Presence Of Entomopathogenic Nematodes Research Articles

Distribution and diversity of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in a South African nature reserve

Entomopathogenic nematodes (EPNs) are microscopic roundworms that are found in soil worldwide. They deliver an important ecosystem service through preventing natural flares in insect reproduction by means of utilising the soil stages of insects as a food source and by acting as natural biocontrol agents. A survey of EPNs was conducted in the JS Marais Nature Reserve, Stellenbosch, in the Western Cape province of South Africa. Soil samples were baited with the larvae of three susceptible hosts, codling moth (Cydia pomonella), wax moth (Galleria mellonella) and mealworm (Tenebrio molitor) to determine the presence of EPN. Of the 76 soil samples collected across the reserve, 39 were found to be positive for the presence of EPN (51.32%). Among the positive samples, 87% contained Steinernema isolates, 8% contained Heterorhabditis and 5% contained the Oscheius sp. Morphological and molecular studies were performed to characterise the isolates to species level. The Steinernema species were identified as Steinernema khoisanae in 34 samples, and as Steinernema nguyeni in five samples. The only species of Heterorhabditis found was H. safricana, which was identified from three samples. An unknown Oscheius sp. was found in two samples. The reserve’s population of S. khoisanae showed interesting inter-individual variation (93%) early in the internal transcribe spacer (ITS) region, leading to short single-usable sequences, which, in most cases, included only the ITS1 or ITS2 region. However, using the D2D3 confirmed their identity as S. khoisanae, with such occurring in all areas and soil types of the reserve.Conservation implications: The undisturbed alluvial fynbos and renosterveld of the JS Marais Nature Reserve showed high EPN abundance and diversity in stark contrast to the agro-ecosystems present in the Cape floristic region. This finding, on a micro level, should be conserved for future bioprospecting in the fynbos for EPNs with potential as biocontrol agents.

First record of entomopathogenic nematodes from Yucatán State, México and their infectivity capacity against Aedes aegypti.

BackgroundBiological control using entomopathogenic nematodes (EPN) has demonstrated good potential to contribute to the integral control of mosquito larvae, which as adults are vectors of diseases such as Dengue fever, Zika and Chikungunya. However, until now there are no records of the presence of EPN or their killing capacity in Yucatán state, southern México. The objectives of the current study were: (1) to report the entomopathogenic nematodes present in Yucatán soils and (2) to determine the killing capacity of the most frequent and abundant EPN against Aedes aegypti mosquito larvae and the microbial community developed by Ae. Aegypti exposed to this EPN.MethodsThe nematodes were collected by the insect trap technique using the great wax moth Galleria mellonella. Internal transcribed spacer (ITS), 28S gene of ribosomal DNA and phylogenetic analyses were performed to identify the EPN. For the bioassay, four concentrations of the most frequent and abundant EPN were tested: 1,260:1 infective juveniles (IJs) per mosquito larvae, 2,520 IJs:1, 3,780 IJs:1 and 5,040 IJs:1. High-throughput sequencing of the 16S rRNA gene was used to identify bacterial amplicon sequences in the mosquito larvae infected with EPN.ResultsSix isolates of Heterorhabditis were recovered from 144 soil samples. Heterorhabditis indica (four isolates) was the most frequent and abundant EPN, followed by Heterorhabditis n. sp. (two isolates). Both nematodes are reported for the first time for Yucatán state, Mexico. The concentration of 2,520 IJs:1 produced 80% of mosquito larvae mortality in 48 h. Representative members of Photorhabdus genus were numerically dominant (74%) in mosquito larvae infected by H. indica. It is most likely that these bacteria produce secondary toxic metabolites that enhance the mortality of these mosquito larvae.

Entomopathogenic nematodes occurring in alfalfa fields

With this study, the presence of entomopathogenic nematodes (EPN) in 15 villages (Ulaş, Taşlıçiftlik, Söngüt, Büyükbağlar, Uğrak, Tahtoba, Dayılıhacı, Çördük, Kızılköy, Bakışlı, Ballıdere, Çöreğibüyük, Gaziosmanpaşa, Günevi, Akyamaç and 2 towns (Güryıldız, Emirseyit) of Tokat province where alfalfa was cultivated intensively was investigated between June-October 2016. For this purpose, 58 soil samples were taken and obtained 10 EPN isolates by trap-insect method. As a result of the morphological and molecular diagnosis, 8 of them were defined as Steinernema carpocapsae, one isolate as S.feltiae and one isolate as Heterorhabditis bacteriophora. This paper is the first report showing the occurrence of EPNs in alfalfa fields in Turkey.

