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  • Articles  (6)
  • biological control  (5)
  • kairomones  (2)
  • Kinetics  (1)
  • Organic Chemistry
  • General Chemistry
  • Biology  (6)
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  • Articles  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Structure and function of viroids (1983)
    Springer
    European biophysics journal 9 (1983), S. 145-170 
    Details
    ISSN: 1432-1017
    Keywords: Viroids ; Thermodynamics ; Kinetics ; Hydrodynamics ; Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Viroids are an independent class of plant pathogens which are distinguished from viruses by the absence of a protein coat and by their unusually small size. They are single-stranded circular RNAs composed of about 360 nucleotide residues. Sequence analysis and physicochemical studies of the potato spindle tuber viroid (PSTV) have shown that, as a result of intra-molecular base pairing, viroids form a unique rod-like secondary structure which is characterized by a serial arrangement of double-helical sections and internal loops. There is no indication for an additional tertiary structure because all parts of the molecule are freely accessible to ligand interaction. During the denaturation all of the native base pairs of viroids are dissociated in one highly cooperative transition, and in the same process very stable hairpins which are not present in the native structure are newly formed. Most of the properties of the structure and structural transitions of PSTV have been found also in citrus exocortis viroid, chrysanthemum stunt viroid and four different viroid-like RNAs associated with the cadang-cadang disease. The close similarity between these viroids is more expressed in the overall structure and in thermodynamic and functional domains than in the primary sequence. The stiffness of all viroids can be described by an unique persistence length of 300 å. Characteristically, regions of premelting, regions of stable hairpins, and the sequence UACUACCCGGUGG which is opposite to one of the stable hairpins, are the most conservative sequences in the molecules. Current hypotheses about the function of viroids are discussed on the basis of their structural and thermodynamic features. The suggestion that viroid RNA has features similar to DNA has been supported by the finding that they are replicated in vitro by the DNA-dependent RNA polymerase II of the host plant. The highly conserved sequence in viroids mentioned above corresponds very closely to a segment at the 5′-end of the small nuclear RNA U1 of eukaryotes. Because this segment is discussed in recent models, to be involved in the splicing process, a hypothesis is proposed in which viroids interfere with the splicing process leading to a pathogenic misregulation of mRNA processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537813
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  • 2
    Electronic Resource
    Electronic Resource
    Kairomones and their use for management of entomophagous insects (1979)
    Springer
    Journal of chemical ecology 5 (1979), S. 673-680 
    Details
    ISSN: 1573-1561
    Keywords: Trichogramma ; Hymenoptera ; Trichogrammatidae ; kairomone ; Heliothis zea ; biological control ; pest management ; parasitoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A kairomone from adultHeliothis zea (Boddie) scales is an important factor in the host selection process ofTrichogrammapretiosum Riley. If the host density is sufficiently high (i.e., 1 egg/500 cm2) and higher), a complete coverage or solid treatment of kairomone spray may be the optimum for increasing parasitization rates, but this is not the case at lower host densities (e.g., 1 egg/2000 cm2). At the lower densities, the kairomone must be distributed in such a way as to retain the parasitoids in the target area without inhibiting their movement from one ovi-position site to the next. Simulated moth scale particles appear to fill this need since their density can be regulated to provide the optimum frequency of parasitoid stimulation and thus maximum rates of parasitization at prevailing host densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00986552
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  • 3
    Electronic Resource
    Electronic Resource
    Kairomones and their use for management of entomophagous insects (1981)
    Springer
    Journal of chemical ecology 7 (1981), S. 909-917 
    Details
    ISSN: 1573-1561
    Keywords: Trichogramma pretiosum ; Hymenoptera ; Trichogrammatidae ; biological control ; kairomone ; Heliothis zea ; Lepidoptera ; Noctuidae ; host density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Trichogramma pretiosum Riley females exhibit success-motivated searching after oviposition. The stimulatory effect of contact with host eggs makes host-egg density an important factor in determining the appropriate strategy for behavioral manipulation, using kairomones, that simulate host seeking, in biological control programs. Host eggs can be used, in conjunction with kairomones or by themselves, to improve the performance of these important beneficial insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987616
