The influence of juvenile hormone on the feeding behaviour of last instar larvae of the codling moth,Laspeyresia pomonella (Lep., Tortricidae), reared under different photoperiods

Summary Duration of the feeding stage and corresponding weight increase during the last larval instar of the codling moth,Laspeyresia pomonella, are controlled by JH. Larvae reared under short day conditions have a relatively high titer of JH during the last larval instar and enter diapause as mature larvae. They feed longer and become heavier than larvae reared under long day conditions, which have no JH during the last larval instar and pupate when mature. By application of the JH mimetic Altosid^® during the first 2 or 3 days of the last larval instar, the duration of feeding activity of larvae reared under respectively long and short day conditions was prolongated and the larvae became significantly heavier. The feeding behaviour could only be influenced by the juvenoid as long as the feeding activity of the larvae had not yet ceased.