The effect of within-crop habitat manipulations on the conservation biological control of aphids in field-grown lettuce

Within-crop habitat manipulations have the potential to increase the biological control of pests in horticultural field crops. Wildflower strips have been shown to increase the abundance of natural enemies, but there is little evidence to date of an impact on pest populations. The aim of this study was to determine whether withincrop wildflower strips can increase the natural regulation of pests in horticultural field crops. Aphid numbers in plots of lettuce grown adjacent to wildflower strips were compared with those in plots grown in the absence of wildflowers. The presence of wildflower strips led to a decrease in aphid numbers on adjacent lettuce plants during June and July, but had less impact in August and September. The decrease in aphid numbers was greatest close to the wildflower strips and, the decrease in aphid numbers declined with increasing distance from the wildflower strips, with little effect at a distance of ten metres. The main natural enemies found in the crop were those that dispersed aerially, which is consistent with data from previous studies on cereal crops. Analysis and interpretation of natural enemy numbers was difficult due to low recovery of natural enemies, and the numbers appeared to follow changes in aphid abundance rather than being directly linked to the presence of wildflower strips. Cutting the wildflower strips, to remove floral resources, had no impact on the reduction in aphid numbers achieved during June and July, but decreased the effect of the wildflower strips during August and September. The results suggest that wildflower strips can lead to increased natural regulation of pest aphids in outdoor lettuce crops, but more research is required to determine how this is mediated by natural enemies and how the impact of wildflower strips on natural pest regulation changes during the growing season

Summary of sand waves and regimes of flow in alluvial channels

CER60MLA24.Includes bibliographical references

International Investment Law and Non-Communicable Diseases Prevention

It is increasingly acknowledged that non-communicable diseases (NCDs) create immense human and economic costs, disproportionately affecting developing countries. This article, which serves as an introduction to this Special Issue on international investment law and NCD prevention, outlines the international framework for the prevention of NCDs, noting the more advanced development of tobacco control policies compared to policies relating to other NCD risk factors, such as unhealthy diets and alcohol consumption. Drawing on the Philip Morris v Uruguay case, the article explains how international investment law and NCD prevention interact and the problems this interaction may raise for States willing to adopt robust NCD prevention strategies involving the regulation of the tobacco, alcohol and food industries. It concludes by introducing other contributions in this Special Issue and by highlighting the need to build legal expertise in this area

Transport of sediment in helical corrugated pipe

CER57ARC9.Includes bibliographical references.Prepared for the February 18-22, 1957 meeting of the American Society of Civil Engineers in Jackson, Mississippi