Farnesoic acid and allatotropin stimulation in relation to locust allatal maturation

Allatal maturation during the first gonotrophic cycle of adult female Locusta migratoria can be measured in vitro by the competence of these glands to produce juvenile hormone III (JH-III) when maximally stimulated by either farnesoic acid (FA) or allatotropin. Maturation precedes the full activation of the corpora allata (CA) during the first cycle of oogenesis. Basal activity of mature active female CA is highly correlated to stimulated activity. This suggests that between-gland variability reflects the inherent competence of each individual CA, and is not a consequence of a mere pulsatile on/off activation. Older glands may be inactive but their competence is equivalent to that of mature active glands. The kinetics of FA and allatotropic stimulation in vitro are equivalent, suggesting that allatotropin affects rate-limiting steps preceding FA biosynthesis.