Serological identification and quantification of potato cyst nematodes from clean cysts and processed soil samples

Two monoclonal antibodies which specifically recognise each of the two species of potato cyst nematodes (PCN) and do not cross react with other species of soil nematodes, were used successfully in an immunoassay to identify and quantify PCN species using clean cysts and mixed populations. These antibodies show reactivity only towards antigens prepared from live eggs and they recognise antigens which are easily released from the nematodes. The results presented in this paper show that serological identification and quantification of PCN, not only from clean cysts but also from processed soil samples is achievable. A simple procedure to recover nematodes from soil samples and then to release nematode antigens was devised. The use of these procedures and the immunoassay for quantification of PCN was validated in tests with soil samples from Northern Portugal. The flotation method proved to be as efficient as the Fen wick Can for cyst recovery from soil samples. A significant correlation was obtained between results from immunoassay estimates and the traditional method of cyst picking and egg counting. The amount of organic matter (OM) present in the soil samples affected the sensitivity of the immunoassay but quantification of nematodes extracted from soil samples was possible with soils containing up to 14% of OM. The challenge remains to optimise the extraction procedures and the immunoassay, in practical conditions with highly organic soils containing cysts of different sizes and ages.     

Comparison of centrifugal and other methods for standardization of extraction of nematodes from soil

The extraction of many genera of nematodes from four different soil types by sedimentation, mobility, sieving and centrifuging was compared. All methods were found to extract similar numbers of nematodes. Centrifuging was the most versatile technique and the best for clay soils. Baerman sieving was generally poor and particularly so for sands and for the genus Tylen-chorhynchus. Rotylenchus was the only genus of those identified that was extracted equally well by all techniques. Centrifugal extraction was selected as the routine method for surveys as it was effective on all soil types, was less likely to be subject to variation and, although poor for Longidorus, extracted a wider spectrum of nematodes.     

An efficient,inexpensive elutriator design for separating benthos from sediment samples

A design for an elutriator is given. The elutriator has an efficiency of 96.1 ± 3.5% in sorting mixed invertebrates from sandy sediments in five minute trial runs. It is easily constructed from PVC pipe and fittings which are available in most hardware stores at low cost. It can also be adapted for portable use in the field.     

An instrumental modification of Gerdemann and Nicolson's method for extracting VAM fungal spores from soil samples

An easily constructed apparatus for extraction of VAM fungal spores from soil samples by a modification of Gerdemann and Nicolson's wet sieving and decanting method is described. For the soils employed in this study, it proved considerably more effective and more precise than either the original wet sieving and decanting method or differential water/sucrose centrifugation. The apparatus gave results that were less subject to interference from extraneous particles than the wet sieving and decanting method. The effect of prior soil dispersion is also reported.     

Bacillus species in the intestine of termites and other soil invertebrates

Soil invertebrates harbour a complex microbial community in their intestinal system. The total number of microbes in the hindgut of soil invertebrates can reach a titre of 10(11) ml(-1). The gut microbes play an indispensable role in the digestion of food and are of ecological importance in the global carbon cycle. The gut microbiota can include a variety of micro-organisms from the three domains Bacteria, Archaea and Eucarya. The bacterial groups from the intestinal systems are mainly affiliated to the proteobacteria, the gram-positive groups Firmicutes and Actinobacteria, the Bacteroides/Flavobacterium branch and the spirochetes. The Archaea are represented by methanogens. The eukaryotic groups consist of protozoa, yeasts and fungi. Intestinal bacteria are involved in the degradation of cellulose, hemicellulose and aromatic compounds as well as nitrogen fixation. They also contribute to the redox status of the gut. Bacilli form a significant portion of the intestinal microbial community of soil invertebrates, especially among cellulose degraders. The diversity and function of bacilli in soil invertebrates will be discussed in this paper.     

