Search

Copyright of Arab Journal of Plant Protection is the property of Arab Society for Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A survey was conducted in some northern regions of Iraq between 2021 and 2022 to evaluate the diversity of entomopathogenic nematodes in these areas. Entomopathogenic nematodes were isolated from soil using the Galleria trap technique. Molecular identification illustrated that these isolates belong to two genera of entomopathogenic nematodes, Heterorhabditis, and Steinernema. The results of the molecular analysis also showed the presence of Steinernema isolates in the Al-Rashidiyah region in Mosul, Iraq. Heterorhabditis nematodes were isolated from Salah Al-Din, Samarra, and Al-Jadriya, Baghdad. Some collected soil samples were negative and had no nematode species such as Dohuk, Sulaymaniyah, Erbil, and Anbar cities. Molecular analyses using 28S genes confirmed that the isolated nematodes were Heterorhabditis indica (OQ653109.1), Heterorhabditis bacteriophora (OR243201.1), and Steinernema carpocapsae (OR243196.1). [ABSTRACT FROM AUTHOR]

Western corn rootworm is one of the most dangerous pests of maize, and both the larvae and the imagoes thereof may cause significant damage to the plants. The options of controlling these pests have recently become highly limited, thus creating a great demand for new control methods complying with sustainable plant protection. These requirements are met by the natural enemies of these pests, such as entomopathogenic nematodes (e.g. Heterorhabditis bacteriophora, Gerritsen, 1994). The objective of this study was to determine whether the viability and larvicide effect of a single injection into the soil of 2 billion nematodes using various amounts of water (50, 100 or 200 L/hectare) was maintained even with the lower quantities. Our studies proved that the entomopathogenic nematodes retain their viability and larvicide effect when applied using 50 L/ha of water. The efficacy of the biological agent did not differ from that of Force 1.5G, a product containing Tefluthrin as active ingredient, which was used as positive control.

The entomopathogenic nematode (EPN) Steinernema feltiae, which carries the symbiotic bacterium Xenorhabdus bovienii in its gut, is an important biocontrol agent. This EPN could produce a suite of complex metabolites and toxin proteins and lead to the death of host insects within 24-48 h. However, few studies have been performed on the key biomarkers released by EPNs to kill host insects. The objective of this study was to examine what substances produced by EPNs cause the death of host insects. We found that all densities of nematode suspensions exhibited insecticidal activities after hemocoelic injection into Galleria mellonella larvae. EPN infection 9 h later led to immunosuppression by activating insect esterase activity, but eventually, the host insect darkened and died. Before insect immunity was activated, we applied a high-resolution mass spectrometry-based metabolomics approach to determine the hemolymph of the wax moth G. mellonella infected by EPNs. The results indicated that the tryptophan (Trp) pathway of G. mellonella was significantly activated, and the contents of kynurenine (Kyn) and 3-hydroxyanthranilic acid (3-HAA) were markedly increased. Additionally, 3-HAA was highly toxic to G. mellonella and resulted in corrected mortalities of 62.50%. Tryptophan metabolites produced by EPNs are a potential marker to kill insects, opening up a novel line of inquiry into exploring the infestation mechanism of EPNs. [ABSTRACT FROM AUTHOR]

The occurrence of entomopathogenic nematodes (EPNs) in arable soil samples from Nigeria was investigated using Baermann extraction tray and insect-bait (White’s trap) techniques. Isolates were tested for infectivity using the larvae of Galleria mellonella (greater moth) and Tenebrio molitor (mealworm). The study revealed a new species of Heterorhabditis (MT371593) in soil samples that were randomly collected from an arable farmland cultivated with cassava TMS-30572 at the Teaching and Research Farm of Landmark University, Nigeria. Amplification of the internal transcribed spacer region (ITS) of the ribosomal DNA produced a nucleotide sequence of 933 base pairs (bp). A BLASTN search of GenBank showed that the sequence of the Nigerian isolate is identical at 99% similarity to that of Heterorhabditis sp. from Thailand. Infectivity test of the isolate showed 100% mortality against T. molitor larvae within 48 h of exposure while only 80% mortality was recorded for G. mellonella after 1 week of exposure. This is the first account of Heterorhabditis sp. in Nigeria. The varying degrees of infectivity against mealworm and greater moth observed in this study proved that the Nigerian isolate of Heterorhabditis sp. could potentially be an attractive option in the management of insect pests of cash crops.

