Endogenous levels of insect juvenile hormones in larval, pupal and adult stages of the tomato moth, Lacanobia oleracea

Abstract

Endogenous levels of juvenile hormones 0, I, II and III have been measured each day during the 4th, 5th and 6th larval stadia of the Tomato moth, Lacanobia oleracea, using physico-chemical methods. Levels of the same hormones have also been measured at selected times during pupal development, and over the first 5 days of adult life in males, and in mated and virgin females. JH I and JH II were the predominant homologues in this insect in all developmental stages, although JH III was also present in some samples. Hormone levels were relatively high in 4th and 5th instar larvae, but were much reduced in 6th (final) instar larvae. Hormone levels increased in larvae that were about to moult to the subsequent stage. Juvenile hormones were absent in pupae during the first half of pupal development, but increased in pharate adults. Adult males and females contained substantially more hormone than pre-adult stages, although levels in virgin moths were lower than in mated adult females. JH 0 was detected in some extracts of mated adult female moths. These results are discussed in relation to the likely role of juvenile hormones in modulating various aspects of the physiology of this insect.