Control of the American dog tick,Dermacentor variabilis Say (Acarina: Ixodidae)

In a 4 ha area, of which 1/3 was meadow vole habitat, the old vole runways were spot treated in early spring with a 1% spray of flowable Sevin^® 4F (42% AI) on ca 4 m centers. New runways, as noted, were treated in June. The application averaged 60 ml of Sevin^® 4F/ha. The spring adult cohort ofDermacentor variabilis was <10% of that usually expected. These adults had been exposed to this treatment the previous year as spring larvae and summer nymphs. The reduction of the adult population occurred in a season of heavy infestation. This treatment is not labor intensive and requires only a minimum of pesticide because it is directed to its target, the attached immatures, by the behavior of the field mice. It should be noted that all the small rodent hosts of the immatures use the vole runways.     

Impact of local slope and aspect assessed from LiDAR records on tree diameter in radiata pine (Pinus radiata D. Don) plantations

Context

Reliable information on tree stem diameter variation at local spatial scales and on the factors controlling it could potentially lead to improved biomass estimation over pine plantations.

Aims

This study addressed the relationship between local topography and tree diameter at breast height (DBH) within two even-aged radiata pine plantation sites in New South Wales, Australia.

Methods

A total of 85 plots were established, and 1,302 trees were sampled from the two sites. Airborne light detection and ranging (LiDAR) was used to derive slope and aspect and to link them to each individual tree.

Results

The results showed a significant relationship between DBH and local topography factors. At both sites, trees on slopes below 20° and on southerly aspects displayed significantly larger DBHs than trees on steeper slopes and northerly aspects. Older trees with similar heights also exhibited a significant relationship between DBH and aspect factor, where greater DBHs were found on southerly aspects.

Conclusions

The observed correlation between tree DBH and LiDAR-derived slope and aspect could contribute to the development of improved biomass estimation approaches in pine plantations. These topographical variables are easily attained with airborne LiDAR, and they could potentially improve DBH predictions in resource inventories (e.g. stand volume or biomass) and support field sampling design.     

Evaluation of microbial and chemical insecticides for the control ofSpodoptera exigua (Lep., Noctuidae) on soybean plants

Field experiments have been carried out to evaluate the potency of the biological control agentBacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafwormSpodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts ofS. exigua, associated with a significant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemical insecticides at the lowest tested doses (62 g ofB. t. +50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control ofS. exigua.     

Population fluctuations on parasites ofLepidosaphes beckii Newm. andCeroplastes floridensis Comst.

Lepidosaphes beckii Newm. (Hom., Diaspididae) andCeroplastes floridensis Comst. (Hom., Coccidae), are dominant pests on citrus trees (Citrus sinensis), in Alexandria district. The population fluctuations of the parasites of both insects were studied during a whole year. Six species of hymenopterous primary parasites together with one secondary parasite were found onL. beckii. These species wereAphytis lepidosaphes Compere,A. bispanicus Compere,Encarsia (Prospaltella) spp.,Aspidiotiphagus citrinus Craw,Aphytis lingnanensis Compere, and the secondary parasiteMarietta javensis Howard.A. lepidosaphes was the most common parasite onL. beckii. ConcerningC. floridensis, four species of hymenopterous parasites were found, namelyTetrastichus ceroplastae (Girault),Aspidiotiphagus citrinus Craw,Metophycus flavus (Howard), andMicroterys flavus (Howard).     

Impact of temperature and nutrition on the toxicity of the insecticide λ-cyhalothrin in full-lifecycle tests with the target mosquito species Aedes albopictus and Culex pipiens

The global spread of the Asian tiger mosquito Aedes albopictus, an urban pest as well as a vector for arboviruses, is a threat for public health. As control measures include the use of insecticides such as the pyrethroid λ-cyhalothrin, it is crucial to assess their efficiency and their potential impact on the biodiversity especially under climate change conditions. To evaluate the environmental risk, biotests are well established for non-target organisms but not yet for mosquitoes. We therefore developed a full-lifecycle biotest for mosquitoes kept under quarantine conditions based on the OECD guideline 219. Therewith we tested the effect of temperature and nutrition on the ecotoxicological response to λ-cyhalothrin on the mosquitoes Ae. albopictus and Culex pipiens by assessing sublethal and life history parameters. The efficiency of λ-cyhalothrin decreased in both mosquito species with increasing temperature and changed with feeding protocol. At effective concentrations for potential mosquito control in surface waters, λ-cyhalothrin poses a high risk for indigenous aquatic key role species inhabiting the same microhabitats. Those aspects should to be taken into account in vector control strategies.     

