EFFECT OF MATING ON PLASMA JUVENILE-HORMONE ESTERASE-ACTIVITY IN FEMALES OF CHORISTONEURA-FUMIFERANA AND C-ROSACEANA

We measured juvenile hormone esterase (JHE) activity in the plasma of virgin and mated Choristoneura fumiferana and C. rosaceana female moth s. In these two species, JH III acid was the only measurable product o f in vitro JH III degradation in the plasma. Rates of JH III ester hyd rolysis were generally higher in C. rosaceana than in C. fumiferana, b ut followed a similar pattern in both species, with high activity meas ured on day 7 of the pupal stage, the lowest activity measured at emer gence, and a subsequent increase observed between days 0 and 1. Mating on day 0, in both species, brought about a significant increase in JH E activity on day 1, relative to virgins. On days 3 and 5, rates of JH degradation did not differ between virgin and mated females. The mati ng-induced increase in JHE activity on day 1 was not the result of a d ecrease in blood volume in mated females relative to virgins. Fluctuat ions in JHE activity did not appear to depend on changes in plasma pro tein concentration. In both species, topical application of JH I or me thoprene, on the day of emergence, resulted in dose- and time-dependen t increases in JHE activity relative to controls. (C) 1996 Wiley-Liss, Inc.