The fate of clover-derived nitrogen (15N) during decomposition under field conditions: Effects of soil type

Seven soils were collected from different field sites in Southern Finland and placed into microplots confined in PVC-cylinders (30 cm i.d. × 50 cm). Subterranean clover material labelled with¹⁵N, contained in mesh bags, was buried into the microplots in October, and the plots were sown with barley the following May. The mesh bags were removed and soil samples taken immediately after the barley harvest. The crop, mesh bags and soil were then analysed for¹⁵N content. The soil type affected release of clover N from the mesh bags and its retention in soil only slightly; at the end of the experiment the mesh bags contained 30–38% and the soil (0–45 cm) 28–37% of the clover N input. The uptake of clover N by the barley crop varied from 11 to 20% and correlated best with the soil electrical conductivity (r=0.820^*). The total recovery of clover-derived N varied from 72 to 92%.     

Tool use by captive chimpanzees at an artificial termite mound

This study examines tool use by a colony of captive chimpanzees at an artificial termite mound. The mound, constructed of concrete, simulates the termite mounds which are used as food sources by wild chimpanzees who extract the termites using grass or twig-type tools. In the present study, tool availability was manipulated, specifically the type of tool, and the distance of tool material from the mound. The type of food available in the mound was also varied. Tool-making and tool-using behavior was examined in relation to individual, age, and sex differences. The artificial mound proved to be a viable simulation of the naturally occurring mounds, with most of the chimpanzees exploiting the food in the mound by using tools over the period of study. Interesting individual differences emerged in the way that the chimpanzees selected and used tools, some preferring to move some distance from the mound to collect “off-the-peg” tools, others preferring to sit and fashion a tool from material available nearer the mound. Also, some chimpanzees used both ends of a tool, while others used only one end. There were significant age differences in activity at the mound, the younger chimpanzees spending more time at the mound, using tools previously used by others, and manipulating the mound holes manually. Sex differences, although not significant, were apparent. The artificial mound provides the chimpanzees with a stimulating and rewarding activity, interest and enjoyment for the public, and an opportunity for researchers to study tool use under more controlled conditions than are possible in the field.     

Subterranean clover decline in permanent pastures in north-eastern Victoria

Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35–140%) were obtained with subterranean clover at both sites, with corresponding decreases in Al in the 0–10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4 μg g⁻¹) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg⁻¹ at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p=0.05) at both sites. An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.     

A conspectus of the Cladocera of the subterranean waters of the world

A synthesis of current knowledge of the Cladocera living in non-surface waters is provided. For all 94 species and subspecies recorded (Dec. 1994) we give information on their ranges, ecological characteristics, and a review of literature data. We also give a historic survey of the development of concepts, identify categories among groundwater-dwelling species, and discuss their adaptations and the evolutionary lines present. Of the estimated total of c. 450 non-marine Cladocera of the world, c. 20% may occur in underground aquatic habitats, but true groundwater forms (stygobionts or stygobites) are relatively few, possibly not more than 10 species (c. 2.5% of the total). This number may increase, as attention is given to subterranean habitats outside Europe.     

Monoclonal antibodies for the detection and differentiation of faba bean necrotic yellows virus isolates