Caribbean pine in an agroforestry system on the Atherton Tableland in north east Australia

A trial demonstrating an establishment and maintenance technique forPinus caribaea var hondurensis in an agroforestry land use system on the Atherton Tableland, north east Australia, is described. The establishment of the tree component involves mechanical cultivation and the application of herbicides which in combination are technically feasible and acceptable to a landholder who wishes to integrate pine trees and pasture grasses. The cost of establishment and maintenance of the pines up to age 39 months was calculated at $A809 ha^?1 (1986 values). This includes the cost of thinning. The sale of some thinnings for Christmas trees realised a net profit of $A564 from 300 trees ($A188 ha^?1). At age 38 months the stand had a stocking of 254 trees ha^?1, a mean height of 6 m and a mean diameter at breast height of 12.1 cm. The growth compares favourably with other plantation grownPinus caribaea var hondurensis on the Atherton Tableland.     

Near-infrared spectroscopy and wavelength selection for estimating basic density in Mimosa tenuiflora [Willd.] Poiret wood

The aim of the present work was to estimate the basic wood density of Mimosa tenuiflora by using near-infrared spectroscopy (NIRS). Fifty-eight wood samples representing sapwood, heartwood and pith were evaluated by gravimetric method and NIRS together with wavelength selection methods. A comparison was made among several multivariate calibration techniques and algorithms for preprocessing and variable selection of data, including full-spectrum partial least squares (PLS), interval PLS, backward interval PLS, synergy interval PLS, genetic algorithm-PLS and successive projections algorithm for interval partial least squares (iSPA–PLS). Finally, the results obtained using iSPA–PLS model for the root mean square error of calibration and prediction were 0.0383 and 0.0166 g/cm³, respectively. A t-test was performed to compare the results of the models with each other and with a reference method. NIRS and iSPA–PLS can be used to predict basic density of Mimosa tenuiflora [Willd.] Poiret wood samples rapidly. In addition, the basic density could also be predicted with only 17 wavelengths in the range from 2,090 to 2,208 nm that should allow for measurement of this parameter using handheld NIR spectrometer.     

Grazing affects shoot growth,nutrient and water status of Quercus ilex L. in Mediterranean open woodlands

Context

Mediterranean open woodlands (dehesa) have faced a dual process of intensification and abandonment of grazing which has resulted in alteration of the understory vegetation.

Aims

We analysed the effects of land use changes on the physiological status of holm oak in different open woodlands (dehesa) in southern Iberian Peninsula.

Methods

In an area of extensive grazing, we selected six paired plots (one grazed, one abandoned) and grouped them by habitat types according to understory composition (nearly all monospecific Cistus ladanifer L. shrub or mixed shrub). Six plots of moderate and heavy grazing intensity were chosen within a settled area of livestock use. Shoot growth, macronutrient concentrations and water content were assessed in samples of holm oak leaves.

Results

Abandonment of grazing affected some nutrient concentrations and water content of holm oak leaves, but the effects were different according to habitat type. C. ladanifer shrub reduced N and P concentrations and water content while mixed shrub increased P concentration and water content. High grazing intensity improved shoot growth and leaf N and Mg concentrations.

Conclusion

Extensive grazing could be a useful management tool to enhance growth, nutritional and water status of holm oak in a habitat with limited resources such as Mediterranean open woodlands (dehesa).     

