Pupal brain transcriptome for Bicyclus anynana

<p><span>Seasonal plasticity in male courtship in <em>Bicyclus anynana</em> butterflies is due to variation in levels of the steroid hormone 20E (20-hydroxyecdysone) during pupation. Wet season (WS) males have high levels of 20E and become active courters. Dry season (DS) males, have lower levels of 20E and reduced courtship rates, although WS courtship rates can be achieved if DS male pupae are injected with 20E at 30% of pupation. Here, we investigated the genes involved in male courtship plasticity and examine whether 20E plays an organizational role in the pupal brain that later influences the sexual behaviour of adults. We show that DS pupal brains have a 7-fold upregulation of the <em>yellow</em> gene relative to the WS and that knocking out <em>yellow</em> leads to increased male courtship. We find that injecting 20E into DS pupa reduced <em>yellow</em> expression although not significantly. Our results show that <em>yellow</em> is a repressor of the neural circuity for male courtship behaviour in B. anynana. 20E levels experienced during pupation could play an organizational role during pupal brain development by regulating <em>yellow</em> expression, however, other factors might also be involved. Our findings are in striking contrast to Drosophila where <em>yellow</em> is required for male courtship.</span></p>