Interactions between a non-terpenoid carbamate with juvenile hormone activity and esterases in the last larval instar of Adoxophyes reticulana Huebn

The summer fruit tortrix moth is very susceptible to compounds with juvenile hormone activity. Ro 13-5223, a non-terpenoid carbamate, is 3–4 orders of magnitude more active in inhibiting metamorphosis in the last-instar larvae than juvenile hormone I. Larvae reared in permanent contact with this substance are characterised by higher juvenile hormone esterase activity but lower α-naphthyl esterase activity when compared to the untreated controls. In vitro Ro 13-5223 inhibits juvenile hormone hydrolysis but only in dosages which are far above the concentrations found in haemolymph of larvae exposed to the ¹⁴C-labelled compound. It does not serve as a substrate for juvenile hormone esterase in vitro even though it induces the enzyme activity in vivo. All these characteristics may account for the very high biological activity of Ro 13-5223 which disrupts humoral coordination of insect development.