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  • 1.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. University of Jyväskylä, Finland.
    Margus, Aigi
    Lindström, Leena
    Inheritance patterns of photoperiodic diapause induction in Leptinotarsa decemlineata2016In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 41, no 3, p. 218-223Article in journal (Refereed)
    Abstract [en]

    Photoperiod is a reliable indicator of season and an important cue that many insects use for phenological synchronization. Undergoing range expansion insects can face a change in the local photoperiod to which they need to resynchronize. Rapid range expansion can be associated with rapid photoperiodic adaptation, which can be associated with intense selection on strongly heritable polygenic traits. Alternatively, it is proposed that, in insects with an XO sex-determination system, genes with large effect residing on the sex chromosome could drive photoperiodic adaptation because the gene or genes are exposed to selection in the sex carrying only a single X-chromosome. The present study seeks to understand which of these alternatives more likely explains the rapid photoperiodic adaptation in European Colorado potato beetles Leptinotarsa decemlineata Say. Diapause induction is assessed in beetles from a northern and a southern population, as well as from reciprocal hybrid crosses between the northern and southern population, when reared at an intermediate length photoperiod. The crosses within population display the expected responses, with the northern and southern populations showing high and low diapause propensity, respectively. The hybrids show intermediate responses in all studied traits. No clear difference in the responses in hybrids depending on the latitudinal origin of their father or mother is detected, even though partial paternal line dominance is seen in the responses of male beetles in one hybrid cross. These results therefore indicate that, in L. decemlineata, photoperiodic diapause induction is strongly heritable, and has an additive polygenic autosomal background.

  • 2.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. University of Jyväskylä, Finland.
    Piiroinen, Saija
    Lyytinen, Anne
    Lindstroem, Leena
    Responses in metabolic rate to changes in temperature in diapausing Colorado potato beetle Leptinotarsa decemlineata from three European populations2015In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 40, no 2, p. 123-130Article in journal (Refereed)
    Abstract [en]

    Many insects survive adverse periods in seasonal environments by entering diapause, a deep resting stage, during which energy consumption is typically low and gas exchange is in the form of a discontinuous gas exchange cycle (DGC). Because insects in high-latitude environments are severely time constrained during summer, an effective diapause termination with careful regulation of metabolic rate is important. The present study examines whether diapausing Colorado potato beetles Leptinotarsa decemlineataSay originating from three latitudinally different regions in Europe differ in their quantitative or qualitative gas exchange patterns in response to an increasing temperature. Overall production of gaseous CO2, as well as qualitative patterns relating to the DGC, are measured at a late stage of diapause at four different temperatures in increasing order from 13, 18, 23 to 28 degrees C. Overall CO2 production is found to be lower in the two northern populations (61 degrees 49N and 55 degrees 75N) compared with the southernmost population (45 degrees 48N) but increases as a function of temperature in all populations in a similar way. However, in the northern populations, raising the temperature increases the amount of CO2 discharged during single DGC peaks, whereas the DGC frequency remains relatively unchanged. By contrast, in the southernmost population, the amount of CO2 discharged during individual DGC peaks remains relatively unchanged, whereas the DGC frequency increases as a function of temperature. The observed differences may relate to water retention benefits or, alternatively, energetic benefits relating to heightened gas exchange efficiency in hypoxic or hypercapnic environments. Overall, the results suggest that, although populations of L. decemlineata may have similar thermal sensitivities, they have different qualitative strategies to regulate metabolic re-activation at diapause termination.

  • 3.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Van der Bijl, Wouter
    Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Timing of diapause termination in relation to variation in winter climate2017In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 42, no 3, p. 232-238Article in journal (Refereed)
    Abstract [en]

    In temperate insects, winters are typically endured by entering diapause, which comprises a deep resting stage. Correct timing of diapause termination is vital for synchronization of emergence with conspecifics and for mobilizing resources when conditions for growth and reproduction become favourable. Although critical to survival, the intrinsic and extrinsic drivers of diapause termination timing are poorly understood. In the present study, we investigate diapause development under a range of durations (10-24weeks) spent at different temperatures (-2 to 10 degrees C) in the pupal diapausing butterfly Pieris napi Linnaeus (Lepidoptera: Pieridae). We determine: (i) the maximum cold temperature for diapause development; (ii) if pupae in diapause count cold days or cold sums; and (iii) whether diapause termination is distinct or gradual. The results indicate large and idiosyncratic effects of high and low nonlethal temperatures on diapause development in P. napi. Although all temperatures tested lead to diapause termination, a thermal optimum between 2 and 4 degrees C is observed. Lower temperatures lead to decreased eclosion propensity, whereas higher temperatures slow down development and increase emergence desynchronization. These data suggest that, rather than a simple cold-summing process with a distinct diapause termination point, there are trade-offs between time and temperature at the low and high end of the thermal range, resulting in a nonlinear thermal landscape showing a ridge of increasing eclosion propensity at moderate temperatures. The present study suggests that the effects of temperature on diapause development should be included in projections on post-winter phenology models of insects, including pest species.