The impact of the environmental factors on the photosynthetic activity of common pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis>) in spring and in autumn in the region of Eastern Siberia

The taiga coniferous forests of the Siberian region are the main carbon sinks in the forest ecosystems. Quantitatively, the size of the carbon accumulation is determined by the photosynthetic productivity, which is strongly influenced by environmental factors. As a result, an assessment of the relationship between environmental factors and photosynthetic productivity makes it possible to calculate and even predict carbon sinks in coniferous forests at the regional level. However, at various stages of the vegetative period, the force of the connection between environmental conditions and the productivity of photosynthesis may change. In this research, correlations between the photosynthetic activity of Scots pine (Pinus sylvestris L.) with the environmental conditions were compared in spring and in autumn. In spring, close positive correlation of the maximum daily net photosynthesis was identified with only one environmental factor. For different years, correlations were for soil temperature (r_s = 0.655, p = 0.00315) or available soil water supply (r_s = 0.892, p = 0.0068). In autumn within different years, significant correlation was shown with two (temperature of air and soil; r_s = 0.789 and 0.896, p = 0.00045 and 0.000006, respectively) and four factors: temperature of air (r_s = 0.749, p = 0.00129) and soil (r_s = 0.84, p = 0.00000), available soil water supply (r_s = 0.846, p = 0.00013) and irradiance (r_s = 0.826, p = 0.000001). Photosynthetic activity has a weaker connection with changes in environmental factors in the spring, as compared to autumn. This is explained by the multidirectional influence of environmental conditions on photosynthesis in this period and by the necessity of earlier photosynthesis onset, despite the unfavorable conditions. This data may be useful for predicting the flow of carbon in dependence on environmental factors in this region in spring and in autumn.     

Colour and chemical changes on photodegraded beech wood with or without red heartwood

The focus of this study was to investigate the chemical and colour changes occurring at different exposure times on artificially photo-irradiated surfaces of normal and red heartwood in beech in order to understand the mechanisms that cause the changes and to evaluate the possibility of usages of beech not only for energy production purposes. In this sense, surface colour modifications are of crucial importance to define the commercial value of beech wood. The artificial photo-irradiation of the wood samples was performed in a Solar Box, equipped with an ultraviolet filter that cuts off the spectrum at 280 nm. Reflectance spectrophotometry and Fourier transform infrared (FTIR) spectroscopy were used to assess artificial sunlight influence. The experimental data were statistically treated to evaluate their significance. Colour monitoring revealed that wood surface colour undergoes an important variation due to photo-irradiation, occurring within the first 24–48 h. Moreover, it was found that the chromatic coordinates (L*a*b*) in normal wood and in red heartwood tended to similar values after 504 h. FTIR spectroscopy allowed for investigating the rate of photodegradation of wood surface due to oxidation reactions of wood components. The results were validated by statistical analysis applied both to the colorimetric and spectroscopic data.     

A review of research on the nun moth (Lymantria monacha L.) conducted with pheromone traps in Czechoslovakia, 1973–1984

A review of research on the nun moth (Lymantria monacha L.) 1973–1984 in Czechoslovakia conducted with pheromone traps is given. By using this method many new results on bionomy, ecology and gradology of this pest could be obtained.     

The decomposition of the leaf mulches ofLeucaena leucocephala Gliricidia sepium andFlemingia macrophylla under humid tropical conditions

The decomposition of the leaf mulches ofLeucaena leecocephala, Gliricidia sepium andFlemingia macrophylla has been studied under field conditions. Mulch samples were analysed over a period of 70 days on carbon, nitrogen, phosphorus,potassium, calcium and magnesium left. Loss rates for the elements show similar patterns for the three mulches. Losses of mulch material are caused by decomposition as well as removal by soil-dwelling fauna (insects, arthropods, etc.) feeding on the mulch. Based on the data decomposition-and nutrient release functions are developed for the three mulches. These functions are useful in alley-cropping system analysis and models.

