Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 22, 1996
Publication Date: N/A
Interpretive Summary: Excretion is a critical physiological function in animals. A dysfunction of the excretory system in vertebrates can lead to ion imbalance and ultimately to death. Excretion is equally important to the welfare of an insect. Bloodsucking insects face a special challenge because of their feeding behavior. Because they do not feed constantly as plant feeders do, ,they usually take in a meal that exceeds their own body weight when they d get a chance to feed. They become very sluggish after such a meal, their speed of flight can be reduced by as much as 75%, and they can fall easy prey to predators. The excretory process is controlled by hormones, and these hormones present an opportunity for the development of insect control agents that interfere with the excretory process that will lead to the death of the insect. Studies on hormones affecting insect excretion have used assay procedures that have been found inadequate. We have designed a new method for studying excretion in insects based upon video recording th excretory process and analyzing the images after they have been digitized on a computer. This relatively inexpensive method was applied to studying excretion in the stable fly after a blood meal and yielded information that cannot be obtained with other methods. This method can be used for studying excretion in other insects and, with some modification, can even be adapted to the investigation of other behaviors of insects such as feeding. Ultimately, this work will contribute to better methods for controlling destructive insects.
Technical Abstract: Excretion immediately after a blood meal was studied in the stable fly, Stomoxys calcitrans by a new, non-invasive technique. The process of excreta formation was recorded on video tape and later analyzed as digitized images. The formation of the excretory droplets takes approximately 0.25 sec. The droplet size, estimated by assuming a spherical shape, ranged between 100 nl and 400 nl. The size of excretory droplets gradually decreased with time while the time interval between droplets increased. The average rate of excretion was ca. 21 nl/min during the 2 h observation period. This was in close agreement with the loss of body weight during the same period.