Comparison of ecological indices between limed and no limed indicates that number of genera and the maturity of the soil nematode community were smaller in no limed soil, indicating that soil health and function were adversely affected. Through those re- sults it can be concluded that nematode community structure have been little influenced by changes in environmental conditions. Even though in this study the nematode genera was the highest with P applica- tion (Fig. 1), Sarathchandra et al. (2001) found that total nematode genera showed a general increase (statistically insignificant) as the application rate of P increased from 0 to 100 kg and that some of these re- sults confirm that phosphate fertiliser at least has no significant (neither adverse nor beneficial) effects on soil microbial populations.
The wild-type C. elegans Bristol strain N2 was obtained from Caenorhabditis Genetic Centre (CGC), USA, and culture was maintained on nematode growth medium (NGM) plates seeded with Escherichia coli strain OP50 at 20 °C, using the standard method . Young adult (3 days old) synchronized culture were used in all the experi- ments. Worms were incubated at 20 °C for 24 h without a food source and were then subjected to the analysis . Nematodes were exposed to three different-sized ZnO- NPs (10, 50 and 100nm). The test consisted series of seven ZnO-NP concentrations (0.1–2.0 g/l). NPs were diluted in K-medium (32 mM KCl, 51 mM NaCl) following Williams and Dusenbery  and buffered in 140 mM sodium acetate (pH 6.0) to avoid aggregation. Each treatment was replicated for three times, and control (K-medium + buffer) was maintained for the entire test.
The maturity index (MI) is a measure of environmental disturbance calculated for non-plant feeding taxa (Neher and Darby, 2006) where low MI indicates a disturbed environment while high MI indicates a more stable environment (Bongers, 1990). MINO is similar to MI but normally excludes the c-p 1 nematodes as they are known to be highly opportunistic nematodes. Ferris and Bongers (2009) stated that when resources become available to soil organisms through soil amendments, environmental changes or disturbance, there is an enrichment pulse of opportunistic guilds. These two indices were both significantly different between the farming systems in both sites whereby highest values were found in the non-amended systems. This may be due to lack of amendments that are known to disturb the soils thus affecting nematode communities’ presence.
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In arid and semi-arid regions, soil nematode commun- ities vary considerably with seasonal rainfall and soil moisture [24-26]. In arid or semi-arid ecosystems, the effects of fire on soil nematode communities may be directly or indirectly influenced by rainfall and soil moisture [27,28]. Moreover, changes in soil structure as a consequence of increasing water evaporation from soil pore caves lead to increases in the predation success of soil free-living nematodes on soil microorganisms . Since there were no studies of the effects of fire on soil decomposition processes, soil nutrient availability, and soil biota in arid juniper savannas, we designed a series of studies to examine the effects of fire on soil processes and soil biota. We hypothesized that the effects of fire on soil nematodes in an arid savanna ecosystem would be very different from those in mesic forests  because of seasonal differences in soil moisture. Therefore, we de- signed studies to examine the seasonal effects of pre- scribed fire on soil nematode communities in montane juniper (Juniperus monosperma) savannas.
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(1990). On the other hand, Bongers et al. (1997) reported that the value of MI decreases with in- creasing nutrient status. However, in our study, the MI in site 1 was the lowest. The result that the MI in site 1 was lower and PPI in site 1 was higher than those in the other sites seems also dif- ferent from that reported by Bongers et al. (1997). The reason for this difference was probably the poor nutrient status in site 1 (soil salt content was high, organic matter and total nitrogen content were lower). In fact, the environmental factors that can affect the nematode population are very complicated. For example, soil physical chemistry characteristics or up-ground vegetation have the effects on nematode population. Therefore, further studies on soil nematode and soil environment of different succession stage in Yellow River Delta will be necessary.
