Preference and performance of <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.) (Lepidoptera: Plutellidae) on canola cultivars

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.     

Susceptibility of the Mexican bean beetle <Emphasis Type="Italic">Epilachna varivestis</Emphasis> Mulsant (Coleoptera: Coccinellidae) to endemic isolates of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae)

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.     

Effects of chlorantraniliprole on development and reproduction of beet armyworm, <Emphasis Type="Italic">Spodoptera exigua</Emphasis> (Hübner)

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.     

The toxicity of selected acaricides against five stored product mites under laboratory assay

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.     

Curing and degradation processes of cement-bonded particleboard by supercritical CO<Subscript>2</Subscript> treatment

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.     

Hidden in the woods? Meaning,determining, and practicing of ‘common welfare’ in the case of the German public forests

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.     

Biomass allocation and foliage heteroblasty in hard pine species respond differentially to reduction in rooting volume

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.     

Cost-effective strategies to conserve boreal forest biodiversity and long-term landscape-level maintenance of habitats

Setting aside parcels of land is the main conservation strategy to reduce the rate of biodiversity loss worldwide. Because funding for biological conservation is limited, it is important to distinguish the most efficient ways to use it. Here, we assess implications of alternative measures to conserve biodiversity in managed boreal forest landscapes. We calculated four alternative spatio-temporal scenarios and compared these to the current management regime over 100-year time period. In the alternative scenarios, a fixed amount of funding was invested in (1) permanent large reserves (each tens of ha in size), (2) permanent small reserves (each a few ha in size), (3) temporary small reserves (based on 10-year contracts with private land owners), and (4) green-tree retention (small groups of trees retained on clear-cuts). To assess biodiversity implications, we used habitat suitability indices to calculate overall habitat availability for five groups of red-listed and habitat-specific species associated with decaying spruce logs. The possibilities for timber harvests did not differ among the scenarios, but biodiversity performance was different. The scenarios with permanent reserves tended to outperform other scenarios, suggesting that conservation policies based on permanent reserves are the most cost-efficient in the long term. Results, however, varied among time scales and species groups. In the short term, a strategy of investment in temporary small reserves was the most efficient. Habitat for species associated with old spruce dead-wood and preferring shade was rare throughout all simulations, and therefore, it is likely that these species cannot be sustained in managed forests. Species that live on fresh dead-wood and are associated with forest edges coped well in all scenarios suggesting that such species will persist in managed landscapes without additional conservation efforts. Explicit definition of conservation objectives and time frames for conservation action are thus prerequisites for successful conservation planning.