Chapter 37-Insects

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Chapter Presentation

Transparencies Standardized Test Prep

Visual Concepts

Resources



InsectsChapter 37

Table of Contents

Section 1 The Insect World

Section 2 Insect Behavior



Section 1 The Insect WorldChapter 37

Objectives

• Relate the major characteristics of insects to insects’ biological success.

• List both harmful and beneficial effects of insects on human society.

• Describe the external structure and organ systems of a grasshopper.

• Compare incomplete and complete metamorphosis in insects.

• Describe defensive adaptations in insects.




Characteristics and Classification of Insects

• The insect body is divided into three tagmata:– The head has mandibles and one pair of

unbranched antennae.– The thorax has three pairs of jointed legs and, in

many species, one or two pairs of wings.– The abdomen has 9 to 11 segments but neither

wings nor legs in adults.



Chapter 37

Exploration of an Insect




Chapter 37

Comparison of Crustaceans and Insects




Chapter 37

Click below to watch the Visual Concept.

Visual Concept

Characteristics of Insects





Characteristics and Classification of Insects

• The study of insects and other terrestrial arthropods is called entomology, and the scientists who engage in it are known as entomologists.

• Entomologists classify insects into more than 25 orders based on characteristics such as:– structure of mouthparts– number of wings– type of development



Chapter 37

Insect Diversity




Chapter 37

Common Insect Orders





Characteristics and Classification of Insects, continuedThe Success of Insects• Insects live in almost every terrestrial and freshwater

environment.• Factors responsible for their success include:

– ability to fly– exoskeleton– jointed appendages– small size– short life span




Characteristics and Classification of Insects, continuedInsects and People• Insects negatively affect humans by:

– competing for food– transmitting diseases– destroying buildings and other manufactured

products• Insects benefit humans by:

– serving as food for other animals– pollinating flowers– making valuable products such as honey– recycling nutrients in ecosystems




The Grasshopper

External Structure• The body of a grasshopper has three tagmata:

– The head bears the mouthparts, a pair of unbranched antennae, and pairs of simple and compound eyes.

– The thorax is composed of the prothorax, the mesothorax, and the metathorax.

– The abdomen has upper and lower plates.• The rigid exoskeleton and its waxy cuticle

covering are adaptations for a terrestrial life.



Chapter 37

External Anatomy of a Grasshopper




Chapter 37


Visual Concept

Anatomy of a Grasshopper





The Grasshopper, continued

Feeding and Digestion

• Insect mouthparts are adapted for different functions in different species.

• Grasshoppers feed on plants, and their mouthparts are modified for cutting and chewing leaves and blades of grass.

• The labrum and labium are mouthparts that function like upper and lower lips, respectively.



Chapter 37

Insect Mouthparts




Chapter 37


Visual Concept

Feeding Habits of Grasshoppers






Circulation, Respiration, and Excretion

• Insects have an open circulatory system that transports nutrients through the body.

• Gas exchange occurs by means of air-filled tracheae that reach deep into the body.

• Malpighian tubules remove cellular wastes from the hemolymph while conserving water.



Chapter 37


Visual Concept

Grasshopper Circulatory and Respiratory Systems






Neural Control

• The grasshopper’s central nervous system consists of a brain and a ventral nerve cord with ganglia located in each body segment.

• Nerves extend from the brain to sensory structures.• Insect sensory structures include :

– simple and compound eyes– sensory hairs on antennae and other body parts– in some species, a sound-sensing tympanum



Chapter 37

Internal Anatomy of a Grasshopper






Reproduction

• Grasshoppers have separate sexes, as do all insects.• During mating, the male deposits sperm into the

female’s seminal receptacle, where the eggs are fertilized internally.

• The last segment of the female’s abdomen forms the ovipositor, which she uses to lay fertilized eggs.




Insect Development

• Most insects go through metamorphosis.• In incomplete metamorphosis, a nymph hatches

from an egg and resembles the adult but has undeveloped reproductive organs and no wings. The nymph molts several times to become an adult.

• In complete metamorphosis, a wormlike larva called a caterpillar hatches from an egg and molts several times before becoming a pupa. The pupa molts to produce the adult, which resembles neither the larva nor the pupa.



Chapter 37

Incomplete Metamorphosis




Chapter 37


Visual Concept

Incomplete Metamorphosis




Chapter 37

Types of Insects That Go Through Incomplete Metamorphosis




Chapter 37

Complete Metamorphosis




Chapter 37


Visual Concept

Complete Metamorphosis




Chapter 37

Types of Insects That Go Through Complete Metamorphosis




Chapter 37

Incomplete Versus Complete Metamorphosis





Insect Development, continued

Importance of Metamorphosis

• Complete metamorphosis allows larvae and adults of the same species to avoid competing for space and food.

• Metamorphosis also allows insects to survive periods of harsh weather or scant resources.



Chapter 37

Life Cycle of a Monarch Butterfly





Insect Defense

• Insects may defend themselves by:– stinging– using camouflage– releasing noxious chemicals

• Insects that are dangerous or taste bad often have warning coloration that makes them recognizable to predators.

• The warning coloration of a dangerous species may be mimicked by harmless species.



