Postnatal treatment of the cabbage aphid with a synthetic juvenile hormone

Abstract

A synthetic preparation with high juvenile hormone activity was tested on postnatal development of the cabbage aphid Brevicoryne brassicae (L.). It produced marked morphological effects in adult alates which had been treated in the third or fourth instars, but much slighter effects in apterae treated at the same stage. Treatment of both forms in the third instar resulted in extra moults, with extra larval instars in the alate form. Treatment of first and second instars produced almost no morphological abnormalities, but suitable doses given in the first instar significantly increased the proportion of apterae. The sensitivity of different structures and the possible mode of action of the synthetic juvenile hormone are discussed.