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991.
Reyes Tárrega Leonor Calvo Ángela Taboada Elena Marcos José Antonio Marcos 《European Journal of Forest Research》2011,130(6):949-957
We compared the structure of the arboreal layer and the diversity and species composition of the understory vegetation of
three types of mature forest communities: oak (Quercus pyrenaica) and beech (Fagus sylvatica) forests and Scots pine (Pinus sylvestris) plantations. Our main aim was to determine whether differences in these variables existed and were due to the identity of
the dominant tree species. We selected four stands or replicates per forest type located geographically close and with relatively
similar conditions. We found no differences in the arboreal structure of oak and beech forests, which were characterised by
great variability in tree size, while in case of plantations, this variability was lower at both the intra-stand (estimated
by the coefficient of variation) and inter-stand (i.e. the four replicates harboured trees of similar sizes) scales. However,
the highest variability in the canopy layer of natural forests was not consistently linked to greater understory species richness.
Indeed, the lowest plant species richness was found in beech forests, while oak forests harboured the highest value at either
the sampling unit (per m2) or stand scales. The greatest negative correlation between plant diversity and the environmental variables measured was
found for litter depth, which was the highest in beech forests. The results obtained by the CCA indicated that the four replicates
of each forest type clustered together, due to the presence of characteristic species. We concluded that pine plantations
did not approach the environmental conditions of native forests, as plantations were characterised by singular understory
species composition and low arboreal layer variability, compared to natural woodlands. 相似文献
992.
Seyed Ali Asghar Fathi Maryam Bozorg-Amirkalaee Rana Muhammad Sarfaraz 《Journal of pest science》2011,84(1):41-47
The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important insect pest of canola, Brassica napus L., in Ardabil, Iran. Host plant resistance is an essential component of integrated management of P. xylostella. We investigated the preferences and performance of P. xylostella on nine commercial cultivars of canola, namely Zarfam, RGS003, Adder, Okapi, Opera, Hyola401, Ebonite Option500 and Elite
under greenhouse conditions at 23 ± 1°C, 50 ± 5% RH and 14L:10D. In free-choice situation, oviposition was lowest on Opera
(23.5) and highest on Zarfam (44.7). In the life table study, fecundity of new generation female moths was lowest on Opera
(95.4) and highest on Adder (145.7). Survival from egg to adult was significantly lower on Opera, Option500 and Hyola401 than
on other tested cultivars. The intrinsic rate of natural increase (r
m) and population growth rate (λ) were lowest on Opera and highest on Zarfam. The generation time (T) was shortest on Zarfam (17.2 days) and longest on Hyola401 (19.9 days) whereas doubling time (DT) was longest on Opera (3.9 days)
and shortest on Zarfam (3.0 days). Our results clearly suggest that Opera was the most resistant host among the tested cultivars
and has the potential to be used in the integrated management of P. xylostella. 相似文献
993.
Jaime A. Ocampo-Hernández Patricia Tamez-Guerra Samuel Pineda Fernando Tamayo-Mejía Ariel Guzmán-Franco José I. Figueroa de la Rosa Ana Mabel Martínez 《Journal of pest science》2011,84(4):471-477
Entomopathogenic fungi represent excellent candidates for biological insecticides. Among the many entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) is one of the most promising species. Here, we report the results of infection studies performed using four B. bassiana native isolates (Bb37, Bb38, Bb40, and Bb45) compared with the commercial product Mycotrol® (strain GHA) on adult Mexican bean beetle Epilachna varivestis Mulsant (Coleoptera: Coccinellidae), one of the most important pests of bean production in Mexico. First, single concentration (1 × 108 conidia mL?1) assays were carried out using all isolates applied using an immersion method. Examinations at 10 days after inoculation indicated that isolates Bb37, Bb38, and Bb40 significantly reduced adult survival, causing 60–75% mortality compared to the commercial strain GHA (33%) and control (29%). Second, using two selected isolates (Bb37 and Bb40), the mean lethal concentration values (LC50) were estimated for third instar larvae and adult E. varivestis. The LC50 values for Bb37 and Bb40 isolates decreased 5.26-fold and 3.19-fold, respectively, in third instars compared with adults. However, such difference for Bb40 isolate was not significant. Finally, an experiment, to compare the median survival time (MST) values between third instar and adult E. varivestis, was conducted using Bb37 and Bb40 at 1 × 109 conidia mL?1. MST values were significantly reduced against larvae (87 and 100 h) compared with adults (130 and 134 h) by Bb37 and Bb40, respectively. We conclude that native isolates of B. bassiana represent an important alternative for the control of E. varivestis. However, to demonstrate its effectiveness under field conditions, detailed studies are needed. 相似文献
994.
The lethal and sublethal effects of chlorantraniliprole against Spodoptera exigua (Hübner) were evaluated under laboratory conditions by oral exposure of neonate larvae to the compound. The 72 h LC50 value of this insecticide to S. exigua was found to be 12.747 μg l−1. A progressive larval mortality of 24.32% for LC30 treatment and 42.61% for LC50 treatment was observed from 4th to 6th day after exposure, which resulted in the reduced pupation rates in exposure groups.
