Regulation of vitellogenin production in armyworm moths, Pseudaletia unipuncta

Abstract

The vitellogenin (Vg) of Pseudaletia unipuncta was identified by SDS-PAGE of egg extracts and male and female hemolymph. It dissociated into two apoproteins of 164 and 40 kDa, the larger of which reacted specifically with a polyclonal antibody raised against the native Vg. An enzyme-linked immunosorbant assay (ELISA) was used to examine Vg production in virgin and mated P. unipuncta females, as well as in neck-ligated individuals to which juvenile hormone (JH) homologs or analogs were applied. During the 2 days following emergence, Vg titers were low ( ca 0.2 mg/ml) in virgin females, but they increased steadily thereafter, reaching values of ca 2.4 mg/ml on day 7. Twenty-four h after mating, Vg titers were significantly higher in mated females than in virgins of the same age, but at 48 h, Vg titers of mated individuals were significantly lower than those of virgins, suggesting that Vg was taken up by the developing oöcytes. Females neck-ligated immediately after emergence did not produce Vg, but production was restored in a dose-dependent manner by topical applications of JH homologs or analogs. JH I and JH II displayed approx. 10 times more biological activity than JH III, and two JH analogs were still more active (ED 50, μg/moth: JH III, 13.0; JH II, 1.8; JH I, 1.0; methoprene, 0.04; pyriproxyfen, 0.003). In a time-course analysis, pyriproxyfen-activated Vg accumulation began between day 1 and day 2 and reached a plateau on day 3 after treatment.