We used a long-term arable cultivation experiment to investigate spatial relationships between earthworm populations and soil physico-chemical properties using Spatial Analysis by Distance Indices methods (SADIE). Red-blue analyses showed that soil C and N were both spatially heterogeneous (patchy) as were total and juvenile earthworm counts. In contrast, theta probe and shear vane measurements, adult earthworm counts and earthworm biomass did not exhibit patchiness. All potential relationships between data classes were analysed using SADIE spatial association tests. Soil chemical properties were generally dissociated from earthworms whereas physical properties were positively associated. These results were largely attributable to juvenile counts, suggesting that this age group may be a more sensitive indicator of spatial relationships between earthworms and soil properties than are adults. We also found that earthworm counts had stronger spatial associations with soil chemical properties than did biomass; the obverse was seen with the measures of soil physical properties. This may provide evidence that earthworm dynamic responses vary between different aspects of the soil environment. © 2007 Elsevier Masson SAS. All rights reserved.

1. Primary and logged lowland dipterocarp forest sites were sampled for subterranean termites using soil pits located on a grid system in order to detect any patchiness in their distribution. 2. A spatial pattern in termite distributions was observed in the primary and logged sites, but the response differed between soil-feeding and non-soil-feeding termites. 3. Spatial analysis showed that soil-feeding termites were homogeneously distributed in the primary forest but significantly aggregated in the logged forest. This pattern was reversed for non-soil-feeding termites and may result from differences in resource provisioning between the two sites. 4. Gaps in termite distribution comprised a greater area than patches for both feeding groups and sites, but gaps dominated the logged site. 5. A significant association between soil-feeding and non-soil-feeding termite distributions occurred at both sites. This arose from an association between patches in the primary forest and between gaps in the logged forest. 6. Termite spatial pattern was optimally observed at a minimum extent of 64 m and lag of 2 m. 7. The spatially explicit SADIE (Spatial Analysis by Distances IndicEs) analyses were more successful than (non-spatially explicit) multivariate analysis (Canonical Correspondence Analysis) at detecting associations between termite spatial distributions and that of other biotic and abiotic variables. © 2007 the Royal Entomological Society.

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 degrees C and 30 degrees 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 degrees 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.

Termites are an important component of tropical soil communities and have a significant effect on the structure and nutrient content of soil. Digestion in termites is related to gut structure, gut physicochemical conditions, and gut symbiotic microbiota. Here we describe the use of 16S rRNA gene sequencing and terminal-restriction fragment length polymorphism (T-RFLP) analysis to examine methanogenic archaea (MA) in the guts and food-soil of the soil-feeder Cubitermes fungifaber Sjostedt across a range of soil types. If these MA are strictly vertically inherited, then the MA in guts should be the same in all individuals even if the soils differ across sites. In contrast, gut MA should reflect what is present in soil if populations are merely a reflection of what is ingested as the insects forage. We show clear differences between the euryarchaeal communities in termite guts and in food-soils from five different sites. Analysis of 16S rRNA gene clones indicated little overlap between the gut and soil communities. Gut clones were related to a termite-derived Methanomicrobiales cluster, to Methanobrevibacter and, surprisingly, to the haloalkaliphile Natronococcus. Soil clones clustered with Methanosarcina, Methanomicrococcus, or rice cluster I. T-RFLP analysis indicated that the archaeal communities in the soil samples differed from site to site, whereas those in termite guts were similar between sites. There was some overlap between the gut and soil communities, but these may represent transient populations in either guts or soil. Our data do not support the hypothesis that termite gut MA are derived from their food-soil but also do not support a purely vertical transmission of gut microflora.

Soil-feeding termites are dominant members of the soil fauna in lowland tropical rainforests. As ecosystem engineers, they have a profound effect on their environment, particularly through modification of the vast quantities of soil that they ingest. There is growing evidence that the processing of the soil in the gut is influenced by the enteric valve-an extremely well-developed feature in the hindgut of the Termitidae, consisting of six ridges, variously armed with spines, teeth and scales. Although this valve has been extensively used in morphological work, little is known of its function. Scanning electron microscopy has been used in this study to better understand the three-dimensional structure of the enteric valve in the Afrotropical Apicotermitinae, a group in which these valves are everted into the following chamber of the hindgut. This configuration lends itself to scanning electron microscopy in a way that it does not in other soil-feeders, since in those species the armature is obscured within the gut lumen. It seems plausible that this structure is instrumental in filtering material through the gut in such a way that the coarse, organic-poor portion of the soil is channeled fast through the centre, while directing the fine, organic-rich portion to the edges for lengthier digestion of recalcitrant plant material. Thus, the enteric valve would appear to be important for the termites to survive on this nutrient-poor but super-abundant food resource.

