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Nematode Eggs (nematode + egg)
Selected AbstractsDecrease of enteric micro-organisms from rural sewage sludge during their composting in straw mixtureJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2005A.-M. Pourcher Abstract Aims:, To study the decrease of enteric micro-organisms including viable nematode eggs, enteroviruses, faecal indicators (Escherichia coli and enterococci) and pathogenic bacteria (Listeria monocytogenes, Salmonella sp. and Clostridium perfringens) of a rural sewage sludge when it is composted for 7 months in mixture with straw. Methods and Results:, Numbers of the test organisms and the physico-chemical parameters were measured on a monthly basis on the mixture, on the compost after being turned, and on the pile in three positions representing the part by which air is incoming, the bottom of the pile and the part through which air is outgoing. The lowest temperature in the pile was observed at the bottom, where it did not exceed 50°C against 66°C in the two other areas. There were no significant differences between the three areas in terms of micro-organism survival. Infectious enteroviruses were inactivated rapidly and were not found after the first turning whereas some genomes were detected until after the third turning. Escherichia coli and enterococci presented a similar survival rate and their number decreased by 4 log10 whereas Salmonella decayed at a greater rate than L. monocytogenes. The numbers of C. perfringens decreased gradually to reach a final concentration in the mature compost of about 102 CFU g,1 dry matter (d.m.), which was similar to that of the faecal indicators. Conclusions:, The hygienic effect of sludge composting in mixture with straw results in a significant reduction of enteric micro-organisms, the concentration of the faecal indicators in the final product being <64 most probable number g,1 d.m. The concentrations of Salmonella, enteroviruses and viable nematode eggs in the final product were not detectable which is in accordance with the French legislation. Significance and Impact of the Study:, The results which pointed out the different behaviour of the test micro-organisms reflect the difficulty to propose a relevant indicator of hygienization. Otherwise, they show that composting is an efficient means for hygienization of sludge of rural wastewater treatment, where the straw is available close to their place of production. [source] Evaluating Pochonia chlamydosporia in a double-cropping system of lettuce and tomato in plastic houses infested with Meloidogyne javanicaPLANT PATHOLOGY, Issue 4 2003S. Verdejo-Lucas The effect of Pochonia chlamydosporia, a facultative fungal parasite of nematode eggs, alone or in combination with oxamyl was evaluated in a double-cropping system of lettuce and tomato in unheated plastic houses infested with Meloidogyne javanica at two sites for two consecutive growing seasons. An additional treatment of methyl bromide fumigation was included to compare crop yield in nematode-free vs. nematode-infested soil. Final population densities, reproductive rate, root gall rating, and egg production were determined after each crop. Pochonia chlamydosporia was isolated from nematode eggs up to nine months after application to soil. The fungus survived in the rhizosphere for the entire growing season at one site, but only at low densities. Final population densities of M. javanica decreased after cultivation of lettuce and increased after tomato, and this pattern of population fluctuation was unaffected by treatment, experiment or site. The reproductive rate on lettuce was equal to or below 1, and it was similar among treatments in both experiments at both sites. Eggs were not found on lettuce roots. On tomato, the reproductive rate in the fungus + oxamyl treatment was significantly lower (P < 0·05) than other treatments in experiment 1 at both sites. Fungus + oxamyl consistently reduced root gall ratings on tomato in all cases, but numbers of eggs per g root varied depending on treatment. Methyl bromide-treated plots remained free of M. javanica at the end of the 2-year study. [source] Relationship between saprotrophic growth in soil of different biotypes of Pochonia chlamydosporia and the infection of nematode eggsANNALS OF APPLIED BIOLOGY, Issue 1 2009I.A. Siddiqui Abstract The ecology of Pochonia chlamydosporia in soil and its interaction with both plant and nematode hosts are important for the successful exploitation of the fungus as a biological control agent. Differences in saprotrophism and parasitism were assessed for biotypes of P. chlamydosporia, which had originated from the eggs of cyst or root-knot nematodes. Colonisation in soils of different textures (compost, sandy loam and loamy sand) measured by the numbers of colony-forming units, differed greatly. Most biotypes were more abundant in sterilised soil of the different textures compared with non-sterilised soils. The proportion of