Ambiguity exists concerning the effects of cli- mate on soil nematode-community composition. In this study, we examined the free-living nema- tode communities in soil along a climatic gra- dient representing humid-Mediterranean, Medi- terranean, semi-arid, and arid climate types. The relationships between abiotic soil characteris- tics (organic carbon, soil moisture (SM), wa- ter-holding capacity) and nematode parameters, such as abundance, trophic group composition, and diversity indices, were explored in the con- text of climate and seasonality. Nematode abun- dance was lowest at the arid site. At the humid- Mediterranean and Mediterranean locations, ne- matode abundance reached its peak in winter, while at the semi-arid and arid sites, an almost opposite trend was observed, with lowest abun- dances in winter, presumably due to a nutrient washout from the soil profile during the rainy season. On the trophic level, one trophic group demonstrated a positive correlation with SM and one trophic group demonstrated a negative one at each location, while the other two groups re- mained constant. Fungi-feeding nematodes were found to be unaffected by SM at the humid- Mediterranean and Mediterranean locations, while at the semi-arid and arid sites their proportion increased in correlation with decreasing SM. Bacteria-feeders increased with SM at the arid site, were unaffected at the semi-arid location, and decreased with SM at the humid-Mediter- ranean and Mediterranean sites. Plant-parasites were associated with SM only at the humid- Mediterranean site. Omnivores-predators were positively affected by SM at the two middle lo- cations, staying constant at the humid-Medi- terranean and arid sites. These findings point to
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Meloidogyne incognita and H. glycines hatch from eggs in soil and penetrate plant roots as motile second-stage juveniles (J2). There they establish feeding sites in root vascular tissues and develop to reproductive maturity as sedentary endoparasites. These species of nematode are obligate biotrophs that must feed from live cells and require the parasitism of a host to complete their life cycle. Due to this life style, M. incognita and H. glycines damage their host plants but rarely to the point of death of the host. Symptoms common in plants during infection of root knot nematode or soybean cyst nematode include stunting, incipient wilt, chlorosis, leaf drop and increased susceptibility to other disease that all contribute to reduced yield (Mitkowski and Abawi, 2003).
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The effects of cowpea (Vignaunguiculata) and groundnut (Arachis hypogea) on succeeding sorghum yields, soil mineral N and nematode in- festation were studied during five cropping sea- sons (2000 to 2004) in a weakly acid Ultisol of the agronomy research station of Farakô-Balo- cated in the Guinean zone of Burkina Faso, West Africa. A factorial 5 × 5 design of five crop rota- tions with five fertilizer treatments in a split-plot arrangement with four replications was used. Sorghum yields were affected by the two factors (rotation with legumes and fertilizer applications) during the four years. But interactions were not observed between the two factors. Monocrop- ping of sorghum produced the lowest yields and legume-sorghum rotations increased sorghum yields by 50% to 300%. Groundnut-sorghum and cowpea-sorghum rotations increased soil mi- neral N by 36% and 52%, respectively. Crop ro- tation influenced nematode infestation but the effects on soil and sorghum root infestation dif- fered according to the rotation. The cowpeasor- ghum rotation increased soil and sorghum root infestationby nematodes while groundnut-sor- ghum decreesed the nematode population. The soil of the cowpea-sorghum rotation contained 1.5 to 2 times more nematodes than the soil of the monocropping of sorghum. In contrast, the soil of the groundnut-sorghum rotation con- tained from 17 to 19 times fewer nematodes than that of themonocropping of sorghum. However, nematode infestation did not affect any of the succeeding sorghum yields. It was concluded that the parasitic effect of nematodes was lim- ited by the predominance of positive N-effects
As for the injection method, two concentrations of Vapcomic as biocide (1 ml abamectin a.i. + 9 ml tap water) and (2 ml abamectin a.i. + 8 ml tap water) were prepared and injected as two treatments immediately with 10 ml disposable syringe into the center of the plant pseudostem at a distance about 25 cm below the first leaf axil at 45 angle down wards then, wait 15-20 seconds before withdrawal of the empty syringe. Then, a plaster tape was stuck above the injection pore for retention of the biocide within plant. Soil and root samples of each treatment were obtained on 45 days intervals after the application time throughout April to July, then the
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Pratylenchus was the most prevalent and abundant nematode in all the AEZs. This lesion nematode has a wide host range including cereals, legumes, fruits and vegetables (Hunt et al., 2005). The extensive nature of agriculture in the study area would therefore favour higher population of this nematode. Pratylenchus spp. is a common pest in agronomic settings and is responsible for significant yield losses worldwide. In Kenya for example, it is the most important nematode parasite of maize (Kimenju et al., 1998) and it has been identified in cabbage in Kenya (Waceke, 2007). In Turkey, Mennan and Handoo (2006) recorded presence of lesion nematode in cabbage while Pratylenchus penetrans has been shown to cause wilting and death of cabbage (Acedo and Rohde, 1968).