Dissemination of Isaria fumosorosea Spores by Steinernema feltiae and Heterorhabditis bacteriophora.

Entomopathogenic nematodes and fungi are globally distributed soil organisms that are frequently used as bioagents in biological control and integrated pest management. Many studies have demonstrated that the combination of biocontrol agents can increase their efficacy against target hosts. In our study, we focused on another potential benefit of the synergy of two species of nematodes, Steinernema feltiae and Heterorhabditis bacteriophora, and the fungus Isaria fumosorosea. According to our hypothesis, these nematodes may be able to disseminate this fungus into the environment. To test this hypothesis, we studied fungal dispersal by the nematodes in different arenas, including potato dextrose agar (PDA) plates, sand heaps, sand barriers, and glass tubes filled with soil. The results of our study showed, for the first time, that the spreading of both conidia and blastospores of I. fumosorosea is significantly enhanced by the presence of entomopathogenic nematodes, but the efficacy of dissemination is negatively influenced by the heterogeneity of the testing arena. We also found that H. bacteriophora spread fungi more effectively than S. feltiae. This phenomenon could be explained by the differences in the presence and persistence of second-stage cuticles or by different foraging behavior. Finally, we observed that blastospores are disseminated more effectively than conidia, which might be due to the different adherence of these spores (conidia are hydrophobic, while blastospores are hydrophilic). The obtained results showed that entomopathogenic nematodes (EPNs) can enhance the efficiency of fungal dispersal.

Isolation, identification of entomopathogenic nematodes, and preliminary study of their virulence against the great wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae)

Entomopathogenic nematodes (EPNs) are a group of biological control agents that are characterized by their ability to search for hosts, safety to non-target insects and environment, and their ability to be used combined with agricultural chemicals. The objectives of this study were to isolate EPNs from agricultural soil in Egypt and study their virulence against the great wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae), for further use in biological control program. Two out of 20 soil samples collected from orchards cultivated with olives and mango were positive for the presence of EPNs, using the Galleria baiting technique. The positive soil samples were sandy clay loam. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong to Heterorhabditis indica. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under the accession nos. MH553167 and MK300683. The efficacy of the isolates was tested on G. mellonella, using different nematodes’ concentrations. Using 50 IJs/larvae from H. indica Aborawash and ERSAG2 showed 100 and 86% mortality rate after 48 h, respectively. The penetration rate reported in dead G. mellonella was 40% at H. indica Aborawash, while it was 35% in case of ERSAG2.

New findings of Heterorhabditis bacteriophora and Steinernema rarum (Nematoda: Heterorhabditidae, Steinernematidae) in Córdoba, Argentina

A total of 152 soil samples collected from gardens of private properties at Cordoba city, Argentina, were evaluated for the presence of entomopathogenic nematodes (EPNs) . The insect bait method was used to isolate EPNs. The nematodes were characterized using both classic (morphometric characters) and molecular methods (analysis of internal transcribed spacer (ITS) and D2/D3 sequences of 28S genes). The recovery frequency of EPNs was 10.53%. Isolates belonging to the genera Heterorhabditis Poinar, 1976 and Steinernema (Travassos, 1927) were detected. Two isolates were identified as Steinernema rarum and four as Heterorhabditis bacteriophora . Granulometry, relative humidity and pH of the soil were determined and no significant differences were found among sites with presence or absence of EPNs when edaphic characteristics of sites were compared. The occurrence of EPNs in home gardens was determined for the first time, expanding S. rarum and H. bacteriophora currently known geographical distribution and increasing the diversity of populations of these nematodes to use against insect pests of urban areas.

