Agromyza nigrociliata Hendel als Getreideschädling (Dipt.)

Ohne Zusammenfassungmit 3 Text-Abbildungen     

Virusnachweis in Blattläusen

Potato virus Y (PVY) causes great economic losses in potato production world-wide. Concerning important it has replaced Potato leafroll virus (PLRV). Virus is transmitted by different aphid species in a non-persistent manner. During last years the developing of new effective methods for PVY monitoring, forecasting and detection in aphids is of increasing interest. Sensitive, rapid detection of virus in its natural vectors is of a great need to investigate the relationship between aphid migration and the spread of PVY. Simple diagnostic protocol for the detection of non-persistent Plum pox virus and semipersistent Citrus tristeza virus in aphids, proposed by Olmos et al. (2005) was probed to validate and estimate the efficiency of its applying for the detection of PVY in different aphid species too.     

Einfluss der biologischen Bewirtschaftung auf die Phytodiversität in der Diasporenbank und oberirdischen Vegetation biologisch bewirtschafteter Ackerflächen

The project deals with the evaluation whether the conversion to organic farming leads to an increase of weed diversity. Additionally to the analysis of the above ground vegetation and the soil seedbank on the small permanent plots a mapping of the surrounding vegetation was conducted in 2012. The number of weed species varies highly over the years, but the inventory of species differs only slightly from the one found on the surrounding fields. The number of seeds per m² is highly correlated with the number of above ground weeds species. The crop has shown the highest influence on both.     

Bodenfauna als Ökologischer Dienstleister – Collembolen und Nematoden fördern den Abbau von Deoxynivalenol in Fusarium-infiziertem Weizenstroh

A minicontainer-study under laboratory conditions was conducted with the following fungivorous members of soil fauna: Aphelenchoides saprophilus, Nematoda and Folsomia candida, Collembola. The objective was to investigate, if the introduced soil fauna is able to reduce the concentration of Fusarium-biomass and the mycotoxin deoxynivalenol (DON) in wheat straw. Furthermore, the study aimed wether the degradation efficiency is affected by different soil texture (sandy loam, silt loam, clay loam). Therefore, minicontainer were filled with soil and wheat straw. Soil fauna was introduced in different combination into the minicontainer (single collembolan, single nematode, faunal interaction and a non-faunal treatment). The minicontainer were divided into 2 sets: one set received artificially Fusarium-infected and DON-contaminated wheat straw, the second set received non-infected straw. After 2 and 4 weeks, soil and straw were sampled for analysing Fusarium-biomass and DON content by using ELISA-technique. After 4 weeks Fusarium-biomass was reduced notably and DON-concentration was degraded significantly throughout all treatments. The highest reduction of DON-concentration was found in the faunal interaction treatment. The DON-concentration in the sandy- and silt loam treatments were reduced more efficiently compared to the clay loam treatment. We conclude that nematodes and collembolans contribute to the degradation of Fusarium-biomass and the mycotoxin DON in wheat straw as ecosystem services.     

Untersuchungen zum gezielten Einsatz von Insektiziden gegen den Rapsglanzkäfer (<Emphasis Type="Italic">Meligethes aeneus</Emphasis>) in der landwirtschaftlichen Praxis des Landes Brandenburg im Zeitraum von 2006 bis 2014