Tree–grass interactions for N in Nothofagus antarctica silvopastoral systems: evidence of facilitation from trees to underneath grasses

Nothofagus antarctica forests in south Patagonia are usually used as silvopastoral systems but how grasses and trees compete for specific resources, such as nitrogen in these systems is unknown. To understand interactions between grasses and N. antarctica trees for N, an experiment with ¹⁵N labeled fertilizer was carried out comparing N absorption by grasses growing under trees (silvopastoral system) with an open site. Labeled ¹⁵NH ₄ ¹⁵ NO₃ fertilizer at 10 % atom excess was added in spring at both sites and ¹⁵N was measured in herbage, soil and trees every 30 days during the growing season. Soil was the component that containing the greatest amount of N and greatest ¹⁵N recovery. Grasses growing in the silvopastoral system absorbed almost double of the fertilizer applied than grasses in the open site (32.4 kg N ha^?1derived from fertilizer based on ¹⁵N recovery). Roots were also an important fate for N absorbed, representing 50 and 63 % of total ¹⁵N recovered in grass roots of open and silvopastoral sites, respectively. Trees absorbed 69 % less applied N than grasses in the silvopastoral system; being mainly allocated in small branches, sapwood and fine roots. Overall, ¹⁵N recovery was 65 % higher in the silvopastoral system (tree + grasses) than in the open site (grasses). Silvopastoral system made more efficient use of the ¹⁵N added. These results indicated that N. antarctica trees in the silvopastoral system may “facilitate” fertilizer N absorption of grasses by improving environmental conditions like water availability or by reducing competition for inorganic N between soil microorganisms and plants.     

Light intensity affects the growth and flavonol biosynthesis of Ginkgo (Ginkgo biloba L.)

Response of growth and secondary metabolites to light intensity are useful measurements to determine suitable silviculture treatments for the cultivation of medicinal plants. Here, we analyzed the growth, flavonols (total flavonol, quercetin, kaempferol, and isorhamnetin) content, flavonols yield per plant, and expression of flavonoid biosynthesis-related genes in 2-year Ginkgo (Ginkgo biloba L.) seedlings at four different light intensities (100, 76, 40, and 25 % of full sunlight) in a greenhouse setting. Across all light intensities, the 76 % sunlight treatment produced the highest growth of total biomass, root, stem, and leaf, indicating negative effects of either fulllight or heavy shading on Ginkgo seedling development. Both flavonols (total flavonol, quercetin, kaempferol, and isorhamnetin) content and expression of flavonoid biosynthesis-related genes [PAL (Phenylalanine ammonia-lyase), CHS (Chalcone synthase), F3H (Flavanone 3-hydroxylase), and FLS (Flavonol synthase)] in leaves were highest under 100 % sunlight, suggesting that full sunlight promotes the expression of flavonoid biosynthesis-related genes and increases flavonoid biosynthesis. The highest and lowest flavonol contents were found in leaves and stems, respectively. The 76 % sunlight treatment produced the highest flavonols yield while the 100 % sunlight produced the highest flavonoids content in leaves, indicating that flavonol production per unit land area depends not only flavonol content but also biomass. Overall, in order to achieve the highest flavonols yield per area in Ginkgo leaf-harvesting plantations, it is important to manipulate light conditions of field.     

Elevated atmospheric CO2 and humidity delay leaf fall in Betula pendula,but not in Alnus glutinosa or Populus tremula × tremuloides

Context

Anthropogenic activity has increased the level of atmospheric CO₂, which is driving an increase of global temperatures and associated changes in precipitation patterns. At Northern latitudes, one of the likely consequences of global warming is increased precipitation and air humidity.

Aims

In this work, the effects of both elevated atmospheric CO₂ and increased air humidity on trees commonly growing in northern European forests were assessed.

Methods

The work was carried out under field conditions by using Free Air Carbon dioxide Enrichment (FACE) and Free Air Humidity Manipulation (FAHM) systems. Leaf litter fall was measured over 4 years (FACE) or 5 years (FAHM) to determine the effects of FACE and FAHM on leaf phenology.

Results

Increasing air humidity delayed leaf litter fall in Betula pendula, but not in Populus tremula?×?tremuloides. Similarly, under elevated atmospheric CO₂, leaf litter fall was delayed in B. pendula, but not in Alnus glutinosa. Increased CO₂ appeared to interact with periods of low precipitation in summer and high ozone levels during these periods to effect leaf fall.

Conclusions

This work shows that increased CO₂ and humidity delay leaf fall, but this effect is species-specific.     

