Hatching and development of maize cyst nematode Heterodera zeae infecting different plant hosts

The occurrence, distribution, and rapid molecular detection technology of Heterodera zeae Koshy et al. 1971, have been reported in China. We explored the biological characteristics of H. zeae sampled in Henan Province, China to understand its interaction with plants. Cysts and second-stage juveniles(J2s) were identified under an optical and scanning electron microscope, internal transcribed spacer(ITS) phylogenetic tree, and sequence characterized amplified region(SCAR)-PCR analyses. The optimum hatching temperatures of H. zeae were 30°C and 28°C, with cumulative hatching rates of 16.5 and 16.1%, respectively, at 30 days post-hatching(dph). The hatching rate of H. zeae eggs was improved by 20-and 50-time maize soil leachate and root juice, and 10-time root exudates. The hatching rate in 10-time root exudates was the highest(25.9%). The 10-time root exudates of maize and millet produced the highest hatching rate at 30 dph(25.9 and 22.9%, respectively), followed by wheat(19.9%), barley(18.3%), and rice(17.6%). Heterodera zeae developed faster in maize than in other crops. Fourth-stage juveniles(J4s) were detected in maize roots 8 days post-inoculation(dpi) at 28°C but not in other crops. Combined with hatching tests, the Huang–Huai–Hai summer maize region and the south and central-southwest mountainous maize areas are highly suitable for H. zeae in China. This is the first systematically study of the hatching and infection characteristics on different plant hosts of corn cyst nematode H. zeae in temperate regions. This study laid a theoretical foundation for the rapid spread and high environmental adaptability of corn cyst nematode.

Prevalence and ecological factors affecting the distribution of plant-parasitic nematodes in Prunus groves in Spain

A wide survey was conducted to study plant-parasitic nematodes(PPNs)associated with Prunus groves in Spain.This research aimed to determine the prevalence and distribution of PPNs in Prunus groves,as well as the influence of explanatory variables describing soil,climate and agricultural management in structuring the variation of PPNs community composition.A total of 218 sampling sites were surveyed and 84 PPN species belonging to 32 genera were identified based of an integrative taxonomic approach.PPN species considered as potential limiting factors in Prunus production,such as Meloidogyne arenaria,M.incognita,M.javanica,Pratylenchus penetrans and P.vulnus,were identified in this survey.Seven soil physico-chemical(C,Mg,N,Na,OM,P,pH and clay,loamy sand and sandy loam texture classes),four climate(Bio04,Bio05,Bio13 and Bio14)and four agricultural management variables(grove-use history less than 10 years,irrigation,apricot seedling rootstock,and Montclar rootstock)were identified as the most influential variables driving spatial patterns of PPNs communities.In particular,younger plantations showed higher values for species richness and diversity indices than groves cultivated for more than 20 years with Prunus spp.Our study increases the knowledge of the distribution and prevalence of PPNs associated with Prunus rhizosphere,as well as on the influence of explanatory variables driving the spatial structure PPNs communities,which has important implications for the successful design of sustainable management strategies in the future in this agricultural system.

Effect of land use on soil nematode community composition and co-occurrence network relationship

Land use influences soil biota community composition and diversity,and then belowground ecosystem processes and functions.To characterize the effect of land use on soil biota,soil nematode communities in crop land,forest land and fallow land were investigated in six regions of northern China.Generic richness,diversity,abundance and biomass of soil nematodes was the lowest in crop land.The richness and diversity of soil nematodes were 28.8and 15.1%higher in fallow land than in crop land,respectively.No significant differences in soil nematode indices were found between forest land and fallow land,but their network keystone genera composition was different.Among the keystone genera,50%of forest land genera were omnivores-predators and 36%of fallow land genera were bacterivores.The proportion of fungivores in forest land was 20.8%lower than in fallow land.The network complexity and the stability were lower in crop land than forest land and fallow land.Soil pH,NH_(4)^(+)-N and NO_(3)^(–)-N were the major factors influencing the soil nematode community in crop land while soil organic carbon and moisture were the major factors in forest land.Soil nematode communities in crop land influenced by artificial management practices were more dependent on the soil environment than communities in forest land and fallow land.Land use induced soil environment variation and altered network relationships by influencing trophic group proportions among keystone nematode genera.

