The nameless counterpart: a reconstruction of the experiences of private forestry extension officers with their clients

The changes to the forest ownership structure of small private forests in recent times have opened up an intensive field of research throughout Europe. Most of the studies completed to date adhere to the classic survey model and describe the behaviour and attitudes of forest owners. The research presented in this article analyses the changes to small private forests with the aid of data collected from focus groups comprised of forestry extension officers in Germany. Through the reconstruction of the experiences gleaned by the consultants, it was possible to describe the manner in which they characterise their clientele, and the changes they have observed, against the backdrop of changes occurring across rural areas. The consultants’ strategies for describing forest owners are presented. The orientation pattern presented by the extension officers is compared with the urban orientation of forest owners’ model developed by social scientists.     

Versuche über die Empfindlichkeit vonTrichogramma (Hymenoptera,Chalcidoidea) gegenüber Fungiziden

Zusammenfassung Die Wirkung von 12 im Obstbau gebräuchlichen Fungiziden in praxisüblichen Anwendungskonzentrationen aufTrichogramma-Imagines wurde in Laborversuchen geprüft.Alle berücksichtigten Mehltau-Bekämpfungsmittel, Binapacryl, Dinocap, Triamphos und Chinomethionat, erwiesen sich als mehr oder weniger toxisch, desgleichen die Schorf-Bekämpfungsmittel Mancozeb, Dichlofluanid, Metiram und TMTD. Für die Schorf-Bekämpfungsmittel Captan, Dithianon, Dodin und Zineb wurde unter den Versuchsbedingungen keine Giftwirkung nachgewiesen.Die Angaben der Literatur über die Wirkung der genannten Fungizide aufTrichogramma und andere Chalcidoidea werden diskutiert.

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Summary The effects uponTrichogramma adults of 12 fungicides which are commonly in use in orchards, in normal concentrations were examined by laboratory trials.The mildew fungicides, binapacryl, dinocap, triamphos, and oxythioquinox proved to be toxic as well as the apple scab fungicides mancozeb (= coordination product of zinc ion and [ethylenebis(dithiocarbamato)] manganese), dichlofluanid, metiram (= zinc-activated polyethylene thiuram disulfide), and thiram. Under the conditions of the experiments, there was no evidence of a toxic effect exerted by the apple scab fungicides captan, dithianon, dodine, and zineb.The available data from literature on the effects of the fungicides mentioned uponTrichogramma and other chalcidoids are discussed.

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Durchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.

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Dem Direktor des Instituts, Herrn Professor Dr. J. M. Franz, danke ich für sein reges Interesse an den Versuchen und die mir jederzeit gewährte Unterstützung.     

Homogeneous shear stress field of wood in an Arcan shear test configuration measured by means of electronic speckle pattern interferometry: description of the test setup

Wood Science and Technology - Several studies have dealt with the problem of how to measure the shear modulus of small clear wood specimens, avoiding bias from normal compression, bending, tension...     

Differential Activity of Carboxylic Acid Amide Fungicides Against Various Developmental Stages of Phytophthora infestans

ABSTRACT Three carboxylic acid amide (CAA) fungicides, mandipropamid (MPD), dimethomorph (DMM) and iprovalicarb (IPRO) were examined for their effects on various asexual developmental stages of Phytophthora infestans in vitro and in planta. Germination of cystospores and direct germination of sporangia were inhibited with nanomole concentrations of MPD (0.005 mug/ml) and micromole concentrations of DMM (0.05 mug/ml) or IPRO (0.5 mug/ml). A temporary exposure of 1 h to CAAs was not detrimental to germination and infectivity of sporangia or cystospores. CAAs applied to cystospores at 1 h after the onset of germination did not prevent the emergence of germ tubes, but inhibited their further growth and deformed their shape. None of the fungicides affected discharge of zoospores from sporangia or the encystment (cell wall formation/assembly) of the zoospores. Mycelium growth in solid or liquid media was inhibited with micromole concentrations. CAAs mixed with sporangia and drop inoculated onto detached leaves strongly suppressed infection. Curative application at 1 day postinoculation (dpi) required higher concentrations of CAAs than preventive application to inhibit infection and lost its effectiveness at 2 dpi. When sprayed on established late blight lesions 4 days after inoculation, CAAs reduced sporangial production in a dose-dependent manner. Trans-laminar protection of potato or tomato leaves, although achieved with higher doses, was more effective with MPD than with DMM or IPRO. Shade house studies demonstrated superior control of late blight epidemics by MPD compared with the other molecules. The data suggest that germ tube formation by cystospores or sporangia is the most sensitive stage in the life cycle of P. infestans to CAAs. Of the three CAAs, MPD had the highest intrinsic activity against spore germination. This property, together with its better trans-laminar activity, makes MPD more effective than DMM or IPRO in controlling epidemics caused by P. infestans.     

After nasopharyngeal infection,foot-and-mouth disease virus serotype A RNA is shed in bovine milk without associated mastitis

Foot-and-mouth disease (FMD) is a highly contagious aphthoviral infection of cloven-hoofed animals, inducing vesiculopustular stomatitis, pododermatitis, and thelitis. Vesicular fluid represents a major pathway of virus excretion, but bovine milk is another important source of virus shedding. We describe here the time course of FMD virus (FMDV) excretion in the milk and characterize associated lesions in the mammary gland. Three dairy cows were infected by nasopharyngeal instillation of FMDV and monitored over 12 d. Autopsy was performed at the end of the study, and specimens were collected for histopathology, IHC, and RT-qPCR. All 3 cows developed fever, drooling, vesiculopustular stomatitis, interdigital dermatitis, and thelitis. FMDV RNA was detectable in whole milk until the end of the trial, but only transiently in saliva, nasal secretions, and blood serum. Although histology confirmed vesiculopustular lesions in the oral and epidermal specimens, the mammary glands did not have unequivocal evidence of FMDV-induced inflammation. FMDV antigen was detectable in skin and oral mucosa, but not in the mammary gland, and FMDV RNA was detectable in 9 of 29 samples of squamous epithelia but only in 1 of 12 samples of mammary gland.     

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.     

Habitat structure and prey aggregation determine the functional response in a soil predator-prey interaction

Functional responses describe the per capita consumption rates of predators depending on prey density, which quantifies the energy transfer between trophic levels. We studied a typical interaction of the litter-soil systems between hunting spiders (Pardosa lugubris; Araneae: Lycosidae) and springtails (Heteromurus nitidus; Collembola: Entomobryidae) at varying habitat structure, i.e. with moss vs. without moss. We found a hyperbolic increase in consumption (functional response type II) in the treatment without habitat structure that was converted into a roller-coaster (or dome-shaped in a broad sense) functional response in treatments with habitat structure. Additional experiments suggest that the reduced per capita consumption rates at high prey densities may be explained by aggregative defence behaviour of the springtails. Experimentally, this behaviour was induced by the presence of habitat structure. We analyzed the net-energy gain of this predator-prey interaction by comparing the predator’s metabolic energy loss to its energy gain by consumption. In treatments with habitat structure, the net-energy gain of the predator was limited at intermediate prey densities where prey aggregation reduced the consumption rates. Our results stress the importance of habitat structure and prey behaviour in shaping the functional response in a typical soil-litter predator-prey interaction.