Transduction of the vitellogenic signal of juvenile hormone by Methoprene-tolerant in the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae)

Abstract

In adult females of the cockroach Blattella germanica, juvenile hormone (JH) promotes vitellogenin production. Depletion of Methoprene-tolerant (Met) mRNA levels with RNAi resulted in a clear reduction of vitellogenin expression in the fat body while basal oocyte growth was impaired. This demonstrates that Met is essential to transduce the vitellogenic signal of JH in this species. Interestingly, the expression of the transcription factor Kruppel homolog 1 (Kr-h1) was also reduced in Met-depleted specimens. This indicates that the JH signaling pathway promotes the transcription of Kr-h1 in adult fat body tissues, as occurs in the epidermis during nymphal development. Treatments with JH show that the expression of Met does not depend on JH, which suggests that Met is upstream the JH signaling pathway acting as JH receptor, as reported in other models and processes, especially in metamorphosis. JH treatments increased the transcription levels of vitellogenin and Kr-h1, which again suggests that Kr-h1 is a JH-dependent transcription factor in the fat body of adult females. The important roles of Met in nymphal development, as previously reported, and those reported herein in relation to reproduction, suggests that it can be an interesting target for the control of B. germanica in urban environments, using RNAi approaches.

Keywords

• German cockroach
• Blattella
• vitellogenesis
• juvenile hormone
• methoprene-tolerant