Published online by Cambridge University Press: 10 July 2009
The result of treating Tenebrio molitor L. pupae with synthetic juvenile hormone (JH) or a juvenile hormone analogue, methyl farnesoate dihydrochloride (DMF), is to arrest pupal development, producing pupal/adult intermediates. Both substances induced approximately 50% pupal/adult intermediates at a topically applied dose of 1 μg. The activity was greatly affected by the age of the pupa at the time of treatment, one- and two-day-old pupae being the most sensitive. Applied to four-day-old and older pupae complete metamorphosis to the adult was possible at a dose of 8 μg of synthetic JH and up to 200 μg for DMF. Doses above these levels merely increased toxicity without juvenilising activity.