Energy Metabolism in Insects

The scientific program for the XVI International Congress of Entomology, held in Kyoto, Japan August 3-9, 1980 included a symposium on the subject of "Energy Metabolism and Its Regulation in Insects." The symposium provided an opportunity to integrate knowledge, and focus attention, on an important and fundamental aspect of insect biochemis­ try/physiology. The energy metabolism of insects differs from that of other animals in a variety of ways, including the prodigious amounts of energy expended by flying insects, the presence in hemolymph of large concentrations of sugar in the form of the nonreducing disaccharide tre­ halose, the transport of fat in the form of diacylglycerol, and the periodic mobilization and deposition of cuticular components during development. These differences, together with hormones, neurohormones, and neu­ rotransmitters that are specific to (or functionally different in) insects, serve to demonstrate the unique nature of energy metabolism in insects. An obvious corollary from the demonstrated uniqueness of insect energy metabolism is that an understanding of the process may lead to the de­ velopment of new, specific agents or strategies for the suppression of insect pests. The present volume is an expanded version of the Kyoto symposium.

1 Physiological and Environmental Considerations in Insect Bioenergetics.- 1. Introduction.- 2. Energy Flow.- 2.1. Sources of Acquired Energy.- 2.2. Fate of Acquired Energy.- 3. Interspecific Considerations in Bioenergetics.- 3.1. Production..- 3.2. Maintenance.- 4. Factors Influencing Bioenergetic Flow in Individuals.- 4.1. Development.- 4.2. Temperature.- 4.3. Excitation.- 4.4. Nutritional State.- 4.5. Circadian Rhythmicity.- 5. Conclusion.- References.- 2 Hormonal Regulation of Substrate Transport and Metabolism.- 1. Introduction.- 1.1. Assessment of Physiological Relevance of Hormones.- 1.2. General Methods Used to Study Insect Hormones.- 2. Hyperglycemic Hormones.- 3. Hypoglycemic Hormones.- 4. Adipokinetic Hormone.- 5. Octopamine.- 6. Juvenile Hormones and Ecdysones.- 7. Other Hormones.- References.- 3 Role of Lipids in Energy Metabolism.- 1. Introduction.- 2. Lipids as an Energy Source in Development.- 2.1. Embryogenesis.- 2.2. Postembryonic Development.- 2.3. Oogenesis.- 2.4. Diapause.- 3. Utilization of Lipids during Flight.- 3.1. Historical Perspectives.- 3.2. Substrate Utilization and Flight Duration.- 3.3. Lipid Mobilization and Transport.- 3.4. Flight Muscle Characteristics Pertinent to Fatty Acid Oxidation.- 3.5. Entrance of Lipids into the Flight Muscle.- 3.6. Fatty Acid Oxidation in Flight Muscle.- 3.7. Endocrine Control of Lipid Utilization and Flight Performance.- References.- 4 The Role of Carbohydrate Metabolism in Physiological Function.- 1. Introduction..- 2. Synthesis of Hemolymph Trehalose.- 2.1. The Biosynthetic Pathway.- 2.2. Hormonal Control of Hemolymph Trehalose.- 2.3. The Source of Energy for Trehalose Synthesis.- 3. Carbohydrate as an Energy Source in Flight Muscle.- 3.1. Glycogen as an Energy Source.- 3.2. Trehalose as an Energy Source.- 3.3. Glycolysis.- 4. The Biosynthesis of Antifreeze.- 4.1. Antifreeze Production in Silkworm Eggs.- 4.2. Polyol Synthesis in Larval and Adult Insects.- 5. Energy Metabolism in the Rectum.- 5.1. Na+ Requirement for ADH Stimulated Water Transport.- 5.2. Glycogen as an Energy Source for Water Transport.- 5.3. Water Transport Associated Respiration.- References.- 5 The Role of Proline in Energy Metabolism.- 1. Introduction.- 2. Proline Metabolism.- 2.1. The Utilization of Proline during Flight.- 2.2. Pathways of Proline Catabolism.- 2.3. The Regulation of Proline Oxidation.- 2.4. The Reconstitution of Proline.- 3. Discussion.- References.- 6 Lipid Transport by Hemolymph Lipoprotein—A Possible Multiple Role of Diacylglycerol-Carrying Lipoprotein.- 1. Introduction.- 2. Purification and Function of DGLP.- 3. Physicochemical Nature of DGLP.- 4. Possible Multiple Role of DGLP—Comparison with Mammalian System.- 5. Possible Metabolic Regulation of DGLP.- References.- 7 Energy Metabolism in the Insect Nervous System.- 1. Introduction.- 2. Oxygen Uptake Studies.- 3. Activities of Enzymes Associated with Glycolysis and the Citric Acid Cycle.- 4. Fuels.- 4.1. Carbohydrate.- 4.2. Enzymes of Carbohydrate Utilization.- 5. Exogenous Substrates Other than Carbohydrate.- 5.1. Amino Acids.- 5.2. Ketone Bodies and Lipids.- 6. Endogenous Substrates.- 6.1. Glycogen.- 7. Conclusion.- References.- 8 Neuroendocrine Regulation of Mitochondrial Development and Function in the Insect Fat Body.- 1. Introduction.- 2. Endocrine Regulation of Fat Body Respiration.- 2.1. Whole Body Respiration.- 2.2. Tissue Respiration.- 2.3. Fat Body Mitochondrial Respiration.- 2.4. Effects of Specific Endocrine Glands.- 3. Respiratory Development in the Fat Body..- 3.1. Patterns of Mitochondrial Respiratory Development.- 3.2. Endocrine Effects on Respiratory Development.- 4. Fat Body Maturation.- 4.1. Fat Body Ultrastructure.- 4.2. Changes in Metabolite Contents.- 5. Endocrine Regulation of Mitochondrial Development.- 5.1. Cytochrome Content.- 5.2. Cytochrome Synthesis.- 6. Cytochromogenic Factor.- 7. Significance and Conclusions.- References.