Juvenile hormone catabolism and oviposition in the codling moth, Cydia pomonella, as functions of age, mating status, and hormone treatment

In vitro catabolism of juvenile hormone (JH) in haemolymph of adult female Cydia pomonella was ascribed mainly to juvenile hormone esterase (JHE) activity. No significant differences were noted between virgin and mated females 0-96 h post-emergence. Changes in (JHE) activity did not appear dependent upon fluctuations in A titre; conversely, changes in JHE activity could not explain the changes in JH titres. Maximal JHE activity was recorded of 24 h (331.47 +/- 47.25 pmol/h/mul; 355.93 +/- 36.68 pmol/h/mul, virgin; mated insects, respectively) and preceded the peak in JH titres at 48 h. Topical application of JH II (10 ng-10 mug) or fenoxycarb (50 ng) enhanced JHE activity up to 640 and 56%, respectively. Treatment upon emergence with 10 mug JH II induced enzymic activity for less than 24 h, and when 10 mug JH II or 50 ng fenoxycorb were applied, circulating JH titres returned to control levels within 24 h. Oviposition was highly sensitive to exagenous JH and declined significantly with dosages > 100 pg. To allow a degree of oocyte maturation before JH treatment, the hormone was administered at 6, 12, 24, or 48 h post-emergence and/or females were mated. Neither measure "protected" the system; oviposition declined immediately after JH application. Arch. Insect Biochem. Physiol. 49:10-21, 2002. (C) 2002 Wiley-Liss, Inc.