Involved in the inactivation of ecdysteroid molting hormones by converting ecdysteroids into 3-dehydroecdysteroids. ecdysone + O2 = 3-dehydroecdysone + H2O2 Expressed in the midgut goblet cell cavities at the 5th instar larval stage (at protein level) (PubMed:26041352). At the pupal stage, expressed in the midgut and to a lesser extent in the fat body, hemocyte, head and testis (PubMed:26041352, PubMed:30262999). At the pupal stage, highly expressed in ovary (PubMed:30262999). Expressed at the late 4th instar larval stage, and disappears during the 4th molting stage (PubMed:22215981). Highly expressed at the early 5th instar larval stage, then expression remains low during the feeding stage, and increases at the wandering stage (PubMed:22215981). During pupal development, expression begins at prepupal stage 1 (PP1), increases until P4 pupal stage, then decreases after P6 pupal stage (PubMed:26041352). During egg maturation, expressed at low level during the vitellogenic stages and increases at the onset of choriogenesis (PubMed:30262999). Causes large body size and prolongs the final instar larval stage (PubMed:26041352). In the midgut of instar larval stage (L5D4), causes an increase of ecdysteroid levels, up-regulation of IRS and PI3K mRNA levels and down-regulation of TSC1 and TSC2 mRNA levels (PubMed:26041352). RNAi-mediated knockdown at the pupal stage, does not affect growth or ovary development (PubMed:30262999). However, the ovary has decreased levels of 3-dehydroecdysone without affecting ecdysone levels (PubMed:30262999). Also, hatching rate is reduced and, laid eggs have lower levels of 20-hydroxyecdysone and are arrested at the organogenesis stage (PubMed:30262999). Belongs to the GMC oxidoreductase family.