A simple ion-exchange resin procedure for extracting plant-available elements from soil

Summary A simplified procedure for extracting ions from soil with ion-exchange resins is reported. The resin, placed in nylon-netting bags, were immersed in soil suspensions and shaken. Compared to the conventional procedure, where the resin beads are freely suspended in the soil-water mixture, this bag-procedure allowed quicker separation of resin from the soil suspensions. Furthermore, the severe soil grinding as done in the conventional procedure was eliminated. Phosphate was extracted from 4 Danish soils using both procedures. The bag-procedure resulted in slightly higher values than did the conventional procedure. re]19760408     

Effects of potnetial trap crops and planting date on soil infestation with potato cyst nematodes and root-knot nematodes

In 1997 and 1998 the stimulation of hatch of potato cyst nematodes (PCN) by a trap crop was studied at various times during the growing season in a container and a field experiment. Solanum nigrum‘90‐4750‐188’was used as the trap crop in both experiments and was sown on 1 May, 16 June or 1 August in two successive years on different plots. Neither experiment revealed much seasonal variation in hatchability of PCN juveniles under a trap crop. In the container experiment, the hatch of the Globodera pallida Pa3 population was equally and strongly stimulated (89%) at all sowing dates in both years, except for the 1 August sowing in 1998 (when the hatch was 77% under extremely wet soil conditions). In the control treatment with non‐hosts (flax followed by barley) the total spontaneous hatch was 50% over 2 yr. In the field experiment, the hatch of PCN, averaged over the four populations, was also equally stimulated (71%) at all sowing dates in both years. In the control treatment with non‐hosts (flax‐barley) the total spontaneous hatch was 36% over 2 yr. Total hatch under the trap crop over 2 yr varied between the four PCN populations from 63% to 80%. In 1998 and 1999, control of potato cyst nematodes (PCN) by the potential trap crops Solanum sisymbriifolium and S. nigrum‘90‐4750‐188’was studied in the field. Potato was also included as a trap crop. In the 1998 experiment, potato, S. sisymbriifolium and S. nigrum strongly stimulated the hatch of PCN compared with the non‐host white mustard (Sinapis alba). Roots of potato and white mustard were mainly found in the top 10 cm of soil, whereas roots of S. sisymbriifolium and S. nigrum were also abundant at depths of 10–20 cm and 20–30 cm. In the 1999 experiment, soil infestation with PCN decreased markedly with potato and S. sisymbriifolium as trap crops. In plots moderately to severely infested with 2‐yr old cysts (2–29 juveniles ml^?1 air dried soil), potato reduced soil infestation by 87% and S. sisymbriifolium by 77%. In plots moderately to severely infested with 1‐yr old cysts the reductions were 74% and 60%, respectively. The reduction was least on plots very severely infested with PCN (110–242 juveniles ml^?1 soil): 69% and 52% for potato and S. sisymbriifolium, respectively. Soil infestations of plots that were initially slightly to severely infested with the root‐knot nematode Meloidogyne hapla were greatly reduced under fallow and S. sisymbriifolium but increased under potato. From these and previous experiments it was concluded that, for several reasons, S. sisymbriifolium is a promising trap crop.     

6种土壤微生物提取剂的比较

比较了6种土壤微生物提取剂（6-偏磷酸钠溶液、焦磷酸钠溶液、磷酸盐缓;中液、林格溶液、NaCl溶液和水）对土壤细菌、真菌和放线菌数量的影响。结果表明：0．1％的6-偏磷酸钠（HMP）和焦磷酸钠（PYS）溶液（w／v）提取的细菌、真菌、放线菌数量最多,磷酸缓冲液（pH值7．2）对土壤真菌提取效率与焦磷酸钠和6-偏磷酸钠溶液相似,而对细菌和放线菌的提取效率则低于焦磷酸钠和6-偏磷酸钠溶液,其余3种提取剂的提取效率相对较低。     

A comparison between two methods of extracting chlorophyll-a from different phytoplankton samples

Summary A comparison has been made between chlorophyll-a estimations based on the cold acetone extraction procedure and on the hot ethanol extraction method. When comparing the results obtained with both methods a standard deviation of 20% must be taken into account. A correlation between extraction efficiency and phytoplankton species composition could not be found. Although the chlorophyll-a yield in ethanol extracts is not better than that in acetone extracts, there are several advantages in using the ethanol method, particularly the short extraction period and the cheaper procedure.     