Murine monoclonal antibodies (MAbs) were produced for the detection of faba bean necrotic yellows virus (FBNYV), an isometric ssDNA virus belonging to a new, yet unnamed genus of plant viruses. A total of 19 FBNYV-specific MAbs were obtained from three fusion experiments and characterised by determining their immunoglobulin types and titres as well as their corresponding epitopes. At least six distinct epitopes were revealed on FBNYV particles of different virus isolates. Only two MAbs reacted with SDS-dissociated FBNYV virions in triple antibody sandwich (TAS)-ELISA and with viral capsid protein in Western blots. Almost all MAbs were more sensitive in detecting FBNYV in viruliferous aphids by TAS-ELISA than polyclonal anti-FBNYV IgG by double antibody sandwich ELISA and permitted virus detection in individual aphids even following short acquisition access feeding periods. Coat protein variation among FBNYV isolates and serological relatedness to taxonomically similar viruses was studied by determining the cross reactivity of these MAbs with several field isolates of FBNYV as well as with milk vetch dwarf (MDV), banana bunchy top (BBTV), and subterranean clover stunt (SCSV) viruses. Whereas none of the MAbs reacted with BBTV, only one reacted with SCSV, indicating that FBNYV and SCSV share a common epitope. By contrast, 16 of the 19 MAbs reacted with MDV, suggesting that FBNYV and MDV are serologically closely related and strains of the same virus. When all 19 MAbs produced were tested against a total of 107 samples of FBNYV collected during virus surveys in Egypt, Ethiopia, Jordan, Morocco and Syria, five MAbs showed differential reactions. While the majority of the samples reacted with all 19 MAbs, about 20% of the 107 FBNYV samples did not react with one and/or other of these five MAbs, permitting the differentiation of seven serotypes of FBNYV and suggesting a considerable coat protein variation in FBNYV isolates from the countries surveyed. The MDV isolate from Japan and five FBNYV samples from Ethiopia appeared to be the least closely related to typical FBNYV isolates by not reacting with three and four, respectively, of the five differentiating Mabs.     

The population genetic structure of Ctenomys porteousi (Rodentia: Octodontidae)

Several aspects of the population biology and the population genetic structure of Ctenomys porteousi were studied. Chromosomal and allozyme polymorphisms in two local populations separated by 10 km were used to infer genetic structure. Heterochromatic addition/deletion rearrangements for six autosomal pairs were employed as genetic markers. Allozyme variants were analysed by the study of thirty-one presumptive loci. Thirteen loci (43%) were polymorphic, average observed heterozygosity per locus was 10%, and mean number of alleles per locus was 1.57. Chromosomal and allozyme frequencies were homogeneous across populations. The estimated F_st values were very low, 0.009 and 0.022 for chromosomal and allozyme data respectively. Gene flow was indirectly estimated by the method of Wright, Nm values (mean number of migrants per generation per deme) was very high (27.2 and 11.3 for chromosomal and allozyme data respectively). The F_is values suggest a significant defect of heterozygotes that could be explained by the Wahlund effect. The ecological data indicate the occurrence of sharp changes in density and in distribution pattern in short time. The genetic and ecological data suggest that the population structure of C. porteousi differs from that found in other species of Ctenomys affected by chromosomal mechanisms of speciation.     

Suppression of termite feeding and symbiotic protozoans by the dye, Sudan Red 7 B

Laboratory groups of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), were fed for 14 days on wood shavings soaked in acetone solutions of 0%, 0.5% or 1% concentrations of the dye, Sudan Red 7B or on shavings not soaked in acetone (0% non-acetone, NA). Termites feeding on dyed wood became visibly stained red. Groups of dyed or non-dyed termites were then placed in containers and allowed to feed on non-dyed wood for 21 days. Dyed termites had lower numbers of symbiotic protozoans, lower feeding rates, and lower survivorship than did non-dyed termites. Survivorship was significantly lower in the 1% concentration than in the 0.5% concentration. Covariate analyses suggested that Sudan Red acts both directly and indirectly (via suppression of gut fauna) to reduce vigor in termites. Because there is variable survival response to this dye by different populations of C. formosanus, we recommend preliminary tests of dye toxicity before using it extensively in experiments.

