Integument, Molting and Endocrine Control Flashcards Preview

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Flashcards in Integument, Molting and Endocrine Control Deck (52)
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What are the major constituents of an insect cuticle? (2)

1. Chitin
2. Proteins


What is lamellae?

A polymer chain of N-acetylglucosamine that are bound by proteins to form sheets


How is the cuticle made unstretchable?

Lamellae are laid down at different angles every half hour


How much of the chitin in the cuticle is reabsorbed during molting?

about 85%


Where are proteins found in the insects cuticle?

Cross-linked to lamellae


What are the layers of the cuticle from the outermost layer to innermost layer? (4)

- Epicuticle
- Exocuticle
- Endocuticle
- Epidermis


What is the function of the Epicuticle?

provides a waterproof layer for the insect and prevent water loss


What is the function of the Exocuticle?

Forms a protective shell (hardened by sclerotization


What is the function of the Endocuticle?

To be reabsorbed during molting. Not sclerotized


What is the function of the Epidermis?

To produce all the layers of the Integument. Only actual living part of the integument


How is wax formed on the Epicuticle and why?

A gland in the epidermis extends all the way up to the top most layer to create the wax covering in order to prevent water loss and waterproof the insect


What are the three stages of molting? (in order)

1. Apolysis
2. Ecdysis
3. Sclerotization


What is Apolysis?

The separation of the epidermis from the cuticle of the previous stage


What is Ecdysis?

The casting off or escape from the residual cuticle of the previous stage. There is a fully formed insect inside the old cuticle prior to this stage


What is Sclerotization (in regard to molting)?

A chemical process that hardens the outer section of cuticle (exocuticle) after ecdysis by cross-linking cuticular proteins with oxidized phenols.
occurs from the outside in.


What is a pharate?

The fully formed insect inside the old cuticle prior to ecdysis


What is an exuvium?

The cast off cuticle after ecdysis


What is a teneral adult?

An insect that has not finished sclerotizing its integument after molting


What are the 6 stages the cuticle goes through during molting?

1. Apolysis
2. Production of cuticulin
3. Digestion of endocuticle
4. Resorption of molting fluid
5. Cuticle immediately after Ecdysis
6. Mature cuticle


What hormone controls sclerotization?



What are the two types of sclerotization? Which is light and which is dark colored?

1. Quinone Tanning - Dark colored
2. Beta-Sclerotization - Light colored


What are some unsclerotized parts of an insect?

the intersegmental membranes, the joints and appendages


What is sclerotized in a holometabolous larvae?

The head capsule, mandibles and true legs


What does ecdysis depend on in many species?

Blood pressure and/or air pressure


How is ecdysis performed in many insects?

Insect contracts abdomen for a prolonged period of time which forces blood into the head and thorax. can be assisted by swallowing air


What is ecdysis often aided by? How?

Aided by gravity
- insect hangs upside down, secured by claws of the hind tarsi. Rupturing of the ecdysial cleavage line on the head capsule allows the insect to slide out of the exuvium


How does the muscid fly perform ecdysis?

They have a specialized structure on the head, the ptilinum, an inflatable bladder that breaks open the puparium and allowing the adult fly to emerge


What do insects often have to do after ecdysis? why?

- Swallow air or contract specific muscles to facilitate expansion of the new cuticle prior to sclerotization.
- Pump blood to wings to make sure they are fully expanded


In some species, what must be done throughout the sclerotization process?

Muscles of the abdominal wall must remain contracted throughout


Why are insects especially vulnerable to predators during molting?

They need to remain motionless during sclerotization and have a weak state of cuticle prior to and during the process