NADP-dependent oxidoreductase with high 3-dehydroecdysone reductase activity. May play a role in the regulation of molting. Has lower activity with phenylglyoxal and isatin (in vitro). Has no activity with NADH as cosubstrate. Has no activity with nitrobenzaldehyde and 3-hydroxybenzaldehyde. Subject to substrate inhibition by high levels of 3-dehydroecdysone. Detected in hemolymph (at protein level). Detected in larval ovary. During larval development, expression in the hemolymph increases at day 3 before the fourth ecdysis and then decreases again. Levels increase again at day 8 and then decrease again. Not detectable in pupae, or present at very low levels. Up-regulated by the insecticide diazinon. Belongs to the short-chain dehydrogenases/reductases (SDR) family.