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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of chemical & engineering data 15 (1970), S. 304-307 
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 2
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 3
    ISSN: 1432-1432
    Keywords: Key words: Mutation rate — Migration — Point mutation — Pesticide resistance —γ-Aminobutyric acid receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The number of origins of pesticide resistance-associated mutations is important not only to our understanding of the evolution of resistance but also in modeling its spread. Previous studies of amplified esterase genes in a highly dispersive Culex mosquito have suggested that insecticide resistance-associated mutations (specifically a single-gene duplication event) can occur a single time and then spread throughout global populations. In order to provide data for resistance-associated point mutations, which are more typical of pesticide mechanisms as a whole, we studied the number of independent origins of cyclodiene insecticide resistance in the red flour beetle Tribolium castaneum. Target-site insensitivity to cyclodienes is conferred by single point mutations in the gene Resistance to dieldrin (Rdl), which codes for a subunit of a γ-aminobutyric acid (GABA) receptor. These point mutations are associated with replacements of alanine 302 which render the receptor insensitive to block by the insecticide. We collected 141 strains of Tribolium worldwide and screened them for resistance. Twenty-four strains contained resistant individuals. After homozygosing 23 of these resistance alleles we derived a nucleotide sequence phylogeny of the resistant strains from a 694-bp section of Rdl, encompassing exon 7 (which contains the resistance-associated mutation) and part of a flanking intron. The phylogeny also included six susceptible alleles chosen at random from a range of geographical locations. Resistance alleles fell into six clades and three clades contained both resistant and susceptible alleles. Although statistical analysis provided support at only the 5–6% level, the pattern of variation in resistance alleles is more readily explained by multiple independent origins of resistance than by spread of a single resistance-associated mutation. For example, two resistance alleles differed from two susceptible alleles only by the resistance-associated mutation itself, suggesting that they form the susceptible ancestors and that resistance arose independently in several susceptible backgrounds. This suggests that in Tribolium Rdl, de novo mutations for resistance have arisen independently in several populations. Identical alleles were found in geographically distant regions as well, also implying that some Rdl alleles have been exported in stored grain. These differences from the Culex study may stem both from differences in the population genetics of Tribolium versus that of mosquitoes and differences in mutation rates associated with point mutations versus gene duplication events. The Tribolium data therefore suggest that multiple origins of insecticide resistance (associated with specific point mutations) may be more common than the spread of single events. These findings have implications for the way in which we model the evolution and spread of insecticide resistance genes and also suggest that parallel adaptive substitutions may not be uncommon in phyletic evolution.
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  • 4
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In recent Petawatt laser experiments at Lawrence Livermore National Laboratory, several hundred joules of 1 μm laser light in 0.5–5.0-ps pulses with intensities up to 3×1020 W cm−2 were incident on solid targets and produced a strongly relativistic interaction. The energy content, spectra, and angular patterns of the photon, electron, and ion radiations have all been diagnosed in a number of ways, including several novel (to laser physics) nuclear activation techniques. About 40%–50% of the laser energy is converted to broadly beamed hot electrons. Their beam centroid direction varies from shot to shot, but the resulting bremsstrahlung beam has a consistent width. Extraordinarily luminous ion beams (primarily protons) almost precisely normal to the rear of various targets are seen—up to 3×1013 protons with kTion∼several MeV representing ∼6% of the laser energy. Ion energies up to at least 55 MeV are observed. The ions appear to originate from the rear target surfaces. The edge of the ion beam is very sharp, and collimation increases with ion energy. At the highest energies, a narrow feature appears in the ion spectra, and the apparent size of the emitting spot is smaller than the full back surface area. Any ion emission from the front of the targets is much less than from the rear and is not sharply beamed. The hot electrons generate a Debye sheath with electrostatic fields of order MV per micron, which apparently accelerate the ions. © 2000 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Entomology 42 (1997), S. 371-391 
    ISSN: 0066-4170
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The sexual behavior of phytophagous insects is often integrated in a variety of ways with their host plants. This integration may be manifested as effects or influences of host plants on insect physiology and behavior, including sex pheromone communication, that reflect strategies by insects to optimize mating and reproduction. Certain insects sequester or otherwise acquire host plant compounds and use them as sex pheromones or sex pheromone precursors. Other insects produce or release sex pheromones in response to particular host plant cues. Chemicals from host plants often synergize or otherwise enhance insect responses to sex pheromones. By these means, host plants may be used by insects to regulate or mediate sexual communication. For many species of insects, host plant influences on insect sex pheromone communication may be important aspects of the formation of feeding and mating aggregations, of insect strategies to locate both hosts and mates, of behavioral reproductive isolation among sibling species, and of the regulation of reproduction to coincide with the availability of food and oviposition sites. Knowledge of these relationships is critical to understanding many different areas of the behavioral ecology of plant-feeding insects.