Nematodes are microscopic eelworms of nearly a hundred thousand species, capable of causing serious abnormality in a wide range of crops. It is a soil-borne pest that causes stunted and unproductive plants. When root knot nematodes (Meloidogyne species), for example, burrow into the roots they stimulate the development of root galls, which become swollen, warty, disfigured and knotty. Plant nematodes can be a real problem in sandy and calcareous soils. They invade growing plant roots and create visible blockages called galls, often described as root knots, which multiply in soil until they eventually destroy the okra.
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Cobb’s method was designed on the principle of differences in shape, size and weight of nematodes and their motility. It is easy to use and can avoid sophisticated apparatus. But it is laborious and can’t provide accurate result in quantitative measurement. On the other hand, the AZC method was designed on the principle of differences in density of suspension and nematodes. Moens and Viaene  observed that alive or preserved nematode and even cysts could be extracted by this method. This method is relatively faster and can obtain clear nematode suspension. But this method alter the shape and influence the vitality of nematodes hence it limits the pathogenicity test or identification. From our results, it is clearly observed that the efficiency of AZC method in extracting vermiform nematodes is superior compare to Cobb’s method. McSorley and Frederick  also reported the superiority of centrifugation method in extracting vermiform nematodes which was similar with our results. The huge cost of AZC apparatus could be minimized by community based farming where this method could be used by many farmers. This apparatus also could be organized institutionally where soil samples could be sent and analyzed by simple cost.
Tomato plants from the variety "Santa Cruz" were sown in polyethylene vases with 4 L capacity, using five seeds per vase filled with a mixture of soil, sand and manure in a ratio 3:2:1 (v/v). This substrate was previously treated with Dazomet (Basamid) at a dose of 50 g/m 2 , and then kept under rest for seven days in order to eliminate all possible phytoparasitic nematodes and other microorganisms. Fifteen days after plants emergence, thinning was done, considering the strength and height of the plant and leaving only one plant per vase as for the evaluation of the extracts.
Abstract: Field experiments were conducted in 2013-14, 2014-15 and 2015-16 planting seasons to evaluate the efficacy of different sources of organic materials and a nematicide Furadan 5G in the control of Meloidogyne incognita infection on the major spices onion, Allium cepa L. The organic materials (poultry refuse, mustard oil cake, rice bran and sawdust) were incorporation with the soil 3 weeks before transplanting of onion seedlings whereas Tricho-composts were added in the soils 5 days before seedling transplanting. The results showed that different organic materials displayed varying levels of effective to the nematode infection. All the treatments gave satisfactory reduction of gall development on roots and increased plant growth as well as yield of onion. Among the treatments, Tricho-composts and poultry refuse appeared to be the best amendments for root knot nematode reduction and significantly influenced the growth of the onion with the highest yield. Saw dust, rice bran and nematicide Furadan 5G were also proved to be better amendment for reduction of root knot nematode which enhanced plant growth and increased yield of onion. These results suggest that exploitation of organic soil amendment in nematode management would be a useful control measure in onion production in Bangladesh.
each of the four anthelmintic drug classes described above, genetic selection approaches have been used to identify the genes involved in modes of action and resistance. However, all of these approaches used the laboratory-adapted N2 strain, which is just one strain in the C. elegans species and does not represent the diversity of genetic backgrounds present across the entire species . Wild isolates of C. elegans can facilitate studies of how natural diversity affects the response to anthelmintics, which could recapitulate responses found in natural parasitic nematode populations. C. elegans is sampled from diverse niches worldwide (Figure 2A), and these strains are readily available from the C. elegans Natural Diversity Resource (CeNDR) . Quantitative genetic studies correlate phenotypic differences across a set of individuals with genetic differences across the same set of individuals . Genomic regions that harbor correlated genetic differences are called Quantitative Trait Loci (QTL). Such loci can be narrowed further to single genes and ultimately specific variants that underlie quantitative traits. This approach can be applied to anthelmintic drug responses to discover modes of action and resistance mechanisms.
