Concentration of ions in the topside ionosphere as measured onboard the DEMETER satellite: Morphology and dependence on solar and geomagnetic activity

International audienceVariations in concentration of ions H+, He+, and O+ are studied at a height of about 700 km using the data of continuous observations onboard the DEMETER satellite at the decline and in the minimum of solar activity from 2004 to 2008. Latitudinal distributions, seasonal behavior, and irregular variations in ion concentrations and their dependence on solar and geomagnetic activity are considered. Within this altitude range, for the first time an analysis is performed of the dataset of many-year continuous observations in both hemispheres from the equatorial to subauroral latitudes. This made it possible to describe the seasonal and irregular variations of the concentrations of main ion species with better time and spatial resolution than in the available empirical models. The dependence of concentrations of three types of ions on solar and geomagnetic activity is studied at time scales from several days to several years, and it is shown that the anti-phase change in concentrations of O+ and light ions known from publications is partly a result of mutual dependence of solar and geomagnetic activity and is observed only at time scales beginning from several months. At time scales from several days to several weeks, variations in the concentration of O+ and light ions are governed mainly by solar and geomagnetic activity, respectively

SEM studies on immature stages of the drone flies (diptera, syrphidae): Eristalis similis (Fallen, 1817) and Eristalis tenax (Linnaeus, 1758)

Adult drone flies (Syrphidae: Eristalis spp.) resemble male honeybees in appearance. Their immature stages are commonly known as rat-tailed maggots due to the presence of a very long anal segment and a telescopic breathing tube. The larvae are associated with decaying organic material in liquid or semi-liquid media, as in the case of other saprophagous eristalines. Biological and morphological data were obtained from both laboratory cultures and sampling in the field. Drone flies are important pollinators for wild flowers and crops. In fact, mass rearing protocols of Eristalis species are being developed to be used as efficient alternative pollinators. However, deeper knowledge of larval morphology and biology is required to improve artificial rearing. The production quality control of artificial rearing must manage the consistency and reliability of the production output avoiding, for example contamination with similar species. This article presents the first description of the larva and puparium of E. similis, including a comparative morphological study of preimaginal stages of the anthropophilic and ubiquitous European hoverfly species E. tenax. Scanning electron microscopy has been used for the first time to describe larvae and puparia of both species. Moreover, the preimaginal morphology of E. similis has been compared with all known descriptions of the genus Eristalis. The main diagnostic characters of the preimaginal stages of E. similis are the morphology of the anterior spiracles (shape of clear area and arrangement of facets) and pupal spiracles (length, shape, and arrangement of tubercles)