Photosynthesis and sink activity of wasp-induced galls in acacia pycnantha

N. Dorchin, Michael Cramer, J. Hoffmann

    Research output: Contribution to journalArticle

    58 Citations (Scopus)

    Abstract

    Although insect galls are widely known to influence source-sink relationships in plants, the relationship between photosynthesis and gall activity has not been extensively studied. In this study we used (CO2)-C-14, photosynthesis, and respiration measurements to examine the capacity of bud galls induced by the wasp Trichilogaster signiventris (Pteromalidae) as carbon sinks in Acacia pycnantha. Galls of this species develop either in vegetative or reproductive buds, depending on the availability of tissues at different times of the year,. and effectively eliminate seed production by the plant. Photosynthetic rates in phyllodes subtending clusters of galls were greater than rates in control phyllodes, a result we attributed to photosynthesis compensating for increased carbon demand by the galls. Contrary to previous studies, we found that photosynthesis within galls contributed substantially to the carbon budgets of the galls, particularly in large, mature galls, which exhibited lower specific respiration rates allowing for a net carbon gain in. the light. To determine the sink capacity and competitive potential of galls, we measured the proportion of specific radioactivity in galls originating from either vegetative or reproductive buds and found no difference between them. The proportion of the total amount of phyllode-derived C-14 accumulated in both clustered and solitary galls was less than that in fruits. Galls and fruits were predominantly reliant on subtending rather than on distant phyllodes for photosynthate. Solitary galls that developed in vegetative buds constituted considerably stronger sinks than galls in clusters on inflorescences where there was competition between galls or fruits for resources from the subtending phyllode. Wasps developing in solitary vegetative galls were correspondingly significantly larger than those from clustered galls. We conclude that, in the absence of inflorescence buds during summer and fall, the ability of the wasps to cause gall formation in vegetative tissues tempers intraspecific competition and substantially increases the availability of plant resources for the development of wasps in such galls.
    Original languageEnglish
    Pages (from-to)1781-1791
    JournalEcology
    Volume87
    Issue number7
    DOIs
    Publication statusPublished - 2006

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    gall
    Acacia
    galls
    wasp
    photosynthesis
    bud
    buds
    fruit
    fruits
    carbon
    respiration
    inflorescences
    gall insect
    seed productivity
    Cynipidae
    source-sink relationships
    Pteromalidae
    carbon sink
    intraspecific competition
    carbon budget

    Cite this

    Dorchin, N. ; Cramer, Michael ; Hoffmann, J. / Photosynthesis and sink activity of wasp-induced galls in acacia pycnantha. In: Ecology. 2006 ; Vol. 87, No. 7. pp. 1781-1791.
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    abstract = "Although insect galls are widely known to influence source-sink relationships in plants, the relationship between photosynthesis and gall activity has not been extensively studied. In this study we used (CO2)-C-14, photosynthesis, and respiration measurements to examine the capacity of bud galls induced by the wasp Trichilogaster signiventris (Pteromalidae) as carbon sinks in Acacia pycnantha. Galls of this species develop either in vegetative or reproductive buds, depending on the availability of tissues at different times of the year,. and effectively eliminate seed production by the plant. Photosynthetic rates in phyllodes subtending clusters of galls were greater than rates in control phyllodes, a result we attributed to photosynthesis compensating for increased carbon demand by the galls. Contrary to previous studies, we found that photosynthesis within galls contributed substantially to the carbon budgets of the galls, particularly in large, mature galls, which exhibited lower specific respiration rates allowing for a net carbon gain in. the light. To determine the sink capacity and competitive potential of galls, we measured the proportion of specific radioactivity in galls originating from either vegetative or reproductive buds and found no difference between them. The proportion of the total amount of phyllode-derived C-14 accumulated in both clustered and solitary galls was less than that in fruits. Galls and fruits were predominantly reliant on subtending rather than on distant phyllodes for photosynthate. Solitary galls that developed in vegetative buds constituted considerably stronger sinks than galls in clusters on inflorescences where there was competition between galls or fruits for resources from the subtending phyllode. Wasps developing in solitary vegetative galls were correspondingly significantly larger than those from clustered galls. We conclude that, in the absence of inflorescence buds during summer and fall, the ability of the wasps to cause gall formation in vegetative tissues tempers intraspecific competition and substantially increases the availability of plant resources for the development of wasps in such galls.",
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    Photosynthesis and sink activity of wasp-induced galls in acacia pycnantha. / Dorchin, N.; Cramer, Michael; Hoffmann, J.

    In: Ecology, Vol. 87, No. 7, 2006, p. 1781-1791.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Photosynthesis and sink activity of wasp-induced galls in acacia pycnantha

    AU - Dorchin, N.

    AU - Cramer, Michael

    AU - Hoffmann, J.

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    AB - Although insect galls are widely known to influence source-sink relationships in plants, the relationship between photosynthesis and gall activity has not been extensively studied. In this study we used (CO2)-C-14, photosynthesis, and respiration measurements to examine the capacity of bud galls induced by the wasp Trichilogaster signiventris (Pteromalidae) as carbon sinks in Acacia pycnantha. Galls of this species develop either in vegetative or reproductive buds, depending on the availability of tissues at different times of the year,. and effectively eliminate seed production by the plant. Photosynthetic rates in phyllodes subtending clusters of galls were greater than rates in control phyllodes, a result we attributed to photosynthesis compensating for increased carbon demand by the galls. Contrary to previous studies, we found that photosynthesis within galls contributed substantially to the carbon budgets of the galls, particularly in large, mature galls, which exhibited lower specific respiration rates allowing for a net carbon gain in. the light. To determine the sink capacity and competitive potential of galls, we measured the proportion of specific radioactivity in galls originating from either vegetative or reproductive buds and found no difference between them. The proportion of the total amount of phyllode-derived C-14 accumulated in both clustered and solitary galls was less than that in fruits. Galls and fruits were predominantly reliant on subtending rather than on distant phyllodes for photosynthate. Solitary galls that developed in vegetative buds constituted considerably stronger sinks than galls in clusters on inflorescences where there was competition between galls or fruits for resources from the subtending phyllode. Wasps developing in solitary vegetative galls were correspondingly significantly larger than those from clustered galls. We conclude that, in the absence of inflorescence buds during summer and fall, the ability of the wasps to cause gall formation in vegetative tissues tempers intraspecific competition and substantially increases the availability of plant resources for the development of wasps in such galls.

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