Summary

The integument is a layered structure that comprises a basal lamina, epidermis, pro-cuticle, epicuticle, and cuticulin envelope. The basal lamina contains carbohydrate and collagenlike material and is mainly a product of the epidermal cells. The epidermis is mostly a one-cell-thick layer of uniform cells, though the cells can differentiate to form dermal glands, oenocytes, or sensory structures. The procuticle includes an inner endocuticle and an outer exocuticle, both of which contain a mixture of chitin (a polymerized nitrogenous polysaccharide of fibrous form) and protein. The endocuticle is laminar, flexible, and capable of being digested by molting fluid; the exocuticle is hard, inflexible, and chemically inert as a result of tanning, the covalent linking of proteins via quinones. Exocuticle is absent from areas of the body where flexibility is required, for example, at joints and intersegmental membranes, and is very thin in soft-bodied larvae. The epicuticle includes a tanned protein layer, the proteinaceous epicuticle, which lies inside the cuticulin envelope, as well as in most terrestrial species wax and cement which sit outside the envelope. Wax is produced by oenocytes, cement by dermal glands. The cuticulin envelope, a very thin layer of unknown composition, is the single most important component of the cuticle.

Cuticle formation is a succession of syntheses by the epidermal cells, with the oenocytes and dermal glands adding their secretions at the appropriate time. After apolysis, ecdysial droplets are released and, after formation of the new cuticulin envelope, the enzymes in the droplets are activated to digest almost all of the old endocuticle. In new procuticle formation, much of the raw material from the digested endocuticle is reused. Wax deposition occurs just prior to ecdysis and, like endocuticle production, continues during intermolt. The cement layer is laid down after ecdysis. Tanning of the outer procuticle, to form the exocuticle, also takes place at this time.

The strength and hardness of the cuticle enable this layer to serve both as an exoskeleton and in the protection of the insect against physical damage and entry of pathogens. The wax layer is important in reducing water loss (entry) in terrestrial (freshwater) insects, is a 371

barrier to insecticides, and, for some insects, contains pheromones. Color is also a function

, , THE integument of the integument, being produced either by pigments in the epidermis or, more frequently, as a result of the structure of the cuticle.

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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