Abstract: | The major radiolabelled product released from ring gland and brain-ring gland complexes of third instar larval and pre-pupal stages of the sheep blowfly Lucilia cuprina upon incubation with L-methyl-3H]methionine corresponded to one diastereomer of juvenile hormone III bisepoxide (JHB3). Endocrine glands incubated with the juvenile hormone precursor 2E,6E-farnesoic acid released increased quantities of JHB3, together with significant amounts of juvenile hormone III but not the isomeric methyl 2E-6,7-epoxyfarnesoate. Synthesis of JHB3 was developmentally and neurally regulated. Ring glands and brain-ring gland complexes from third instar larvae released more JHB3 than comparable preparations from pre-pupae, while isolated corpus allatum segments of the gland were more active than intact brain-gland complexes. These results reinforce the emerging status of JHB3 as the characteristic juvenile hormone of dipteran insects. Arch. Insect Biochem. Physiol. 34:239–253, 1997. © 1997 Wiley-Liss, Inc. |