In the present study, we investigated the natural control of aphids by predators in wheat fields in a low (L) and high-input cropping region (H) of Germany during a 10-year period. Data for the statistical analyses were obtained from weekly after the start of aphid emergence. The mean annual aphid indices, calculated as the sum of Sitobion avenae (Fabr.), Rhopalosiphum padi (L.), Metopolophium dirhodum (Walk.)(Homoptera: Aphididae), were 30.4 and 81.5 · 10 3 aphid days per m 2 , for L and H, respectively. Nine predator fractions were analysed: Coccinella septempunctata L., adults (1) and larvae (2), Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae) adults (3) and larvae (4), syrphid larvae (mostly Episyrphus balteatus [De Geer] (Diptera: Syrphidae)) (5), Chrysoperla carnea Steph. (Neuroptera: Chrysopidae) larvae (6), and adult carabids (7), staphylinids (8) and spiders (9). The two sites were comparable in terms of the mean size of the overall predator community, expressed in predator units (PU): 4.9 PU/m 2 (L) vs. 5.4 PU/m 2 (H). Most predator fractions responded numerically to increasing aphid densities. The numerical response was strongest in syrphid larvae, scarcely detectable in adult coccinellids, and virtually non-existent in epigeic arthropods. Multiple regression models revealed indirect relationships between the weekly overall predator community densities (PU/m 2 ) and individual predator fractions (individuals/m 2 ) and absolute rates of aphid density increase (individuals/m 2 ) one or two weeks after baseline. A site-independent reduction of the aphid density increase to nil (y = 0) was observed at 3.9 to 4.2 PU/m 2 . Consequently, the 2.7 times higher aphid density at H cannot be attributed to the presence of fewer predators or lower effects of the overall predator community or of any individual predator fraction.
Studies conducted in the 2000 cropping season at two different localities, Flaeming and Magdeburger Boerde in Germany, have provided new information on cereal aphid (Sitobion avenae (F.), Metopolophium dirhodum (Walker), and Rhopalosiphum padi (L.)) parasitoids in winter wheat; their species composition, relative abundance, hosts, and location effects. The average aphid population density was higher at Magdeburger Boerde and lower at Flaeming. Among the aphid species, Sitobion avenae was more abundant at Flaeming and Metopolophium dirhodum at Magdeburger Boerde. In total, eight species of primary parasitoids were recorded: Aphidius colemani Viereck, Aphidius rhopalosiphi DeStefani Perez, Aphidius uzbekistanicus Luzhetzki, Aphidius ervi Haliday, Aphidius picipes (Nees), Ephedrus plagiator (Nees), Praon gallicum Stary Â, and Praon volucre (Haliday). The predominant parasitoid species were Aphidius colemani and Aphidius rhopalosiphi on Metopolophium dirhodum and Aphidius uzbekistanicus on Sitobion avenae. A low number of hyperparasitoids were also recorded. Aphidius colemani was recorded for the first time in the open winter wheat fields in Germany, although it has been used as a biocontrol agent in glasshouses in many European countries and overseas. An analysis of the aforementioned information shows that Aphidius colemani detected as a parasitoid of cereal aphids in Germany is likely a result of an accidental escape of parasitoids from a glasshouse, as well as their successful overwintering and establishment in the area. This study provides baseline information essential for assessing future changes in aphid parasitoid species guild and dynamics in cereal fields in Germany.U.S.
