Hausrattennachweise (<Emphasis Type="Italic">Rattus rattus</Emphasis> L.) in bewohnten Wohnhäusern in Magdeburg

Storehouses and mills in the Magdeburg region are known to be infested with black (ore house) rats. In residential buildings, however, house rats (Rattus rattus L.) have not been detected for at least 20 years. Therefore, it was of much interest for the expert to note that this rat species had been seen in two occupied residential buildings (a refurbished old building and a terraced house). It has been suspected for a longer time that black rats can be found in certain residential buildings in towns or even cities.     

Two-year dynamics of foliage labelling in 8-year-old <Emphasis Type="Italic">Pinus pinaster</Emphasis> trees with <Superscript>15</Superscript>N, <Superscript>26</Superscript>Mg and <Superscript>42</Superscript>Ca—simulation of Ca transport in xylem using an upscaling approach

• Introduction   

Atmospheric deposition is an important input of major nutrients into forest ecosystems. The long-term goal of this work was to apply stable isotope methodology to assess atmospheric nutrient deposition in forest systems.     

Seasonal variation of selected trace elements in rare endemic species <Emphasis Type="Italic">Thuriferous Juniper</Emphasis> growing in the <Emphasis Type="Italic">Aurès</Emphasis> Mountains of Algeria

We used energy dispersive X-ray fluorescence (EDXRF) to determine the seasonal variation of selected trace elements (Cr, Mn, Zn, Cu, Se and Fe) and some potential toxic elements (Cd, Pb and Br) in Juniperus thurifera subsp. africana Maire (Cupressaceae) a rare medicinal tree, growing indigenously in Aurès Mountains of Algeria. The precision of the results was assessed by analyzing the certified reference material IPE44 (WEPAL) grass leaves. Results showed J. thurifera was characterized by high Cr and Mn contents. During autumn and winter mineral concentrations were higher in general. The levels of Cr, Se and Mn were higher during autumn and winter than during spring and summer. Zn contents were higher during summer than in other seasons. Cu content did not vary by season. The potential toxic elements in J. thurifera (Pb > Cd > Br) were below the permissible limits recommended by the Joint WHO/FAO guidelines except for Pb in autumn and winter.     

Comparative data on the insecticide resistance of <Emphasis Type="Italic">Anopheles</Emphasis> <Emphasis Type="Italic">albimanus</Emphasis> in relation to agricultural practices in northern Belize,CA

Anopheles albimanus Wiedemann is one of the primary vectors of malaria in northern Belize. The primary breeding sites for this species in Central America are fresh water wetlands that are found in close proximity to agriculture and, in particular, sugarcane fields. The use of insecticides and herbicides on these crops leads to the introduction of chemicals into the surrounding wetlands. The potential for the development of insecticide resistance is, therefore, quite high. A study was undertaken to obtain comparative data on the resistance status of An. albimanus in northern Belize in relation to agriculture practices. Larval surveys were conducted at four collection points in marshes juxtaposed to different crop types: Dubloon (DB)—control site located 300 m from any agriculture; Little Belize (LB)—mixed crop agricultural with some human settlements; and Chan Chen (CC) and Buena Vista (BV)—year round sugarcane production. Time mortality curves were obtained by exposing F1 larvae to DDT 1 μg/ml, malathion 1 μg/ml, and permethrin 0.05 μg/ml. Significant differences in mortality rates from the four sites were observed only to malathion. The DB sites contained larvae that were the most susceptible overall, in congruence with its distance from crops. Larvae from LB exhibited a medium level of tolerance. Finally, the two populations collected at the edge of sugarcane fields (CC and BV) exhibited the highest tolerance to malathion. These results represent first data on the impact of agriculture on the resistance status of malaria vectors in northern Belize. The effect of malathion on An. albimanus insecticide resistance reinforces the concerns of the potential impact of agriculture usage on the efficacy of vector control program.     

Ruling out genetic erosion in <Emphasis Type="Italic">Picea chihuahuana</Emphasis> Martínez

Genetic erosion has been variously defined as the loss of particular alleles, the reduction in richness of the total number of alleles, and the reduction in evenness of the frequencies of alleles in a given place within populations or across species. Picea chihuahuana Martínez is an endangered endemic species known to occur in at least 40 locations along the Sierra Madre Occidental, in the states of Durango and Chihuahua (Mexico), but covering a total area of no more than 300 ha. The total number of individuals has been estimated to be around 42,600, and the number of mature individuals may be <2500. The populations (including mature trees, saplings and seedlings) vary in size from 21 to 5546 individuals. It has been suggested that small populations may be more susceptible to loss of genetic variability via genetic erosion caused by genetic drift, endogamy depression and strong unidirectional selection. The predicted reduction and eventual disappearance of a suitable habitat for P. chihuahuana due to climatic change imposes an additional risk of extinction. The principal aim of this study was therefore to estimate genetic erosion in 14 populations of P. chihuahuana Martínez by comparing genetic diversity across diameter at breast height classes (as a proxy for age classes) by using AFLP markers and four indices of genetic diversity that are commonly applied in combination with dominant genetic markers. No evidence of genetic erosion was found in the 14 P. chihuahuana populations analyzed.     