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Résumé Le colorant rouge Soudan 7B (BASF, Wyandotte Corp.) soluble dans l'huile, est un marqueur efficace des termites pour les études dans la nature. Quand les termites consomment des matériaux marqués par ce colorant, ils deviennent nettement colorés en rouge. Bien que certains travaux indiquent que le rouge Soudan n'augmente pas considérablement la mortalité, il n'y a aucune donnée concernant l'effet du colorant sur l'alimentation des termites.Un groupe de Coptotermes formosanus récolté au lac Charles en Louisiane, a été alimenté pendant 14 jours sur copeaux de Pinus sp. colorés avec des solutions 0, 0.5% et 1% (en poids) de rouge Soudan 7B dans l'acétone, ou sur copeaux non colorés et sans acétone (NA). Les groupes de termites colorés ou non sont alors placés dans des récipients pour s'alimenter sur bois non coloré pendant 21 jours. Des différences significatives ont été observées (t. 1): les termites colorés avaient moins de protozoaires symbiontes, consommaient moins de bois et vivaient moins long-temps que les termites sans colorant (t. 2). La survie a été plus faible avec la concentration 1% qu'avec 0.5%. Le nombre de protozoaires était plus faible avec une solution acétonique sans rouge Soudan qu'avec du bois sans acétone, ce qui suggère que l'effet négatif du rouge Soudan sur les protozoaires a pu être augmenté par l'extraction d'une substance favorisant les protozoaires contenue dans les copeaux de pin.La chute de la prise de nourriture a été accompagnée d'une chute parallèle de l'effectif de protozoaires. En réexaminant les résultats de Lai et al. (1983), nous constatons qu'eux aussi avaient observé une réduction de l'effectif de protozoaires de C. formosanus sous l'effet du rouge Soudan. Dans notre étude, nous trouvons que 49,6% de l'effet réducteur du colorant sur la nutrition est expliqué par l'effet simultané sur les protozoaires. Nos résultats sur la survie confirment dans l'ensemble ceux de Su et al. (1983 a) sur C. formosanus de Louisiane. Cependant, C. formosanus de Hawaï (Lai et al., 1983) et de Floride (Su et al., 1988) avaient des taux de survie bien plus élevés. C. formosanus présente nettement des réactions variables au rouge Soudan. Dans notre travail, 64,1% de l'effet du colorant sur la survie a été expliqué par des modifications chez les protozoaires. Ainsi, il semble que le rouge Soudan agisse directement sur l'alimentation et la survie de C. formosanus, et indirectement par la suppression de sa faune intestinale.Bien que nos résultats montrent les effets délétères du rouge Soudan 7B sur C. formosanus, il reste le meilleur colorant pour les termitologistes. par suite de la variabilité de son effet sur la survie, nous conseillons des tests de toxicité avant son utilisation intensive dans des expériences.

     

Transport of volatile fatty acids across the hindgut of the cockroach Panesthia cribrata Saussure and the termite, Mastotermes darwiniensis Froggatt

Acetate ion was actively transported from the lumen across the colon wall of the cockroach Panesthia cribrata. A maximal initial rate of transport of 81 μmol/h was obtained when the concentration of acetate was increased 400 times the physiological level to over 2 M. The transport system could not be saturated. Transport was not affected by 2,4-dinitrophenol or cyanide nor was it dependent on the maintenance of a sodium gradient. Propionate was transported to a lesser extent, but butyrate was transported at rates comparable to acetate. Acetate was also actively transported by the paunch and upper colon of Mastotermes darwiniensis but the transport system could not be saturated. A maximal initial rate of 3 μmol/h was obtained.     

Open-Air Litter Foraging in the Nasute Termite Longipeditermes longipes (Isoptera: Termitidae)

The Southeast Asian nasute termite Longipeditermes longipes forages on the open ground on leaf litter. Its monomorphic workers carry back food balls in their mandibles while dimorphic soldiers defensively surround the marching columns and the foraging patches. When mechanically disturbed, workers hide under the litter, whereas antennating soldiers face as closely as possible the source of disturbance. Foragers prefer the lower, nitrogen-rich layer of the litter. Soldier behavior and column organization (returning workers in the center lanes, outgoing workers in the two flanking lanes) are similar to those in the related genera Hospitalitermes and Lacessititermes, which, however, tend to forage above ground.