Juvenile hormone esterase activity during the reproductive cycle of the ring-legged earwig

Corpora allata of the ring-legged earwig, Euborellia annulipes, produce and secrete juvenile hormone III (JH III). The primary degradation product of JH III in vitro by diluted hemolymph was juvenile hormone acid, as assessed by thin-layer and high-performance liquid chromatography. This result was confirmed by derivatization of the degradation product using diazomethane. Conversion of JH III to JH acid by E. annulipes hemolymph in vitro occurred at a constant rate for at least 4 hr. The addition of 10−6 M O-ethyl-S-phenyl phosphoamidothiolate or, alternatively, 3-octyl thio-1,1,1-trifluoropropan-2-one inhibited hemolymph esterase activity; O,O-diisopropylphosphorofluoridate and ethanol alone had no effect on the conversion of JH III to JH acid. At 10−4 M, each of the selected inhibitors reduced hemolymph esterase activity relative to ethanol-treated and untreated controls. JH esterase activity of diluted hemolymph was relatively high in females with basal follicles < 0.2 mm and low in those with larger basal follicles. The change in JH esterase activity of the hemolymph was not correlated with changes in hemolymph protein content; hemolymph protein content was generally 50–100 μg/μ1 and did not change significantly with either age or basal follicle length.