen • one pair of antennae on head • one pair of legs per segment • some have wings

2. What do insects do? • What problems do we have with insects? • What happens because of our “treatment”? • Where do some of the “new” insects come from? • Do insects help us? How? How have insects adapted and become so successful? ( hint consider their variations) • Where do they live? • How are insects classified? Mouthparts, wings • What is DDT? • What are two diseases which are spread by insects? Malaria and typhoid fever Facts: 17, 000 species of insects in Illinois Biomass of humans is equal to the biomass of insects. Why are insects successful?????

3. Insect’s Success Three types of variations: • Structural-These are changes in body parts to help insects adapt or have an advantage. Types of Movement: a. Cursorial - walk/run b. Saltatorial - jump/hop c. fossorial - dig/burrow d. Aerial - fly e. Natatorial -swim 2. Physiological(inside) - These are differences in the way their bodies work internally. These include enzymes that help them digest special “foods” such as grass, wood or blood. This also includes any immune responses to chemicals. 3. Behavioral - These are differences in the ways that insects respond to stimulus. These include being active at night or day, living alone or in groups, and being aggressive or not.

4. External Structure of insects 1. Head - brain, mouthparts, antenna an compound eyes, three simple eyes 2.Thorax - legs and wings attached 3 parts - prothorax, mesothorax, metathorax Wings - two pair - forewings to protect - hindwings used to fly Where do the wings come from? exoskeleton 3. Abdomen - reproduction, digestion, excretion Functions?

5. Internal Structure • 1. Complete digestive system • 2. Circulatory system- Aorta - is a large blood vessel that pumps blood at muscular regions. No true heart. • 3. Respiratory System- use spiracles and tracheato move oxygen and gases in and out of body. • 4. Nervous system- three simple eyes detect light, two compound eyes help it to see in all directions (detects movement). • Tympanum- sound sensor membrane Brain with ganglia. • 5. Reproduction -sexes separate, internal fertilization. • Ovipositor of female is used to lay eggs. • Development- Two types: 1. Complete - egglarvapupaadult 2. Incomplete - eggnymphadult Complete metamorphosis- caterpillar changes to an adult after going through a pupa stage. Chrysalis vs. Cocoon? Chrysalis- butterfly cocoon- moth

6. Nutrition What do insects eat? A.Predation - hunting/killing other organisms. 99% of all prey is eaten alive. 1. Common in all habitats 2. Broad range of prey 3. Large eyes B.Herbivory- eat plants 1. Monophagous- eat only one thing 2. Oligophagous - eat few different things 3. Polyphagous - eat many different things C.Saprophytes/detritovores- eat decaying matter D.Sanguinivore - blood eating E.Parasitism- eat on other organisms normally without killing 1. Unkown # of species (1 million +) 2. Every insect has a parasite(s) which attacks certain stages Parasitoid species www.nysaes.cornell.edu/ent/biocontrol/parasitoids/parasintro.html

7. Why do insects go through metamorphosis? • Hormones regulate metamorphosis. • Caterpillars are specialized for growth • Adults with wings are specialized for reproduction and growing. • Both stages need large amounts of energy. • Metamorphosis reduces competition between larva and adults. How? Hint: What do they eat? Different things. Where do they live? How does it help them survive better? different places (some have aquatic stages) How do insects survive in cold weather? Eggs/ dormant stages What is an imaginal disc?http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Student/fly_webo4/web%20presentation/fly1 A physical structure on the larvae which produces body parts in adults.

8. Defense 1. Apatetic coloration (Camouflage)blending in to background 2. Warning coloration (aposematic)-insects advertise their danger of chemicals, stings and bad taste with brightand bold colors. 3. Intimidation-look like a large item or scary “eyes/face” 4. Mimicry - false advertisement of poison or bad taste. • Mullerian mimicry - Some types of insects have very similar colorings to warn that all are harmful. • Batesian mimicry- this is a “fake” warning coloration that fools predators that the insect is harmful (some flies look like bees) Facts: Females have the mimic coloration for protection. Males tend to not have mimic coloration. Females don’t respond to males with changes in coloration. Ex: Tiger Swallowtail females take on dark color of Pipevine Swallowtail to look poisonous. Males are yellow and do not mimic pipevineor red-spotted purple.

9. Class Insect - common Orders to know!Ephemeroptera - Mayflies Plecoptera- stonefliesOrthoptera- grasshoppers, cricketsIsoptera- termitesDermaptera- earwigsHomoptera- leafhoppers, aphids, cicadasHemiptera- true bugsAnoplura - liceNeuroptera- nerve-wingedColeoptera- beetlesTrichoptera - caddisflesLepidoptera-butterflies and mothsMecoptera-scorpionfliesDiptera- flies and kinHymenoptera- bees, wasps and antsMantodea – MantidsPhasmida – walking sticksBlattaria- CockroachesOdonata – dragonflies, damselflies