A spatio-temporal multi-scale fusion algorithm for pine wood nematode disease tree detection

Pine wood nematode infection is a devastating disease.Unmanned aerial vehicle(UAV)remote sensing enables timely and precise monitoring.However,UAV aerial images are challenged by small target size and complex sur-face backgrounds which hinder their effectiveness in moni-toring.To address these challenges,based on the analysis and optimization of UAV remote sensing images,this study developed a spatio-temporal multi-scale fusion algorithm for disease detection.The multi-head,self-attention mechanism is incorporated to address the issue of excessive features generated by complex surface backgrounds in UAV images.This enables adaptive feature control to suppress redundant information and boost the model’s feature extraction capa-bilities.The SPD-Conv module was introduced to address the problem of loss of small target feature information dur-ing feature extraction,enhancing the preservation of key features.Additionally,the gather-and-distribute mechanism was implemented to augment the model’s multi-scale feature fusion capacity,preventing the loss of local details during fusion and enriching small target feature information.This study established a dataset of pine wood nematode disease in the Huangshan area using DJI(DJ-Innovations)UAVs.The results show that the accuracy of the proposed model with spatio-temporal multi-scale fusion reached 78.5%,6.6%higher than that of the benchmark model.Building upon the timeliness and flexibility of UAV remote sensing,the pro-posed model effectively addressed the challenges of detect-ing small and medium-size targets in complex backgrounds,thereby enhancing the detection efficiency for pine wood nematode disease.This facilitates early preemptive preser-vation of diseased trees,augments the overall monitoring proficiency of pine wood nematode diseases,and supplies technical aid for proficient monitoring.

Selectivin:A nematicide from parasitic nematodes-specifically activated chemical

The latest study published in Nature by Andrew R.Burns,Peter J.Roy and co-authors is highlighted in this paper,they investigated a series of novel nematicidal compounds,including Selectivin-A and Selectivin-E,and explored their mechanism of action.Experiments have displayed that the Selectivin compound is inactive to human cells,fish,fungi,insects and even beneficial nematodes.In the exploration of its mechanism of action,it was found that the mechanism of action of Selectivin is different with those of commercial nematocides:Selectivin needs to be activated by biotin produced by nematodes,after that they can be transformed into compounds with high nematicidal activity.This proves that the family of Selectivin compounds has the advantages of high selectivity and environmental friendliness,and their mechanism of action is completely new,proposing a completely new path for the development of new nematicides.

Soil nematode community structure on the northern slope of Changbai Mountain, Northeast China

Soil nematode communities were investigated in the Changbai Mountain in Broad-leaved Korean Pine forest, Korean Pine and spruce-fix mixed forest, Dark Coniferous forest, Erman＇s birch forest and Alpine tundra along different altitude gradients from 762 m to 2 200 m a.s.l. Soil animal samples were collected from the litter layer and the soil depth of 0-5 cm, 5-10 cm and 10-20 cm at each site in the spring of 2001 and 2002. In total 27 nematode families and 60 genera were observed. The dominant genera were Plectus Bastian and Tylenchus Bastian and most of them live in litter layer. The total number of soil nematode was significantly correlated with soil moisture （r=0.357; p〈0.01）. Nematodes were classified in bacterivores, fungivores, plant parasites, omnivores-predators, and omnivores according to known feeding habitats or stoma and esophageal morphology. Species richness of fungivorous nematode was higher than others in different vegetation communities and soil depths. The total number of soil nematode and trophic groups varied significantly （o〈0.05） in response to different soil depths. The fungivore/bacterivore ratio （F/B） and the ratio of （fungivores ＋ bacterivores）/plant-parasites （WI） also changed significantly （p〈0.05） in different soil depths. In conclusion, soil moisture is proved to be one of the most important variables affecting nematode density and trophic composition, and the altitude gradient does not significantly affect the ecological indices of soil nematode such as trophic diversity （TD） and the Shannon index （H＇）.