Termites were surveyed at three altitudes (Brachystegia woodland at 1676 m and 1905 m, and Juniper woodland at 2210 m) in forests within the Nyika Plateau, northern Malawi. Sampling was by a standardized 100 m transect protocol. Termite diversity was highest in the mid-altitude site and lowest in the Juniper forest. The assemblages were dominated by soil-feeding termites in the Termitidae subfamilies Apicotermitinae and Termitinae, and included one new soldierless Apicotermitinae genus. The structure of the assemblages was clearly due to a mixture of altitudinal and site history factors. This was especially true of the lowest altitude forest where burning and other anthropogenic disturbance factors appear to have reduced termite diversity relative to the mid-altitude site. The Nyika plateau shows a much higher diversity at mid-altitudes than similar SE Asian sites, probably due to the larger area of highland in Africa than in SE Asia. In addition, the clade composition of the Nyika assemblages differs completely from that found at similar altitudes in SE Asia. This preliminary study supports the hypothesis that mid- to high- altitude assemblages in both SE Asia and Africa appear to be derived from depauperated random subsets of the lowland fauna rather than from clades specifically adapted to higher altitudes.

1. Gut content analysis of termites was undertaken using microscopical techniques. The 46 study species covered the entire range of taxonomic and feeding forms within the Order. 2. Inter-specific gut contents data were analysed using principal components analysis, placing species along a clear humification gradient based on variations in the amount of silica and plant tissue fragments in the gut. 3. Redundancy analysis was used to find morphological correlates of the observed variation in gut contents. A total of 22 morphological characters (out of 45 candidate characters) were correlated significantly with the gut contents. 4. Three of the 22 significantly correlated characters unambiguously defined feeding groups, which were designated groups I to IV in increasing order of humification of the feeding substrate. Group I contains lower termite dead wood and grass-feeders; group II contains Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro-epiphytes; group III contains Termitidae feeding in the organic rich upper layers of the soil; group IV contains the true soil-feeders (again all Termitidae), ingesting apparently mineral soil. These groupings were generally supported statistically in a canonical covariance analysis, although group II apparently represents termite species with a rather wide range of feeding habits. 5. Using existing hypotheses of termite phylogenetic relationships, it seems probable that group I feeders are phylogenetically basal, and that the other groupings have arisen independently on a number of occasions. Soil-feeding (i.e. group III and group IV feeding) may have evolved due to the co-option of faecal material as a fungal substrate by Macrotermitinae-like ancestral forms. As a consequence, these forms would have been constrained to build nest structures from soil and would therefore have passed at least some soil through their guts.

We measured the effect of a typical soil-feeding termite on soil quality using experimental mesocosms. We obtained soil from five different sites in the humid forest zone of southern Cameroon. The sites were along a disturbance gradient, from near primary, to highly degraded agricultural soil. We allowed colonies of Cubitermes fungifaber to work the soils for 13 days. We measured physical and chemical parameters in the worked soils that are known to be important in soil quality, and therefore to influence fertility. We found that C. fungifaber raised pH in soils with an initial low pH, increased organic carbon, water content and relative amount of kaolinite, and decreased the relative amount of quartz. The main effect of these termites is to raise local microsite soil quality, and these effects are greatest in the near primary and old secondary forests. Termites are, therefore, potentially important sources of heterogeneity in tropical forest soil systems.

Isoptera (termites) are an ecologically important order, with both a high abundance and biomass in tropical ecosystems. However, there have been few phylogenetic hypotheses for termites, and we present here the first comprehensive cladistic analysis for the group. We analysed relationships between all seven termite families, including representatives of all known feeding group, plus a number of systematically critical taxa. Termite species richness is biased towards the higher termites (Termitidae), and our taxon sampling reflects this. Our analysis was based essentially on morphological characters (96 workers, 93 soldiers) plus seven biological characters. The cladistic analysis gave four equally parsimonious trees, representing two islands of topologies. The strict consensus tree is fully resolved for the higher termites, but less so for the lower termites. Overall there is low statistical support for the suggested topology, and this can be explained by the high incongruence between the data sets (worker, soldier and biological). This study highlights the particular problems of coding morphological characters in social insects with multiple castes. Without the input of additional data sets, e.g. alates, biological, behavioural and molecular, it will not be possible to obtain a well-supported termite phylogeny. (C) 2000 the Linnean Society of London.