Field Monitoring and Efficacy of Entomopathogenic Nematodes Against Chamomile Stem Weevil Microplontus rugulosus and Chamomile Smooth Beetle Olibrus aeneus Under Greenhouse Conditions

Chamomile Matricaria recutita (L.) is an ancient healing plant; it is used for a sore stomach, a mild laxative, anti-inflammatory and a gentle sleep aid. Chamomile plants are infested by chamomile stem-weevil Microplontus rugulosus (Col., Curculionidae) and chamomile smooth beetle Olibrus aeneus (Col., Phalacridae), and can lead to a high reduction in chamomile yield. This work aimed to survey M. rugulosus and O. aeneus by different monitoring methods as well as to manage them by using entomopathogenic nematodes.     

Jasmonic acid induces resistance to economically important insect pests in winter wheat

BACKGROUND: Insect damage induces chemical changes in plants, and frequently these changes are part of a defensive response to the insect injury. Induced resistance was activated in winter wheat using a foliar application of synthetic jasmonic acid. Field trials were conducted to observe effects of jasmonic acid application on some wheat insects. Two wheat cultivars (Cubus and Tommi) were sprayed twice at growth stages (GS) 41 and 59 with two concentrations of jasmonic acid, along with control plots that were sprayed with water. RESULTS: There was a significant difference in the number of thrips and wheat blossom midges (WBM) among treatments in both cultivars. Plants in control plots had higher numbers of thrips and midges than in treated plots. There were higher numbers of thrips in the Tommi cultivar than in the Cubus cultivar, while the latter had higher numbers of WBM larvae than the Tommi cultivar. There was a positive correlation between WBM numbers and infested kernels in both cultivars. This study also indicated that jasmonic acid enhances the wheat yield in sprayed plots compared with control plots. CONCLUSIONS: The results indicate that jasmonic acid induced pest resistance in wheat plants and may act as a resistance mechanism of wheat against insect herbivores. Copyright © 2010 Society of Chemical Industry     

Dynamics of mineral components in the forest floor of an acidic beech (Fagus sylvatica L.) forest

Seasonal changes of the mineral components Na, K, Mg, Ca, Mn, Fe, Al, Si and ash were investigated in the L1 horizon of an acidic beech (Fagus sylvatica L.) forest using litterbags (1 mm and 45 μm mesh-size) buried for up to 467 days in the forest floor. The element dynamics in this surface horizon were compared with the concentration and the total amount stored in a complete sequence of horizons (L1, L2, F1, F2 and H) taken from a moder profile in the Solling area. In the 1 mm litterbags with free access of the mesofauna, the concentrations of all cations were increased in comparison to the 45 μm treatment. This increase was highly significant, especially with regard to Fe and Al. The concentrations of these two cations were closely related to Si during the decomposition of fresh leaf litter in the L1 horizon. Si is the dominant element of ash in the litterbags and down the profile. The total amounts stored in the forest floor revealed that the Fe and Al input considerably exceeded the input by litter fall, and dry and wet deposition due to incorporation of mineral soil material. The input of soil material was also indicated by a decrease in the molar Si/Al ratio from 17 to 6 and in the relation of nutrient cations to ash from 30% to 2.5%.     

Earthworm effects on the use of C sources by microorganisms: Non-linear response to temperature alteration

A microcosm was used to study the effect of the endogeic earthworm Aporrectodea caliginosa (Savigny) on the use of C by microorganisms in a calcareous beech forest soil and its dependence on temperature (5–25%C). Inclusion of ¹⁴C-labelled beech leaf litter made it possible to differentiate between C use by litter-colonizing microflora and by autochthonous soil microflora. The effect of temperature on the soil microbial biomass ¹²C was confined to a significant increase at 15 and 20°C. The size of the ¹⁴C-labelled microbial biomass, in contrast, was positively correlated with temperature. The ¹²C mineralization increased exponentially with temperature. The relationship between ¹⁴C mineralization and temperature, in contrast, followed a logistic curve. Significant main effects of A. caliginosa were confined to ¹²C mineralization, reflecting an increase in ¹²CO₂–C production in the earthworm treatments. The earthworm effects on ¹²CO₂–C production and on ¹⁴C incorporation of the microflora were not linear. The effect of A. caliginosa on ¹²CO₂–C production was most pronouned at intermediate temperatures. It is concluded that temperature alterations affect the microbial use of different C sources in different ways and that the temperature effects can be significantly modified by endogeic earthworms.     

Modulation of cell adhesion and motility in the immune system by Myo1f

Although class I myosins are known to play a wide range of roles, the physiological function of long-tailed class I myosins in vertebrates remains elusive. We demonstrated that one of these proteins, Myo1f, is expressed predominantly in the mammalian immune system. Cells from Myo1f-deficient mice exhibited abnormally increased adhesion and reduced motility, resulting from augmented exocytosis of beta2 integrin-containing granules. Also, the cortical actin that co-localizes with Myo1f was reduced in Myo1f-deficient cells. In vivo, Myo1f-deficient mice showed increased susceptibility to infection by Listeria monocytogenes and an impaired neutrophil response. Thus, Myo1f directs immune cell motility and innate host defense against infection.     

