Effects of ultrasound on Drosophila--IV. Pulsed exposures of eggs.

Drosophila larvae are damaged by exposures to low temporal average intensity pulsed ultrasound with peak intensities of 10-20W/cm2 (2 MHz). Eggs of the same organism are affected by exposures to 3W/cm2 c.w. ultrasound. This experiment shows that eggs become sensitive to high peak intensity (50-100 W/cm2) pulsed ultrasound only shortly before hatching. At this age the larvae have formed and have taken air into the respiratory system. This observation supports the postulate that the sites of action of the ultrasound are the small stabilized gas bodies within the organisms.