TheleafbeetlePhratoravulgatissima（Linnaeus 1758）iscommonlyunivoltine in south-central Sweden but may sometimes initiate a partial second generation. The current study was set out to investigate under what abiotic co...TheleafbeetlePhratoravulgatissima（Linnaeus 1758）iscommonlyunivoltine in south-central Sweden but may sometimes initiate a partial second generation. The current study was set out to investigate under what abiotic conditions the beetles initiate a second generation. Using climate chamber experiments, the beetles were shown to have a facultative reproductive diapause induced by declining day-length. The critical day-length （CDL） for diapause induction was estimated to be 18 h and 10 min. In the field, firstgeneration beetles developing to adulthood before August in 2009 became reproductively active and produced a second generation, but most individuals emerged later and were in reproductive diapause. P vulgatissima overwinter as adults and diapause was shown to be maintained until mid-winter in 2008/2009. The cumulative temperature requirement for oviposition after diapause termination was estimated to be 222 day-degrees with a 5.5℃ temperature threshold. Three different day-degree models that were developed to predict the phenology of female oviposition in the spring were validated by comparing model results with field data on the timing of oviposition in previous years. The study suggests that P vulgatissima may initiate a second generation in Sweden if development of the first generation is completed before August. Warmer spring and summer temperatures due to ongoing climate change may cause advanced insect phenology and faster completion of insect life-cycles at northern latitudes, which will affect the proportion of insects that initiate a second generation.展开更多
Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray （Lepidoptera： Papilionidae） in China, knowledge about local adaptations is important for the conservation and...Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray （Lepidoptera： Papilionidae） in China, knowledge about local adaptations is important for the conservation and economical utilization of the species. In the present study, photoperiodie diapause induction and diapause intensity of S. montelus populations from Jiamusi （46°37＇N）, Beijing （40° 15＇N）, Zibo （36°48＇N）, Fangxian （32°36＇N）, Wuhan （30°33＇N） and Huaihua （27°33＇N） were characterized at 25℃. Logistic regression analysis revealed a significant population x hours of light interaction, confirming that photoperiodic responses varied among populations. The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude. Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25℃ and 16 ： 8 L ＂D h. The mean duration of pupal diapause was also positively correlated with latitude. Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S. montelus. These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.展开更多
文摘TheleafbeetlePhratoravulgatissima（Linnaeus 1758）iscommonlyunivoltine in south-central Sweden but may sometimes initiate a partial second generation. The current study was set out to investigate under what abiotic conditions the beetles initiate a second generation. Using climate chamber experiments, the beetles were shown to have a facultative reproductive diapause induced by declining day-length. The critical day-length （CDL） for diapause induction was estimated to be 18 h and 10 min. In the field, firstgeneration beetles developing to adulthood before August in 2009 became reproductively active and produced a second generation, but most individuals emerged later and were in reproductive diapause. P vulgatissima overwinter as adults and diapause was shown to be maintained until mid-winter in 2008/2009. The cumulative temperature requirement for oviposition after diapause termination was estimated to be 222 day-degrees with a 5.5℃ temperature threshold. Three different day-degree models that were developed to predict the phenology of female oviposition in the spring were validated by comparing model results with field data on the timing of oviposition in previous years. The study suggests that P vulgatissima may initiate a second generation in Sweden if development of the first generation is completed before August. Warmer spring and summer temperatures due to ongoing climate change may cause advanced insect phenology and faster completion of insect life-cycles at northern latitudes, which will affect the proportion of insects that initiate a second generation.
文摘Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray （Lepidoptera： Papilionidae） in China, knowledge about local adaptations is important for the conservation and economical utilization of the species. In the present study, photoperiodie diapause induction and diapause intensity of S. montelus populations from Jiamusi （46°37＇N）, Beijing （40° 15＇N）, Zibo （36°48＇N）, Fangxian （32°36＇N）, Wuhan （30°33＇N） and Huaihua （27°33＇N） were characterized at 25℃. Logistic regression analysis revealed a significant population x hours of light interaction, confirming that photoperiodic responses varied among populations. The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude. Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25℃ and 16 ： 8 L ＂D h. The mean duration of pupal diapause was also positively correlated with latitude. Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S. montelus. These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.
