Postembryonic Development

the hemolymph protein by the time a mature larva stops feeding. The calliphorin is used in 627

the pupa as a major source of nitrogen (in the form of amino acids) for formation of adult tissues and as a source of the energy required in biosynthesis. Thus, at eclosion (emergence of the adult), the hemolymph calliphorin content has fallen to 0.03 mg, and, 1 week after emergence, the protein has entirely disappeared.

During metamorphosis some of the above trends may be reversed. The proportions of fat and/or glycogen decline as these molecules are utilized in energy production. In Calliphora the fat content decreases from 7% to 3% of the dry weight through the pupal period. In the honey bee, which mainly uses glycogen as an energy source, the glycogen content drops to less than 10% of its initial value as metamorphosis proceeds. For most insects there is little change in the net protein content during pupation, though major qualitative changes occur as adult tissues develop. In members of a few species a significant decline in total protein content occurs during metamorphosis as protein is used as an energy source. The moth Celerio, for example, obtains only 20% of its energy requirements in metamorphosis from fat, the remaining 80% coming largely from protein.

Superimposed on the overall biochemical changes from hatching to adulthood are changes that occur in each stadium, related to the cyclic nature of growth and molting. Factors to be considered include the phasic pattern of feeding activity throughout the stadium, synthesis of new and degradation of old cuticle, and net production of new tissues (though some histolysis also occurs in each instar).

Measurement of oxygen consumption shows that it follows a U-shaped curve through each stadium with maximum values being obtained at the time of molting. The maxima are correlated with the great increase in metabolic activity at this time, associated especially with the synthesis of new cuticle and formation of new tissues. In Locusta larvae there are significant decreases in the carbohydrate and lipid contents of the fat body and hemolymph at ecdysis, probably correlated with the use of these substrates to supply energy (Hill and Goldsworthy, 1968). Conversely, as feeding restarts after a molt, these materials are again accumulated.

Changes in the amount of protein in the fat body and hemolymph of Locusta are also cyclical, with maximum values occurring in the second half of each stadium (Hill and Goldsworthy, 1968). The early increase in protein content is related to renewed feeding activity after the molt. Feeding activity reaches a peak in the middle of the stadium, providing materials for growth of muscles (and presumably other tissues, though these were not studied by Hill and Goldsworthy) and for the synthesis of cuticle. Excess material is stored in the fat body and hemolymph. In the second half of the stadium feeding activity declines, and this is followed by a decrease in the level of protein in the hemolymph and fat body. Hill and Goldsworthy (1968) suggested that the latter probably reflects the use of protein in the synthesis of new cuticle. However, recycled protein from the old cuticle may account for most (about 80% in Locusta) of the protein content of the new 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.

Get My Free Ebook


Post a comment