Inspired by the pioneering work in Canada and California in the early 1950s, the first European IPM task force -the "Working Group for Integrated Plant Protection in Fruit Orchards" -was established by the International Organisation for Biological and Integrated Control of Noxious Animals and Plants (IOBC) in 1959. From the beginning, the implementation of IPM proved to be a problem because of its complicated and non-uniform requirements and insufficient economic benefits. In spite of these obstacles, IPM has become an accepted model for plant protection in all European countries and in the European Union. More than 30 working groups of the West and East Palaearctic Regional Sections of the IOBC (IOBC/wprs and eprs) organise research programs and information exchanges and actively promote the implementation of IPM into practice. IPM can be well implemented within the scope of Integrated Production (IP). Respective IP guidelines developed by IOBC/wprs working groups and local production organisations are currently being used, particularly in pome fruits and grapes. Studies have shown that IPM systems yield greater biodiversity and reduce pesticide use by at least 20% compared to conventional farming, as assessed using the treatment index. Some countries, such as Denmark, Germany and Switzerland, have developed national pesticide reduction programs. The European Union also supports IPM by issuing regulations and directives and by funding research programs. National action plans shall help to achieve faster and more consistent implementation of IPM in the Member States.July 11, 1976, is the historic landmark date on which, after reviewing current developments, five IOBC specialists coined the term "Integrated Production" (IP). This important evolutionary step became known as the "Message of Ovronnaz" (Steiner 1977;Boller et al. 1998), widened the dimension of IPM into a holistic approach.
The effects of the insecticide lambda‐cyhalothrin (Karate) on non‐target arthropods in winter wheat were studied throughout two successive seasons in 1998 and 1999. The study particularly focussed on the crop in the growing season after insecticide application (also winter wheat) for detection of potential long‐term effects and for determination of the suitability of different sampling methods.The investigations were based on the assumption that arthropod immigration from surrounding areas is limited in large fields. For this reason a simple approach seemed to be feasible. Two plots of equal size (10 ha, adjusted to each other) were defined in a 100 ha field and designated control and treatment plots. Ten sampling points were established on each plot. The following monitoring methods were utilised: visual counting, sweep netting and pitfall trapping. In the first year of investigation, countings and catches were carried out 2 days prior to insecticide application and 2, 16, 30 and 44 days after application. In the next year, they were carried out 365 days and 384 days after insecticide application in the successive crop of winter wheat.At the time of the first sampling prior to insecticide application, the two plots showed significant differences with respect to arthropod density or activity, particularly in visual counting and to a minor degree to sweep netting and pitfall trapping. Lower densities or activities were observed in the plot reserved for treatment. Measures for mathematical equalisation of the results of population densities before pesticide treatment should be considered.After insecticide application, the densities or activities of non‐target arthropods decreased, particularly in visual counting and sweep netting. After one year, these effects disappeared to a large extent. Several groups of arthropods reached even higher levels in the treated plot than in the untreated one. The pitfall traps revealed weak activity‐decreasing effects in carabids and spiders in the treated plot, but the opposite tendency for staphylinids. Hence, it seems that the conditions in a large field are less homogeneous, and that smaller scale conditions can support processes of recovery in non‐target populations.
This study was performed in the Oderbruch region, a landscape where Ostrinia nubilalis occurs in high densities. From 2000 to 2005, field pairs (half-fields) planted with Bt maize (Cry 1Ab) and a conventional maize variety, respectively, were investigated using different monitoring methods (visual counts, wholeplant harvesting and pitfall trapping) to determine densities of taxa on plants, activity densities and diversity of ground-dwelling arthropods. A total of 48 taxa were determined in counts and 90 in whole-plant harvests; 75 carabid species and 62 spider species were identified by pitfall trapping. Density comparisons of different taxa, such as aphids, thrips, heteropterans, aphid specific predators, spiders and carabids, revealed a few significant differences for specific taxa but no general tendencies during the six years. Canonical corresponding analyses revealed small but statistically significant differences in community composition between Bt and conventional maize fields. Generally, year-toyear changes in environmental conditions, field characteristics, and population dynamics had much stronger effects on the arthropod community than the use of Bt maize. Three baselines were used for evaluation of findings: (1) mean and variation of a specific variable (e. g. density) in a given conventional maize field, (2) mean and variation of a specific variable in conventional maize fields in the last five years and (3) mean and variation of a specific variable in conventional maize fields within a given year. This methodological approach is tested for suitability for casespecific monitoring.
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