Effects of methyl bromide on phosphorus metabolism in the adult housefly, Musca domestica L.

Abstract

Adult female houseflies were exposed to a saturation concentration of methyl bromide vapor for 1 minute (lethal but not excessive exposure) or for longer periods (excessive exposures) at 30[degree]. Insects exposed for 1 or 2 minutes were immobilized but recovered temporarily in fresh air. These insects finally collapsed again 1-3 hours later and failed to recover. Respiration continued at a near normal rate for several hours after the delayed collapse. Initial immobilization of the insect by brief exposure to methyl bromide was apparently due to a reversible breakdown of adenosine triphosphate (ATP) according to the overall equation: ATP v adenosine 5[image]-phosphate - 2PO4 . Excessive exposures to methyl bromide immediately and irreversibly immobilized the insect. Such exposures were associated with depletions of ATP, arginine phosphoric acid and phosphoglyceric acid. Temporary recovery of the insects after brief exposures was associated with a return towards normal levels of thoracic ATP. The reversible effects of brief exposures on the level of ATP, the delayed collapse of the insect without marked changes in distribution of soluble phosphorus and the sustained respiration were not consistent with the action of methyl bromide as an SH-enzyme inhibitor. The effects of excessive exposures to methyl bromide resembled those of lethal but not excessive doses of iodoacetate characterized by depletion of ATP and phosphoglycerate in the thoracic tissues.