Forecasting of outbreaks ofSpodoptera exempta Wik. (Lep., Noctuidae) based on sex-pheromone trapping in the republic of Yemen

Spodoptera exempta (Wlk.) is recorded every year in the Republic of Yemen. Based on the use of pheromone traps, a very simple but effectively applicable monitoring and forecasting system was developed. Areas from which infestations have been reported and the frequency of attacks are mapped in detail. The monthly distributions and frequencies of incidence are presented in two tables. The range of recordedS. exempta moths is illustrated and the number of outbreaks for the last 32 years described.     

Ectomycorrhizal communities associated with silver fir seedlings (Abies alba Mill.) differ largely in mature silver fir stands and in Scots pine forecrops

Context

The requirement for rebuilding forecrop stands besides replacement of meadow vegetation with forest plants and formation of soil humus is the presence of a compatible ectomycorrhizal (ECM) fungal community.

Aims

This study aims to assess ectomycorrhizal fungi diversity associated with silver fir (Abies alba Mill.) seedlings regenerating in silver fir stands and Scots pine forecrops.

Methods

One-year-old seedlings were sampled in six study sites: three mature fir forests and three pine forests. ECM fungi were identified by polymerase chain reaction amplification and sequencing of the internal transcribed spacer of rDNA.

Results

The mean mycorrhizal colonization exceeded 90 %. Thirty-six ectomycorrhizal taxa were identified in fir stands and 23 in pine forecrops; ten out of these species were common to both stands. The fungal communities were different between study sites (R?=?0.1721, p?=?0.0001). Tomentella stuposa was the only species present at all sites.

Conclusion

Silver fir seedlings in Scots pine forecrops supported smaller ECM fungal communities than communities identified in mature silver fir stands. Nevertheless, fungal colonization of seedling roots was similar in both cases. This suggests that pine stands afforested on formerly arable land bear enough ECM species to allow survival and growth of silver fir seedlings.     

Tropical forest sheep on legume forage/fuelwood fallows

In Amazonian Ecuador, studies are being realized to intensify fallow periods by grazing African tropical forest type sheep (Red Afro-Colombian X Barbados Black Belly) on Asian tropical forest legume cover forage (Desmodium ovalifolium) under American tropical forest legume fuelwood trees (Inga edulis). The specific approach represents an innovative effort to address the complex problems associated with the pernicious use of less fertile lands by small-scale farmers and graziers in the humid tropics. The technologies developed are closely compatible with traditional socio-cultural patterns. For example, shifting cultivators are encouraged to plant contour strips of legume fuelwood trees in their cassava fields. With the cassava harvest, legume cover forage is planted between the fuelwood trees, to be grazed later by tropical forest sheep. Forage and fuelwood legumes increase soil aeration, organic matter, nitrogen and available phosphorus, control soil erosion and leaching, as well as provide a break in cropping that checks insect, disease and weed build-ups. Tropical forest sheep improve soil fertility by depositing organic matter which stimulates legume/Rhizobium symbiosis and by supplying fecal microorganisms which mineralize crop residues. In addition, tropical forest sheep cause little soil compaction and erosion, produce high quality food protein from legume cover forage, as well as generate cash income, capital and employment for small-scale farmers. Tropical forest sheep on legume forage/fuelwood fallows not only intensify land use under shifting field cultivation, but also form the basis for rehabilitating already degraded lands for further foodcrop production.     

Circumferential variation of heartwood and stem quality in maritime pine stems

Maritime pine (Pinus pinaster Ait.) is an important timber and pulpwood species covering about 4 million ha in Portugal, Spain and France. This work studied the cross-sectional distribution of heartwood and sapwood along the stem using 3D modelling on 20 trees. The target was to assess the potential of this species for the industrial production of heartwood sawn products. The maritime pine stems were characterized by wide sapwood of 10 cm, in average, and the presence of heartwood at all height levels with constant diameter up to 35 % tree height, decreasing afterwards. In the radial section, the heartwood follows a circumferential-like shape which changes along the stem. Pith eccentricity index values were low and homogeneous regarding to stem and higher for heartwood. Heartwood cross-sectional shape was constant up to 45 % of total height of the tree and more elongated upwards. The constant heartwood diameter, low taper and pith eccentricity index, and an approximate circular shape up to 10 m height indicated these species’ potential to produce solid wood products made out of heartwood.