Identification of Endophytic Bacillus BHL3501 from Wild Soybean and Its Inhibitory Effect against Soybean Cyst Nematode (Heterodera glycines Ichinohe)

[ Objective] The paper was to identify endophytic bacillus BHL3501 from wild soybean and its inhibitory effect against soybean cyst nematode. [ Meth- od] Through morphological characteristic, physiological and biochemical characteristics and 16S rDNA analysis, a strain of endophytic bacterium BHL3501 with ne- maticidal activity isolated and screened from the root of wild soybean was identified, the effects of BHL3501 metabolite solutions with different dilution multiples on egg hatching and activity of 2rd instar juvenile of soybean cyst nematode were also studied. [ Result ] BHL3501 strain was preliminarily identified to be Bacillus sp.. The relative inhibitory rate of its original fermentation broth on egg hatching of soybean cyst nematode after 24 h was 98.3% ; the relative inhibitory rate under 10- time diluted solution treatment was 79.5%, which had significant difference with sterile water control. The corrected mortality rate of 24 instar juvenile was 93.1% after treated by original fermentation broth for 24 h, the treatments of all diluted solutions had significant difference with sterile water control. [ Conclusion ] BHL3501 metabolites had strong inhibitory effect against egg hatching of soybean cyst nematode, which also had strong toxic effect on its 2nd instar juvenile.

Study on the Activity of Herbal Extract to Kill Root-knot Nematode of Cucumber Seedlings Stage

Present mature plants hydroponic technology was used,combined with some excellent characteristics,such as growth conditions was easy to control and process of root growth was easy to continuously observe,the nematicidal activity of 5 kinds of Chinese herbs extracts and the compound solution of Avermectin,with strong contact toxicity effect indoor,was systematically studied and investigated the affection on the root-knot nematode parasitized on the cucumber seeding stage. It is found that under the premise of no influence on root growth of cucumber,extracts from Picrorhiza scrophulariiflora and Punica granatum showed strong prevention and nematicidal activity,and had the similar efficacy of Avermectin; while the extracts from Cibotium barometz,Aucklandia lappa Decne and Fructus cnidii showed low nematicidal activity and various degrees inhibition effect on plant growth.

Investigation on Pathogenic Factors of Tobacco Root-Knot Nematode Disease in Gengma County,Yunnan Province

Tobacco root-knot nematode disease has caused severe damage in Geng- ma County, Yunnan Province. In order to identify the pathogenic factors of the tobac- co root-knot nematode disease in this county, the pathogenic nematodes, hosts and environment of tobacco fields in Mengsa, Hepai and Sipaishan 3 main tobacco-grow- ing towns in Gengma County were investigated and analyzed based on the local re- lated field survey on tobacco root-knot nematode disease in this county in 2012. The results showed the incidence and severity of the tobacco root-knot nematode disease were all higher than those of previous years. dominant pathogens of the tobacco root-knot The species identification showed the nematode disease were Meloidogyne arenaria and M. javanica in Gengma County. The lacking of disease-resistant culti- vars, poor management and climatic anomaly were the main causes of the tobacco root-knot nematode disease in Gengma. According to the occurrence characteristics of the disease, the agricultural prevention-based control measures were proposed.

Effect of Anti-nematode Preparations on Physiological Traits of Tomato Leaves Affected by Root-knot Nematode

[ Objective ] The paper was to study the effects of anti-nematode preparations with different mechanisms on changes of enzyme systems and membrane permeability of tomato leaves, so as to provide reference basis for effective control of soil root-knot nematode in greenhouse. [ Method] With tomato seedlings af- fected by root-knot nematode as material, changes of superoxide dismutase（SOD）, peroxidase（ POD）, relative conductivity and malondialdehyde （MDA） in toma- toes were tested after the seedling soil was treated by preparations of Wuxianmei, Hailvsu, Duxiandna and Avermectin. [ Result] After treated by different prepara- tions, SOD and POD activity of tomato leaves were higher than control, and that treated by Wuxianmei was the highest. In addition to Duxiandna, the relative con- ductivity and MDA content of other treatments were significantly lower than control. When tomatoes were planted for 70 d, the effect of Avermectin against reot-knot nematode Was the best of 66.3%. [ Conclusion] After tomatoes were infected by root-knot nematode, different preparation treatments all had certain control effect, which made the physical indicators of tomato have obvious change. Integrated control of multiple preparations in greenhouse was beneficial to control soil root-knot nematode.

