Figure 1.

Induction of silkworm superlarvae by JHA application. Silkworm superlarvae were induced by applying the JH analogue (JHA) methoprene to newly molted silkworm larvae at the fourth instar. Silkworm larvae treated with pure acetone were used as a control. (a) Dose-dependent effects of JHA application on silkworm larval molting and survival. (b) JHA application at a dose of 20 μg per larva results in precocious larval molting and induces silkworm superlarvae. (c) Comparison of normal larva with pure acetone treatment (left) and larva with precocious onset of the fourth larval molting at 48 hours after JHA application. The developmental time point is at approximately 60–72 hours after treatment. (d) JHA application changes the body weight of silkworm larvae. (e) The mRNA expression of Kr-h1, a JH-responsive gene, is increased after JHA application. Hat: hours after treatment.