Natural occurrence of entomopathogenic nematode species (Rhabditida: Steinernematidae and Heterorhabditidae) in cotton fields of Tamil Nadu, India

A total of 200 soil samples collected from the cotton fields of 10 different districts of the state of Tamil Nadu in India were evaluated for the presence of entomopathogenic nematodes (EPN) belonging to Steinernematidae and Heterorhabditidae during 2008–2009. This survey detected the occurrence of EPN in arable lands through the use of a standard insect baiting bioassay technique. EPN were recovered from all 10 cotton growing districts with 27 positive sites (13.5%) ranging from irrigated to rain-fed cotton fields of varied soil types (sandy to clayey), soil pH (4.9–8.4), electrical conductivity (0.11–1.25 dS/m) and organic matter content (0.21–3.8%). Both morphological and molecular tools were used to identify the isolates. Among 27 positive samples, 20 samples yielded steinernematids (74%) and seven samples yielded heterorhabditids (26%). The Heterorhabditis isolates were identified as Heterorhabditis bacteriophora. The Steinernema included Steinernema carpocapsae, Steinernema siamkayai and Steinernema monticolum. Steinernema carpocapsae was the predominant species. The cropping patterns comprising cotton–vegetables had higher EPN prevalence (26%) than cotton–pulses (22%), cotton–banana (3.3%) and cotton–millets (2.8%). Steinernema carpocapsae was recovered from cotton–pulses, cotton–millets and cotton–vegetables cropping patterns, whereas H. bacteriophora was isolated from cotton–pulses, cotton–vegetables and cotton–banana cropping patterns. This study demonstrated that EPN are prevalent in the cotton fields of Tamil Nadu, India and could potentially be incorporated into biological control or integrated pest management programmes.

Effect of entomopathogenic nematodes on the plant-parasitic nematode Nacobbus aberrans

Nacobbus aberrans is a sedentary endoparasite nematode that forms galls in the roots of infected plants and produces important economic losses in some countries of the American continent. It has a wide host range, attacking mainly potato, tomato, sugar beet, and pepper crops. A reduction in the plant-parasitic nematode populations in the presence of entomopathogenic nematodes (EPNs) has been frequently reported. In the present work, the effect of the application of two native EPN isolates (Steinernema rarum and Heterorhabditis bacteriophora) on a N. aberrans population was evaluated in tomato plants under greenhouse conditions. Sixty days after inoculation, the number of galls and egg masses and the reproduction factor (RF) of N. aberrans were calculated. Of the variables analyzed, only the RF was significantly lower in both EPN treatments than in control. N. aberrans reproduction decreased by 57 and 53 % in plants inoculated with S. rarum and H. bacteriophora, respectively. These results showed that EPNs and their bacterial symbionts affected the reproductive potential of the N. aberrans population. This is the first study addressing the use of EPNs in the control of this important plant-parasitic nematode.

First record of a cold-active entomopathogenic nematode Steinernema kraussei (Steiner) (Rhabditida: Steinernematidae) in Slovenia

In preceding researches on occurrence of entomopathogenic nematodes in Slovenia, which started in 2007, we already recorded Steinernema affine (Bovien), S. feltiae (Filipjev) and S. carpocapsae (Weiser). In April 2008, 120 soil samples from 24 locations were collected in Gorenjska, Notranjska and Primorska regions as well as in Ljubljansko barje. The presence of entomopathogenic nematodes was confirmed in 9 samples from 6 locations. Only the sample C46, which was taken in the village Podbrezje in Gorenjska region, was sent to genetic analysis. Molecular biological analysis have proved the identity of the sample with the species Steinernema kraussei (Steiner). This was the first record of Steinernema kraussei in Slovenia.

First record of a cold-active entomopathogenic nematode Steinernema kraussei (Steiner) (Rhabditida: Steinernematidae) in Slovenia

In preceding researches on occurrence of entomopathogenic nematodes in Slovenia, which started in 2007, we already recorded Steinernema affine (Bovien), S. feltiae (Filipjev) and S. carpocapsae (Weiser). In April 2008, 120 soil samples from 24 locations were collected in Gorenjska, Notranjska and Primorska regions as well as in Ljubljansko barje. The presence of entomopathogenic nematodes was confirmed in 9 samples from 6 locations. Only the sample C46, which was taken in the village Podbrezje in Gorenjska region, was sent to genetic analysis. Molecular biological analysis have proved the identity of the sample with the species Steinernema kraussei (Steiner). This was the first record of Steinernema kraussei in Slovenia.

