A survey of entomopathogenic nematodes of the families Steinernematidae and Heterorhabditidae (Nematoda: Rhabditida) in Damascus countryside of Syria

A survey of entomopathogenic nematodes was conducted in Damascus countryside from January 2011 to December 2013. Soil samples were tested for the presence of steinernematid and heterorhabditid nematodes by baiting with Galleria mellonella larvae. Of the 189 soil samples studied 17 were positive for entomopathogenic nematodes (9%), with 11 of these positive samples (65%) containing Heterorhabditis and 6 (35%) Steinernema isolates. Morphological studies were carried out to characterize eight isolates. The Heterorhabditis isolates collected in Syria were identified as Heterorhabditis zealandica (Poinar, 1990), Heterorhabditis indica (Poinar et al., 1992) and Heterorhabditis bacteriophora (Poinar, 1990). Heterorhabditis zealandica was isolated from 4 sites. Heterorhabditis indica and H. bacteriophora were isolated from two sites each. Entomopathogenic nematodes were mainly found in stone fruit orchards and apple orchards but also in citrus groves, vineyards, and walnut orchards.     

Biological control potential of Turkish entomopathogenic nematodes against the Mediterranean fruit fly <Emphasis Type="Italic">Ceratitis capitata</Emphasis>

The entomopathogenic nematodes Steinernema weiseri, S. feltiae, S. carpocapsae and two strains of Heterorhabditis bacteriophora, isolated from Turkish soils, were evaluated against larvae of the Mediterranean fruit fly (medfly) Ceratitis capitata in plastic cups under laboratory conditions with sandy loam soil and 10% moisture level. At a rate of 100 infective juveniles (IJs)/cm², the last instar larvae of C. capitata were susceptible to the entomopathogenic nematodes: the S. feltiae 09-31 strain recovered from Aydin provided 78% mortality, whereas S. weiseri and S. carpocapsae killed 50% and 56% of the larvae, respectively. Both strains of H. bacteriophora species caused less than 50% mortality. Except for S. feltiae, the majority of infected medflies died as prepupae or pupae within the puparia. More than 90% larval mortality was recorded at 200 and 400 IJs/cm² for S. feltiae. None of the nematode isolates infected the medfly pupae within the puparia. In pot experiments containing soil, S. feltiae caused 96% and 97% mortality at 100 and 200 IJs/cm², respectively. In pot experiments with grass present, more than 94% mortality was obtained in the presence of grass roots.     

应用昆虫病原线虫防治小菜蛾的研究

小菜蛾Ｐｌｕｔｅｌｌａ ｘｙｌｏｓｔｅｌｌａ,ＤＢＭ是十字花科的重要害虫。本文应用昆虫病原线虫斯氏线虫的六个种和异小杆线虫的一个种对小菜蛾四龄幼虫进行室内测定,筛选出斯氏线虫Ｓｔｅｉｎｅｒｎｅｍａ ｃａｒｐｏｃａｐｓａｅ Ａ２４和异小杆线虫Ｈｅｔｅｒｏｒｈａｂｄｉｔｉｓ ｂａｃｔｅｒｉｏｐｈｏｒａ ８４０６为防治小菜蛾的较理想线虫种,田间小区试验也主宰了这点。     

Steinernematid and heterorhabditid nematodes for biological control of the giant looper,Boarmia selenaria

The pathogenicity of steinernematid and heterorhabditid nematodes to caterpillars of the giant looper,Boarmia selenaria (Schiffermüller) (Lepidoptera: Geometridae), was determined under laboratory conditions. High mortality (over 80%) was achieved, in a petri dish bioassay, with a minimum of 20,000 infective juveniles (IJ) ofSteinernema carpocapsae (Filipjev) (=Neoaplectana carpocapsae Weiser), strain ‘All’. The LD₅₀ was 4250 IJ per caterpillar. Similar results were obtained withS. carpocapsae, strain ‘Mexican’,Steinernema sp., strain ‘CR’;Heterorhabditis bacteriophora, strain ‘HP88’; andHeterorhabditis sp., strain ‘IS’. The first and second instars were the most susceptible stages to nematode infection. A laboratory model assay indicated that 80–90% of the caterpillars were killed when they migrated to the soil to pupate; this occurred when IJ were applied to sandy and heavy soils at a concentration of 400 IJ/cm³ soil. A greenhouse test reconfirmed the effectiveness of utilizing the entomopathogenic nematodes in an “ambush” system against caterpillars migrating to the soil.     

