Quantitative studies on the activity of the corpora allata in adult male Locusta and Schistocerca

Juvenile hormone has been detected in the haemolymph and corpora allata of adult male Locusta and the haemolymph of adult male Schistocera by a modified Galleria bioassay. The hormone was readily detected in the haemolymph of insects immediately after the final ecdysis, but then became difficult to detect until 2 days prior to the onset of sexual maturation. In sexually mature insects the titre of juvenile hormone was maintained at a constant level. The corpora allata of adult male Locusta increased in size throughout adult life. The juvenile hormone content of the corpora allata was low during the period of somatic growth, but increased at the onset of sexual maturation. Sectioning of the nervi corporis allati I in insects immediately after the final ecdysis prevented the normal increase in size of the corpora allata, but did not render them inactive since juvenile hormone was detected in the haemolymph after the operation. The half life of juvenile hormone in the haemolymph of allatectomized adult male Locusta was 1 to 2 hr.