Optimum pruning intensity for reducing crop suppression in a <Emphasis Type="Italic">Gmelina</Emphasis>–maize smallholder agroforestry system in Claveria,Philippines

On-farm trials were conducted to assess the effects of four branch pruning levels on maize grain yield, tree growth and stem shape. The experimental plots consisted of Gmelina (Gmelina arborea R.Br.) trees planted at 1 × 10 m with maize intercropped in the 10 m-wide alleys between lines of trees. Pruning levels consisted of retaining a live crown ratio of 60–70% (T ₁), 40–50% (T ₂); 30–40% (T ₃) and of 20–30% (T ₄). At the end of the experiment, the total maize grain yield was highest under the high pruning intensity (T ₄) (18.06 t ha⁻¹) and lowest under T ₁ (14.48 t ha⁻¹). Maize grain yield under the pruning regime T ₂ and T ₃ were 16.08 and 17.21 t ha⁻¹, respectively. Mean annual increment (MAI) in tree diameter was greater (5.0 cm year⁻¹) under T ₁ than those at T ₄ (4.1 cm year⁻¹). Pruning regimes T ₂ and T ₃ resulted in a MAI of 4.7 and 4.5 cm year⁻¹, respectively. Financial analysis showed that maize-tree systems under T ₄ were more profitable than under T ₁ as long as the reduction of the average dbh at harvest were not greater than 1 cm. Pruning trees intensively also generated greater returns from labour than moderate pruning, as the greater maize grain yields under T ₄ compensated for the cost of pruning and the lower timber yield. In the context of resource-poor farmers, intensive branch pruning was a practice that prolonged the period of profitable intercropping and was compatible with commercial timber production.     

Factors Affecting Small-Scale Farmers’ Land Allocation and Tree Density Decisions in an <Emphasis Type="Italic">Acacia decurrens</Emphasis>-Based <Emphasis Type="Italic">taungya</Emphasis> System in Fagita Lekoma District,North-Western Ethiopia

The development of woodlots as an additional source of livelihood and as a land management option for small-scale farmers is a challenging issue in the cereal-based subsistence farming systems of north-western Ethiopia. There is a need to understand why and which factors determine the decisions of small-scale farmers to grow short-rotation woodlots on their land. Data used in this study were collected from a survey of 200 randomly selected households in the region. A Tobit regression model was used to determine predictor variables for farmers’ decisions to allocate land to planting Acacia decurrens (J.C. Wendl.) Willd. and at what density trees are planted on the respective plots. The most important motivations for planting A. decurrens were income, soil fertility management, and soil and water conservation. Having a male head of household, long distance to markets and plots being on marginal land, among other factors, increased the allocation of land to A. decurrens woodlots. Having a male head of household, access to credit and plots being on marginal land, among other factors, increased tree planting density. Age had a negative effect on both allocation of land to woodlots and tree density, whereas farm size had an inverted U-shaped relationship with both decisions. These results suggest that wider expansion of A. decurrens-based plantation systems could be achieved through improving extension, credit access and road infrastructure to connect small-scale farmers to markets and finance.     

Interactive effects of irrigation and exponential fertilization on nutritional characteristics in <Emphasis Type="Italic">Populus</Emphasis> × <Emphasis Type="Italic">euramericana</Emphasis> cv. ‘74/76’ cuttings in an open-air nursery in Beijing,China

