Maikäferbekämpfung

Ohne Zusammenfassung     

The effects of agricultural fields and human settlements on the use of rivers by wildlife in the mid-Zambezi valley,Zimbabwe

After the eradication of the Tse-Tse fly in the Mid-Zambezi valley, human settlements and fields extended mainly along the main rivers. In order to investigate the consequences of this human development on wildlife diversity we monitored three rivers of the Mid-Zambezi valley in Zimbabwe: Angwa, Manyame and Kadzi. The rivers were divided in segments of 200 m which were checked for spoors in order to assess the number of species and the number of individuals that used the segments. Human settlements were also recorded. We used a GIS to define the spatial characteristics of the fields present along the rivers, and related them to the distribution and abundance of wild species spoors in the river beds and banks. Our results show that the number of species in one segment of the river decreased with the increasing size of the field area bordering the segment. For all the major ungulate species, the numbers of individuals recorded per segment decreased with increasing field area. A similar trend was observed for small and medium-sized carnivores, though they were in lower numbers when present. Our analyses thus confirm that the extension of human agriculture in wildlife areas has an impact on most wild species, but we also define some threshold value of field size above which there seem to be an acceleration of the decrease in wildlife density and diversity: 3.2 ha for medium and small herbivores and carnivores; only the elephant seem to tolerate larger field area with a threshold value of 32 ha.This revised version was published online in May 2005 with corrections to the Cover Date.     

Combining endophytic fungi and bacteria for the biocontrol of Radopholus similis (Cobb) Thorne and for effects on plant growth

Eight endophytic fungal and bacterial isolates with antagonistic activity against Radopholus similis were evaluated in vivo for their individual and combined effects on biocontrol of R. similis and on the growth of “Grand Naine” cultivar banana plantlets in the greenhouse. Penetration efficiency (PE) of R. similis was between 3 and 21% in 29 biological agents (BAs) treatments, less than the 29% of the nematode-alone control (p ≤ 0.0001); 24 of the BAs treatments did not differ from the PE of 5% for a nematicide control. Twenty nine BAs treatments exhibited antagonistic activity against nematodes which reduced final population levels between 18 and 93%, relative to those on nematode-alone control plants (p ≤ 0.0001), and 14 BAs treatments were statistically similar to the nematicide treatment (88% reduction). Twenty four BAs treatments had increments of plant root biomass ranging from 20 to 58%, greater than the control plants; 37% of the treatments with single and combined BAs inoculations had root length increments ranging from 29 to 54% compared with control and chemical treatment. The nematicide, Terbufos 10GR, did not affect plant growth.     

Anwendung der Schädlingsbekämpfungsmittel im Pflanzenschutz

Zusammenfassung Aus den in einer Tabelle dargestellten Zusammenhängen zwischen Ausbringungsmenge und Tropfengröße bei der flüssigen Anwendung von Schädlingsbekämpfungsmitteln werden die Forderungen für ihre zweckmäßigste Anwendung abgeleitet. Die Verwendung von Flugzeugen erfordert für jeden Fall eine vorhergehende Überprüfung, um unerwünschte Nachteile zu vermeiden.     

Werden Ratten durch die Färbung von Giftpräparaten abgeschreckt?

Ohne Zusammenfassung     

Arbeitszahlen für die Schädlingsbekämpfung

Zusammenfassung Auf Grund umfangreichen Beobachtungen bei einer Anzahl verschiedener Schädlingsbekämpfungsarbeiten werden durchschnittliche Erfahrungswerte für Arbeitsleistungen mitgeteilt, die allgemeine Gültigkeit beanspruchen können.     

Response of mountain plovers to plague-driven dynamics of black-tailed prairie dog colonies

Sylvatic plague is a major factor influencing the dynamics of black-tailed prairie dog (Cynomys ludovicianus) colonies in the western Great Plains. We studied the nesting response of the mountain plover (Charadrius montanus), a grassland bird that nests on prairie dog colonies, to plague-driven dynamics of prairie dog colonies at three sites in the western Great Plains. First, we examined plover nest distribution on colonies that were previously affected by plague, but that had been recovering (expanding) for at least 6 years. Plovers consistently nested in both young (colonized in the past 1–2 years) and old (colonized for 6 or more years) portions of prairie dog colonies in proportion to their availability. Second, we examined changes in plover nest frequency at two sites following plague epizootics, and found that mountain plover nest numbers declined relatively rapidly (≤2 years) on plague-affected colonies. Taken together, our findings indicate that available plover nesting habitat associated with prairie dog colonies closely tracks the area actively occupied by prairie dogs each year. Given the presence of plague throughout most of the mountain plover’s breeding range in the western Great Plains, important factors affecting plover populations likely include landscape features that determine the scale of plague outbreaks, the distance that plovers move in response to changing breeding habitat conditions, and the availability and quality of alternate breeding habitat within the landscape.     

Veränderung des Scher- und Kompressionsverhaltens von Ap-Horizont-Material aus Löß-Parabraunerden durch Kalkung

Change of shear resistance and compressibility of Ap-horizon material from loess-derived Parabraunerde Standardized artificial bodies prepared from soil material of a loessderived parabraunerde-Ap-horizon were tested with respect to their shear resistance and compressibility. The noncalcareous material was enriched with lime (2 stepts), soil humidity changed (3 steps) and the normal pressure increased (4 steps). Liming generally caused an increased initial shear resistance and led to a lowering of compressibility. The effect of lime is interpreted as an result of flocculation of the clay particles at the points of contact between silt grains in the soil matrix. The problems of transferring those results to the field are discussed.