The effect of cold temperature exposure and long-day photoperiod on the termination of the reproductive diapause of newly emerged female Pissodes strobi (Coleoptera: Curculionidae)
Abstract:1 There is confusion in the literature concerning a possible reproductive diapause in the adult white pine weevil Pissodes strobi.
2 We evaluated the effects of temperature, photoperiod, feeding substrate and mating status on the sexual maturation and oviposition of female white pine weevils.
3 Less than 30% of female P. strobi became sexually mature and laid eggs without experiencing dormancy under a temperature regime of 2 °C for 4 weeks.
4 Among the females that experienced a cold temperature treatment after emergence, 80% laid eggs after dormancy when exposed to a long-day (LD 16 : 8 h) photoperiod and 17.6% laid eggs when exposed to a short-day (LD 8 : 16 h) photoperiod.
5 Significantly more eggs were laid by all the females (with and without a cold treatment) when subjected to a long-day photoperiod compared with a short-day photoperiod.
6 A period of cold temperature followed by exposure to a long-day photoperiod with warmer temperatures is required to break reproductive diapause and to obtain a good oviposition response in female P. strobi.
7 This study reveals the existence of much intraspecific variation in the response of the white pine weevil to temperature and photoperiod with respect to the induction and termination of reproductive diapause.