Leupeptin, a protease inhibitor, blocks insemination-induced flight muscle histolysis in the fire ant Solenopsis.

The effect of the protease inhibitor leupeptin on flight muscle histolysis in queen fire ants was studied by electron microscopy. In untreated animals artificially inseminated, muscle involution was apparent at 6 hr post-insemination and complete by 24 hr post-insemination. However, in animals pre-treated with leupeptin and subsequently artificially inseminated, no morphologic evidence of flight muscle breakdown was seen at any interval between 6 and 24 hr post-insemination. Such information appears to indicate that one or more proteases are involved in the process of insemination-induced muscle atrophy in fire ants. The most likely candidate is a soluble, calcium-activated myofilament-associated protease.