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  • 1
    In: Australian Journal of Agricultural Research, CSIRO Publishing, Vol. 57, No. 4 ( 2006), p. 439-
    Abstract: Commercially grown canola, Brassica napus, is negatively affected by both water deficiency and herbivory. A glasshouse experiment evaluated the relationship between water deficiency and herbivory of two aphid species, Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae), on canola. The effect of water deficiency on aphid performance was also evaluated. Brassica napus plants were provided with either continuous water (well-watered) or were watered only once per week (water-deficient). The plants were exposed to either B. brassicae, L. erysimi, or no aphids at all. Aphid population increase, plant growth, and water relations were measured after 3 weeks. Water deficiency reduced plant growth and altered water relations in B. napus. Feeding by the aphid L. erysimi substantially reduced growth of both water-deficient and well-watered B. napus. However, herbivory by B. brassicae reduced plant growth only in conjunction with water limitation, demonstrating an interaction between limited water and insect infestation on the performance of B. napus. The aphid species and water deficiency treatments also differentially affected turgor potential, osmotic potential, leaf water potential, and leaf water content. The two species of aphids responded differently to changes in their host plants. The average size and numbers of B. brassicae aphids were lower but the percentage of alates was higher on plants with limited water relative to those on well-watered plants. The average size and numbers of L. erysimi aphids were unaffected by water limitation and the percentage of alates produced was slightly reduced in the water-deficient plants. Water limitation is likely to reduce the growth of plants, particularly when B. brassicae infests the crop. However, L. erysimi is probably the more serious pest of the two aphids in that it reduced plant growth regardless of watering regime and its development was unaffected by the status of the host plant.
    Type of Medium: Online Resource
    ISSN: 0004-9409
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2006
    SSG: 21
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  • 2
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2006
    In:  Weed Science Vol. 54, No. 1 ( 2006-02), p. 148-155
    In: Weed Science, Cambridge University Press (CUP), Vol. 54, No. 1 ( 2006-02), p. 148-155
    Abstract: Postdispersal weed seed predation by animals during the summer fallow period may lead to a reduction in the number of weeds that grow in the following winter cropping season. In this study, we investigated the patterns of weed seed removal, the influence of crop residue cover on seed removal, the types of granivores present and their seed preferences in a 16-ha postharvest cropping field in Western Australia during the summer months over 2 yr. Seed removal from caches was extremely variable (from 0 to 100%). Removal rates were generally highest along the edges of the field near bordering vegetation and lowest in the center of the field and within the bordering vegetation. However, there were many deviations from this general pattern. There was no change in rates of predation with different levels of residue cover. Ants or other small invertebrates were found to remove the most seeds. However, seed removal by other animals, such as rodents, was also evident. Annual ryegrass seeds were preferred over wild oat seeds, followed by wild radish pod segments. Seed harvesting was lowest in late January, peaked in February, and decreased in March. Results from this study suggest seed harvesters could reduce the number of surface seeds in the field, reducing the weed seed bank. Management options that increase the activity of the seed harvesters may lead to less variability in seed predation and could, therefore, be incorporated into an integrated weed management program.
    Type of Medium: Online Resource
    ISSN: 0043-1745 , 1550-2759
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2006
    detail.hit.zdb_id: 2123881-9
    SSG: 12
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  • 3
    In: Plant Physiology, Oxford University Press (OUP), Vol. 137, No. 4 ( 2005-04-01), p. 1445-1455
    Abstract: Aphids and related insects feed from a single cell type in plants: the phloem sieve element. Genetic resistance to Acyrthosiphon kondoi Shinji (bluegreen aphid or blue alfalfa aphid) has been identified in Medicago truncatula Gaert. (barrel medic) and backcrossed into susceptible cultivars. The status of M. truncatula as a model legume allows an in-depth study of defense against this aphid at physiological, biochemical, and molecular levels. In this study, two closely related resistant and susceptible genotypes were used to characterize the aphid-resistance phenotype. Resistance conditions antixenosis since migratory aphids were deterred from settling on resistant plants within 6 h of release, preferring to settle on susceptible plants. Analysis of feeding behavior revealed the trait affects A. kondoi at the level of the phloem sieve element. Aphid reproduction on excised shoots demonstrated that resistance requires an intact plant. Antibiosis against A. kondoi is enhanced by prior infestation, indicating induction of this phloem-specific defense. Resistance segregates as a single dominant gene, AKR (Acyrthosiphon kondoi resistance), in two mapping populations, which have been used to map the locus to a region flanked by resistance gene analogs predicted to encode the CC-NBS-LRR subfamily of resistance proteins. This work provides the basis for future molecular analysis of defense against phloem parasitism in a plant model system.
    Type of Medium: Online Resource
    ISSN: 1532-2548 , 0032-0889
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
    detail.hit.zdb_id: 2004346-6
    detail.hit.zdb_id: 208914-2
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    CSIRO Publishing ; 2006
    In:  The Rangeland Journal Vol. 28, No. 1 ( 2006), p. 55-
    In: The Rangeland Journal, CSIRO Publishing, Vol. 28, No. 1 ( 2006), p. 55-
    Abstract: Australia’s rangelands are under pressure from many sources, not the least of which is exotic plants often intentionally introduced as pasture or fodder crops. Before being intentionally introduced into Australia, a plant must pass a weed risk assessment administered by Biosecurity Australia. In addition, there are checks by Australian Quarantine and Inspection Service of shipments and international mail before it is allowed entry into Australia, restricting the unintentional and illegal introduction of plants. However, there are many ways in which plants can bypass these procedures and once inside Australia there is little to prevent these plants moving from state to state. Closing these gaps at the international borders and developing effective policies to deal with interstate movement of plants is essential to reduce the impacts of weeds on biodiversity, pastoral activities and other uses of Australian rangelands. This paper highlights these issues and provides recommendations to correct the problems.
    Type of Medium: Online Resource
    ISSN: 1036-9872
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2006
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  • 5
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2006
    In:  Environmental Entomology Vol. 35, No. 3 ( 2006-06-01), p. 630-636
    In: Environmental Entomology, Oxford University Press (OUP), Vol. 35, No. 3 ( 2006-06-01), p. 630-636
    Type of Medium: Online Resource
    ISSN: 0046-225X , 0046-225X
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2006
    detail.hit.zdb_id: 2027540-7
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2007
    In:  BioControl Vol. 52, No. 1 ( 2007-02), p. 113-127
    In: BioControl, Springer Science and Business Media LLC, Vol. 52, No. 1 ( 2007-02), p. 113-127
    Type of Medium: Online Resource
    ISSN: 1386-6141 , 1573-8248
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2007
    detail.hit.zdb_id: 2014979-7
    SSG: 12
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