Entomopathogenic nematodes (Nematoda: Steinernematidae, heterorhabditidae) as control agents forParahypopta caestrum, a pest in the culture ofAsparagus officinalis

The entomopathogenic nematodes (EPNs)Steinernema feltiae (under the trade name Entonem) andHeterorhabditis bacteriophora (under the trade name Larvanem) were evaluated as potential control agents ofParahypopta caestrum, the major pest of the asparagus crop in Greece. In laboratory experiments the two nematodes provided equal insect suppression, but significant differences were found in the time it took them to kill the larvae.S. feltiae caused high levels of mortality within 24 h and the highest level at 48 h. In contrast,H. bacteriophora required 96 h to achieve the highest level of mortality. In field experiments, the nematodes provided equal insect suppression as compared with the insecticide cadusaphos and the mixture teflubenzuron +Bacillus thuringiensis var.kurstaki. No significant differences were found in the effectiveness of the insecticides used, but there were significant differences between the control and treatments. The findings showed thatS. feltiae andH. bacteriophora could be used to control the insectP. caestrum in asparagus culture. http://www.phytoparasitica.org posting Jan. 10, 2007.     

昆虫病原线虫rDNA多态性分析

本文对国内外昆虫病原线虫斯氏属和异小杆属的47个品系进行rDNA—ITS PCR—RFLP分析，研究其DNA多态性，并构建了分子系统发育树状图。各品系的ITS区无明显的长度差异，PCR—RFLP分析将47个品系分为斯氏属和异小杆属两大类，两属线虫又分别分为11组和4组。所得结果丰富了ITS PCR—RFLP图谱库，为弄清我国的昆虫病原线虫与国外种类的分子系统发育关系及未定名线虫的鉴定提供重要依据，同时为筛选适合的线虫种类防治害虫奠定基础。     

Native entomopathogenic nematodes isolated from Turkey and their effectiveness on pine processionary moth,Thaumetopoea wilkinsoni Tams

Two native entomopathogenic nematodes were isolated from soil samples in Eastern Mediterranean region of Turkey and characterized based on 28S rDNA region. BLASTN homology and phylogenetic analysis of SK17 and SK-71 isolates indicated 98% and 99% identity to Steinernema affine and Steinernema feltiae, respectively. The results were constructed by neighbour-joining and bootstrap tree methods. Efficacy of S. affine (SK-17 strain) and S. feltiae (SK-71 strain) was tested against the larvae of pine processionary moth, Thaumetopoea wilkinsoni Tams, and remarkable mortality rates were obtained. Both strains caused complete mortality upon application of 500 IJs in foliar tests. However, the same strains caused 30% and 33% mortality at 80 IJs/cm² in soil applications. It was concluded that these native strains could be considered as potential biocontrol agents for reducing the damage caused by T. wilkinsoni larvae.     

Association between entomopathogenic nematodes and non-synthetic insecticides for improved control of Nasutitermes spp. (Isoptera: Termitidae) in sugarcane plantations

The aim of this study was to evaluate the in vitro efficacy of the combination of entomopathogenic nematodes and non-synthetic insecticides in the control of Nasutitermes spp. (Isoptera: Termitidae). Bioassays were performed upon insect collection from areas with the high incidence of this pest. The experimental arena for insecticide assays consisted of 80-mL plastic containers with a screened cover. We tested six insecticides and the nematode species Heterorhabditidis bacteriophora RS58, Steinernema glaseri RS38, and Heterorhabditis sp. isolates AL39, AL40, AL41, AL42, AL43, AL44, AL46, and AL47, all of which were grown in last-instar larvae of Galleria mellonella L. (Lepidoptera: Pyralidae). The insecticides Codipirol®, Pure Neem Oil®, and Pyroligneous Acid Extract® caused high mortality in adults of Nasutitermes. The nematode Heterorhabditis sp. AL40 presented a median lethal concentration of 7976 infectious juveniles per adult of Nasutitermes sp. In addition, the mixture of these three non-synthetic products at a concentration of 3% caused complete mortality in Heterorhabditis sp. AL40 and S. glaseri RS38. Future trials should be encouraged in order to evaluate the field efficiency of non-synthetic insecticides mixed or not with entomopathogenic nematodes.     