Entomopathogenic nematode Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), a new member of Slovenian fauna

In April 2008, 120 soil samples from 24 locations were collected in Gorenjska, Notranjska and Primorska regions as well as in Ljubljansko barje. The presence of entomopathogenic nematodes was confirmed in 9 samples from 6 locations. Only the sample C101, which was taken in the village Svino in the area of Breginjski kot (western part of Slovenia, the vicinity of Italian border), was sent to genetic analysis. Molecular biological analysis was proved the identity of the sample with the species Steinernema carpocapsae (Weiser). This was the first record of Steinernema carpocapsae in Slovenia. In preceding researches on the fauna of entomopathogenic nematodes in Slovenia, which started in 2007, we already established the occurrence of Steinernema affine (Bovien) and Steinernema feltiae (Filipjev).

Entomopathogenic nematode Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), a new member of Slovenian fauna

In April 2008, 120 soil samples from 24 locations were collected in Gorenjska, Notranjska and Primorska regions as well as in Ljubljansko barje. The presence of entomopathogenic nematodes was confirmed in 9 samples from 6 locations. Only the sample C101, which was taken in the village Svino in the area of Breginjski kot (western part of Slovenia, the vicinity of Italian border), was sent to genetic analysis. Molecular biological analysis was proved the identity of the sample with the species Steinernema carpocapsae (Weiser). This was the first record of Steinernema carpocapsae in Slovenia. In preceding researches on the fauna of entomopathogenic nematodes in Slovenia, which started in 2007, we already established the occurrence of Steinernema affine (Bovien) and Steinernema feltiae (Filipjev).

Black Turfgrass Ataenius Control, 1991

Abstract The study was located on a golf course fairway at Jeromesville, OH. Insecticides and entomopathogenic nematodes were applied 13 Jun to plots 3.5 X 3.5 m arranged in a complete randomized block replicated 4 times. Granular insecticides were applied using a drop spreader and liquids using a C02 sprayer with Teejet 8003 lp nozzles at 1.05 kg/cm2 pressure that delivered a vol of 466 liter/ha. Nematodes were applied with a C02 sprayer using Teejet 8015 nozzles at 2.92 kg/cm2 pressure that delivered a spray vol of 1600 liter/ha. The experimental area was irrigated approximately 1.25 cm after all treatments were applied but before sprays had dried on the grass blades. Environmental conditions at time of treatment were: BTA: ca. 80/0.093 m2, 5% 1st, 10% 2nd, 80% 3rd instars, and 5% pupae. Turf: level, dry, 3.2 cm height, 50% Kentucky bluegrass, 40% perennial ryegrass, 10% annual bluegrass. Thatch: moist, 1.2 cm. Soil: moist, 64°F at 2.54 cm and 68°F at 7.62 cm. Weather: sunny, 70°F, 0-8 km/h. Water: pH 7.22. Efficacy data taken 24 Jun (11 DAT) were based on the number of live BTA larvae and pupae in 8, 10.8 cm in diam samples from each plot. At the time of treatment evaluation, soil samples were collected from the check and nematode treated plots and tested for’ presence of entomopathogenic nematodes. Five Galleria larvae were placed in each of two subsamples of soil from each plot.

A survey of entomopathogenic nematodes (rhabditida) in the negev desert

The aim of the present survey was to isolate entomopathogenic rhabditids in an arid region. The survey was conducted in the Negev desert, located in the southern part of Israel. Soil samples were collected from 21 sites and the presence of entomopathogenic nematodes in the soil samples was determined by usingGalleria mellonella larvae as bait. Entomopathogenic nematodes, identified as heterorhabditids, were isolated only from soil samples obtained from under the canopy of irrigated fruit trees, planted in sandy soils. The nematodes from the new isolated populations were subjected to low relative humidity (75%) for 3 days after preconditioning for 72 h at 97% RH. Under these conditions, fewer than 10% survived for 48 h.