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  • 1
    Electronic Resource
    Electronic Resource
    Gel-electrophoretic description of European populations ofTerellia virens (Loew) (Diptera, Tephritidae); implications for its use as an agent for the biological control ofCentaurea spp. (Asteraceae) in North America (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 859-864 
    Details
    ISSN: 1420-9071
    Keywords: Terellia ; Centaurea ; allozymes ; host races ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Allozyme frequencies of 15 enzyme loci, 14 of which were polymorphic, were used to characterize sevenTerellia virens populations originating from three allopatrically distributedCentaurea species. The two populations whose origins were geographically furthest apart, from Israel (onC. iberica) and from Switzerland (onC. vallesiaca), showed relatively high values of genetic distance from the 5 populations sampled in Austria and Hungary (onC. maculosa) (Nei's D〉0.07). The latter five displayed a high degree of genetic similarity. No diagnostic (fixed) allelic differences were observed between these three groups ofT. virens populations, but they could be well characterized by significant differences in allelic frequencies at 9 enzyme loci. Independently of this study, the populations from Switzerland (C. vallesiaca) and eastern Austria (C. maculosa) were selected as potential source populations for future introductions into North America for the biological control of introducedC. maculosa andC. diffusa. Based on the observed genetic differences and results from field experiments on the host specificity of these two potential source populations, it is argued that host specificity screening tests should be conducted separately for local (host plant) populations, as such populations might accept a different set of hosts. Biotype mismatch and the risk of spill-overs to native species could thus possibly be reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01922473
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  • 2
    Electronic Resource
    Electronic Resource
    Impact of root mining by Eteobalea spp. on clonal growth and sexual reproduction of common toadflax, Linaria vulgaris Mill. (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 34 (1994), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Experiments with potted plants of the weed Li naria vulgaris Mill. (Scrophulariaceae) were carried out to evaluate the effects of root mining by Eteobalea (syn. Stagmatophora) spp. (Lep. Cos-mopterigidae). Attacked plants had a shorter flowering season and produced seeds of lower weight. Continuous mining during winter resulted in a doubling of the number of stems in spring, but the total plant biomass remained un affected. This may have been caused by dis rupted apical dominance due to root-crown damage. The observed effects are expected to complement those of other agents used in the biological control of L. vulgaris in North America. L'incidence du minage des racines par Eteobalea spp. sur la croissance végétative et la reproduction sexuée de la linaire commune Linaria vulgaris Mill.Des expériences en pot sur Linaria vulgaris Mill. (Scrophulariacées) ont été conduites pour évaluer 1'effet du minage des racines par Eteobalea (syn Stagmatophora) spp. (Lep. Cosmo-pterigidae). La période florale des plantes attaquées était plus courte et les graines pro-duites avaient un plus faible poids. Un minage continu pendant 1'hiver se traduisait par un dou-blement du nombre de tiges au printemps mais la biomasse totale de la plante n'était pas affec-tée. Cela pourrait être dûà 1'arrêt de la dominance apicale par suite de dommages au collet. On attend des effets observés qu'il complètent ceux d'autres agents utilisés dans la lutte biolo-gique centre L. vulgaris en Amérique du Nord. Einfluß der Befalls der Wurzelbohrer Eteobalea spp. auf Wachstum und sexuelle Fortpflanzung des Gemeinen Leinkrauts (Linaria vulgaris Mill.) Bei Topfversuchen über die Wirkung des Fraßes von Eteobalea (= Stagmatophora) spp. in den Wurzeln von Linaria vulgaris Mill. hatten die be-fallenen Pflanzen eine kürzere Blühperiode, und die Samen waren leichter. über den Winter an-hallender Befall führte zur Verdopplung der Sproßdichte, doch die Gesamt-Biomasse blieb unverändert. Dies könnte auf die Unterbrechung der Apikaldominanz infolge der Schädigung der Wurzelkrone zurückzuführen sein. Die be-obachteten Wirkungen könnten die anderer biologischer Agentien zur biologischen Bekämpfung von Linaria vulgaris in Nord-amerika ergänzen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.1994.tb01987.x
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  • 3
    Electronic Resource
    Electronic Resource
    Complex relation between triazine-susceptible phenotype and genotype in the weed Senecio vulgaris may be caused by chloroplast DNA polymorphism (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 578-586 
    Details
    ISSN: 1432-2242
