The genetic basis of photoperiodic diapause in the jewel wasp Nasonia vitripennis

All organisms on Earth experience daily photoperiod variation in their natural environment, with alternating light and dark phases. Photoperiod also varies over the year, with longer light phase in summer and longer dark phase in winter, depending on latitude. Light is therefore one of the most reliable predictors of future conditions in nature. Some insects use these periodic seasonal alterations in photoperiod to anticipate on unfavourable conditions for reproduction and overwinter in a hibernation state called diapause. Much of the details of the molecular pathways processing these external cues into this adaptive behaviour remain unknown.
Females of the parasitic wasp Nasonia vitripennis induce diapause in their offspring, depending on the number of days with a critical day-length that they experience. Wasps from Southern Europe need more critical days before inducing diapause than wasps from Northern Europe. As wasps can time day length and count the number of days, it was hypothesised that their internal clock is involved. A clear effect of one clock-gene, period¸ was found, but it is unknown if other known clock genes and additional factors are involved.
In this thesis, I determined the effect of clock gene variants on diapause. Period was confirmed as the main factor, but cryptochrome-2 also had an effect. I conclude that photoperiodic induction of diapause response in N. vitripennis is affected by some, but not all, clock genes and additionally governed by other genetic and physiological factors, the nature of which remain to be further investigated.