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- Schlyter, F, et al.
(författare)
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A model for peak and width of signaling windows: Ips duplicatus and Chilo partellus pheromone component proportions - Does response have a wider window than production?
- 2001
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Ingår i: Journal of Chemical Ecology. - 1573-1561. ; 27:7, s. 1481-1511
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Tidskriftsartikel (refereegranskat)abstract
- Pheromone communication systems have a reliable signal with a restricted window of amounts and ratios released and perceived. We propose a model based on a Gaussian response profile that allows a quantification of the response peak (location of optimum) and a measure of the peak width (response window). Interpreting the Gaussian curve, fitted by nonlinear regression (NLR), as a standard normal distribution, the peak location equals the mean (mu) and the window width equals 2x the standard deviation (2 sigma). The NLR procedure can provide an objective measure for both peak location and width for a wide range of data sets. Four empirical data sets as well as 10 literature data sets were analyzed. The double-spined spruce engraver, fps duplicatus, was field tested in four populations to find the optimum proportion for attraction to the two male aggregation pheromone components. ipsdienol (Id) and (E)-myrcenol (EM), ranging from 0 to 100% of Id. Tests in Norway and the Czech Republic confirmed the preference of western populations for a blend between 50 and 90% Id. A population in Inner Mongolia showed a preference for traps with the 10 and 50% Id baits. The NLR fitted values for response peak and width (mu; 2 sigma) were: Norway 0.64,0.73 Czech Republic 0.53, 0.73; NE China 0.77,0.29; and Inner Mongolia 0.33, 0.50. The signal produced by Norwegian field-collected males had a narrower window width (2 sigma = 0.12). Males of the maize stem borer, Chilo partellus, were tested in a flight tunnel for their response to variation in the two major female sex pheromone gland components, (Z)-11-hexadecenal and the corresponding alcohol (OH). Variation of the alcohol in seven levels from 2 to 29% OH showed the highest male response for 17% OH. For all behavioral steps, the peak of male response was near mu = 0.14, while the window width fell from 2 sigma = 0.5 to 0.2 for eight sequential behavioral steps from take-off to copulation. Female production had a similar peak location (mu = 0.13) but a narrower width, 2 sigma = 0.14. Literature data from other moth species showed similar patterns, with a wider male response relative to the female production windows. Literature data on response to enantiomer ratios in a hymenopteran and to pheromone amounts in a dipteran were also described by our model. In a bark beetle population (Ips pini), with two hybridizing enantiomeric strains, the production peaks were narrower (0.1) than the response peaks (0.5). Thus, it in general, seems that in the pheromone systems analyzed. the width of the response window (2 sigma = 0.1 to 0.9) is larger than that of the production window (2 sigma = 0.03 to 0.14), irrespective of the sex of the sender.
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| 3. |
- Schlyter, F, et al.
(författare)
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Carvone and less volatile analogues as repellent and deterrent antifeedants against the pine weevil, Hylobius abietis
- 2004
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Ingår i: Journal of applied entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 128:9-10, s. 610-619
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Tidskriftsartikel (refereegranskat)abstract
- The monoterpenoid carvone (1) has been shown to have strong antifeedant effects on Hylobius spp. However, because of the high volatility of carvone, long-time protection of conifer seedlings in the field using this compound has not been possible. We demonstrate, in several bioassay steps, that less-volatile, heavier analogues retain their pre-ingestive feeding inhibition activity in the large pine weevil, Hylobius abietis (L.) for a longer time. The first step in the evaluation of the biological activity of 12 carvone analogues was a micro-assay, a choice test lasting 4 h. Compounds active at 100 nmol/cm(2) were further dose-response tested to give the effective dose needed to inhibit feeding by 50% (ED50). Of the 14 compounds tested, including both carvone enantiomers, seven heavier analogues were active at low doses (had low ED50 values). As expected from their lower vapour pressure compared with carvone, the heavier analogues proved more resistant to evaporation before testing. Thus, whereas the effect of 8-hydroxy-p-menth-en-6-one 4 declined after 2 days, some of the compounds with high molar masses, such as the alkylhydroxymenthenones 6 and 8, retained a stable activity for 4 days. The retained activity at 4 days was strongly correlated to molecular mass and boiling point. When tested on natural material (host Pinus sylvestris L. twig sections for 48 h), the heavier analogues showed a rather low activity. Probably, the activity of the more volatile compound carvone (1) is due to a repellent effect (olfactory mode) rather than the deterrent effects (gustatory mode) of the heavier compounds. In agreement with the relatively low activity on twigs in the laboratory, the hydroxymenthenone 4 was not active in the field when tested for 2 months as a 1 : 9 mixture with a polar wax.
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- Zhang, QH, et al.
(författare)
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Olfactory responses of Ips duplicatus from inner Mongolia, China to nonhost leaf and bark volatiles
- 2001
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Ingår i: Journal of Chemical Ecology. - 1573-1561. ; 27:5, s. 995-1009
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Tidskriftsartikel (refereegranskat)abstract
- Leaf and bark volatiles from nonhost angiosperm trees were tested on lps duplicatus by gas chromatographic-electroantennographic detection (GC-EAD) and by pheromone-baited traps in Sweden and Inner Mongolia, China, respectively. GC-EAD analysis of the headspace volatiles from fresh bark chips of Betula pubescens revealed trans-conophthorin, two green leaf Volatiles (GLVs): 1-hexanol and (Z)-3-hexen-1-ol, and two Cs alcohols: 3-octanol and 1-octen-3-ol, that consistently elicited antennal responses by I. duplicatus. The identification of these EAD-active compounds was confirmed in further GC-EAD recordings with synthetic mixtures. Antennal responses were also found to synthetic (E)-2-hexen-1-ol and linalool, which have been identifed from the leaves of nonhost birch and aspen species. No antennal responses of I. duplicatus were found to hexanal, (E)-2-hexenal, and (Z)-3-hexyl acetates. In field trapping experiments, blends of EAD-active green leaf alcohols or C-8 alcohols, or trans-conophthorin alone resulted in significant reductions (27-60%) in the number of I. duplicatus captured compared with pheromone-baited traps. The unsuitable host compound, verbenone (Vn), also significantly reduced trap catches by up to 60% in both experiments. The strongest disruptive effect resulted from the addition of the combination of green leaf alcohols, C-8 alcohols, and verbenone to the pheromone trap, which caused an 84% reduction in trap catch. The blend of two green leaf aldehydes plus the acetate increased the trap catches in 1998 and had no negative or positive effects in 1999. Our results suggest that these nonhost volatiles (NHVs) are important olfactory signals used by I. duplicatus in host selection. They may have great significance in developing semiochemical-based management programs for I. duplicatus by reducing or stopping attacks on suitable hosts.
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