Before 2006, agents of class II pyrethroids were used to control rape pests including the rape pollen beetle mainly. Thus, the selection of pyrethroids-resistant pollen beetle populations was encouraged. The aim of our study was to identify ways to combat these populations. Therefore, data of 465 real on-farm insecticide applications from nine years since 2006 were analyzed with regard to their effects on the pollen beetle and own experiments were carried out to test the efficacy of approved insecticides and control strategies. The analysis showed that the highest efficiencies were obtained with agents of the group of organophosphates and with the active substances indoxacarb and pymetrozine. Beyond that, the data examined revealed that the efficiency of thiacloprid (an insecticide of the class of neonicotinoids) has remained relatively constant throughout the observation period. In contrast, the increase in pyrethroid-resistant pollen beetle populations reflects the further decrease in efficacy of class II pyrethroids in the period 2011–2014.In summary, it should be noted that currently available insecticides achieve a maximal abatement level of 80–85?%. Therefore, an economic damage cannot be prevented on rapeseed locations with a very strong pollen beetle infestation even if multiple use of insecticides happens.To prevent further escalation of the resistance problem, another aspect should be given greater attention in the future. 55?% of the insecticide applications in the practice dataset where carried out before the control threshold (BRW) for weakly developed oilseed rape crops was achieved; often in the stage of micro-bud (BBCH 51). In compliance with the currently suggested higher control threshold, only 15?% of the insecticide applications would have been necessary. Thus, a reduction of the number of insecticide applications could be achieved by considering the higher thresholds. This would significantly reduce the selection pressure. Therefore, plant protection advice should mediate between exploiting the control thresholds and using the most appropriate insecticide.     

Alternative Bekämpfungsstrategien gegen die Kleine Weiße Rosenschildlaus Aulacaspis rosae (Bouché) (Hemiptera: Diaspididae) an Schnittrosen unter Glas mittels dem Einsatz von Leinöl

The rose scale Aulacaspis rosae has proven to be extremely difficult to control. For some years Hamburg flower producers have reported an increase in infestations in greenhouse grown rose crops. So far no pest management program, including natural, mechanical and chemical methods, have provided effective control. The rose scale feeds on parenchyma plant sap and is mainly found on the woody parts of roses. Under greenhouse conditions several generations may appear in a single year. Contact insecticides do not penetrate the protective covering of the scale insects and are most effective when applied on young larvae stages which are not protected by the shield-like cover yet. However due to long hatching periods the occurance of larvae overlaps with the hatching of the following generation. The outcome of this is a continuous presence of newly emerged larvae on the plants. Resulting in that pesticides need to be frequently applied which is both time consuming and impractical for the gardeners. Another problem is the limited coverage of the infested plant parts when pesticides get sprayed. The scale insects are well protected by both the leafage of the roses and also they tend to crowd together and stack in layers making it harder for contact pesticides to be effective. Systemic insecticides may be effective only on those scales infesting the leaves or those that are actively producing honeydew and showed no sufficient efficacy in practical usage against the rose scale. By searching for an adequate pest management method, linseed oil was tested as an alternative application agent. Linseed oil is a drying oil and polymerizes into a solid form by reacting with oxygen in air. Treatments on permanent rose crops infested by rose scales could decrease the occurance of larvae in a knock-down effect. Newly emerged larvae could be kept sustainably on a low infestation level. The results are showing a promising pest control with good efficacy.     

Rückgang von Ackerunkräutern in Baden-Württemberg – ein Vergleich von vegetationskundlichen Erhebungen in den Jahren 1948/49, 1975–1978 und 2011 im Raum Mehrstetten – Empfehlungen für Landwirtschaft und Naturschutz

In the period from the beginning of grain cultivation in Central Europe until the middle of the last century, the number of arable weed species has steadily increased due to diverse and extensive cropping systems. Since 1950, crop production systems have been intensified, arable land has been used for development (construction), chemical and mechanical weed control has improved and many crops have disappeared. These factors all have contributed to a strong decrease of weed species diversity. Based on detailed vegetation assessments this pattern was confirmed in the Mehrstetten area (Reutlingen County). Sampling data from 2011 were compared to data available for the same sites from 1948/1949 and 1975–1978. In the period covered, weed diversity decreased from by 64 % (97 species). Abundance of weed species was significantly higher in the field margins as compared to the center of the fields. Vegetation data obtained in 2011 no longer allowed for the identification of plant species communities since no species distinctly characterizing certain communities were recorded. There was no shift in the Ellenberg, Zeigerwerte von Pflanzen in Mitteleuropa, 1991, indicator values. None of the 23 endangered species still present in 1948/49 was recorded in 2011. Based on survey results, we assume that decrease in weed species diversity was caused by intensive cropping practices associated with the use of mineral fertilizer and herbicides as well as other effective methods of weed control.