“Cyst nematode”中文译名应该为“孢囊线虫”

农作物孢囊线虫病害(crop cyst nematode diseases)近年来已经成为威胁我国农业生产安全的重要植物病原线虫病害,鉴于国内部分有关学术论著与文献中,对"cyst nematode"的中译名写法有歧义,作者通过文献的阐述与论证,认为"cyst nematode"的中译名称应该为"孢囊线虫",而不用"胞囊线虫",以免引起混乱。

Study on Controlling Tobacco Root-knot Nematode by Fertilizer and Pesticide Synergy

Synergism between pesticide and fertilizer in controlling root-knot nematode was investigated by field randomized block test. The results showed that the best control efficiency was shared by 0.5% abamectin and 25% mixed pesticide （abamectin and carbosulfan）, 24.1% and 28.0%, respectively. The positive effect was found by synergism between pesticide and fertiUzer in controlling reot-knot nematode. The economic benefit and agricultural benefit were gained by controlling root-knot nematodes. The results suggested that the agricultural and ecological benefit could be gained through the integration of agricultural practice and chemical technology in controlling root-knot nematode.

Effect of heavy metals on soil nematode communities in the vicinity of a metallurgical factory

The influence of Cu and Zn on soil nematode communities was examined along a pollution gradient with increasing distance from a metallurgical factory. Total and available heavy metal contents were used to study the effects of heavy metals on nematode abundance, trophic groups and ecological indices. The results demonstrated significant correlations between the number of total nematodes, bacterivores, plant-parasites and the total and available heavy metals. Bacterivores and plant-parasites were the dominant trophic groups. Significant differences in different sampling sites were found only in the number of bacterivores（P〈0.01）. The Shannon-Weaver diversity index（W）, trophic diversity index（TD）, evenness index（J＇） and dominance index（λ） were found to be sensitive to soil pH and C/N ratios. Significant correlations were found between the total nematodes （TNEM）, some genera （A crobeloides, Aphelenchoides, Cephalobus, Ditylenchus, Mesorhabditis, Tetylenchus and Tylenchus） and distance from the factory.

The synergistic advantage of combining chloropicrin or dazomet with fosthiazate nematicide to control root-knot nematode in cucumber production

The highly-damaging root-knot nematode(Meloidogyne spp.,RKN)cannot be reliably controlled using only a nematicide such as fosthiazate because of increasing pest resistance.In laboratory and greenhouse trials,we showed that chloropicrin(CP)or dazomet(DZ)synergized the efficacy of fosthiazate against RKN.The combination significantly extended the degradation half-life of fosthiazate by an average of about 1.25 times.CP or DZ with fosthiazate reduced the time for fosthiazate to penetrate the RKN cuticle compared to fosthiazate alone.CP or DZ combined with low or medium rate of fosthiazate increased the total cucumber yield,compared to the use of each product alone.A low-dose fosthiazate with DZ improved total yield more than a low dose fosthiazate with CP.Extending the half-life of fosthiazate and reducing the time for fosthiazate or fumigant to penetrate the RKN cuticle were the two features that gave the fumigant-fosthiazate combination its synergistic advantage over these products used singularly.This synergy provides the opportunity for farmers to use a low dose of fosthiazate which lowers the risk of RKN resistance.Farmers could combine DZ at 30 g m^-2 with fosthiazate at a low rate of 0.375 g m^-2 to control RKN and adequately control two major soil-borne diseases in cucumber greenhouses.

Current Status of Soil-transmitted Nematode Infection in China

Objective To carry out national surveys for ascertaining the current status and trends of soil-transmitted nematode infections in China, providing scientific basis for further developing control strategies. Methods In 1988-1992 （hereinafter abbreriated as ＂survey in 1990＂）, a stratified cluster random sampling method was used in the survey. In 2001-2004 （hereinafter abbreriated as ＂survey in 2003＂）, in order to compare with the survey in 1990, two-characteristic stratified cluster random sampling method was used and 687 investigation spots were sampled from the 2848 spots selected in the survey in 1990. Kato-Katz thick smear method was used to examine the eggs of soil-transmitted nematodes in fecal samples. Results The prevalence rates were 53.6% and 19.6% for soil-transmitted nematodes, 14.6% and 6.120% for hookworms, 44.6% and 12.7% for Ascaris lumbricoides, 17.4% and 4.630% for Trichuris trichiura in survey 1990 and survey 2003, respectively. The prevalence rates of soil-transmitted nematodes were higher in 13 provinces than the average level in China in the survey in 1990, and higher in 8 provinces than the average level in the survey in 2003. The prevalence of hookworms, Ascaris lumbricoides, Trichuris trichiura and the overall prevalence of soil-transmitted nematodes were higher in females than in males. It is estimated from the results of survey in 2003 that the number of persons with soil-transmitted nematode infections in the country is about 129 million, less than that in the survey in 1990. Conclusion The prevalence of soil-transmitted nematodes has declined considerably but is still relatively high in some provinces and autonomous regions. Control activities and socioeconomic development may have contributed to the decreased prevalence.