A collection device for small electronically sorted samples from flow cytometers

A device (Hunziker chamber) has been fabricated which facilitates the collection and biochemical analysis of electrostatically sorted nuclei. The G₀ + G₁ and G₂ + M populations and the 2N and 4N populations of rat liver nuclei were sorted on the basis of light scatter or fluorescence by the fluorescent activated cell sorter (Becton-Dickinson). Sufficient amounts of nuclear samples were sorted and collected in the Hunziker chamber for the analysis of nuclear proteins by sodium dodecyl sulfate discontinuous polyacrylamide gel electrophoresis. An example of the electrophoretic banding patterns of nuclear proteins from these populations is given.     

Wireworm populations in relation to crop production: I. A large-scale flotation method for extracting wireworms from soil samples and results from a survey of 600 fields

The wireworm survey in the Eastern Counties revealed many cases where the observed wireworm damage failed to correspond with the estimated field population. A possible explanation for this was the inaccuracy of counts made by picking wireworms out of the soil samples by hand. Tests showed that such methods recovered an extremely variable proportion of the wireworms in the- samples and, on the average, only two-fifths of the larvae were obtained. A modified form of the washing and flotation technique used by Salt & Hollick (1944) was introduced for large-scale work and is described. By this method, ten samples of soil (4 in. diam. and 6 in. deep) bulked together are examined at a time and can be dealt with at the rate of 13 samples per man per hour with an efficiency of 95-100% in the extraction of wireworms. The populations estimated on 600 fields sampled between December 1942 and May 1943 have thrown more light on the size and composition of the wireworm population in grass and arable fields. Inspection of the crop results on fields tested by the washing process showed a much closer relationship between wireworm population and wireworm damage than had been obtained by the hand-sorting method in the previous year.     

A method for wet-ashing small plant samples

Summary An inexpensive but efficient and fast method is described for the wetashing of small samples of plant materials.Contribution No. 582, Department of Botany and Plant Pathology, Kansas Agricultural Experiment Station. Botany serial No. 744.     

Integrated control of potato cyst nematodes using small amounts of nematicide and potatoes with partial resistance

The control of potato cyst nematode (PCN) by less than approved amounts of nematicide combined with partially resistant potato clones was studied in a series of field experiments. On a site heavily infested with Globodera pallida only the most resistant clone (12380ac2) decreased the population density in untreated soil. With aldicarb at its full approved rate (3·36 kg ha^-1) numbers of PCN were decreased under all the genotypes, including the non-resistant Maris Piper. Aldicarb at 1·68 kg ha^-1significantly decreased populations on all clones except 12380ac2. Aldicarb at 0·84 kg ha^-1still significantly decreased population densities and multiplication rates of G. pallida on two clones with intermediate resistance (12243acl and 11233ab22). At two G. rostochiensis sites with light infestations nematode multiplication rates were greater and the control given by aldicarb and partially resistant genotypes of potato was not as great as that at the site with G. pallida. Tuber yields were not increased by the application of aldicarb at the G. rostochiensis infested sites. However, at the site heavily infested with G. pallida the yield of the most intolerant genotype (12380ac2) was increased seven-fold by the full rate of aldicarb (3·36 kg ha^-1) and four-fold by the quarter rate (0·84 kg ha^-1)-Yield of the most tolerant genotype (12243acl) was unaffected by the application of aldicarb.     