Nutritional characteristics determine tree stock quality to a considerable extent. Exponential fertilization can induce nutrient reserves within juvenile trees, but its validity on poplar is contingent on interaction with a scientific irrigation regime due to limited water resources under global warming. In the present study, we raised 3200 Populus × euramericana cv. ‘74/76’ cuttings under four irrigation regimes of 0 (I0), 60 % (I60), 80 % (I80), and 100 % (I100) of field capacity for soil moisture content with or without (control) the employment of nitrogen (N) addition delivered as exponential fertilization at the rate of 8 g N cutting^?1 (E8) in an open-air nursery in Beijing, China. Both height and diameter increased with the increment of soil moisture ratio or in response to exponential fertilization (EF) without any interactive effects. In general, concentrations of N, phosphorus (P), and potassium (K) declined with time in stem but foliar N concentration did not change. Under the I100 regime, EF increased foliar N concentration relative to the control but failed to affect N concentration in stem in September, when both N concentration and N content were increased by EF under the I80 regime. Stem-K content and concentration by EF under the I80 regime also increased in September, therefore EF-treated cuttings had a higher ratio of K content in stem to that in whole plant (%ANAR). Vector diagnosis for nutritional status indicated that EF resulted in dilution of K concentration but induced a steady-state P uptake in leaves under all irrigation regimes. Therefore, EF of N addition could promote N uptake to leaves of P. × euramericana cv. ‘74/76’ cuttings, but it had a null effect on N and P reserves in stem and impaired K reserves. In conclusion, the irrigation regime of 80 % field capacity of soil moisture content was suggested for the culture of juvenile P. × euramericana cv. ‘74/76’ cuttings. As the interactive meaning, EF was also suggested for its excellent promotion on both N and K uptakes.     

Comparison of selected statistical distributions for modelling the diameter distributions in near-natural <Emphasis Type="Italic">Abies</Emphasis>–<Emphasis Type="Italic">Fagus</Emphasis> forests in the Świętokrzyski National Park (Poland)

The aim of the study is to compare selected theoretical distributions (normal, lognormal, Weibull, gamma, logistic, and exponential) in describing the tree diameter (DBH) distributions of mixed near-natural forests consisting of fir Abies alba Mill. and beech Fagus sylvatica L. growing in various vertical structures. Tree DBH data were collected between 1997 and 2008 from 51 sample plots established in the Świętokrzyski National Park in Poland. The empirical data represent differentiated DBH distributions, ranging from almost symmetric to extremely asymmetric ones. The chi-square test and the modified Kolmogorov–Smirnov test were chosen for the goodness-of-fit testing. In addition to the test statistics, the bias (B), the root mean square error (RMSE) and the graphical method (quantile–quantile plots) were used. In one-storied stands, the most suitable distributions were the normal and logistic distributions; in two-storied and multilayered stands, the Weibull and gamma distribution were the most suitable; and in selection stands, the exponential distribution was the most appropriate to describe the DBH distribution. The order of precision of the tested distributions (from the highest to the lowest) was Weibull, gamma, logistic, normal, exponential, and lognormal. The normal and exponential distribution should be applied only to one-storied and selection forests, respectively. The least suitable distribution for DBH distribution modelling was the lognormal one.     

The economic potential of <Emphasis Type="Italic">Gevuina avellana</Emphasis> in New Zealand planted forests

Gevuina avellana (gevuina) is a South American tree that produces edible nuts. This study conceptualizes the transformation of a planted radiata forest into an agroforestry system that integrates radiata and gevuina trees to produce timber and Non Timber Forest Products (NTFPs). This study assesses the economic potential of growing gevuina nuts in a New Zealand planted forest case study. Findings suggest that planted forests offer the potential for commercial scale using land use opportunities created around road infrastructure, and in pocket areas connected by roads. The economic returns determined in this study were significant, even in small areas. The key to realising this potential will be in the identification and use of the production strategies to handle the complex system.     

Identifying plant DNA in the sponging–feeding insect pest <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is a highly polyphagous invasive pest threatening fruit production in the Americas and Europe. The current knowledge of its host plants is mainly based on oviposition and larval development in fruits, while little is known on the diet of the adult flies. This information is important for developing effective control strategies. Here, we examine DNA-based techniques to determine food plants of D. suzukii. Adult flies were fed with raspberries (Rubus idaeus) and allowed to digest up to 72 h after feeding. Raspberry DNA was detected by diagnostic PCR for up to 48 h post-feeding with a significant negative effect of time on DNA detection success but no significant differences between male and female flies in detection probabilities. As D. suzukii walks on plants, its body surface can get contaminated with DNA. With a bleaching experiment, we succeeded to remove contaminating external plant DNA, while the DNA in the gut content stayed unaffected. Finally, field-collected flies were subjected to a next-generation sequencing approach, demonstrating that plant DNA from different host plants can be efficiently detected in both bleached and non-bleached specimens. In order to safeguard against erroneous host plant detections, we recommend bleaching flies before they are subjected to DNA extraction. The current findings encourage the use of DNA-based gut content analysis in D. suzukii to obtain a better understanding of its feeding ecology which is a prerequisite for developing successful control strategies.     

