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In a two year field experiment in Switzerland we tested if vole barriers combined with traps was a suitable tool to protect meadows and orchards from vole damage. We used a special kind of vole live trap that could be opened by terrestrial predators to feed on the captured animals. The experiment was designed to compare fences with traps, fences without traps and control lines without fences or traps. Predators preferred to move along fences with traps, which has been presented elsewhere. Voles on the other hand showed a preference for control lines as a general pattern but clear effects were masked by other factors. In practice, however, self service traps will attract natural predators and can therefore enhance the effect of simple fences to stop invading voles.

The Mediterranean recluse spider, Loxosceles rufescens (Dufour, 1820) (Araneae: Sicariidae) is a cosmopolitan spider that has been introduced in many parts of the world. Its bite can be dangerous to humans. However, the potential distribution of this alien species, which is able to spread fairly quickly with human aid, is completely unknown. Using a combination of global and regional niche models, it is possible to analyse the spread of this species in relation to environmental conditions. This analysis found that the successful spreading of this species varies according to the region invaded. The majority of populations in Asia are stable and show niche conservatism, whereas in North America this spider is expected to be less successful in occupying niches that differ from those in its native region and that do not support its synanthropic way of living. The global distribution of Loxosceles rufescens (Araneae: Sicariidae) was analysed by comparing global and regional niche models.Temperature was important in both models: the highest contributor to the global model was 'annual mean temperature' (Bio1, 68.1%), whereas the most important variable in the regional models (including the native area) was 'mean diurnal range' (Bio2).The global model predicted the probability of presence was highest (0.7–1.0) for Mediterranean North Africa and for Europe, high in invaded areas of Asia, and low and medium in the warmer climates of the U.S.A. (Florida) and southeastern Brazil. [ABSTRACT FROM AUTHOR]

Two independent food choice experiments were conducted in the laboratory to study the effects of four transgenic and five non-GM fungicidal wheat varieties on the food selection behaviour of the woodlouse Porcellio scaber. In general, woodlice did not avoid GM wheat as a food source and we detected no adverse effects of GM wheat on the non-target P. scaber. Moreover, we found a food preference of the woodlouse for one of the four GM varieties, Pm3b1, but not for the closely related GM Pm3b2 or for their non-GM isolines. We assume either a pleiotropic effect like lower lignin content or more suitable leaf litter coverage by microorganisms that may cause this preference and thus increasing palatability or digestibility. We discuss that this effect is ecologically not relevant. [ABSTRACT FROM AUTHOR]

Although habitat fragmentation is suspected to pose a major threat to biodiversity, its impact on abundant invertebrate species has been little investigated. We assessed the genetic population structure of the flightless ground beetle Abax parallelepipedus in a forest fragmented by two main roads and a highway using five microsatellite loci. We detected low levels of genetic differentiation, which was concordant with the high population densities of 632–1707 individuals/ha estimated with a mark—recapture method. A Mantel test detected a highly significant increase of pairwise FST-values with the number of roads between sampling locations. As expected, the most pronounced effect of the isolation due to roads was observed in the sample from the smallest fragment (highway exit loop), which was differentiated significantly from most other locations. However, no signs of a recent bottleneck or a loss of genetic variability were detected in this population, indicating a still relatively large effective population size (Ne). Computer simulations confirmed that the observed FST-values were indeed compatible with a Ne of a few hundred individuals in this fragment, assuming strong or absolute isolation since the construction of the roads. We discuss the implications of our findings for the conservation of abundant but poorly dispersing species in fragmented habitats. [ABSTRACT FROM AUTHOR]

Abstract A 200-day study was carried out to investigate the impact of transgenic Bacillus thuringiensis (Bt) corn on immature and adult Lumbricus terrestris in the field and in the laboratory. Another objective of this study was to develop test methods that could be used for standard testing of the impact of transgenic plants on different earthworm species in the field and in the laboratory. For this purpose two different experiments were involved, a laboratory experiment with adult L. terrestris and a field experiment with immature L. terrestris . No lethal effects of transgenic Bt corn on immature and adult earthworms were observed. Immature L. terrestris in the field had a very similar growth pattern when fed either (Bt+) or (Bt-) corn litter. No significant differences in relative weights of (Bt+) and (Bt-) corn-fed adult L. terrestris were observed during the first 160 days of the laboratory trial, but after 200 days adult L. terrestris had a significant weight loss of 18% of their initial weight when fed (Bt+) corn litter compared to a weight gain of 4% of the initial weight of (Bt-) corn-fed earthworms. Further studies are necessary to see whether or not this difference in relative weight was due to the Bt toxin or other factors discussed in the study. Degradation of Cry1Ab toxin in corn residues was significantly slower in the field than at 10 °C in the laboratory. Enzyme-linked immunosorbent assay results indicated that earthworms in both experiments were exposed to the Bt toxin throughout the whole experimental time. [ABSTRACT FROM AUTHOR]