  • 4.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Induction of diapause and seasonal morphs in butterflies and other insects: knowns, unknowns and the challenge of integration2013In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 38, no 2, p. 96-104Article in journal (Refereed)
    Abstract [en]

    The choice' of whether to enter diapause or to develop directly has profound effects on the life histories of insects, and may thus have cascading consequences such as seasonal morphs and other less obvious forms of seasonal plasticity. Present knowledge of the control of diapause and seasonal morphs at the physiological and molecular levels is briefly reviewed. Examples, mainly derived from personal research (primarily on butterflies), are given as a starting point with the aim of outlining areas of research that are still poorly understood. These include: the role of the direction of change in photoperiod; the role of factors such as temperature and diet in modifying the photoperiodic responses; and the role of sex, parental effects and sex linkage on photoperiodic control. More generally, there is still a limited understanding of how external cues and physiological pathways regulating various traits are interconnected via gene action to form a co-adapted complete phenotype that is adaptive in the wild despite environmental fluctuation and change.

  • 5.
    Pruisscher, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Larsdotter-Mellström, Helena
    Stockholm University, Faculty of Science, Department of Zoology. The University of Western Australia, Australia.
    Stefanescu, Constantí
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Sex-linked inheritance of diapause induction in the butterfly Pieris napi2017In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 42, no 3, p. 257-265Article in journal (Refereed)
    Abstract [en]

    Many temperate insects survive harsh environmental conditions, such as winter, by entering a state of developmental arrest. This diapause state is predominantly induced by photoperiod. The photoperiod varies with latitude and has led to local adaptation in the photoperiodic induction of diapause in many insects. To understand the rapid evolution of the photoperiodic threshold, it is important to investigate and understand the underlying genetic mechanisms. In the present study, the genetic basis of photoperiodic diapause induction is investigated in the green-veined white butterfly Pieris napi (Lepidoptera, Pieridae) by assaying diapause induction in a range of conditions for a Swedish and Spanish population. Furthermore, the inheritance of diapause induction is assessed in reciprocal F1 hybrids and backcrosses between the two populations. The southern population shows a clear photoperiodic threshold determining diapause or direct development, whereas the northern populations show a high incidence of diapause, regardless of photoperiod. The hybrid crosses reveal that the inheritance of diapause induction is strongly sex-linked, and that diapause incidence in the genetic crosses is highly dependent on photoperiod. This emphasizes the importance of assaying a range of conditions in diapause inheritance studies. The results indicate a strongly heritable diapause induction with a major component on the Z-chromosome, as well as a minor effect of the autosomal background.

  • 6. Salman, Md Habibur R.
    et al.
    Giomi, Folco
    Laparie, Mathieu
    Lehmann, Philipp
    Stockholm University, Faculty of Science, Department of Zoology.
    Pitacco, Andrea
    Battisti, Andrea
    Termination of pupal diapause in the pine processionary moth Thaumetopoea pityocampa2019In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 44, no 1, p. 53-59Article in journal (Refereed)
    Abstract [en]

    Diapause development is a complex process involving several eco-physiological phases. Understanding these phases, especially diapause termination, is vital for interpreting the life history of many insect species and for developing suitable predictive models of population dynamics. The pine processionary moth is a major defoliator of pine and a vertebrate health hazard in the Mediterranean region. This species can display either univoltine or semivoltine development, with a pupal diapause extending from a few months to several years, respectively. Although the ecological and applied importance of diapause is acknowledged, its physiological regulation in either case remains obscure. In the present study, we characterize pre-termination, termination and post-termination phases of pupae developing as univoltine or remaining in prolonged diapause. Changes in metabolic activity are monitored continuously using thermocouples, comprising a novel method based on direct calorimetry, and periodically by use of O-2 respirometry. The two methods clearly detect diapause termination in both types of pupae before any visible morphological or behavioural changes can be observed. Univoltine individuals are characterized by an increase in metabolic activity from pre-termination through to termination and post-termination, ultimately resulting in emergence. Remarkably, a synchronous termination is observed in individuals that enter prolonged diapause instead of emerging; however, in these pupae, the increased metabolic activity is only transient. The present study represents a starting point toward understanding the eco-physiology of diapause development processes in the pupae of the pine processionary moth.

  • 7.
    Söderlind, Lina
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Genetics of diapause in the comma butterfly Polygonia c-album2011In: Physiological entomology (Print), ISSN 0307-6962, E-ISSN 1365-3032, Vol. 36, no 1, p. 8-13Article in journal (Refereed)
    Abstract [en]

    The processes of local adaptation and ecological speciation can be better understood by studying the genetic background of life-history decisions. The sex chromosomes host genes for many population differences in the Lepidoptera and therefore the inheritance of diapause determination in the butterfly Polygonia c-album may be hypothesized to be sex-linked. In the present study, Polygonia c-album (L.) from Spain and Sweden and hybrid offspring are raised under an LD 17 : 7 h photocycle that induces most pure Swedish individuals to develop into the diapausing dark morph and most pure Spanish individuals into the light and directly-developing morph. If inheritance of the daylength threshold for diapause is X-linked, as is known to be the case for host-plant preferences, females should follow the developmental path of their male parents' populations. However, female hybrids instead have a diapause propensity intermediate to that of their parental stocks and, consequentially, diapause determination is not X-linked. However, male hybrids eclose as the diapausing morph to a higher extent than females and, moreover, this pattern is more pronounced in the Spanish female x Swedish male cross than in the reciprocal cross. Hence, it is concluded that the genetic determination of the critical daylength for diapause is mainly autosomal but with some influence of sex-linked genes and/or parental effects, possibly as an effect of the importance of protandry for males. Such sex effects could provide a starting point for the evolution of population differences inherited on the sex chromosomes.

1 - 7 of 7
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