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 185-192 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Pyralidae ; Indianmeal moth ; semiochemicals ; attraction ; oviposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Substrates contaminated by wandering fifth instar larvae ofPlodia interpunctella (Hübner) (Lepidoptera: Pyralidae) elicit oviposition by conspecific female moths, and larval rearing diet enhances oviposition and also induces upwind flight. Two-choice oviposition assays determined that four-day-old gravid femaleP. interpunctella preferred to lay eggs on dishes containing cornmeal-based rearing diet compared to empty dishes. Pieces of cheesecloth contaminated by fifth instar larvae elicited more oviposition than untreated cheesecloth or dishes with food. The combination of larval contamination and food was preferred over food only or larval contamination only in both two- and four-choice experiments. The factor(s) in larval contamination responsible for eliciting oviposition in female moths was extracted in hexane, confirming that organic semiochemicals are responsible for the effect. The oviposition-eliciting activity of larval contamination was retained on cheesecloth for up to 30 days following treatment with larvae, suggesting the active component(s) is stable and of low relative volatility. In two-choice windtunnel bioassays female moths initiated flight only when rearing food was present in one of the treatments, and they displayed the highest landing responses to a combination of larval contamination and food. Earlier work onP. interpunctella and related pyralid species found that larval contamination due to secretions from the mandibular glands acted as both a spacing pheromone for wandering larvae and as a kairomone for host-seeking parasitoid wasps. The present study suggests that the same or a similar secretion acts as an oviposition-eliciting pheromone for conspecific females.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 75 (1995), S. 33-42 
    ISSN: 1570-7458
    Keywords: Lyctocoris campestris ; Anthocoridae ; Heteroptera ; seasonal abundance ; trapping efficiency ; disersion pattern ; stored-product ; predator ; sex-ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A two-year sampling study (1992–93) in a flat storage of shelled corn showed that the larger pirate bugLyctocoris campestris (F.) (Heteroptera: Anthocoridae), can be detected by relative sampling techniques as early as the second week of May. The perceived seasonal pattern ofL. campestris varied with trapping method. Of the three relative sampling methods used, probe traps consistently captured more bugs of both sexes than cardboard traps in the grain and sticky flight traps. Probe traps showed a third degree polynomial trend through the season. On the other hand, flight traps were effective for monitoringL. campestris population during early and mid-summer when temperatures were high, but the effectiveness declined during late summer and early fall. Cardboard traps showed the opposite trend to those of flight traps, with increasingL. campestris abundance during the fall when bugs sought refuge as temperature decreased. Sampling date and environmental factors, including grain moisture content, air and grain temperatures were correlated with trap capture. Earlier work reported thatL. campestris showed a highly female biased sex ratio in the field as opposed to a 1∶1 sex ratio in laboratory colonies. The present study found that the estimate of sex ratios in the field can differ with trapping methods. Of the three relative sampling methods used, flight and cardboard traps, in most cases, showed no deviation from a 1∶1, sex ratio. Probe traps, however, indicated a highly female biased sex ratio in field populations. Absolute sampling using a 1140 ml cup sampler also showed no deviation from a 1∶1 sex ratio in the field population. The data suggested that relative sampling methods may be inappropriate for sex ratio estimation in the field. Thus, an absolute sampling method is required for determination of the true field sex ratio ofL. campestris. Analyses of dispersion patterns showed that both males and females ofL. campestris exhibit an aggregated spatial distribution in the grain.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 12 (1986), S. 1587-1601 
    ISSN: 1573-1561
    Keywords: Pissodes ; Coleoptera ; Curculionidae ; aggregation pheromone ; cross-attraction ; synomone ; reproductive isolation ; grandisol ; grandisal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Pissodes strobi, P. approximatus, andP. nemorensis are sibling species of pine weevils that can hybridize in the laboratory but are presumed to be reproductively isolated in nature. Males of all three species produce the terpenoids grandisol and grandisal; these compounds serve as an aggregation pheromone forP. approximatus andP. nemorensis when deployed with odors from pine bolts. A series of field experiments examined the possibility of cross-attraction among the three species. Tests in New York and Florida found that parapatrically distributedP. approximatus andP. nemorensis were cross-attractive, but different photoperiodic conditioning was required for pheromone production in males of the two species. Long-day pheromone production (P. approximatus-type.) was inherited in interspecific hybrids. Other tests showed thatP. strobi males, or hybrid males from crosses ofP. strobi withP. approximatus, were not attractive to sympatricP. approximatus. When the response ofP. strobi was assessed to males of eitherP. strobi orP. approximatus confined on white pine leaders (the breeding site ofP. strobi), no evidence of cross-attraction or pheromone activity was found;P. strobi were caught in equal numbers onP. strobi-baited leaders,P. approximatus-baited leaders, and unbaited leaders. Tests of interspecific interactions found that maleP. strobi produce an allelochemical signal that interrupts the response ofP. approximatus to its natural or synthetic aggregation pheromone. This interspecific response is apparently adaptive for members of both species (classified as an allomone-kairomone or synomone) because it may ultimately serve to prevent interspecific matings that would lower the fitness of the parents.