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  • 4
    Electronic Resource
    Electronic Resource
    Kairomones and their use for management of entomophagous insects: II. Mechanisms causing increase in rate of parasitization byTrichogramma spp. (1975)
    Springer
    Journal of chemical ecology 1 (1975), S. 349-360 
    Details
    ISSN: 1573-1561
    Keywords: Trichogramma achaeae ; Heliothis zea ; biological control ; kairomones ; pest management ; parasitoids ; host finding ; insect behavior ; pheromones ; behavior chemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract When the effect of the kairomone, tricosane, on parasitization byTrichogramma achaeae Nagaraja and Nagarkatti of eggs ofHeliothis zea (Boddie) was studied in petri dish tests, the greatest percentage parasitization ( $$\mathop X\limits^\_$$ = 64%) was obtained if the entire filter paper was treated. Treatment of smaller areas (about the eggs) resulted in decreased parasitism. In the greenhouse, highest parasitization ( $$\mathop X\limits^\_$$ = 71%) byT. pretiosum (Riley) ofH. zea eggs placed on pea seedlings grown in pie pans was obtained if the whole pan was treated; lowest parasitism ( $$\mathop X\limits^\_$$ = 29%) occurred when the pans were untreated. Parasitization was intermediate ( $$\mathop X\limits^\_$$ = 52%) in other pans treated only at selected spots. Dissections ofH. zea eggs collected from kairomonetreated and untreated field plots revealed that eggs ofTrichogramma spp. were more efficiently distributed (less superparasitism) among host eggs in treated plots. These kairomones increase parasitization ofTrichogramma spp. by releasing and continuously reinforcing an intensified searching behavior rather than by attracting and guiding the parasite directly to the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00988837
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  • 5
    Electronic Resource
    Electronic Resource
    Kairomones and their use for management of entomophagous insects: X. Laboratory studies on manipulation of host-finding behavior ofTrichogramma pretiosum riley1 with a kairomone extracted fromHeliothis zea (boddie) moth scales (1981)
    Springer
    Journal of chemical ecology 7 (1981), S. 635-648 
    Details
    ISSN: 1573-1561
    Keywords: Kairomone ; parasitoids ; biological control ; Trichogramma pretiosum ; Hymenoptera ; Trichogramma tidae ; Heliothis zea ; Lepidoptera ; Noeturidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The behavioral response ofTrichogramma pretiosum Riley females to the kairomone found inHeliothis zea (Boddie) moth scales is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987711
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  • 6
    Electronic Resource
    Electronic Resource
    Kairomones and their use for management of entomophagous insects: III. Stimulation ofTrichogramma achaeae,T. pretiosum, andMicroplitis croceipes with host-seeking stimuli at time of release to improve their efficiency (1975)
    Springer
    Journal of chemical ecology 1 (1975), S. 431-438 
    Details
    ISSN: 1573-1561
    Keywords: kairomones ; Trichogramma achaeae ; Trichogramma pretiosum ; Microplitis croceipes ; Heliothis Spp. ; host-seeking stimuli ; insect behavior ; releasers ; pest management ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Frass from larvae of the corn earworm,Heliothis zea (Boddie) and scales fromH. zea moths (that are known to contain the host-seeking stimulus, tricosane) stimulate and orient host-seeking activity in femaleMicroplitis croceipes (Cresson), a larval parasite ofH. zea, andTrichogramma spp., egg parasites ofH. zea. When larval frass, moth scales, and tricosane were used as sign stimuli (releasers) forM. croceipes, T. pretiosum (Riley), andT. achaeae Nagaraji and Nagarkatti, respectively, at time of their release from laboratory containers, parasite performance improved, resulting in significantly increased rates of parasitization over that of unstimulated parasites. Stimulation ofM. croceipes with larval frass had an overriding effect on this parasite's innate tendency to disperse upon release, thereby increasing the numbers remaining and prolonging their retention in the target area. Supplying the appropriate host-seeking stimuli to these 3 hymenopterous parasites ofH. zea at time of their release to improve their efficiency greatly increases the probability of their effective utilization in pest management systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00988584
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