Effects of photoperiodism, melatonin and pesticide exposure on Homeobox and N-acetyl transferase gene expression profiles in Spodoptera litura (Insecta: Lepidoptera)

Homeobox (HOX) genes play a major role in shaping the anteroposterior body axis during insect development. Melatonin is a photoperiodic hormone that is involved in insect developmental mechanisms. Here, we demonstrate the presence of Hox and melatonin genes (aanat) in the whole body of S. litu The results showed increased expression of Dfd (4.3 fold) and Lab (8.4 fold) in abamectin exposed 12:12 h light-dark (LD) condition, suggesting the formation of insect head responsive genes. While Abd-A (55 fold), abd-B (182 fold), and aanat(40 fold) expression were high in mel + aba-exposed DD, ubx (137 fold) expression in aba-exposed DD conditions suggests control of abdominal and wing development due to nocturnal synthesis of melatonin, which is confirmed by higher aanat expression in darkness. Our results show that vitellogenin (85 and 120 fold) expression is high under mel and mel + aba exposed light photoperiod (LL), suggesting that vitellogenin production and accumulation requires continuous light.