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  • 9
    ISSN: 1573-1561
    Keywords: Dendroctonus terebrans ; Coleoptera ; Scolytidae ; bark beetles ; pheromones ; primary attraction ; secondary attraction ; host selection ; frontalin ; exo-brevicomin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Controlled infestation ofDendroctonus terebrans (Olivier) on bolts of slash pine,Pinus ellionii Engelm. var.elliottii, elicited greater attraction of wild conspecifics than uninfested bolts. Secondary attraction was not apparent, however, to standing slash pines that had received volunteer attacks, when compared with attraction to unattacked but susceptible trees. Hindguts from in-flight or attacking femaleD. terebrans contained frontalin, and those from in-flight or attacking males containedexo-brevicomin.Trans-pinocarveol,cis-verbenol,trans-verbenol, myrtenal, verbenone, myrtenol, and other compounds were produced by both sexes during gallery construction in host trees. Synthetic frontalin, when deployed with a standard host odor mixture of turpentine and ethanol, was very attractive to maleD. terebrans in field-trapping experiments. The addition of eitherexo-brevicomin orendo-brevicomin to the frontalin-turpentine combination negated the attractive effect of frontalin for males.Trans-verbenol, myrtenol, and verbenone had little effect onD. terebrans behavior. Responses of females did not differ among treatments in any of the 11 field experiments.
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  • 10
    ISSN: 1573-1561
    Keywords: Carboxylic acids ; Leguminosae ; pulses ; stored products ; seed weevils ; Callosobruchus maculatus ; Coleoptera ; cowpea weevil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Female cowpea weevils,Callosobruchus maculatus, produce a sex pheromone that elicits orientation and sexual behavior in males. Bioassay-directed isolation of the sex pheromone was conducted and compounds in the active fraction were identified and synthesized. Volatiles were collected from individual virgin females by adsorption on filter paper dises and hexane extraction. A bioassay was used in which the locomotory response of single males in glass vials was recorded upon exposure to treatments or controls. Crude extracts were subjected to silica gel column chromatography with solvents of increasing polarity; all activity eluted with methanol. Activity in the highly polar methanol fraction suggested a carboxylic acid or a compound with multiple polar functionality. Acid-base partitioning of the crude extract isolated all activity in the acid fraction, confirming that the pheromone was a carboxylic acid. The acid fraction was further fractionated by preparative GC with a Carbowax column. The most active GC fraction contained the following five 8-carbon acids identified by GC-MS and comparison with synthetic candidates: 3-methyleneheptanoic acid, (Z)-3-methyl-3-heptenoic acid, (E)-3-methyl-3-heptenoic acid, (Z)-3-methyl-2-heptenoic acid, and (E)-3-methyl-2-heptenoic acid. Each of the synthetic acids was active individually for males, and combinations of two or more of the acid pheromones had an additive effect. Upwind flight responses to natural and synthetic pheromones were observed in a flight tunnel. (Z)-3-Methyl-2-heptenoic acid was previously identified as the sex pheromone for the relatedC. analis, but this and the other four acid pheromones fromC. maculatus were inactive for maleC. analis. There was no cross-attraction betweenC. maculatus andC. analis in reciprocal studies using extracted volatiles from females of both species, GC-MS analysis ofC. analis female volatiles failed to detect any of theC. maculatus compounds but did find an unidentified C-8 acid with a GC retention time different from any of theC. maculatus pheromones.
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