Virulence and efficacy of different entomopathogenic nematode species against western flower thrips (Frankliniella occidentalis)

Virulence and efficacy of five species and strains of the entomopathogenic nematodes of the families Steinernematidae and Heterorhabditidae:Steinernema riobravis, Steinernema feltiae strains Ger. and UK, andHeterorhabditis bacteriophora strains HP88 and IS5, against the prepupal and pupal stages of the western flower thrips (WFT),Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were investigated in the laboratory. Although all these nematodes controlled WFT to some extent, they differed in efficiency. The heterorhabditid nematodeH. bacteriophora strain HP88 was more specific to the soil-inhabiting WFT stages (36–49% thrips mortality). The steinernematid nematodesS. riobravis andS. feltiae strains Ger. and UK had only a slight effect (10% mortality) on prepupal and pupal populations of WFT, andH. bacteriophora strain IS5 had the least effect of all. A possible reason for such species variation is suggested and discussed.     

Effect of rapid and gradual increase of osmotic stress on survival of entomopathogenic nematodes

The effect of rapid and gradual exposure of entomopathogenic nematodes to osmotic stresses on the induction of a dormant state was determined with the nematodeSteinernema feltiae IS-6 infective juveniles (IJs). Rapid exposure of nematodes to glycerol at concentrations of 24% and 28% (w/w) caused the nematodes to enter a dormant state which was characterized by shrinking and impeded motility of all nematodes within 8 h. However, pre-exposure to gradually increasing glycerol concentrations of 5%, 10% and 18% at 4-h intervals resulted in dormancy after 4 h exposure to 24% glycerol. The total time of exposure to glycerol solution was 16 h in gradual osmotic stress. For nematodes exposed to 24% glycerol solution either rapidly or gradually, recovery occurred after 40 min in distilled water. Infectivity of osmotically stressedS. feltiae IJs was evaluated by two criteria, insect mortality and invasion rate. The assays indicated that infectivity of nematodes desiccated by rapid and gradual osmotic stresses was similar to that of fresh nematodes. Rapid exposure ofS. carpocapsae ‘All’,S. riobravis ‘Texas’,S. glaseri ‘NI’ andHeterorhabditis bacteriophora HP88 IJs to the 24% glycerol solution resulted in dormancy within 8 h. These treatments caused mortality of 48.4% and 11.7% amongS. glaseri Nl andH. bacteriophora HP88 IJs, respectively. Similar effects were observed when these nematode species were exposed to increasing osmotic stress of 5%, 10% and 18% at 6-h intervals. Under these same conditions, mortality ofH. bacteriophora HP88 andS. glaseri Nl IJs was 27.5% and 61.8%, respectively. http://www.phytoparasitica.org posting Sept. 29, 2004.     

不同种昆虫病原线虫对同一寄主个体的竞争及对线虫繁殖的影响

采用注射侵染和自然侵染法，测试了长尾斯氏线虫X-7品系、小卷蛾斯氏线虫All品系和嗜菌异小杆线虫H06品系对同一寄主大蜡螟幼虫的相互作用，及其对线虫繁殖的影响。结果表明，无论是注射侵染还是自然侵染法，对大蜡螟幼虫个体的致死竞争能力最强的是长尾斯氏线虫，其次是小卷蛾斯氏线虫，嗜菌异小杆线虫的致死能力最弱。在同一大蜡螟幼虫体内时。异小杆线虫的繁殖受斯氏线虫的不利影响较大，而两种斯氏线虫的繁殖受异小杆线虫的不利影响较小。两种斯氏线虫对各自的繁殖影响不大。     

