A failed invasion? Commercially introduced pollinators in Southern France

The natural diversity of Bombus terrestris subspecies could be under threat from the commercialisation of bumblebees. Therefore, to determine whether commercially imported bumblebees are able to establish and spread, we carried out long-term observations of bumblebees in southern France. Our surveys occurred before, during, and after the importation (between 1989 and 1996) of thousands of colonies of the Sardinian subspecies B. t. sassaricus. Queens and males of B. t. sassaricus were observed foraging outside commercial greenhouses in 1991, 1993, and 1994 and feral workers were observed foraging on native vegetation nearly two years after the importation of B. t. sassaricus ceased. However, no B. t. sassaricus, or F1 hybrids were observed after 1998. We conclude that B. t. sassaricus remains inconspicuous in France and competition from the three native subspecies may have prevented it from becoming invasive. However, genetic interference through introgression cannot be ruled out

Population-Level Metrics of Trophic Structure Based on Stable Isotopes and Their Application to Invasion Ecology

Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications

Agricultural policies exacerbate honeybee pollination service supply-demand mismatches across Europe

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue

Pharmacokinetics and Pharmacodynamics of Antibacterials, Antifungals, and Antivirals Used Most Frequently in Neonates and Infants

Antimicrobials and antivirals are widely used in young infants and neonates. These patients have historically been largely excluded from clinical trials and, as a consequence, the pharmacokinetics and pharmacodynamics of commonly used antibacterials, antifungals, and antivirals are incompletely understood in this population. This review summarizes the current literature specific to neonates and infants regarding pharmacokinetic parameters and changes in neonatal development that affect antimicrobial and antiviral pharmacodynamics. Specific drug classes addressed include aminoglycosides, aminopenicillins, cephalosporins, glycopeptides, azole antifungals, echinocandins, polyenes, and guanosine analogs. Within each drug class, the pharmacodynamics, pharmacokinetics, and clinical implications and future directions for prototypical agents are discussed. β-Lactam antibacterial activity is maximized when the plasma concentration exceeds the minimum inhibitory concentration for a prolonged period, suggesting that more frequent dosing may optimize β-lactam therapy. Aminoglycosides are typically administered at longer intervals with larger doses in order to maximize exposure (i.e., area under the plasma concentration–time curve) with gestational age and weight strongly influencing the pharmacokinetic profile. Nonetheless, safety concerns necessitate therapeutic drug monitoring across the entire neonatal and young infant spectrum. Vancomycin, representing the glycopeptide class of antibacterials, has a long history of clinical utility, yet there is still uncertainty about the optimal pharmacodynamic index in neonates and young infants. The high degree of pharmacokinetic variability in this population makes therapeutic drug monitoring essential to ensure adequate therapeutic exposure. Among neonates treated with the triazole agent fluconazole, it has been speculated that loading doses may improve pharmacodynamic target attainment rates. The use of voriconazole necessitates therapeutic drug monitoring and dose adjustments for patients with hepatic dysfunction. Neonates treated with lipid-based formulations of the polyene amphotericin B may be at an increased risk of death, such that alternative antifungal agents should be considered for neonates with invasive fungal infections. Alternative antifungal agents such as micafungin and caspofungin also exhibit unique pharmacokinetic considerations in this population. Neonates rapidly eliminate micafungin and require nearly three times the normal adult dose to achieve comparable levels of systemic exposure. Conversely, peak caspofungin concentrations have been reported to be similar among neonates and adults. However, both of these drugs feature favorable safety profiles. Recent studies with acyclovir have suggested that current dosing regimens may not result in therapeutic central nervous system concentrations and more frequent dosing may be required for neonates at later postmenstrual ages. Though ganciclovir and valganciclovir demonstrate excellent activity against cytomegalovirus, they are associated with significant neutropenia. In summary, many pharmacokinetic and pharmacodynamic studies have been conducted in this vulnerable population; however, there are also substantial gaps in our knowledge that require further investigation. These studies will be invaluable in determining optimal neonatal dosing regimens that have the potential to improve clinical outcomes and decrease adverse effects associated with antimicrobial and antiviral treatments