The sublethal effects of this chemical were indicated by prolongation of larval period, the increase of pupal weight and decrease
in hatch rate of egg. Chlorantraniliprole at LC30 and LC50 rate significantly delayed larval development; the developmental duration of surviving larvae was extended for 22.5 and 28.6%,
respectively, compared with that of control group. LC30 treatment increased the mean weight of pupa and induced to the production of heavier pupa (>150 mg). In LC50 treatment, heavier pupa also showed up but the mean weight of pupa was not influenced. The egg hatch rate in LC50 group was significant lower than that in control and LC30 groups. No significant differences in pupal duration, emergence rate, sex ratio, egg number per female, and longevity of
adults were observed among treatments. Chlorantraniliprole had exceptional activity against S. exigua according to concentration–response bioassay in laboratory, and the toxicities were primarily resulted from immediate lethality. 相似文献
995.
In laboratory tests, the toxicity of acaricides targeted against house dust mites was tested on five species of stored product
mites (Acarus siro, Aleuroglyphus ovatus, Carpoglyphus lactis, Lepidoglyphus destructor, and Tyroborus lini). The formulations of benzyl-benzoate, benzyl-benzoate/permethrin/pyriproxyfen, and neem were diluted in water and applied
to filter paper in an unventilated chamber. The mortality of mites was observed after 24 h of exposure to acaricide-impregnated
filter paper. All of the tested acaricides were toxic to all of the mite species. There were significant differences in mortality
among the species and the acaricides. Benzyl-benzoate/permethrin/pyriproxyfen was the most effective, followed by benzyl-benzoate
and neem. L. destructor (LD50 0.01–0.11 μg) was the most sensitive mite species, followed by A. siro (LD50 0.04–0.12 μg), T. lini (LD50 2–21 μg), A. ovatus (LD50 3–18 μg), and C. lactis (LD50 4–64 μg). Based on the highly toxic effects of the tested acaricides against the stored product mites, the acaricides should
be considered as a potential tool in the control of stored product mites, although next screening is necessary. 相似文献
996.
Rohny Setiawan Maail Kenji Umemura Hideo Aizawa Shuichi Kawai 《Journal of Wood Science》2011,57(4):302-307
This study examined the effects of supercritical CO2 treatment on the curing and degradation of cementbonded particleboard (CBP). Significant correlations were found between
the supercritical CO2 treatment and mechanical properties during both curing and degradation processes. Internal bond (IB) strength, modulus of
rupture (MOR), and modulus of elasticity (MOE) values of CBP achieved their maximums by supercritical CO2 treatment in 30 min. These conditions indicated that supercritical CO2 treatment accelerates the curing process rapidly and enhances the mechanical properties of the CBP. However, these values
decreased in treatment from 60 min to 10 days and had a negative effect on board performance, indicating that supercritical
CO2 treatment over a longer time span leads to degradation of the CBP. Furthermore, X-ray diffractometry (XRD), thermal gravimetry
(TG-DTG), and scanning electron microscopy (SEM) observation clarified that the mechanisms of degradation are directly affected
by the mineralogical composition of the system, in par ticular, by the calcium carbonate content as caused by carbonation. 相似文献
997.
This article addresses the German debate on the issue of the common welfare designation of public forests. In the first part,
drawing on two case studies, the political discourse on the issue is introduced. Two major competing ‘story lines’ can be
made out that are both based on a long tradition of controversially discussed concepts of regulatory forest policy. While
they both emphasise that common welfare services in forestry run counter to profit orientation, they fundamentally differ
with regard to the consequences for forest policy, e.g., considering the degree of state intervention. Afterwards, an overview
on the scientific debate on common welfare in the German context is given, and different concepts of common welfare determination
are distinguished. Existing approaches of common welfare determination in German forest policy are related to these concepts
and discussed. It is argued that the common welfare designation of the public forest is only insufficiently implemented by
the actual governance arrangements. Based on this consideration, eventually, the implementation of a procedural concept of
common welfare operationalisation in Germany’s public forests at the local level is proposed. While such a concept will not
solve all complex problems related to the determination of common welfare in public forestry, it would notably contribute
to a more operational definition of common welfare in public forestry and a more informed public debate on the issue. 相似文献
998.
999.
1000.
José Climent Maria Regina Chambel Marta Pardos Francisco Lario Pedro Villar-Salvador 《European Journal of Forest Research》2011,130(5):841-850
Rooting space is considered as a resource in plants, but comparative studies on the biomass allocation plasticity in response
to rooting volume (RV) are rare. We compared responses in growth, biomass allocation and ontogenetic heteroblasty in nine
hard pine species of contrasted ecology. Seedlings were cultivated in containers of 0.2, 0.5, 1.0, 2.8 and 7 L for two growing
seasons (425 days). Reduction in RV caused a reduction in plant absolute and relative growth rate and biomass allocated to
stems but it increased biomass allocated to roots. RV affected to a lesser extent and in a less consistent direction allocation
to leaves. Species that grew faster (higher relative growth rate) had a steeper decrease in growth with the reduction in RV.
Ontogenetic heteroblasty, evaluated as the proportion of secondary needles in the needle biomass, showed highly different
plasticity patterns in response to RV. Decrease in RV caused negligible or no change either in the most ontogenetically delayed
Mediterranean pines or in the most ontogenetically advanced pines, the mesic Pinus sylvestris and P. uncinata. By contrast, ontogenetically intermediate species showed steep reaction norms in response to reduction in RV. While P. pinaster and P. brutia showed marked rejuvenation, P. nigra accelerated the development of adult foliage. 相似文献