The influence of herbicides on the viability of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae)

Entomopathogenic nematodes (EPNs) are agents that can be used for the biological control of pests associated with pesticides in a tank mix. Compatibility studies need to be conducted to analyse which products are compatible with EPNs. The survival of infective juveniles (IJs) of four species of EPNs (Steinernema, Heterorhabditis) was determined after exposure to eight chemical herbicides. The effect of direct IJs exposure to herbicides for 1, 4 and 24 h was tested in a Petri dish at 15, 20 and 25 °C. The study showed that Steinernema kraussei was the most tolerant among the tested EPN species, while S. carpocapsae was the most sensitive to all tested herbicides. The lowest mortality of IJs was at 15 °C (19%). Our investigation showed, overall, the herbicides negatively affected EPN survival. The results confirmed that the compatibility is a species-specific characteristic, influenced by the temperature and time of exposure. Application of two different control ingredients (insecticide and herbicide) at the same time would reduce cost and time consumption in pest/weed control.     

Oulema melanopus (L.) (Coleoptera: Chrysomelidae) adults are susceptible to entomopathogenic nematodes (Rhabditida) attack: results from a laboratory study

Journal of Plant Diseases and Protection - Three species of entomopathogenic nematodes from Slovenia (Steinernema feltiae B30, S. carpocapsae C101, and Heterorhabditis bacteriophora D54) and...     

Entomopathogenic fungi and nematodes against larvae of the chestnut weevil,Curculio elephas (Coleoptera: Curculionidae): a laboratory evaluation

Pest control in chestnut orchards is mainly achieved by chemicals, but there is growing focus on the potential use of biological control agents. The larval susceptibility of the chestnut weevil Curculio elephas L. (Coleoptera: Curculionidae) to different strains/species of entomopathogenic fungi and nematodes was evaluated in laboratory by soil cup bioassays. In the experiments with fungi, a wild strain of Metarhizium anisopliae caused the highest larval mortality (about 90%) compared with a commercial and a wild strain of Beauveria bassiana (80% and 77% respectively). Regarding nematodes, the commercial strain of Heterorhabditis bacteriophora was more effective in the control of chestnut larvae (77% insect mortality) than Steinernema carpocapsae (43%).     

Note: Molecular identification of three entomopathogenic nematodes from turkey by PCR-RFLP of the ITS regions

Molecular identification methods are widely used for the classification of organisms worldwide. Entomopathogenic nematodes are the most often isolated insect parasitic nematodes in the tropical and subtropical regions. In our investigation, PCR-RFLP (Polymerase Chain Reaction — Restriction Fragment Length Polymorphism) of the ITS region (Internal Transcribed Spacer) on the ribosomal (r) DNA of three entomopathogenic nematodes isolated from Ankara, Turkey, was analyzed for identification. The ITS region of rDNA was amplified by PCR and then digested with the following nine restriction enzymes: Alu I, Dde I, Hae III, Hha I, Hind III, Hinf I, Hpa II, Rsa I and Sau 3AI. The amplified and restricted sequences of the ITS regions were separated by agarose gel electrophoresis and the RFLP patterns of these three species were shown in this study. According to our results, these species were identified asSteinernema feltiae, Steinernema carpocapsae andHeterorhabditis bacteriophora. http://www.phytoparasitica.org posting Nov. 4, 2005.     

Characterization of populations of entomopathogenic nematodes isolated at diverse sites across Israel

Entomopathogenic nematodes (EPNs) are known as effective biological agents against soil-dwelling stages of insect pests. In the present study new EPN populations from the Steinernematidae and Heterorhabditidae families were isolated at different locations in Israel. The newly isolated populations were subjected to a series of bioassays for beneficial traits, for selection of a superior isolate for biological control of insect pests. Nematode motility was measured in sand columns, with and without the susceptible insect Galleria mellonella. Infectivity was evaluated using an invasion rate assay, as well as a dose response assay in which LD₅₀ values were calculated. Nematode tolerance to environmental stresses was examined in heat and desiccation tolerance assays. The reproductive potentials of the new isolates were assessed in cadavers of G. mellonella. All Steinernematid populations were identified as Steinernema feltiae and the Heterorhabditids as Heterorhabditis sp. Large variation between the various populations was recorded in all assays. In order to identify a superior isolate, each strain was scored as 1 if its performance did not differ significantly from the highest level recorded in the particular assay; −1 if its performance did not differ significantly from the lowest level; and 0 if its performance was between the highest and lowest levels or did not differ from either. The scores for the different traits were then summed for each population and the totals were compared. The best score (+4) was obtained for a S. feltiae population isolated in northern Israel. These results will be used for the utilization of the new population as a biological control agent.     

