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Insects & Human Society - Sessions 8-16


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Any limb or other organ, such as an antenna, which is attached to the body by a joint
One of the rings or divisions of the body, or one of the sections of a jointed limb.
A nerve mass that serves as a center of nervous influence.
Cerci (singular: cercus)
The paired appendages, often very long, which spring from the tip of the abdomen in many insects.
Complete metamorphosis or Complex metamorphosis
Metamorphosis in which the insect develops through four distinct stages, e.g.., ova or egg, larva, pupa, and adult or imago; the wings (when present) develop internally during the larval stage.
Pupa (pl., pupae)
The 3rd stage in the life history of butterflies and other insects undergoing a complete metamorphosis during which the larval body is rebuilt into that of the adult insect a non-feeding and usually inactive stage.
Name given to the changes that take place during an insect's life as it turns from a young animal to an adult. These changes may be gradual and not too large, as in the grasshopper, and metamorphosis is then said to be partial or incomplete. On the other hand, the changes may be much greater and they may take place in one big step - as in the butterflies and moths, which change from caterpillars to adults during the pupal stage. Metamorphosis of this kind is said to be complete.
A period of suspended animation of regular occurrence in the lives of many insects, especially in the young stages.
A substance secreted by an animal which when released externally in small amounts causes a specific reaction, such as stimulation to mate with or supply food to a receiving individual of the same species.
More diapause stuff...
-Physciological state controlled by absence of a particular hormone (either JH or ecdysine) that prepares the insect for overwintering or extremely dry conditions
-can occur in any of the life stages of an insect (ie, embryo, nymph, naiad, pupa or adult)
Characteristics of Adult Diapause
a. Is due to lack of JH
b. Adults don't mate
c. Accumulate large amounts of fat reserves like bears do before going into hibernation
d. produce glycerol, which is an antifreeze
e. usually find a place to spend the winter
f. deplete as much water as possible
Empronic, larval, or pupal diapause
Is due to lack of ecdysone
Autonomy or autoamputation
-stick insects, cockroaches & some others are able to "break off" a leg or antennae if a predator grabs them, thus escaping.
- can regenerate lost structure as nymphs, probably not as adults.
movement of animals to a site and then back again
Social living & collective security
-social insects- stay and hold fort
-collective security- tent caterpillars & fall webworm caterpillars. Overwintering lady bugs (distasteful) and ephids (alarm pheromone)
Defensive tactics
a. cryptic coloration or camouflage
-cryptis- color or shape resembles its background or environment
a. Special resemblance- like something in environment
b. camouflage- color of environment
Aposematic coloration & mimicry (defensive tactic)
-warning coloration- usually reds, yellows, oranges
- warns predators it's a bad thing- like poisons
-mimicry- when something looks like something else and benefits from it.
Avoiding the hunt (Defensive tactic)
bats & moths and praying mantids
Startle (defensive tactic)
-flashing color from hindwings- mantids & moths
allomones (defensive tactic)
-Pheromones- chemicals produced by 1 member of a species that influence another member
-allomones- chemicals produced by one member of a species that benefit that species by influencing another individual of a different species
Concluding remarks on insect evolution
1. Fossils tell us a lot about evolutionary trends

2. Living insects, when compared to the fossil record, provide a much better
picture of evolutionary trends.

3. Insects were initially wingless.

4. 1st winged insects could not fold them over their abdomen.

