The spatio-temporal variability of necrophagous fly assemblages in a linear series of habitats from central London to the rural surroundings in the south-west was studied using bottle traps between June 2001 and September 2002. A total of 3,314 individuals in 20 dipteran families were identified from 127 sampling occasions. Calliphoridae accounted for 78.6% of all the dipteran specimens, with Calliphora vicina Robineau-Desvoidy, being the most abundant species (2,603 individuals, 46.9%). Using canonical correspondence analyses (CCA) on 72 fly taxa, six sampled sites and 36 environmental variables, three habitat types corresponding to three groups of flies were identified. These were an urban habitat characterized by C. vicina, Lucilia illustris (Meigen) and L. sericata (Meigen), a rural grassland habitat, characterized by L. caesar (Linnaeus) and a rural woodland habitat characterized by Calliphora vomitoria (Linnaeus), Phaonia subventa (Harris), Neuroctena anilis (Fallén) and Tephrochlamys flavipes (Zetterstedt). Intermediate species (L. ampullacea Villeneuve and P. pallida (Fabricius), located between the three habitats, were also found. Temporal abundance of the 10 most abundant species showed fluctuations between seasons, having low numbers of captured individuals during winter. Correspondence analysis showed clearly seasonal patterns at Box Hill site. The species-habitat associations suggest habitat differentiation between necrophagous guilds in this area and may be of ecological value.

Abstract. Blowfly larvae (Diptera: Calliphoridae) fulfil an important ecological function in the decomposition of animal remains. They are also used extensively in forensic entomology, predominantly to establish a minimum time since death, or a minimum post-mortem interval, using the larval length as a 'biological clock'. This study examined the larval growth rate of a forensically important fly species, Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) at temperatures of between 4 C and 30 C, under controlled laboratory conditions. The laboratory flies had been trapped initially in London, U.K. The minimum developmental temperature was estimated to be 1 C and 4700 accumulated degree hours (ADH) were required for development from egg hatch to the point of pupariation. Lines fitted to the laboratory larval growth data were found to adequately explain the growth of larvae in the field. The nature of variation in growth rates from geographically isolated populations is discussed.

Rickettsiae are well known as intracellular pathogens of animals, humans, and plants and facultative and unorganized symbionts of invertebrates. No close relative of mitochondria has yet been associated with nutritional or developmental dependency of its host cell or organism. We have found a mycetomic Rickettsia that is a strict obligatory symbiont of the parthenogenetic booklouse Liposcelis bostrychophila (Psocoptera). These rickettsiae show an evolutionary transition from a solitary to a primary mycetomic bacterium adapted to the development of its host. These intracellular and intranuclear bacteria reside in specialized cells in several tissues. Their distribution changes markedly with the development of their host. The most advanced phenotype is a paired mycetome in the abdomen, described for the first time for Rickettsia and this host order. The mycetomic rickettsiae of two parthenogenetic book lice species are in the spotted fever group and in the basal limoniae group. While mycetomic bacteria are well known for their metabolic or light-emitting functions, these rickettsiae have an essential role in the early development of the oocyte. Removal of the Rickettsia stops egg production and reproduction in the book louse. In two phylogenetically distant psocopteran species, Rickettsia are shown to be associated with four transitional stages from free bacteria, infected cells, through single mycetocytes to organ-forming mycetomes.

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