Genetic parameters for growth and wood chemical properties in <Emphasis Type="Italic">Eucalyptus urophylla</Emphasis> × <Emphasis Type="Italic">E. tereticornis</Emphasis> hybrids

Key message

Growth and wood chemical properties are important pulpwood traits. Their narrow-sense heritability ranged from 0.03 to 0.49 in Eucalyptus urophylla × E. tereticornis hybrids, indicating low to moderate levels of genetic control. Genetic correlations were mostly favorable for simultaneous improvement on growth and wood traits. Additive and non-additive genetic effects should be considered in making a hybrid breeding strategy.

Context

Eucalypt hybrids are widely planted for pulpwood production purposes. Genetic variations and correlations for growth and wood chemical traits remain to be explored in Eucalyptus interspecific hybrids.

Aims

Our objectives were to clarify the heritability of growth and wood chemical traits and determine the genetic correlations between traits and between trials in E. urophylla × E. tereticornis hybrids.

Methods

Two trials of 59 E. urophylla × E. tereticornis hybrids derived from an incomplete factorial mating design were investigated at age 10 for growth (height and diameter) and wood chemical properties (basic density, cellulose content, hemi-cellulose content, lignin content, and syringyl-to-guaiacyl ratio). Mixed linear models were used to estimate genetic parameters.

Results

Narrow-sense heritability estimates were 0.13?0.22 in growth and 0.03?0.49 in wood traits, indicating low to moderate levels of additive genetic control. Genetic correlations were mostly positively significant for growth with basic density and cellulose content but negatively significant with hemi-cellulose and lignin contents, being favourablefavorable for pulpwood breeding purpose. Type-B correlations between sites were significant for all the traits except diameter and lignin content.

Conclusion

Hybrid superiority warrants the breeding efforts. An appropriate breeding strategy should be able to capture both additive and non-additive genetic effects.

     

<Emphasis Type="Italic">Asaia</Emphasis> symbionts interfere with infection by Flavescence dorée phytoplasma in leafhoppers

The transmission of microbial pathogens by insect vectors can be affected by the insect’s microbial symbionts, which may compete in colonizing organs, express antagonistic factors or activate host immune response. Acetic acid bacteria of the genus Asaia are symbionts of the leafhopper Scaphoideus titanus, which transmits Flavescence dorée phytoplasma. These bacteria could be used as control agents against the disease. Here, we experimentally investigated the interaction between different strains of Asaia and phytoplasma transmission in the laboratory by using the model leafhopper Euscelidius variegatus and the plant host Vicia faba. We found that uncultivable and low concentrations of Asaia phylotypes were associated with E. variegatus. When we supplied different Asaia strains isolated from other insects and exhibiting different phenotypes to E. variegatus orally, the bacteria stably colonized the leafhopper, reached relatively higher densities and could then be isolated from the host. We conducted transmission trials of Flavescence dorée phytoplasma with individuals colonized with three exogenous Asaia strains. When the phytoplasma became established in the bodies of E. variegatus, leafhoppers were able to transmit it to broad beans, with transmission rates ranging from 33 to 76% in different experiments. However, leafhoppers that were colonized by one of the Asaia strains producing an air–liquid interface biofilm exhibited significantly reduced phytoplasma acquisition, with infection rates at 5–28%, whereas they were 25–77% in control insects. Although the mechanisms regulating this interference remain to be elucidated, our results provide evidence of the potential use of Asaia as a biocontrol agent.     

Do harrowing and fertilisation at middle rotation improve tree growth and site quality in <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> Labill. plantations in Mediterranean conditions?

Effects of harrowing and fertilisation on tree growth, understory vegetation, forest floor litter and soil properties were studied in a field experiment installed in a 5-year-old first rotation eucalypt plantation. The treatments were harrowing (H), fertilisation (F), harrowing and fertilisation (HF) and a control without any treatments (C), with four replicates. Tree growth, root mass, tree nutrition status, understory vegetation, mass of forest floor litter and soil physical and chemical properties were monitored till the end of the rotation (stand was 14-year old). Effects of treatments on tree growth, root mass and timber production were not significant. Root nutrient concentration differed between treatments only few months after the beginning of the experiment, while differences regarding specific root length and area were observed during the first year. Harrowing (H and HF) led to significantly smaller biomass of understory vegetation (<13.4 g m⁻²) than other treatments (33−61 g m⁻²) during the first 3 years, but at the end of the experiment differences were less important. Forest floor litter mass after 3 years and at the end of the experiment were similar among treatments. Soil bulk density significantly decreased by harrowing (H and HF treatments), but 16 months after treatments were similar. Although soil chemical properties were not significantly affected by treatments, a decrease in base cations occurred during the rotation period. Fertiliser application is a questionable practice under the economic point of view, whereas harrowing can reduce the fuel load only during a short period, without negative effects on productivity and soil quality.     