Efficiency of different methods of extracting the rice root nematode Hirschmanniella oryzae from rice and wheat soil and root samples

The nematode extraction method of centrifugal-floatation proved to be more efficient and significant (p ≤ 0.01) in extracting the rice root nematode, Hirschmanniella oryzae adults and larvae from soil or roots of rice and wheat crops than those extracted by sieving and tissue paper filtration technique. The extracted nematode from rice roots using incubation method is time-dependent and the peak of nematodes occurred four days after incubation. The number of extracted nematode varied according to crop, nematode mobility in soil particles, the number of nematodes present and tissue paper permeability.     

Device for evaporation of solvent from small samples

A device for the simultaneous evaporation of six samples under separately controlled streams of nitrogen is described.     

Effect of potato used as a trap crop on potato cyst nematodes and other soil pathogens and on the growth of a subsequent main potato crop

A field experiment in which main‐crop potatoes were grown every other year was conducted on a sandy soil from 1994 to 1999. The aim of the experiment was to control soil‐borne pathogens of potato with ecologically sound methods. Potato grown as a trap crop from the end of April to the end of June (8 wk) was used to control potato cyst nematodes (PCN) (Globodera pallida), and its effects on other important soil pathogens and on the growth of a subsequent potato crop were also assessed. Additional experimental treatments were a potato crop from which the haulm was removed and a green manure crop. Three potato cultivars with different degrees of resistance to PCN were grown as the main crop. Duplicate sets of the experiment were run concurrently. The PCN were effectively controlled by the potato trap crop. When a highly resistant potato cultivar was grown as a main crop after the trap crop, the post‐harvest soil infestation was very low. When a moderately resistant cultivar was grown after the trap crop the soil infestation also remained low. When the trap crop was alternated with a susceptible potato cultivar as a main crop, soil infestation increased slightly, but the degree of control when compared with no trap crop averaged 96%. Soil infestation with root‐knot nematodes (mainly Meloidogyne hapla) increased when potato was grown as a trap crop, but soil infestation with the root‐lesion nematode Pratylenchus crenatus was not affected. Stem canker caused by Rhizoctonia solani was not affected by the trap crop but black scurf (sclerotia of R. solani) on tubers was reduced. Soil infestation with Verticillium dahliae declined in one of the duplicate sets of the experiment but not in the other. However, stem infections by V. dahliae were significantly decreased in both sets, although the effect depended on the PCN‐resistance level of the potato cultivar. When a highly resistant potato cultivar was grown Verticillium stem infections were not significantly affected, they were decreased with a moderately resistant cultivar but the decrease was most pronounced with a PCN‐susceptible cultivar. Senescence of a following potato crop was not influenced by the trap crop when a highly PCN‐resistant cultivar was grown, but it was delayed in the case of a moderately resistant or a susceptible cultivar, resulting in higher tuber yields for those cultivars. The experiment proved that a trap crop can be an alternative to chemical soil disinfection but, for several reasons, the potato itself is not an ideal crop for this purpose; a trap crop other than potato must be developed.     

A comprehensive and user-friendly framework for 3D-data visualisation in invertebrates and other organisms

Methods for 3D-imaging of biological samples are experiencing unprecedented development, with tools such as X-ray micro-computed tomography (μCT) becoming more accessible to biologists. These techniques are inherently suited to small subjects and can simultaneously image both external and internal morphology, thus offering considerable benefits for invertebrate research. However, methods for visualising 3D-data are trailing behind the development of tools for generating such data. Our aim in this article is to make the processing, visualisation and presentation of 3D-data easier, thereby encouraging more researchers to utilise 3D-imaging. Here, we present a comprehensive workflow for manipulating and visualising 3D-data, including basic and advanced options for producing images, videos and interactive 3D-PDFs, from both volume and surface-mesh renderings. We discuss the importance of visualisation for quantitative analysis of invertebrate morphology from 3D-data, and provide example figures illustrating the different options for generating 3D-figures for publication. As more biology journals adopt 3D-PDFs as a standard option, research on microscopic invertebrates and other organisms can be presented in high-resolution 3D-figures, enhancing the way we communicate science.