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The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for
interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable
depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored
whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants (cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on
the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both
cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves
offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones. 相似文献
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Pilot survey of a broad range of priority pollutants in sediment and fish from the Ebro river basin (NE Spain) 总被引:2,自引:0,他引:2
Lacorte S Raldúa D Martínez E Navarro A Diez S Bayona JM Barceló D 《Environmental pollution (Barking, Essex : 1987)》2006,140(3):471-482
Priority organic pollutants were investigated in sediments and fish collected along the Ebro river basin (NE Spain) to evaluate their occurrence, transport and bioavailability. Sediments were collected in 18 sites and two species of fish were captured in nine sites according to the availability in each area. The sampling sites covered industrial, urban and agricultural areas. Four methods were used to detect 20 organochlorine compounds (OCs), 8 polycyclic aromatic hydrocarbons, 3 organotin compounds, 2 alkylphenols and 40 polybrominated diphenyl ethers (PBDEs) from purified extracts. The contamination pattern was site specific and no downstream increase in concentration of pollutants was observed but rather a generalized low level diffuse pollution. Target compounds were detected in sediments at 0.01 to 2331 microg/kg dry weight, and only OCs and PBDEs were accumulated in benthopelagic fish. Toxicological assessment was performed according to predicted environmental levels and revealed sites where adverse effects could occur. 相似文献
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Pau Sunyer Josep Maria Espelta Raúl Bonal Alberto Muñoz 《Behavioral ecology and sociobiology》2014,68(7):1205-1213
Scatter-hoarding rodents influence the population dynamics of plants by acting as seed predators and dispersers. Therefore, rodent foraging preferences for certain seed traits (species, size, condition) have been extensively studied. However, to what extent these preferences are fixed or they track the temporal changes on seed characteristics due to phenological differences has been seldom explored. We studied the temporal variability in seed preferences by wood mouse (Apodemus sylvaticus), according to phenological changes in seed characteristics of two co-occurring oaks (Quercus ilex and Quercus pubescens). The phenology of acorn abundance and the acorn predation/dispersal patterns by rodents were monitored over an entire seeding season. Results revealed temporal changes in rodent preferences for acorns of the two oaks, matching their different seeding phenology (earlier in Q. pubescens and later in Q. ilex). On the other hand, whatever the species considered, rodents preferred larger and sound acorns along the entire season, although the dispersal of infested ones increased slightly during the peaks of acorn drop. The observed influence of seeding phenology on seed choices by rodents warns about inferring definite conclusions regarding their foraging behavior when arising from short-term experiments. Indeed, this study reveals that foraging preferences may be highly dynamic and context-dependent for some seed traits (e.g., species and condition), rather than fixed behavioral patterns. Plasticity in rodent foraging choices may allow them to successfully exploit different oaks with uncoupled seeding phenologies, while potentially favoring their coexistence. 相似文献
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Pere Pons Josep M. Bas Roger Prodon Núria Roura-Pascual Miguel Clavero 《Behavioral ecology and sociobiology》2008,62(8):1217-1228
The study of successional gradients may help to understand the relative influence of habitat structure and competition on
territory characteristics. Here, we evaluate the effects of vegetation cover, conspecific and heterospecific densities, and
distance to the nearest neighbor on territory size, shape, and overlap in insectivorous birds. We studied these effects along
a gradient of postfire habitat regeneration in which foliage cover and densities of focal species varied several-fold. We
delineate 197 territories (minimum convex polygons) of the shrub-dwelling Dartford warbler (Sylvia undata) and 255 of the syntopic Sardinian (Sylvia melanocephala), subalpine (Sylvia cantillans) and melodious (Hippolais polyglotta) warblers at three plots in NE Catalonia (Spain and France) in 1987–2005. After accounting for the effect of the number of
locations used to delineate polygons, generalized linear mixed models (GLMM) showed a reduction in territory area of the Dartford
warbler as conspecific density increased and distance to nearest neighbor decreased, in accordance with the contender pressure
hypothesis for territory size regulation. Heterospecific density was not included in the final model of territory size and
the effect of habitat structure was marginal. Territory roundness was positively correlated with its size and with conspecific
density, probably in relation to energetic constraints, and negatively with heterospecific density. Territorial exclusion
was almost complete among Dartford warblers, whereas interspecific territory overlap was extensive and tended to increase
with heterospecific density and with structural diversity along the gradient. Our results support the hypothesis that Mediterranean
warbler coexistence derives from ecological segregation and not from interspecific territoriality. 相似文献
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Hctor Medina Josep Arnaldos Joaquim Casal 《Journal of Loss Prevention in the Process Industries》2009,22(5):566-573
Hazard identification and risk assessment are key aspects in process plant design. They are often applied in the final stages of the process at whatever the cost, unless financial constraints are imposed. However, a much better solution would be to introduce risk analysis earlier by including it in earlier stages of the design process, such as when the cost of a plant and the cost of any accidents that may occur are estimated. In this paper, an optimization methodology is proposed, in which both cost and risk (with a deterministic approach) are taken into account, to improve on the current situation. If a decision variable is chosen, an objective function will be established that makes it possible to analyze variations in overall costs, including the cost of the investment and the cost of accidents. This leads to an optimum situation in which costs are kept to a minimum. Of course, this optimization is subject to constraints, the greatest of which is the fact that risk must not exceed tolerated threshold levels. The procedure is explained and two examples, one involving a toxic release and the other a BLEVE/fireball, are used to illustrate it. 相似文献