Author
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Cook, Benjamin |
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Chen, Andrew |
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Pryor, Nan |
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Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/26/1997 Publication Date: N/A Citation: N/A Interpretive Summary: The stable fly is a major pest of livestock and other animals, especially cattle that are held in confinement. Because the stable fly is a worldwide pest that causes heavy economic losses each year, it is essential to search continuously for new of improved methods for its control. An effective systematic approach to the development of novel chemical control agents depends upon a thorough understanding of physiological systems in the pest that will be targeted by new management technology. Current research is focusing on the development of ways to disrupt the functions of neuropeptides, natural hormonal agents which serve as indispensable chemical intermediates in the regulation of a variety of essential physiological functions of the stable fly. This report presents detailed information on the same properties of the muscle systems that move the excretory ducts of the stable fly. The research provides important new information on certain characteristics of the pest's excretory system, a potentially vulnerable target for new chemical agents aimed at disrupting that critical life process. It is anticipated that novel chemicals which mimic the actions of the neuropeptides will be active at very low concentrations and highly selective for a specific pest, thus providing a new control technology that will be less harmful to the environment and to non target organisms than are conventional insecticides. Technical Abstract: The four Malpighian tubules observed in the female stable fly were divided into an anterior dorsal pair and a posterior ventral pair. Intrinsic muscles were found only in the short proximal section (ureter) of each pair of tubules that emptied into the midgut. Isolated preparations with the ureter demonstrated four types of organized rhythmic activity: compression, peristalsis, reverse peristalsis, and segmentation. Compression caused a momentary (0.4 to 0.6 sec.) shortening of the longitudinal muscle fibers in a localized region of the ureter. Peristalsis was the dominant type of activity. Each wave progressed along the duct with a duration that ranged from 0.9 to 1.7 sec. Segmentation consisted of a localized annular constriction of the ureter without progression that lasted for a duration of 0.3 to 0.6 sec. The large distal ends of the dorsal pair of tubules showed spontaneous movement in situ. Close examination revealed a network of extrinsic muscle cells attached to the distal tubular ends. The motile properties of the extrinsic muscles were different from those of the ureter. The sequence from the resting state to contraction and return was much slower with durations that ranged from 10.8 to 27.1 sec. Also, the time for peak tension was 7.2 to 25.9 sec in duration. The extrinsic muscles did not show the organized and rhythmic activity observed in the ureter. |