Biodiversity of soil animals and its function

Current knowledge suggests a high redundancy of soil organism communities, i.e. saturation of function at low levels of species richness. This does not imply, however, that research on soil organism biodiversity and its function is irrelevant. First, it is well established that several species of the decomposer community are functionally more important than others. The ‘step’ hypothesis developed in this paper shows that under these conditions random loss of species is much more likely to impact ecosystem processes than expected from the redundancy hypothesis. Second, redundant species may gain functional significance by interacting with functionally important species. Third, the number of ‘important species’ is increased by the multiplicity of functions carried out by soil biota. And finally, alteration in species composition will not be a random process. In fact, functionally important soil biota might be among the first to be affected by large-scale changes in land use. Even if we were to accept that conservation efforts should be confined to the functionally most important species, we would have no idea how to do so. Crossing the ‘spatial barrier’ seems to be the biggest challenge for future investigations on soil biodiversity, because traditional approaches of community ecology will not be sufficient to answer the questions originating from large-scale impoverishment of the soil fauna. Some examples of promising macroecological topics are discussed: (i) the impact of the regional species pool on local species richness, (ii) the relationship between α- and γ-diversity, and (iii) abundance-occupancy relationships. It is argued that research in this direction will be essential for answering the question of how populations and communities must be organised to resist alterations of the soil habitat at the landscape-level.     

Limitations of faunal effects on soil carbon flow: density dependence, biotic regulation and mutual inhibition

Soil animals are known to stimulate soil microbial activity and thereby to accelerate decomposition of soil organic matter. In this paper, we investigate potential limitations of soil animal effects on soil carbon flow by analysing how animal effects relate to the density of four major faunal groups. Specifically, we analyse the extent to which faunal effects are subject to biotic regulation or to mutual inhibition between groups under different levels of resource supply.In an extensive laboratory experiment, 96 microcosms established in three consecutive blocks were inoculated with nematodes, enchytraeids, microarthropods, and lumbricids. Each faunal group was inoculated in three densities, including combinations of groups. Introduced animal densities were within the natural range of densities in fallow soil. Bare agricultural soil and soil covered with maize litter were used as substrates. The microcosms were kept under constant conditions at 12 °C and 50% water holding capacity for 8 weeks. Soil CO₂ evolution was measured daily by means of gas chromatography.Animal effects were on an average relatively stronger in bare soil (+95% CO₂; R²=0.76) than in soil with litter (+14% CO₂; R²=0.40), where organic matter decomposition was seven times more intense. Higher animal densities generally led to accelerated decomposition up to three times that of the controls. However, beyond a specific density, decomposition rates stopped increasing or even declined, depending on the faunal group. In addition, animal effects were limited by mutual inhibition between groups in bare soil where effects were strong, while stimulatory interactions were prominent in the litter treatments where effects were generally weak.We interpret the limitation of soil faunal effects on soil carbon flow in terms of incomplete habitat exploitation and biotic regulation. Under conditions of substrate homogeneity, such as in the bare soil treatments, animal effects were stronger, but they were limited by overexploitation. Under conditions of substrate heterogeneity, such as in the litter treatments, animal effects were limited by incomplete habitat utilisation. We assume that complementary habitat colonisation by different faunal groups in the litter treatments gave rise to positive diversity effects, but that these effects did not compensate for reduced overall habitat utilisation. We infer that a knowledge of faunal resource utilisation and of mutual inhibition of faunal groups can be exploited for ecological soil management towards stabilisation of soil organic matter.     

Susceptibility of winter wheat cultivars to wheat ear insects in Central Germany

The intensity of thrips and wheat blossom midges (WBM) infestations in twelve wheat cultivars was evaluated at the Plant Breeding Station, Silstedt, central Germany in 2008 & 2009 growing crop seasons. The research aimed at selecting the least infested cultivar to be profitably used in the forthcoming cultivation. Infestation levels were studied in flowering and milky stages (GS 65 and 73) of each cultivar in every single-spikelet in sample of 10 ears in both years. There were significant differences in thrips and (WBM) densities among different cultivars in both years. Thrips numbers were the highest in T??rkis, Global and Esket cultivars, while the lowest values were recorded in Robigus, Brompton and Carenius. The results showed that the highest WBM infestation was observed in T??rkis, Tommi and Potenzial; on the other hand the lowest WBM infestation was found in some insect resistant cultivars (Brompton, Skalmeje, Robigus, Welford and Glasgow). The infested ears were positively correlated with the numbers of WBM among cultivars. The obtained results would give a good guide for choosing the proper cultivars which proved highly resistant to their specific pests.     

Susceptibility of spring wheat to infestation with wheat blossom midges and thrips

Journal of Plant Diseases and Protection - Susceptibility of spring wheat to infestation with wheat blossom midges (WBM) and thrips was studied in Central Germany in the two seasons, 2008 and 2009....     

Nematoda response to forest conversion

This study investigates the response of the Nematoda community to forest conversion from pure coniferous stands into semi-natural montane forests in the southern Black Forest (Germany). The investigation was carried out by comparing existing stands that represent the four major stages of the envisaged conversion process. Major results are: (i) the number of Nematoda genera was highest at the species enrichment stage pointing to a positive influence of a rich ground vegetation on the diversity of Nematoda, (ii) predaceous species reached a particularly high, and omnivorous species having a particularly low, density at the species enrichment stage, and (iii) root-hair feeding Nematoda profited from qualitative changes of fine roots during the conversion process and gradually increased in abundance from the even-aged pure spruce stands to the diverse continuous cover forests. Altogether the comprehensive investigation of the Nematoda of the four conversion stages indicates that forest conversion only weakly alters the structure of the Nematoda community. Neither an overall change nor a clear trend in Nematoda richness and abundance could be established. However, due to the specific responses of the different Nematoda feeding groups to the conditions of the individual conversion stages it seems to be ecological useful to maintain special qualities of each conversion stage (e.g. forest gaps in the species enrichment stage) during forest conversion protecting the structure and diversity of the Nematoda communities.