Abstract Large quantities of Bacillus thuringiensis (Bt) corn plant residue are left in the field after harvest, which may have implications for the soil ecosystem. Potential impacts on soil organisms will also depend on the persistence of the Bt toxin in plant residues. Therefore, it is important to know how long the toxin persists in plant residues. In two field studies in the temperate corn-growing region of Switzerland we investigated degradation of the Cry1Ab toxin in transgenic Bt corn leaves during autumn, winter and spring using an enzyme-linked immunosorbent assay (ELISA). In the first field trial, representing a tillage system, no degradation of the Cry1Ab toxin was observed during the first month. During the second month, Cry1Ab toxin concentrations decreased to ≈ 20% of their initial values. During winter, there was no further degradation. When temperatures again increased in spring, the toxin continued to degrade slowly, but could still be detected in June. In the second field trial, representing a no-tillage system, Cry1Ab toxin concentrations decreased without initial delay as for soil-incorporated Bt plants, to 38% of the initial concentration during the first 40 days. They then continued to decrease until the end of the trial after 200 days in June, when 0.3% of the initial amount of Cry1Ab toxin was detected. Our results suggest that extended pre- and post-commercial monitoring are necessary to assess the long-term impact of Bt toxin in transgenic plant residues on soil organisms. [ABSTRACT FROM AUTHOR]

Since several years the aphid parasitoid Aphidius colemani is used in greenhouses to control Myzus persicae and Aphis gossypii. Aphidius is reared by different commercial producers under artificial conditions and due to inbreeding runs the risk of losing some of its quality. The IOBC (International Organisation for Biological Control) designed quality control tests and guidelines to maintain products of high quality and to avoid negative advertisement against biological control. This study was set out to determine the quality of A. colemani from four commercial producers using tests proposed by the IOBC in conjunction with additional parameters. Quality control was performed after all packaging procedures and transport. Quality of the following parameters was assessed under laboratory conditions: parasitoid species, quantity, adult mortality, sex ratio, longevity, flight capacity, parasitation rate and number of hyperparasitoids. Eleven shipments of 1000 parasitoids each were used for the tests. The results showed that the quality of A. colemani was frequently unsatisfactory. Quality of products from the same producer often differed as much as products between producers. Conditions during transport had a great influence on the quality of the parasitoids. Different parameters to improve the present lack of quality are discussed. [ABSTRACT FROM AUTHOR]

Aphids and their predators were studied in an apple orchard near Berne, Switzerland. To augment the density of the predators of aphids weed strips were sown in tramlines and along the border parallel to the first and the last row of trees in one half of the orchard (the other half served as control) in April 1992. Weekly visual observations, monthly beating-tray samples, branch samples in winter, and assessment of the density of spider webs and their trapping efficiency on randomly chosen trees were carried out in 1993. During 1993, significant differences in the number of aphids, aphidophagous insects, and spiders were observed on the apple trees within both the strip-managed area and the control area. The impact on aphids by the aphidophagous insects was important during the flowering time of weeds in spring and summer. In autumn, however, spiders (i.e. Araniella spp.) were the dominant predators of aphids on the trees; during this time of the year they were more abundant within the strip-managed area of the orchard. With a higher density of webs, spiders significantly reduced the number of aphids able to return from their summer host plants. Consequently, less hatching aphids were found on branch samples of the strip-managed area compared to the control area. The effects of the weed strips on spiders and aphidophagous insects, and the resulting impact of predation on the aphids are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Genetically modified Bt-corn is able to fight main insect pests on corn very specifically and currently varieties against the European corn borer (Ostrinia nubilalis) and the Western corn rootworm (Diabrotica virgifera virgifera) are available. A transgenic corn plant, however, expresses not only Bt-proteins, it also differs from the near-isoline in the amount of major plant components such as cellulose or lignin which in turn affect the degradability of dead plant material. In a 9 months litter bag field study we therefore investigated the decomposer community on decaying leaf material for nine corn varieties (2x Cry1Ab, 1x Cry3Bb1, their untransformed corresponding near-isolines and three conventional varieties). Monthly the degradation of leaf material was analysed and the meso- and macrofauna was extracted. Nearly 67% of the decomposer community consisted of Collembola, Acari contributed 24% and Clitellata 6% to the total abundance of animals. Twelve taxa of other arthropods added less than 4%. All corn varieties were likewise used as food resource by decomposers, thus the Bt-proteins obviously did not affect the soil organisms. Decomposer communities and degradation speed did not differ between the nine corn varieties, thus there was no evidence for any effect related to the genetically modification or any variety effect at all. [Copyright &y& Elsevier]