Furfural–biochar-based formulations show synergistic and potentiating effects against <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> in tomato

The nematicidal activity of furfural, biochar and urea on plant-parasitic nematodes is rather well documented and approved; however, there is no information about combination treatment with those anti-nematode agents. We tested the nematicidal effect of combinations that paired furfural and biochar (F₀B, F_2.5B, F₅B and F₁₀B) or biochar-coated urea (F₀BCU, F_8.25BCU, F_16.5BCU and F₃₃BCU) to the root-knot nematode, Meloidogyne incognita (RKN) in the absence and presence of tomato plant, and characterized their possible mode of action. After biochar or BCU being paired with furfural, the accompanying effect of FB or FBCU, at all their application rates, resulted in superior control of RKN to that obtained when each component was applied individually. All applied levels of furfural–biochar-based formulations significantly inhibited RKN criteria compared to untreated control. Specifically, the FBCU formulation showed more synergistic interactions and greater nematicidal activity than FB on RKN. Nevertheless, the potentiating effect was the most common interaction between furfural and biochar with FB formulations on RKN. Despite their nematicidal activity, the applied furfural–biochar-based formulations were favorable to tomato growth and free-living nematodes when containing furfural at rates <1.0 g kg^?1 soil. In SEM study, the cuticle surface of J ₂ incubated in FBCU extracts for 12 h lost its normal aspect showing crimped appearance with distorted anus. In conclusion, the FBCU combination could be a sound alternate method of RKN control as it may reduce the cost of individual application of its inner components and thereby increase the net profit of economic crops.     

Plantlet regeneration through somatic embryogenesis in Nordmann’s fir (<Emphasis Type="Italic">Abies nordmanniana</Emphasis>)

I studied the influence of various combinations of auxin and cytokinin concentrations, and the increased content of zinc and enzymatic casein hydrolizate in SH medium on initiation and proliferation of embryogenic callus of Abies nordmanniana (Steven) Spach. Additionally, the effect of ABA, PEG-4000 and different wavelengths on the maturation of somatic embryos was tested. The use of optimum composition of modified SH medium with BA, KIN and 2.4-D while simultaneously ensuring appropriate external conditions resulted in 15.5 % embryogenesis. Finally, satisfactory results of micropropagation of A. nordmanniana by somatic embryogenesis were obtained providing seven lines of embryogenic callus with high proliferation capacity. Those lines gave properly developed seedlings in white LED light with a wavelength of 400-700 nm, preceded by eight-week vernalization treatment of the callus. This paper may provide a protocol by which all stages of somatic embryogenesis of A. nordmanniana can be carried out, including the preceding 24-h seed disinfection with NaOCl and PVP, which resulted in 100 % frequency of uninfected zygotic embryos that were capable of starting embryogenesis.     

Does tree-ring formation follow leaf phenology in Pedunculate oak (<Emphasis Type="Italic">Quercus robur</Emphasis> L.)?

We monitored leaf phenology and xylogenesis of 12 Pedunculate oaks in northern Poland in 2014. We hypothesized that the individual trees, which differed in size, age and habitat (tree stand or gap), also diverged in terms of the seasonal patterns of leaf phenology and xylogenesis. The samples used for wood formation observations were collected most frequently during the early leaf phenophases (from March to end of June). The transverse sections of the cambial region were cut with a sledge microtome. We counted the number of cambial cells, measured the width of xylem increment and assessed the timing of xylogenesis and earlywood-vessel formation. We found significant differences in leaf phenology and timing of xylogenesis among individual trees. The smallest differences in wood formation among the trees were observed at the beginning of the vegetation season when the first earlywood vessels were detected (9 days). The dates of completion of the first tangential row of earlywood vessels varied by up to 30 days, while for the completion of the entire earlywood dates varied by up to 32 days. The highest productivity of cambial cells (13 cell layers) was observed around the time of bud swelling at mid-April. In the last days of April, the number of cambial cell layers decreased and subsequently increased again when the leaves were nearly fully expanded at the end of May. To summarize, we observed a high seasonal variability in the number of cambial cell layers. Differences in the time of cessation of cambial activity and xylogenesis amounted to 1 month. We conclude that: (1) oak tree-ring widths and earlywood-vessel sizes and numbers may not be sensitive indicators for early spring temperature and spring defoliation; (2) the missing association between leaf phenophases and xylogenesis as well as the phenological variability may be the reasons for the lack of a clear climatic effect on the above-mentioned parameters.