Advance of entomopathogenic nematodes

This paper summarized the history and present condition of studying and utilizing entomopathogenic nematodes at home and abroad, expounded its taxonomy, life cycle and the mechanism with symbiotic bacteria killing host insect. Taxonomy, mycelial form, pathogenic function and anti-bacteria function of symbiotic bacteria were introduced. Production and utilization of entomopathogenic nematodes, the characteristic genetic improvement by use of biological engineering technology, as well as the existing problem and applying foreground were also discussed.

Species composition and distribution of marine nematode community in the North Taiwan Strait

Marine free-living nematodes were investigated at 13 sampling stations divided into three transects in the northern Taiwan Strait in February 1998. One hundred species of marine nematodes belonging to 91 Genera 28 Families 3 Orders were identified and were first recorded in the northern Taiwan Strait. The dominant species were Vasostoma sp., Sabatieria sp. 1, Linhystera sp. 1, Spilophorella sp., Daptonema sp., Halalaimus sp. and Dorylaimopsis variabilis. Their main densities were all over 4 950 ind./m2. According to mean density at transects, marine nematode density decreased from coastal Weitou to off Minjiang Estuary, which was similar to polychaete distribution in northern Taiwan Strait. The selective deposit feeder (1A) was the dominant food type of marine nematodes in the northern Taiwan Strait, but non-selective deposit feeders (1B) and epigrowth feeders (2A) occupied high proportion, indicating diverse feeding types of marine nematodes in the northern Taiwan Strait. Some environmental factors such as currents are discussed.

Two new free-living nematode species (Comesomatidae) from the mangrove wetlands in Fujian Province, China

Two new free-living marine nematode species from the mangrove wetlands of Fujian Province, China are identified and illustrated. Sabatieria conicoseta sp. nov. is characterized by its short conical somatic setae. There are 12-15 tubular pre-cloacal supplements and 12-15/Jm long straight gubernacular apophyses. Dorylaimopsis papilla sp. nov. is characterized by spicules which are 1.5-1.8 a. b. d, long with media cuticularized strip along entire spicules, and have a cephalated proximal end with small hooked. There are 16-18 small papillate precloacal supplements and 37-40 μm long dorso-caudal gubernacular apophyses.

Vertical distribution of plant nematodes in an aquic brown soil under different land uses

The vertical distribution of the dominant genera of plant nematodes at the depth of 0–150 cm of an aquic brown soil were studied for four land use patterns, i.e., paddy field, maize field, fallow field and woodland in the Shenyang Experimental Station of Ecology, Chi- nese Academy of Sciences in November of 2003. The results showed that the numbers of some dominant genera under different land uses decreased with the increase of soil depth. Helicotylenchus was most dominant genus under each land use type. Genera of Filenchus, Psilen- chus and Tylenchus in paddy field occurred at the depth of 0–20 cm; while Paratylenchus in fallow field and woodland, as well as Praty- lenchus in maize field presented in the deeper soil layers (0–80 cm). Significant correlations between the numbers of dominant genera of plant nematodes and soil chemical properties were found in this study. The number of Helicotylenchus under different land uses was posi- tively correlated with C/N ratio, total C, total N, total P, alkai-N, and Olsen-P. The numbers of Filenchus and Paratylenchus in paddy field, Pratylenchus in maize field and Paratylenchus in fallow field were negatively correlated with soil pH, and positively correlated with total C, total N and alkai-N. This study results showed that it is essential to sample at a certain depth according to the vertical distribution informa- tion of different genera of plant nematodes in adequately assessing the population size of plant nematodes.

Freeliving marine nematodes as a pollution indicator of the Bohai Sea

A hierarchical diversity index—taxonomic distinctness index Δ +, which was first defined by Warwick and Clark in 1998, was employed to evaluate the pollution status of the Bohai Sea with freeliving marine nematodes. The result showed that the Bohai Bay and other coastal sampling sites might be affected by oil and gas production and other anthropogenic influences. In other words,anthropogenic disturbance was affecting this component of the benthos in these locations. And most offshore sampling sites in the middle of the Bohai Sea were clear and unpolluted.