Lipid Metabolism

For most insects, fats stored in the fat body are the primary energy reserve and, like those of other animals, are mostly triglycerides. They may be formed directly by combination of the fatty acids and glycerol produced during digestion or from amino acids and simple sugars. Typically, fat is stored throughout the juvenile period, especially in endopterygotes where at metamorphosis it may make up between one-third and one-half of the dry weight of an insect. Large amounts of fat also accumulate in the egg during vitellogenesis. Fats are used as an energy source during "long-term" energy-requiring events, for example, embryogenesis, metamorphosis, starvation, and sustained flight (Chapter 14, Section 3.3.5). On a weight-for-weight basis, fats contain twice as much energy as carbohydrates; they are therefore more economical to store.

In addition to the fats just described which serve solely as energy reserves or sources of carbon, many other lipids having structural or metabolic functions occur in insects. Waxes are mixtures of long-chain alcohols or acids, their esters, and paraffins. The number of carbon atoms that form the chain ranges between 12 and 36, and both unsaturated and saturated compounds have been identified. It seems that the various components of wax are synthesized from fatty acid precursors. The paraffins and, possibly, some acids are produced by oenocytes, whereas alcohol and ester synthesis occurs in the fat body. Compound lipids are fatty acids combined with a variety of organic or inorganic residues, for example, carbohydrates, nitrogenous bases, amino acids, phosphate, and sulfate. The metabolism of these lipids in insects is for the most part poorly known. Certain of them, for example, choline, a phospholipid, cannot be synthesized by insects and must be included in the diet. Likewise, sterols are essential components of the diet in almost all insects.

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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