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Modern computerized harvest-management and data systems offer new opportunities for more precise management of nematodes and general crop production. This technology has the potential to improve water use and limit fertilizer and pesticide application on a spatial and temporal basis as dictated by soil fertility and, more important, differential spatial crop yields. Based on early results, this management tool should allow specially prescribed nematode control in high-intensive crop production such as Radopholus similis on banana (DH Marin-Vargas, personal communication) and root-knot nematodes on potato in the northwestern United States. Approaches that focus on a harvest index to locate environmental stress should be able to relate nematode kinds and numbers to poor yield and other stress factors. This approach is now being used in some banana operations in which fruit is harvested in small subunits and yield data are recorded and analyzed by computer (DH Marin-Vargas, personal communication). Poor-yielding sections can be examined for nematode densities and other potential problems  .
Experimental data on biocontrol activity of nematopha- gous fungi in orchards are minimal. In a kiwifruit orchard, populations of P. chlamydosporia and Purpureocillium lilacinum were dominant species infecting root-knot nem- atodes (Mertens and Stirling 1993). Chlamydospores are the survival stage of fungi and their germination is trig- gered by nutrients leaking from roots, or by the presence of organic matter (De Leij et al. 1993). P. chlamydosporia is a saprotrophic in soil and could grow on crop residues (Dallemole-Giaretta et al. 2011). The continual presence of endoparasitic nematodes in an undisturbed environ- ment such as perennial crops provides a food source for P. chlamydosporia, while during the unfavorable season of winter, the fungus would survive by switching to the saprophytic stage using organic matter instead of nema- tode hosts (Stirling 2014).
comparisons a reasonable objective. The original paper goes on to test the effect of sowing date based on degree days. (Thompson 2015) reported a 61% increase in yield on average from sowing the susceptible, intolerant cultivar Gatcher at the end of May than sowing it in the third week of June. By June the soil temperatures and nematode populations were both greater, leading to lower wheat yield. The effects were less pronounced in the moderately resistant cultivar, GS50a, but were similar with a reduction in nematode population densities occurring due to earlier planting.
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The extraction of plant-parasitic nematodes from cassava soil and root samples was carried out at the Department of Crop and Soil Science Laboratory, Faculty of Agriculture, University of Port Harcourt. The modified Baermann’s method (Whitehead and Hemming, 1965; Coyne et al., 2007) was used in the extraction of plant parasitic nematodes from soil samples. Soil in each plastic bag were placed in a different labeled dish and sieved to remove stones and dirt and then mixed thoroughly. The procedure include placing a facial tissue in a plastic sieve with an extraction tray under it, 200 ml soil sample was poured on the facial tissue, then water was added to the extraction plate. The extraction set up was allowed to stay for 48 hours after which the sieve was removed and the nematode suspension was poured into a labeled beaker. The suspension was allowed to settle for six hours after which it was decanted and the suspension containing nematodes were poured into 10 ml vials and preserved in the refrigerator at 4 0 C prior to identification and counting. The vials containing nematode suspension were later sent to Nematology Research Laboratory, International Institute for Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria in heat-insulated boxes for identification and counting.
Heavy metals contamination in soil has become a widespread problem all over the world. As a consequence of rapid social and economic development over the past several decades, soil pollution by heavy metals has been both serious and widespread in China -. Although heavy metals may occur naturally in soil based on the origin of soil, additional contributions come from various source including agricultural activities, urbanization, industrialization, and mine activities. Among these, mine activity is considered as one of the most influential anthropogenic activities which results in changes in landscapes, destruction of habitats, contamination of soil and water, and degradation of land resources -.