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  • 1
    Electronic Resource
    Electronic Resource
    Intrinsic rate of population increase of the spider mite Tetranychus urticae on the ornamental crop gerbera: intraspecific variation in host plant and herbivore (1998)
    Springer
    Entomologia experimentalis et applicata 89 (1998), S. 159-168 
    Details
    ISSN: 1570-7458
    Keywords: integrated pest management ; genotypes ; rm ; plant breeding ; adaptation ; Acari
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eight cultivars of the ornamental crop Gerbera jamesonii Bolus (Asteraceae) were compared in host plant suitability for the two spotted spider mite Tetranychus urticae Koch (Acarina: Tetranychidae). This was done by determining the intrinsic rate of population increase, rm, of spider mites on leaf discs of plants from each of the cultivars. Large differences in rm values were found, ranging from 0.088/day on cultivar Bianca to 0.242/day on cultivar Sirtaki. This variation in rm was mainly caused by differences in developmental time of the spider mites. We assessed the performance of spider mites on young and old leaves of the two gerbera cultivars Bianca and Sirtaki. On Sirtaki the spider mites had a shorter developmental time and higher peak oviposition rate on young leaves than on old leaves. However, on Bianca such an effect was not found. We also determined the performance of two spider mite strains on the resistant gerbera cultivar Bianca. We compared the rm of a strain that had been reared on this cultivar for approximately half a year with the rm of a strain that was reared on bean. The rm of the strain that was reared on cultivar Bianca increased to 0.208/day, which is however still substantially lower than the rm on the susceptible cultivar Sirtaki.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003516213213
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  • 2
    Electronic Resource
    Electronic Resource
    Jasmonic acid induces the production of gerbera volatiles that attract the biological control agent Phytoseiulus persimilis (1999)
    Springer
    Entomologia experimentalis et applicata 93 (1999), S. 77-86 
    Details
    ISSN: 1570-7458
    Keywords: Acari ; behaviour ; biological control ; Gerbera jamesonii ; herbivore induced synomones ; infochemicals ; indirect defence ; Phytoseiidae ; semiochemicals ; terpenoids ; Tetranychus urticae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Jasmonic acid (JA) is a plant hormone that is involved in the induction of plant defence in response to herbivore attack. We studied the effect of exposure of gerbera leaves to JA on indirect plant defence, i.e. attraction of natural enemies of herbivores. Treatment of gerbera leaves with JA or feeding damage by the herbivorous spider mite Tetranychus urticae, both induced the production of a complex odour blend that attracts the predatory mite Phytoseiulus persimilis. This phytoseiid predator is a very effective biological control agent of the spider mite T. urticae. Comparison of headspace composition of gerbera leaves exposed to either JA or T. urticae revealed a large degree of resemblance, but some quantitative and qualitative differences were recorded. The major chemical group in both treatments is formed by the terpenoids which quantitatively comprised up to 80% of the total odour blend. These terpenoids included (E)-4,8-dimethyl-1,3,7-nonatriene, (E)-β-ocimene and linalool that are known to attract P. persimilis. Aldehydes, alcohols, esters and ketones, together with nitrogenous compounds formed the remaining constituents of the odour blend. The induction of predator attractants in plants by JA may be applied in biological control programs, which is discussed in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003826309751
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  • 3
    Electronic Resource
    Electronic Resource
    Larval parasitoid uses aggregation pheromone of adult hosts in foraging behaviour: a solution to the reliability-detectability problem (1993)
    Springer
    Oecologia 93 (1993), S. 145-148 
    Details
    ISSN: 1432-1939
    Keywords: Hymenoptera ; Eucoilidae ; Leptopilina heterotoma ; Infochemicals ; Kairomone ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Parasitoids that forage for herbivorous hosts by using infochemicals may have a problem concerning the reliability and detectability of these stimuli: host stimuli are highly reliable but not very detectable at a distance, while stimuli from the host's food are very detectable but generally not very reliable in indicating host presence. One solution to this problem is to learn to link highly detectable stimuli to reliable but not very detectable stimuli. Ample knowledge is available on how associative learning aids foraging parasitoids in the location of suitable microhabitats. However, in this paper we report on another solution to the reliability-detectability problem and present evidence for an essential, but as yet overlooked, aspect of Drosophila parasitoid ecology. For the first time it is shown that a parasitoid of Drosophila larvae spies on the communication system of adult Drosophila flies to locate potential host sites: naive parasitoids strongly respond to a volatile aggregation pheromone that is deposited in the oviposition site by recently mated female flies. Thus, the parasitoids resort to using highly detectable information from a host stage different from the one under attack (i.e. infochemical detour). The function and ecological implications of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321204
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical stimuli in host-habitat location byLeptopilina heterotoma (Thomson) (Hymenoptera: Eucoilidae), a parasite ofDrosophila (1984)
    Springer
    Journal of chemical ecology 10 (1984), S. 695-712 
    Details
