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Moth pests of stored products included in this work were Ephestia elutella (Hubner), Ephestia kuehniella Zeller, Ephestia cautella (Walker), and Plodia interpunctella (Hubner). Information was gathered on the physical limits of the four species, on the properties of cultures set up in the laboratory, and on the factors involved in the induction and termination of diapause. Diapause was induced by low temperature and short daylength in fully grown larvae of E. elutella and P. interpunctella. Light intensities below 1 lux affected the induction of diapause in both species. In P. interpunctella, another factor inducing diapauses was high population density. Attempts to produce an arrest in the development of E. cautella were unsuccessful. Termination of diapause was hastened by such factors as long photoperiod, high temperature, chilling periods, and fumigation. Diapausing larvae of E. elutella were tolerant to methyl bromide, requiring concentration time (CT) products for 99% kill of 281 and 164 mg h/1 at 15 and 25 ºC respectively. Diapausing larvae of P. interpunctella required CT products of 225 and 67 mg h/1 at 10 and 25°C respectively for 99% kill. In the absence of diapause all stages were susceptible to methyl bromide, succumbing to a CT product of 64 mg h/1 at 15°C. With phosphine, the egg stage of all four species was highly tolerant for the first 40% of the developmental period. Eggs exposed beyond this period showed a marked increase in susceptibility, and were controlled by less than 0.04 mg/l in 4-day exposures at 25ºC. Longer exposures of phosphine were more efficient than shorter ones of similar CT product, and Haber's rule could not be applied. Factors controlling diapause in laboratory and field stocks were different, and a correlation was observed between diapause intensity and tolerance to fumigation. Further information was gained by fumigating the high intensity diapausing stages of Pieris brassicae (L) and Bombyx mori (L).

Many parasites of mammals avoid elimination by varying their exposed antigens. African trypanosomes—deadly parasites of humans and livestock in tropical Africa—possess a comprehensive system of antigenic variation (AV). Trypanosoma brucei undergo frequent, stochastic changes to their variant surface glycoprotein (VSG) coats, and therefore a developing immune response will be only partially effective against the trypanosome population as some trypanosomes will have already switched to a different VSG coat. The source of VSG variability is an archive of ~2000, mostly pseudogenic, silent VSG genes, of which only one is expressed. VSG genes can also be segmentally recombined: ‘mosaic’ VSGs, constructed from more than one silent VSG donor, allow both the reparation of pseudogenes and potentially generation of additional VSG variability. The aim of this research was to investigate the patterns of segmental VSG gene conversion in T. brucei, and assess its contribution to AV. Multiple, longitudinal samples were taken from chronic infections to follow the course of AV, and VSG cDNA sequences were analysed, building a detailed portrait of VSG expression across infection. VSG variability during an infection was extensive, and segmental gene conversion was found to be a frequent occurrence from approximately week three. Two main patterns were found: (i) expressed VSGs readily acquired a 3’ end different from their silent copy, a pattern that probably represents the 3’ boundary of gene conversion occurring within the coding sequence; (ii) expressed VSGs often appeared in sets of related ‘mosaics’, whereby more than one donor gene had contributed to the putative epitope-encoding part of the VSG. To test whether varying donor contributions represents an additional source of antigenic variability available to trypanosomes, a set of five mosaic VSGs retrieved from a single infection was expressed in non-switching trypanosomes and used to raise antibody responses. Indirect immuno-fluorescence, complement-mediated lysis, and agglutination assays using both polyclonal and monoclonal antibodies showed that although 4/5 mosaics were cross-reactive, one variant was completely antigenically distinct. Segmental gene conversion was therefore found to be both prominent in chronic African trypanosome antigenic variation, and capable of bringing antigenic novelty to an infection, with important consequences for the dynamics of AV, and the nature of selection pressure on the silent VSG archive.

Die Softwareanwendung »Sächsisches Wildmonitoring« löst Papierdokumente zwischen Jagdausübungsberechtigten und Jagdbehörden ab und gestattet eine einheitliche Erfassung jagdrelevanter Daten. Das Internetportal optimiert somit den Verwaltungsaufwand für die Jagdbehörden in Bezug auf Abschussplanung und Streckenerfassung. Redaktionsschluss: 31.10.2016