5. Later, wing folding developed

6. Other important evol. trends were different types of legs, mouthparts, and

7. Body segments fused forming 3 main body regions and appendages of
segments 2-4 became the mouthparts.

8. Insects are still going instinct and undergoing selective forces which will
lead to evolution.
-complexity leads to greater stability
-the more complex an ecosystem the more stable and diverse it is
- the less complex, the less stable and less diverse
What factors lead to biodiversity?
1. Small size
2. High reproductive potential
3. Ability to inhabit almost every suitable habitat except the oceans
4. Ability to fly
Taxonomist or systematist
An entomologist that identifies and classifies insects.
E.O. Wilson
Father of Diversity. "The Diversity of Life"; "Naturalist"
Factors leading to extinction or threatening extinction
1. Overkill, overuse, or overconsumption
2. Habitat destruction and fragmentation
3. Competition due to introduced species
4. Chains of extinctions
5. Combinations of the above
1. Overkill, overuse, or overconsumption
-most states have a lsit of endangered insects
-many are highly endangered but beautiful; "black market collectors"
-collected for insect jewelry, etc.
2. Habitat destruction & fragmentation
-good habitat is usually converted to:
a. Agricultural land
b. Deforested for lumber
c. For houses & urbanization
3. Comptetition
-Hawaii as a special case
-Rats into New Zealand
-Tachnid fly into MA to control gypsy moth
4. Chains of Exctinction
-Extinction usually due to several factors
Elytron (plural elytra)
The tough, horny forewing of a beetle or an earwig (See also Hemi-elytron)
Groups of individuals that become irreversibly behaviorally distinct at some point prior to reproductive maturity. One of three or more distinct forms which make up the population among social insects. The usual three castes are queen, drone (male), and worker. The termites and some of the ants have one or more soldier castes as well.
Breathing organ possessed by many aquatic creatures, including numerous young insects. Insect gills are usually very fine outgrowths from the body and they contain numerous air-tubes, or tracheae. Oxygen passes into the tubes from the water by diffusion.
Wing pads
The undeveloped wings of nymphs and naiads, which appear as two flat structures on each side.
Ootheca (pl., oothecae)
An egg case formed by the secretions of accessory genital glands or oviducts, such as the purse-like structure carried around by cockroaches or the spongy mass in which mantids lay their eggs
The sweet liquid emitted from the anus of aphids and some other sap sucking bugs.

Definition asked for "alarm pheromone"...
A substance secreted by an animal which when released externally in small amounts causes a specific reaction, such as stimulation to mate with or supply food to a receiving individual of the same species.
Wingless Insect Orders
-Collembola (springtails)
-Thysanura (silverfish, bristletails)
Winged Insects
-Odonata (dragonflies & damselflies)
-Ephemeroptera (mayflies)
-Blattodea (cockroaches)
-Mantodea (praying mantids)
-Isoptera (termites)
-Plecoptera (stoneflies)
-Orthoptera (grasshoppers, crickets)
-Hemiptera (true bugs)
-Homoptera (aphids, scales, cicadas)
Collembola (springtails)
Thysanura (silverfish)
1. These are orders of wingless insects
2. They have chewing
3. Metamorphosis not
Odonata (dragonflies + damselflies)
Ephemeroptera (mayflies)
1. These 2 orders HAVE WINGS but can't
fold them flat over their abdomens
2. They still have chewing mouthparts and
cerci are present
3. Metamorphosis gradual
-Plecoptera (stoneflies)
-Orthoptera (grasshoppers, crickets, katydids)
-Blattodea (cockroaches)
-Mantodea (praying mantids)
-Isoptera (termites)
1. These orders have
wings and they can
fold them over their

2. They still have chewing
mouthparts and cerci are

3. Metamorphosis gradual
-Hemiptera (the true bugs, milkweed bugs)
-Homoptera (aphids, leafhoppers, planthoppers, spittle bugs, and scale insects)
1. These orders have wings
and can fold them over their abdomens