    ISSN: 1573-1561
    Keywords: Leptopilinaheterotoma ; Hymenoptera ; Eucoilidae ; Saccharomyces cerevisiae ; host-habitat searching ; chemoreception ; fermentation products ; ethanol ; ethyl acetate ; acetaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Chemical stimuli play an important role in the process of searching for a host habitat by parasitic wasps. Volatile compounds originating from host habitats and/or hosts are the cues that enable such a location.Leptopilina heterotoma, a larval parasite ofDrosophila, is attracted to the food of its host, baker's yeast. Analysis of the fermentation products of baker's yeast, using a mass spectrometer, and olfactometer studies indicate that three fermentation products of this yeast, the main component of the host habitat in our laboratory, attractL. heterotoma: ethanol (5%), ethyl acetate (10−2, 10−3%), and acetaldehyde (1%). A combination of these three compounds, however, cannot compete with baker's yeast in attracting the parasites. Thus other factors, such as different compounds, concentrations, and/or combinations, also, play a role and remain to be tested.Leptopilina heterotoma does not use host-related olfactory cues in long-distance habitat location as it cannot distinguish between host habitat and host habitat with hosts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00988537
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  • 5
    Electronic Resource
    Electronic Resource
    Leaf hairs influence searching efficiency and predation rate of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae) (1999)
    Springer
    Experimental and applied acarology 23 (1999), S. 119-131 
    Details
    ISSN: 1572-9702
    Keywords: Phytoseiidae ; walking speed ; biological control ; tritrophic interactions ; Gerbera jamesonii ; trichomes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of leaf hairs on searching efficiency of adult female Phytoseiulus persimilis was investigated. For this purpose we used the ornamental crop Gerbera jamesonii and determined the predator's searching efficiency on three cultivars that differ largely in the density of leaf hairs on the undersurface of the leaves. Walking speed of the mites was highest on the cultivar with the lowest leaf hair density. Walking activity, defined as the percentage of time spent walking, was not dependent on leaf hair density of the cultivars. At both prey densities tested, time until first predation increased with leaf hair density. The predation rate of adult female P. persimilis is affected by trichome density, particularly when prey density is low. At prey densities of 1.3 and 2.5 Tetranychus urticae eggs cm–2, predation rate was inversely related to leaf hair density. At a prey density of 8.0 eggs cm–2 no significant effect of leaf hair density on predation rate was found. These negative effects on searching efficiency and predation success at low prey density of P. persimilis suggest that biological control of T. urticae on gerbera may be hampered by leaf hairs. © Rapid Science Ltd. 1998
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006098410165
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  • 6
    Electronic Resource
    Electronic Resource
    Intensification and prolongation of host searching inLeptopilina heterotoma (Thomson) (Hymenoptera: Eucoilidae) through a kairomone produced byDrosophila melanogaster (1985)
    Springer
    Journal of chemical ecology 11 (1985), S. 125-136 
    Details
    ISSN: 1573-1561
    Keywords: Leptopilina heterotoma ; Hymenoptera ; Eucoilidae ; Drosophila melanogaster ; Diptera ; Drosophilidae ; host searching ; kairomone ; concentration effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A chemical cue (kairomone) of the host, larvae ofDrosophila, was found to influence patch-time allocation of the parasiteLeptopilina heterotoma. This kairomone is soluble in water and chloroform. The kairomone was purified using thin-layer chromatography. The concentration of the kairomone increases with an increasing number of hosts. The parasites may use presence and concentration of the kairomone as cues to determine patch-time allocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987611
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  • 7
    Electronic Resource
    Electronic Resource
    Leaf age affects composition of herbivore-induced synomones and attraction of predatory mites (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 373-386 
    Details
    ISSN: 1573-1561
    Keywords: Cucumber plant ; Tetranychus urticae ; Phytoseiulus persimilis ; Acari ; herbivore-induced synomone ; tritrophic interaction ; oximes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We investigated the olfactory response of the predatory mitePhytoseiulus persimilis to cucumber leaves infested with prey, the herbivorous spider miteTetranychus urticae. The predators responded to volatiles from young rather than old infested cucumber leaves. GC-MS analysis of the head-space of spider mite-infested, artificially damaged and undamaged cucumber plants showed that herbivore-induced plant volatiles were present among the volatiles of both old and young infested cucumber leaves. The major components of the herbivore-induced plant volatiles were (3E)-4,8-dimethyl-1,3,7-nonatriene and (E)-β-ocimene: these compounds are known to attract the predatory mites. In addition, we found three oximes (2-methylbutanalO-methyloxime, 3-methylbutanalO-methyloxime, and an unknown oxime) in the headspace of both old and young infested cucumber leaves. 3-MethylbutanalO-methyloxime and the unknown oxime were much more abundant in the headspace of infested old cucumber leaves. The potential adaptive value of differential attractiveness of cucumber plant leaves of different age is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02064444
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