异小杆线虫D_1对迟眼蕈蚊侵染力的研究

本文报道6个昆虫病原线虫品系对危害韭菜的迟眼(?)蚊的侵染力,以Heoerorhabditissp.D_1的侵染力为最高。室内试验表明,当沙土中D_1线虫与裸露的迟眼(?)蚊幼虫的比为15:1时,幼虫死亡率可达81.8％.盆栽试验中益害比为38:1时,由于该幼虫大部分在韭菜茎内为害,寄生率仅35.1％,但对茎外的蛹寄生率可达82.7％.     

昆虫病原斯氏和异小杆线虫人工大量培养的研究概况

昆虫病原斯氏和异小杆线虫的大面积田间应用要求线虫有效地生产，本文介绍业已建立线虫大量培养方法及合适于大规模生产线虫的工厂化培养系统及有关的技术参数，并讨论其优化管理问题。     

Susceptibility of the taro beetle,Papuana uninodis,to entomopathogenic nematodes

Six strains of entomopathogenic nematodes, Steinernema glaseri (Steiner) (Biosys #326, nc 34, gb), S. feltiae = bibionis (Filipjev) (Biosys #349), S. carpocapsae Weiser (Biosys #25) and Heterorhabditis zealandica Poinar, were evaluated in laboratory tests against taro beetles, Papuana uninodis Prell. Larvae of this species and adult Papuana Arrow spp. were found to be susceptible to entomopathogenic nematodes. The best results were obtained with S. glaseri #326 in larval and adult P. uninodis . The dose causing 50% mortality (LD ) for third instar P. uninodis larvae in Petri dish assays ranged from almost 7000 nematodes/larva for 1 days exposure to less than 250 nematodes/larva for 6 days; in pot assays the concentration causing 50% mortality (LC ) in 2 weeks was 1.4 106 nematodes/m2. For 50 adults in Petri dishes with soil, the LD was ca 20 000 nematodes/ 50 adult for 1 weeks exposure and ca 6000 nematodes/adult for 3 weeks. In pot assays the LC was 2.5 106 nematodes/m2 in 3 weeks. 50 Preliminary tests showed that P. huebneri (Fairmaire) and P. woodlarkiana laevipennis Arrow adults were also most susceptible to S. glaseri #326. A field test on adults Papuana uninodis did not result in damage reduction but served to illustrate the practical difficulties of applying nematodes in remote areas. 50     

Sensitivity of caterpillars of the pine tree lappet moth Dendrolimus pini to native isolates of entomopathogenic nematodes

Abstract

The pine tree lappet moth Dendrolimus pini (Lasiocampidae) is one of the most dangerous pests of pine Pinus sylvestris stands in Central Europe. To develop biological control method of this pest, the bioassay was made to assess the sensitivity of D. pini caterpillars to native EPMs strains representing two species: Steinernema feltiae and Heterorhabditis megidis in laboratory conditions. The results showed higher activity of S. feltiae strains which parasitized 86.7 - 100% of D. pini caterpillars, compared to the 20-100% of insects parasitized by H. megidis strain. Most nematodes were found in caterpillars treated with S. feltiae (in average 40 IJs/caterpillar), the least – in individuals parasitized by H. megidis (in average IJs/caterpillar). No effect of dose and temperature on parasitizm was found with S. feltiae strains while in H. megidis increased doses resulted in higher extensity of parasitism. The results indicate higher biological activity of S. feltiae strains and advisability of their further studies in field experiments.