2. These insects lack cerci

3. There has been a transition
from chewing to piercing-
sucking mouthparts

4. Development is still
gradual metamorphosis
Dragonfly Mating Behavior!
-the males have a sperm pouch on their second abdominal segment where they deposit their sperm
-He can now use the tip of his abdomen to go and grab a willing female behind the neck with special structures called claspers. The female now bends her abdomen foreward to the sperm pouch on the abdomen to get the sperm
-When completed, she lets go but the male holds on and flies with the female to the pond where she will lay eggs (guarding her)
-In fact, the males have a special adaptation where they can go into
the female's vagina with a special structure at the tip of the abdomen and remove any sperm from another male
COLLEMBOLA (springtails)
IMPORTANCE: none really
THYSANURA (silverfish, bristletails and firebrats)
IMPORTANCE: can be a minor pest eating starchy materials in homes
ODONATA (damselflies and dragonflies)
IMPORTANCE: Excellent predators on mosquitoes (often called mosquito hawks)(immatures are excellent food for fish and are themselves major predators of the ponds where they occur)
IMPORTANCE: excellent food for fish, thus good indicator species
PLECOPTERA (stoneflies)
IMPORTANCE: good indicators of quality streams; excellent
food for fish
ORTHOPTERA (grasshoppers, crickets, katydids)
IMPORTANCE: grasshoppers can be destructive pests, as are cockroaches
Blattodea (cockroaches)
MANTODEA (praying mantis)
IMPORTANCE: good biological control agent because predators
ISOPTERA (termites)
IMPORTANCE: Major pest of dwellings, especially in the south
HEMIPTERA (the true bugs)
IMPORTANCE: majority are plant feeders; some serious pest of plants; some are bloodsuckers
HOMOPTERA (aphids, scale insects, mealybugs, planthoppers, spittle bugs and leafhoppers)
IMPORTANCE: all are phytophagous or plant feeders. Aphids are a pest and can vector disease agents to plants
One of the club-shaped 'balancers' found on each side of the metathorax among the true flies(Diptera). They are the much-modified hind wings.
The pupa of a butterfly.
A case, made partly or completely of silk, which protects the pupa in many insects, especially the moths. The cocoon is made by the larva before it pupates.
Name given to various kinds of sucking mouths in which some of the mouth- parts are drawn out to form tubes.
One of the fleshy, stumpy legs on the hind region of a caterpillar.
A packet os sperm.
A small sac-like branch of the female reproductive tract of arthropods in which sperm may be stored.
The tubular or valved egg-laying apparatus of a female insect: concealed in many insects, but extremely large among the bush-crickets and some parasitic hymenopterans.
A difference in size, form, or color, between individuals of the same species, characterizing two distinct types.
Insect Reproduction
1. Mating readiness
2. Mate finding
a. sound or auditory
b. sex pheromones
c. light production- femme fatle
3. Courtship rituals, nuptual gifts, & conflict
4. Sperm transfer & matrone
5. Ovipositor & behavior
6. Hormonal control of egg development
7. Sexual selection
Mating Readiness
1. Sound or auditory (cicadas, grasshoppers, crickets, & katydids)
2. Contact Pheromones
a. Social insects recognize nest mates
b. Phormia regina fly- copulatory stimulus
3. Light production- femme fatale
4. Mating sites or swarms- leks. Group sex- the sexes getting together because of: a. sites for sex (called leks)
- hill topping
- On the host plant or animal
Synchronous emergences
-like mayflies
Courtship rituals, nuptual gifts, and conflict
Importance of courtship Rituals:
1. Puts the female into a receptive mode
a. Nuptual gifts
b. Aphrodisiacs
2. The complex rituals are often the factor that seperates breeding of closely related species
3. Male conflict & territoriality
Male conflict & territoriality
-Males will defend resources & even guard females in order to ensure their sperm fertilizes the eggs of the female.
a. Male dragonflies will chase off other males
b. Male crickets use sound to define territory, defend it against other males
c. The ancient art of cricket fighting
Sexual selection
1. Darwin recognized that insects are sexually dimorphic
2. Often have secondary sex traits- to do with attraction
3. wing color, horns, songs
4. Some used by females for recognizing males
Insects that feed on plants
Insects that feed on blood
Insects that feed on other insects
Insects that feed on decaying material
Single host (specificity of food sources)
Many hosts (specificity of food sources)
The dilated section of the foregut just behind the esophagus.
The insect's foot: primitively a single segment but consisting of several segments in most living insects.
Compound eye
An eye consisting of many individual elements or ommatidia each of which is represented externally by a facet.
Vincent G. Dethier
"To Know a Fly"; "The Hungry Fly"
Asked- 'How do flies taste?'
Why is insect feeding behavior so important to humans?
1. Destruction to crops, stored products, plants, etc.
2. Destruction to human clothing & houses
3. Results in insects serving as rectors of important disease causing agents to humans- viruses.
Model Systems... why they are important
- soemthing that has been well studied- a biological system
- puts information into a simple form & helps generate new hypotheses
Why use insects as model biological systems?
1. Easy to rear
2. Little room needed
3. Economical
4. Short life span
5. High fecundity
6. Animal rights groups are less interested in them
Crop Emptying
1. Concentration of blood sugar
2. Activity level of insect
3. Concentration of fluid

- There is a nerve going to the crop which suggests that the croup is under nervous control
Sensory Organs (respond to stimulus)
a. Compound eyes - light & motion
b. antennae - odors
c. ocelli - light intensity
d. tympanum - sound
Different types of thresholds
1. Electrophysiological
2. Behavorial
a. Recognition
b. Acceptance
c. Rejection
a. Chemoreceptors
b. Mechanoreceptors
c. Thermorecepors
d. Stretch receptors

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