nematode eggs parasitised in a baiting technique demonstrated that biotypes had host preferences. Those biotypes that originated from root-knot nematodes (RKN-biotypes) infected significantly more Meloidogyne hapla eggs than Globodera pallida eggs, whereas biotypes from cyst nematodes (CN-biotypes) parasitised more G. pallida eggs than M. hapla eggs. Differences in virulence between biotypes in an in vitro assay in which the fungi were placed directly onto the egg masses of M. hapla and those differences observed in the baiting technique showed similar trends. There was a negative linear correlation between the growth of the eight biotypes in soil and the proportion of eggs they infected in compatible interactions (i.e. fungal biotype originated from the same nematode genus as the target eggs). Those biotypes that infected most nematode eggs colonised soil the least extensively, suggesting that virulence may have a fitness cost. However, the relationship between saprotrophic growth and virulence is complex. The relative abundance of the different biotypes in soil in Petri dish assays was similar to that under glasshouse conditions using potato but not tomato as the plant host. Chlamydospores of some biotypes applied to soil significantly reduced (>50%) the population densities of M. hapla on tomato and of G. pallida on potato plants. Some biotypes that were both effective and virulent are good candidates for biological control of specific nematode pests. Data presented here and elsewhere indicate that RKN-biotypes have different host preferences to CN-biotypes; the specific primers based on the vcp1 gene from P. chlamydosporia rapidly confirmed the host origin of seven of the eight biotypes. [source] Use of real-time quantitative PCR to investigate root and gall colonisation by co-inoculated isolates of the nematophagous fungus Pochonia chlamydosporiaANNALS OF APPLIED BIOLOGY, Issue 1 2009S.D. Atkins Abstract The fungus Pochonia chlamydosporia is a potential biological control agent for plant parasitic nematodes, but to date, there has been little investigation of interactions (competitive, antagonistic or synergistic) between different isolates that occur together on roots and nematode galls. Real-time quantitative PCR (qPCR) has greatly improved the study of many fungi in situ on plant and nematode hosts, but distinguishing closely related isolates remains difficult. In this study, primers to discriminate P. chlamydosporia var. chlamydosporia and P. chlamydosporia var. catenulata were used to measure the relative abundance of isolates of the two varieties when inoculated singly or together on tomato plants. Also, sequence-characterised amplified polymorphic regions were identified to distinguish two different isolates of P. chlamydosporia var. chlamydosporia. Individual 1-cm root segments and nematode galls were excised, DNA extracted and subjected to real-time qPCR with the discriminatory primers. The qPCR method proved sensitive and reproducible and demonstrated that roots and nematode galls were not uniformly colonised by the fungi. Results indicated that the P. chalmydosporia var. catenulata isolate was more abundant on roots and eggs than P. chlamydosporia var. chlamydosporia, but all the isolates infected a similar proportion of nematode eggs. There was an indication that the abundance of each fungal isolate was reduced in co-inoculation experiments compared with single inoculations, but the number of root segments and galls colonised was not statistically significantly different. [source] Glyphosate applied to genetically modified herbicide-tolerant sugar beet and ,volunteer' potatoes reduces populations of potato cyst nematodes and the number and size of daughter tubersANNALS OF APPLIED BIOLOGY, Issue 3 2000A M DEWAR Summary Glyphosate, applied early or later or twice to genetically modified glyphosate-tolerant sugar beet, gave excellent control of planted ,volunteer' potatoes growing within the crop compared to conventional herbicide programmes with or without clopyralid. In three out of four trials, this resulted in significant reductions in the numbers of eggs and cysts of potato cyst nematodes (Globodera rostochiensis and G. pallida) where infestations were moderate (23,89 eggs g,1 soil). In the fourth trial, which had very high initial populations (130 eggs ,1 soil), none of the herbicide treatments had any significant effect on numbers of nematode eggs or cysts. This was probably due to competition for feeding sites, and the early death of the potatoes in all treatments caused by feeding damage by the nematodes and infection by blight, which prevented the nematodes from completing their life cycle. Glyphosate also significantly reduced the number and size of daughter tubers produced, thus helping to prevent a further volunteer problem in the next crop in the rotation. This was achieved by one or two applications of one chemical compared to 2,5 applications of cocktails of conventional herbicides. [source] | ||||||||||