10. Ants, Bees & Wasps(12 records) Hymenoptera membranous wing; Hymen = membrane, ptera = wings. Winged forms of ants, bees and wasps possess 2 pair of membranous wings. Butterflies & Moths(67 records) Lepidoptera means scale wings; lepido = scale, ptera = wings. Wings of butterflies and moths are often covered with a colorful mosaic of minute scales. Flies(7 records) Diptera means two wings; di = two, ptera = wings. Flies do very well with their single pair of fore wings. The hind pair are often reduced to a couple of knob-like balance organs. Beetles(16 records) Coleoptera means sheath wings; coleo - sheath, ptera = wings. Beetles front pair of wings are modified to hardened casings, known as elytra, to protect the hind wings and body below. Lacewings & Antlions(1 record) Neuroptera means nerve wings; neuro = nerve, ptera = wings. Wings of these insects are constructed with an elaborate network of supporting veins. Cicada, Hoppers & Aphids(7 records) Homoptera means uniform wings; homo = alike, ptera = wings. The front wings of these insects have a uniform textured appearance in contrast to their Hemiptera relatives. True Bugs(12 records) Hemiptera means half wings; hemi = half, ptera = wings. The front wings of these insects are divided between a thickened basal region and a membranous tip. Cockroaches(1 record) Cockroaches are fast-running insects often with wings. A few well know species have successfully evolved to exploit human dwellings and food supplies. Mantids(1 record) Mantodea means soothsayer; a person claiming to be able to predict the future. These insects have highly modified front legs often held in a position suggestive of prayer. Grasshoppers & Crickets(9 records) Orthoptera means straight wings; ortho = straight, ptera = wings. These insects often have a pair of elongated and thickened forewings and a membranous hind pair. Walking Sticks(3 records) Stick insects are usually extremely elongated and twig-like in appearance. Sometimes this camouflage is taken a step further with the addition of leaf-like structures. Dragonflies & Damselflies(7 records) Odonata means tooth. Apart from jet propulsion, the aquatic nymph often possess an extendable jaw capable of catching prey some distance away from the rest of the head. Mayflies(1 record) Ephemeroptera means short-lived wings; emphemera = one day, ptera = wings. After a year or more as an aquatic nymph, adults emerge in swarming nuptial flights and live for only a day or so. Some Are Not Insects(6 records) Arthropod means segmented feet; arthro = joint, poda = foot. Including insects, this huge group contain animals often mistaken for insects such as spiders and centipedes.

11. Arthropods CompleteMetamorphosis • Most insects develop through the four stages of complete metamorphosis—egg, larva, pupa, and adult. • Competition reduced within a species by metamorphosis. Complete metamorphosis has a larval stage that is very different from the adult and eats different food.

12. Arthropods Incomplete Metamorphosis • Insects that undergo incomplete metamorphosis hatch from eggs as nymphs. • After several molts, young nymphs become winged adults.

13. Monarchs -Adults (butterflies) lay eggs under leaves on milkweed plants. (April -August) They usually only lay one egg per plant unless few plants are found.-Monarch females lay about 400 eggs. Butterflies have “tasters” on their front legs to test plants.-Life cycle from egg to adult =30 days (this can vary during seasons)-Eggs can be harvested from plants by taking plant or leaf. They will only eat milkweed so have plenty on hand. -Eggs hatch in about 3 days after laying. Faceplate of caterpillar can be seen in egg when ready to hatch. It is also shed with moltings, but not eaten by growing caterpillar.-5 Instars or stages are named for the 5 moltings of exoskeleton (skin). --They grow and shed five times as caterpillars. They should be 2-2 1/2 inches long at last instar.Metamorphosis is complete egg--> larva-->pupa->adult

14. monarch life cycle linkSteps in change:1.Larva attached itself to high point (top of cage or underside of leaf)2. Thread mat is made of silk and a silk button is made where prolegs (last two) are anchored with hooks. 3. Caterpillar hangs like a J shape. Changes start taking place internally. Body will straighten and skin will be shed in about 1 hour. The skin comes up and is dropped. Green body is different and visible. Chremaster (looks like a stinger) comes out of chrysalis to find silk button and attach. Prolegs are knocked off.Metallic gold spots - affect color and density of scales on wings. Egg to chrysalis in 18 days… hangs as chrysalis for about 10-14 days. Total time from egg to adult 30 days.4. Chrysalis cuticle is clear. Color changes due to changes inside. 5. Adult emerges- blood must be pumped into wings. Proboscis is zipped together. Frass comes out. Hangs for 1 hour +.

15. Adults migration linkMales - have 2 scent glands on their back. (large black increase in vein). Spiracles are also visible on the chrysalis.As a pupa - males have dimples in chrysalis under spiraclesAdults live about 4 weeks on average. They mate, lay eggs and die. Those that emerge after Aug. 15th go into sexual diapause. They do not mature --They migrate to mountains of Mexico and California for the winter (cool and moist). They have antifreeze in their bodies and cluster for warmth. Illinois is along the migration route. They have fat cells to help them on their trip and through the winter. Return late spring/summer to lay eggs and die.Milkweed linkThis is main food of monarchs - various types exist.Milkweed is pollinated by insects and is vital for seed production. Legs pull out the pollen. Of all the flower heads, only one pod develops, even if all flowers are fertilized. Milkweed can be dug up in the fall and planted in various areas- perennial and will come back each year.