In vitro effects of juvenile hormone analog on wing disc morphogenesis under ecdysteroid treatment in the female-wingless bagworm moth Eumeta variegata (Insecta: Lepidoptera, Psychidae)

Female adults of the bagworm moth, Eumeta variegata, lack wings completely, whereas male adults of this species have functional wings. We previously found that ecdysteroid induces apoptotic events in the female wing rudiment of E. variegata in vitro, whereas the male wing discs cultured with 20-hydroxyecdysone (20E) underwent apolysis and then cell differentiation. To investigate whether juvenile hormone (JH) in involved in sex-specific cellular response to ecdysteroid during wing development between sexes of E. variegata, we tested the effects of juvenile hormone analog (JHA), methoprene, and 20E on wing disc morphogenesis between sexes in vitro. Using transmission electron microscopy (TEM), we found that both higher concentration of JHA (5 μg/ml) and 20E (1 μg/ml) addition induced cell death (apoptosis) in the male wing discs but not induced cell death in the female wing rudiments in vitro in E. variegata. These culture experiments clearly detected the differential responses of wing discs to JHA under ecdysteroid treatment between sexes. We propose two important hypotheses: (1) JH is not significantly involved in the suppression of the female wing rudiment morphogenesis under 20E treatment, (2) female wing rudiment has lost the ability for cell proliferation in response to the stimulus of 20E.