Temperature-Dependent Juvenile Hormone Effects on Pupation of Adoxophyes orana12

Abstract

The degree of juvenilization of pupae of Adoxophyes orana (Fischler von Rosenstamm), brought about by 2 insect growth regulators, isomer mixtures of methyl 10,11-epoxy-7-ethyl-3,11-dimethyl-2,6-tridecadienoate (JH) and 6,7-epoxy-3,7-dimethyl-1-[3,4-(methylenedioxy)phenoxy]-2-nonene (JHA), was largely dependent on the rearing temperature at which the last-instars were kept. Maximal morphogenetic effects were obtained at 20°C. Specifically, high temperatures resulted in a sharp decrease in effect, even when they occurred for only a short period in a cyclically changing day-night temperature regime. The hormones were effective only when applied during the first 40% of the final larval instar, regardless of temperature. Higher rearing temperatures require a more precisely timed application if optimal effects are desired. JHA proved to be a hundred times more potent than JH in inducing morphogenetic effects.