    Keywords: Key words CpDNA polymorphism ; Heteroplasmy ; psbA gene ; Triazine resistance ; Senecio vulgaris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The weed Senecio vulgaris acquired high levels of resistance to triazine herbicides soon after the latter’s introduction. As in most weeds, triazine resistance is conferred by a point mutation in the chloroplast psbA gene that negatively affects the fitness of its carrier. To assess levels of triazine resistance in S. vulgaris field populations, we adopted a PCR-RFLP-based molecular diagnostic test recently developed for the triazine resistance-conferring region of the psbA gene of other weeds, including Brassica napus, Chenopodium spp. and Amaranthus spp., and compared these molecular results to the phenotypic response after triazine application. A highly significant linear correlation was found between phytotoxic symptoms and biomass reduction. Variability in phenotypic response was not only found between populations or inbred lines of S. vulgaris but also within replicates of the same inbred line. No clear relationship, however, was found between the DNA restriction pattern and the phenotypic response to triazine application, thereby throwing doubt on the use of such molecular diagnostic tests to track triazine resistance in S. vulgaris. Our results indicate that the chloroplast genome of S. vulgaris is polymorphic and that the level of polymorphism may be variable within single leaves of individual plants. We discuss the possible genetic basis of this polymorphism and its consequence for the acquisition and inheritance of chloroplast-based traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051271
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of cnicin, a sesquiterpene lactone ofCentaurea maculosa (Asteraceae), on specialist and generalist insect herbivores (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 929-942 
    Details
    ISSN: 1573-1561
    Keywords: Centaurea maculosa ; sesquiterpene lactone ; cnicin ; host-plant selection ; oviposition behavior ; antifeedant ; attractant ; Spodoptera littoralis ; Agapeta zoegana ; Stenodes straminea ; Pterolonche inspersa ; Lepidoptera ; Noctuidae ; Cochylidae ; Pterolonchidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The sesquiterpene lactone cnicin was extracted fromCentaurea maculosa andCentaurea vallesiaca. We examined its effects on the ovipositional response and larval development of generalist and specialist insect herbivores associated withC. maculosa. For the oviposition trials, three plant species (C. maculosa, Achillea millefolium, andCichorium intybus), half of which were sprayed with 3% of cnicin, were exposed to the specialist mothsStenodes straminea, Agapeta zoegana, andPterolonche inspersa in field cages. All three species significantly preferredC. maculosa to other plants andP. inspersa significantly preferred cnicin-sprayed plants to untreated plants for oviposition. Tested over all species, cnicin significantly increased the number of eggs laid on a given plant. A larval diet test examined the toxicity of cnicin for larvae of the generalist noctuid mothSpodoptera littoralis. Cnicin concentrations of 3% and 6% were lethal and 1% and 0.5% seriously inhibited growth and development. The larvae of theC. maculosa specialistStenodes straminea survived at 6% cnicin, but none of the pupae hatched.Agapeta zoegana was able to survive at 1% and 3% cnicin. Both specialists had difficulties with the artificial diet, but weight increase and survival was not further reduced when cnicin was present compared with on the control diet. In conclusion, cnicin influenced host recognition by the specialist species, and larvae of the generalist did not survive on natural levels of cnicin. Growth and survival of the specialist were not influenced by cnicin but were considerably hampered on artificial diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059588
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  • 5
    Electronic Resource
    Electronic Resource
    The potential of three native insect predators to control the rosy apple aphid, Dysaphis plantaginea (1999)
    Springer
    BioControl 44 (1999), S. 171-182 
    Details
    ISSN: 1573-8248
    Keywords: Adalia bipunctata ; Aphidoletes aphidimyza ; apple seedling ; augmentative release ; biocontrol ; Episyrphus balteatus ; field cage trials ; laboratory trials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of three aphidophagous predators, Adalia bipunctata, Aphidoletes aphidimyza, and Episyrphus balteatus to control the rosy apple aphid, Dysaphis plantaginea Pass., a major pest on apple in Europe, was assessed by means of laboratory and field cage experiments in Northern Switzerland. Under laboratory conditions, all three predators efficiently preyed upon D. plantaginea on apple seedlings. The searching success of larvae of A. bipunctata for individual aphids was not dependent on the size of branches of apple trees varying in leaf surface area from 150 cm2 to 960 cm2. Fifty and 70% of individual aphids were found and killed 6 hours and 48 hours, respectively, after release of single second instar larva of A. bipunctata. In a first field cage experiment in 1996, A. bipunctata, and to a lesser extent E. balteatus, proved to be effective and consistent predators of D. plantaginea during spring conditions, being little affected by cool temperatures and wet weather. In a subsequent field cage experiment in 1997, larvae of A. bipunctata and E. balteatus were released singly and in combination on aphid infested apple seedlings to study interactions between these two promising control agents. Both species had a significant negative effect on aphid population increase. The two species did not significantly interact and thus, their joint effect is best explained by an additive model. Combined releases of the two predator species reduced aphid densities to 5% of the control. This indicates the potential for augmentative releases of these native aphid predators to control D. plantaginea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009934214927
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