Chapter 37

Digestive Tract of a Bee




Chapter 37

Tracheal System of a Beetle




Chapter 37


Visual Concept

Parts of an Insect Mouth




Section 2 Insect BehaviorChapter 37

Objectives

• Identify three ways that insects communicate, and give an example of each.

• Describe the social organization of honeybees.

• Explain how honeybees communicate information about the location of food.




Communication

Insects communicate by behaviors such as:– releasing pheromones– producing sounds – producing flashes of light




Behavior in Honey Bees

• Social insects live in complex groups or colonies.• The division of labor among social insects creates

interdependence and a need for communication. • The social behavior of these insects is genetically

determined behavior, or innate behavior. • Honeybee colonies consist mostly of female worker

bees. They perform all duties but they do not produce their own offspring.

• Reproduction in each colony is the exclusive function of one queen bee and a few hundred male drones.




Behavior in Honey Bees, continued

• Worker bees perform many functions during their lifetime, which lasts about six weeks.

• At one stage, worker bees are called nurse bees and secrete royal jelly, which they feed to the queen and youngest larvae.

• The queen bee develops when selected larvae are fed a continuous diet of royal jelly.

• As a new queen matures, she secretes queen factor, which prevents other female larvae from developing into queens.





The Dances of the Bees

• Honeybees communicate the direction and distance to food sources by performing dances inside the hive.

• Honeybees use two types of dances: – The round dance indicates that a food source is

nearby.– The waggle dance indicates the direction of food

and the food’s distance from the hive.





Altruistic Behavior

• In defending the colony, worker bees show altruistic behavior toward their close relatives in the colony.

• By working for the colony, the worker bees increase the propagation of their own genes.



Chapter 37


Visual Concept

Social Insects

Section 2 Insect Behavior



Multiple Choice

1. What are an insect’s legs and wings attached to?

A. head

B. thorax

C. labrum

D. abdomen

Standardized Test PrepChapter 37



Multiple Choice, continued

1. What are an insect’s legs and wings attached to?

A. head

B. thorax

C. labrum

D. abdomen





2. What are the mouthparts of a grasshopper specialized for?

F. sucking fluids

G. lapping up liquids

H. cutting and tearing fibers

J. filtering food out of muddy water





2. What are the mouthparts of a grasshopper specialized for?

F. sucking fluids

G. lapping up liquids

H. cutting and tearing fibers

J. filtering food out of muddy water





3. What is the term for the immature form of an insect that undergoes incomplete metamorphosis?

A. adult

B. pupa

C. infant

D. nymph





3. What is the term for the immature form of an insect that undergoes incomplete metamorphosis?

A. adult

B. pupa

C. infant

D. nymph





The illustration below shows the life cycle of a butterfly. Use the illustration to answer the questions that follow.





4. What kind of life cycle is shown?

F. direct development

G. seasonal development

H. complete metamorphosis

J. incomplete metamorphosis





4. What kind of life cycle is shown?

F. direct development

G. seasonal development

H. complete metamorphosis

J. incomplete metamorphosis





5. What is the term for the developmental stage labeled C?

A. pupa

B. larva

C. nymph

D. caterpillar





5. What is the term for the developmental stage labeled C?

A. pupa

B. larva

C. nymph

D. caterpillar





6. queen factor : queen bee :: royal jelly

F. drone

G. worker

H. queen bee

J. pheromone





6. queen factor : queen bee :: royal jelly

F. drone

G. worker

H. queen bee

J. pheromone





The diagram below shows the external structure of a grasshopper. Use the diagram to answer the questions that follow.





7. What is the term for the structure(s) labeled D?

A. thorax

B. labrum

C. abdomen

D. antennae





7. What is the term for the structure(s) labeled D?

A. thorax

B. labrum

C. abdomen

D. antennae





8. Which of the following structures is part of the structure labeled B?

F. ovipositor

G. mandibles

H. tympanum

J. malphigian tubules





8. Which of the following structures is part of the structure labeled B?

F. ovipositor

G. mandibles

H. tympanum

J. malphigian tubules




Short Response

Defensive adaptations in insects increase the chances of insects’ survival.

Distinguish between passive defenses and aggressive defenses, and give two examples of each.




Short Response, continued

Defensive adaptations in insects increase the chances of insects’ survival.

Distinguish between passive defenses and aggressive defenses, and give two examples of each.

Answer:

Passive defenses don’t involve behavior. Examples include camouflage, warning coloration, being poisonous, or tasting bad. Aggressive defenses involve aggressive behavior, such as stinging a potential predator or spraying it with a noxious chemical.





Extended Response

Base your answers to parts A & B on the information below.

Farmers often try to limit the number of insects on crops by applying chemical insecticides to the crops. Sometimes, an insecticide that had previously been effective no longer affects certain types of insects.

Part AWhy do farmers try to control insects?

Part B How can the effect of insecticides on certain insect populations change?




Extended Response, continued

Answer Part A

Insects can cause extensive crop damage.Part B

Insecticides may control pest populations at first. However, insects with genes that confer pesticide resistance may survive and reproduce in large numbers while non-resistant insects die off. The result is an insect population that has evolved resistance to the insecticide.

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Chapter 37-Insects