The influence of clothing and wrapping on carcass decomposition and arthropod succession was investigated to provide data to enable estimated postmortem interval in homicide investigations. Six pig carcasses, Sus scrofa, were divided into three sample groups, each with a clothed carcass wrapped and a carcass wrapped with no clothes. Two more carcasses, one with no clothes or wrapping, the other with clothes and no wrapping were used as controls. The clothed or wrapped carcasses had larger visible maggot masses, which moved more freely and these carcasses took longer to dry out. The blow fly maggot masses were dominated by Chrysomya marginalis and Chrysomya albiceps. Oviposition occurred simultaneously on all carcasses. High temperatures in one case caused significant maggot mortality. The Coleoptera community was dominated by Silphidae, Thanathopilus micans larvae, Dermestidae, Dermestes maculatus adults and larvae, and Cleridae, Necrobia rufipes.

No abstract

Twenty-two isolates of African horse sickness virus (AHSV), representing its distinct serotypes, geographical and historical origins, were fed to three populations of South African livestock-associated Culicoides spp. (Diptera, Ceratopogonidae). Infective blood meals included 12 recent isolates, nine historical reference strains and one live attenuated vaccine strain serotype 7 (AHSV-7) of the virus. Field-collected midges were fed through a chicken-skin membrane on sheep blood spiked with one of the viruses, which concentrations ranged from 5.4 to 8.8 log(10)TCID(50)/mL of blood. After 10 days incubation at 23.5 degrees C, AHSV was isolated from 11 Culicoides species. Standard in vitro passaging of AHSV-7, used for the preparation of live attenuated vaccine, did not reduce its ability to infect Culicoides species. Virus recovery rates in orally infected Culicoides midges differed significantly between species and populations, serotypes, isolates and seasons. Significant variations in oral susceptibility recorded in this study emphasize a complex inter-relationship between virus and vector, which is further influenced by multiple intrinsic and extrinsic factors. As it is not possible to standardize all these factors under laboratory conditions, conclusive assessment of the role of field-collected Culicoides midges in the transmission of orbiviruses remains problematic. Nevertheless, results of this study suggest the potential for multi-vector transmission of AHSV virus in South Africa.

This study investigated the influence of different types of physical wounds as well as clothing on carcass decomposition and arthropod succession during all seasons over one year in South Africa. The trials for each season included six pigs, Sus scrofa, carcasses: two carcasses with wounds, one carcass was clothed the other was not; two carcasses with stab wounds, one carcass was clothed and the other was not; two carcasses with severe trauma wounds, one carcass was clothed and the other was not. The decomposition process and arthropod succession were not influenced by the absence or presence of wounds. Adult female Diptera did not select the wounds as oviposition sites. The presence of clothing caused a slight change in decomposition process only during summer and winter trials. The dominant Diptera in autumn and summer were Chrysomya marginalis and Chrysomya albiceps. In spring, it was Chrysomya chloropyga and C. albiceps and in winter it was Sarcophaga spp., C. chloropyga, Calliphora vicina, and Lucilia spp. During the warmer seasons, maggot predation by C. albiceps on C. marginalis was observed. In all seasons the Coleoptera were dominated by Dermestes maculatus and Necrobia rufipes, however, in summer, Thanatophilus micans and Histeridae spp. were also recorded. RésuméCette étude a examiné l'influence des différents types de blessures physiques ainsi que des vêtements sur la décomposition des carcasses et de la succession d'arthropodes pendant toutes les saisons sur un an en Afrique du Sud. Les essais pour chaque saison ont été réalisés avec les carcasses de six cochons Sus scrofa,: deux carcasses avec des blessures, l'une habillée et l'autre pas, deux carcasses avec blessures par arme blanche, l'une habillée et l'autre pas, et deux carcasses avec de graves traumatismes, l'une habillée et l'autre pas. Le processus de décomposition et la succession des arthropodes ne sont pas influencés par l'absence ou la présence de blessures. La femelle adulte Diptère n'a pas choisi les blessures comme sites de ponte. La présence de l'habillement n'a provoqué qu'un léger changement dans le processus de décom-position et ce, uniquement durant les essais d'été et d'hiver. Les diptères dominantes en automne et en été ont été la Chrysomya marginalis et la Chrysomya albiceps. Au printemps, elles ont été les Chrysomya chloropyga et la C. albiceps tandis qu'en hiver, elles étaient plutôt les Sarcophaga spp., C. chloropyga, Calliphora vicina et Lucilia spp. Pendant les saisons chaudes, la prédation par la mouche C. albiceps sur la C. marginalis a été observée. En toutes saisons, les coléoptères dominantes ont été le Dermestes maculatus et la Necrobia rufipes. En été cependant, le Thanatophilus micans et les Histeridae spp. ont également été enregistrées.

Aphid behaviour-modifying semiochemicals were tested against Russian wheat aphid Diuraphis noxia in South African wheat. Volatile substances from plant essential oils, methyl salicylate, 1,8-cineole and menthol were tested in the laboratory and field in combination with the D. noxia-susceptible wheat variety Betta and the resistant variety Elands. All three substances were repellent to D. noxia in olfactometric tests. Diuraphis noxia settled less on Elands plants that had been exposed to the volatiles, whereas the effect of the volatiles on D. noxia settling on Betta was less obvious. A slow-release pellet formulation was used to apply semiochemicals in wheat in replicated plot field trials in 2004 and 2005. In 2004, semiochemicals reduced aphid populations in Elands, but led to increased aphid populations in Betta. Further, the impact of the chemicals on aphid numbers and grain quality (thousand grain weight) varied according to plant variety, indicating an interaction between semiochemicals and plant resistance ⁄ variety.