The clock gene period is essential for the photoperiodic response in the jewel wasp Nasonia vitripennis (Hymenoptera: Pteromalidae)

Abstract

The role of the clock gene period (per) in photoperiodism was investigated in the jewel wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae). Typically, females reared under long days lay eggs that develop to adulthood without developmental interruption, whereas those reared under short days lay eggs that enter larval diapause. We found that RNA interference (RNAi) of per disrupts the photoperiodic response; RNAi wasps failed to produce diapause-destined eggs in response to short days. This indicates that per is essential for the photoperiodic response in this species. Exposure to low temperature swiftly affects maternal physiology and prompts N. vitripennis females to lay diapause-destined eggs. Interestingly, per RNAi females also laid diapause-destined eggs in response to the low temperature treatment in the current study. This finding indicates that per RNAi did not disrupt the maternal physiology that was directly involved in production of diapause-destined eggs, but it did affect photoperiodic perception. We also investigated the expression patterns of several clock genes, per, mammalian-type cryptochrome (cry-m), cycle (cyc), PAR-domain protein 1 (Pdp1), and clockwork orange (cwo), to determine whether their expression patterns were affected by different photoperiods.