The impact of imidacloprid and thiacloprid on the mean species abundance in aquatic ecosystems.

Neonicotinoids are currently the most widely used and sold insecticides in the world, providing effective pest control. Risk assessment of these and other pesticides by lab-based indicators is common. Yet, empirically and theoretically underpinning of extrapolation to indicators used in field surveys is severely limited. Consequently, the aim of our study was to quantify the toxicological and ecological impact of the neonicotinoids imidacloprid and thiacloprid to aquatic invertebrates. We derived Species Sensitivity Distributions (SSDs) based on chronic LC50 data and Mean Species Abundance Relationships (MSARs), comparing these lab-based approaches to field data as well. MSARs are changes in mean species abundance (MSA) as a function of chemical exposure, providing insight into the overall decline of a community. The MSA expresses the mean abundance of species in disturbed conditions relative to their abundance in undisturbed habitat. The medians of the SSD of imidacloprid and thiacloprid for the different species were 16.45 µg/L and 26.40 µg/L, respectively. HC50s of the MSAR of imidacloprid and thiacloprid were 4.25 µg/L and 5.12 µg/L, respectively. The three taxonomic groups tested (insects, crustaceans and mollusks) did not differ significantly in sensitivity for imidacloprid and thiacloprid, both according to the SSDs and MSARs derived. Quantile exposure-response curves (99%-tile) were plotted showing the relative abundance (RA) of aquatic invertebrate species at increasing imidacloprid levels. The 99%-tile of the Relative Abundances (RA99) of species and corresponding imidacloprid concentrations monitored in field surveys in the Netherlands was significantly lower than the Potentially Affected Fraction (PAF) calculated from the SSD. Yet, the MSA was similar to the RA99, suggesting that MSAR is an ecologically meaningful relationship for toxic stress estimated from lab data. Future efforts should be directed to additional empirical underpinning as well as determining the relationship of PAF to other metrics for ecosystem diversity and productivity.

Dominance of an invasive fruit fly species, Bactrocera invadens, along an altitudinal transect in Morogoro, Eastern Central Tanzania.

Bactrocera invadens, a fruit fly from Asia, is an invasive pest species across Africa. It appears to continue spreading, not only in latitude but also in altitude. To assess its capacity to infest a large variety of hosts and its competition with other fruit fly species, a study along an altitudinal gradient was conducted. At low altitudes, the high abundance in the field and high infestation of B. invadens in different fruit species make it a serious pest. At high altitudes, colonization has started and B. invadens occurs in low numbers by reproducing successfully in high altitude fruits. Overall the abundance and infestation of B. invadens is influenced by its direct competitor Ceratitis rosa and the presence of its preferred host species. C. rosa is still the dominant species in temperate fruits grown at high altitude. Ceratitis cosyra, however, is negatively affected by B. invadens, this species seems to have shifted hosts to avoid competition. The broad host range and competitive potential of B. invadens increase the risk for further spread not only to higher areas, but also to subtropical regions.

Childbirth and pragmatic midwifery in rural Ghana.

Conceptual categories such as traditional, modern, and postmodern do not further our understanding of the empirical situation of midwifery in late 20th-century rural Ghana. Processes of "modernization," it is argued, have not had much impact on the domain of childbirth. And, despite efforts to "medicalize" birth (by the state and the international movement for safe motherhood and child survival), in Anlo-Ewe cultural contexts in the mid-1990s the lineage still controlled most deliveries, with many babies continuing to be born at home. This article provides an in-depth portrait of one midwife, Sena, who practiced in this rural locale--a locale that is marked by increased "professionalization" and competing ideologies of healing and health. Exemplifying what might best be referred to as critical midwifery grounded in pragmatism, Sena mediated, translated, and maneuvered as she involved herself in the imbroglios of birth and as she worked to improve maternal and infant health.