Author
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Cook, Benjamin |
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Pryor, Nan |
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Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/16/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Increasing concerns of pest management specialists and the general public about the broad spectrum toxicity of conventional chemical insecticides, and their potential for polluting the environment, have led to greater emphasis on research to develop alternative means for insect control that will be safe, specific, and non-polluting. One logical approach to effective long-term control of insects is to find a way to control their ability to reproduce. For this reason, we are studying the reproductive system in selected species of biting flies, with emphasis on the natural hormones and other chemicals in the insect that regulate this process. When we made extracts of the accessory glands of the female stable fly, Stomoxys calcitrans, minute quantities of a unique series of peptides were discovered. In bioassays, these peptides were shown to regulate the contraction of a semi-isolated oviduct. This study resulted in the first description of the main anatomical features of the oviduct glands and provided good clues on the possible secretory processes for peptides that are present in these glands. This study thus provided a strong basis for continued studies aimed at identifying the chemical structures of these hormonal peptides and exploring their potential for exploitation in the search for novel new chemical control agents. Technical Abstract: The accessory reproductive glands of the female stable fly are translucent structures that run parallel to the common oviduct when the ovipositor is extended. The only muscles found associated with the gland were those at either end of the long tube of simple cuboidal epithelial cells. The posterior region of each gland is connected to the anterior vagina by means sof a valve of circular muscle. The myofibrils of the valve are separated into sarcomeres of irregular alignment with Z disks that appear as discontinuous rows of dense bodies. Transections through the Z disk region also revealed a perforated character which is common in muscles that have the ability to super contract. The sarcolemma of many cells have tubular invaginations that correspond to the T-system of tubules found in most muscles. Terminal axons with both synaptic vesicles and larger neurosecretory granules were found in close apposition to muscle fibers of the valve. Large vacuoles (with a mean of 26 um and an upper limit of 40 um in diameter) were the most prominent structures in the cytoplasm of the glandular epithelium. The fine structure of these vacuoles showed a microvillar border and a central portion that contains clumps of secretory material in a granular matrix. Many vacuoles also contain dense inclusion bodies while other inclusion bodies were observed in apical membranous networks just beneath the cuticular intima. Such ultrastructural features suggest a largely merocrine type secretion for this gland. |