Entomopathogenic nematodes (EPNs) have been identified as promising biocontrol agents for controlling economically important insect pests of agricultural and horticultural crops. The compatibility of entomopathogenic nematode Heterorhabditis indica with 7 CIB registered insecticides was investigated under laboratory conditions. The effect of these insecticides on nematode survival at recommended concentrations was observed after 12, 24, 48, 72 hours upon direct exposure. EPN H. indica was compatible with Imidacloprid 17.8% SL as maximum per cent of live H. indica were observed after 72 h of exposure to this insecticide. Similarly, H. indica was compatible with Fipronil 5% SC up to 48 h of exposure whereas, less than 70% live EPN were there in Thiamethoxam 25% WG, Diafenthiuron 50% WP and Cypermethrin 25% EC resulting these insecticides to be least compatible. Emamectin benzoate 5% SG and chlorpyriphos 20% EC were incompatible with H. indica after 48 h of exposure. The result of this experiment will help in reducing the dependence on chemical insecticides and thus slowing down the development of insecticide resistance and preventing adverse effects on public health and the environment. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) have been identified as promising biocontrol agents for controlling economically important insect pests of agricultural and horticultural crops. The compatibility of entomopathogenic nematode Heterorhabditis indica with 7 CIB registered insecticides was investigated under laboratory conditions. The effect of these insecticides on nematode survival at recommended concentrations was observed after 12, 24, 48, 72 hours upon direct exposure. EPN H. indica was compatible with Imidacloprid 17.8% SL as maximum per cent of live H. indica were observed after 72 h of exposure to this insecticide. Similarly, H. indica was compatible with Fipronil 5% SC up to 48 h of exposure whereas, less than 70% live EPN were there in Thiamethoxam 25% WG, Diafenthiuron 50% WP and Cypermethrin 25% EC resulting these insecticides to be least compatible. Emamectin benzoate 5% SG and chlorpyriphos 20% EC were incompatible with H. indica after 48 h of exposure. The result of this experiment will help in reducing the dependence on chemical insecticides and thus slowing down the development of insecticide resistance and preventing adverse effects on public health and the environment.

Abstract The potato tuber moth (PTM), Phthorimaea operculella, is one of the most economically important potato pests worldwide. In the present study, the potential of Steinernema carpocapsae for controlling PTM in infested potato tubers was evaluated and compared with S. feltiae and the pyrethroid alpha-cypermethrin. The results for efficacy percentage showed that S.carpocapsae [72.52 and 65.49% for 12.6 × 106 and 6.2 × 106 infective juveniles (IJs), respectively] and S. feltiae (69.56% for 12.6 × 106 IJs) were as efficient as alpha-cypermethrin (66.76% for10 mg ai L−1). Both concentrations of alpha-cypermethrin and S. carpocapsae showed the least tuber damage with no significant differences (33.5–39.33%), while it was as high as the control (59.26%) in both concentrations of S. feltiae. The median lethal concentration (LC50) value for S. carpocapsae [5.46 (4.41–6.55) IJs per prepupa] was significantly lower than S. feltiae [8.52 (7.12-10.20) IJs per prepupa] which confirms the superiority of S. carpocapsae. These promising findings introduce S. carpocapsae as a part of the potato tuber protection programs for treating the tubers. Accordingly, EPNs can be considered as an appropriate alternative to synthetic chemicals for PTM control. [ABSTRACT FROM AUTHOR]

Parasitic nematodes infect a variety of organisms including insects and vertebrates. To survive, they evade host immune responses to cause morbidity and mortality. Despite the vast clinical knowledge regarding nematode infections and their biological makeup, molecular understanding of the interactions between host and parasite remains poorly understood. The utilization of model systems has thus been employed to help elucidate the molecular interactions of the host immune response during parasitic nematode infection. Using model systems, it has been well established that parasitic nematodes evade host immunity by releasing excretory/secretory proteins (ESPs), which are involved in immunomodulation. Model systems have enabled researchers to characterize further the underlying mechanisms ESPs use to facilitate evasion and modulation of the host immune response. This review assessed notable ESPs from parasitic nematodes that infect vertebrates or insects and have been studied in mechanistic detail. Being able to characterize how ESPs affect the immune systems of hosts on a molecular level increases our understanding of host–parasite interactions and could lead to the identification of novel therapeutic targets and important molecular pathways. [ABSTRACT FROM AUTHOR]

The susceptibility of the elm leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae), 3rd instar larvae and adults to the entomopathogenic nematodes Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora was determined in laboratory assays. Larval mortality was assessed at 0, 16, 32, 48, 64, 80, 96, and 112 h after exposure of the larvae and adults to six concentrations (0, 100, 200, 300, 400, and 500) of infective juveniles (IJs) per mL. The median lethal concentration (LC50) values for each nematode species against the larvae and adults of X. luteola were 167.59 and 6.73 IJ.mL-1 for S. feltiae, 218.23 and 204.09 IJ.mL-1 for S. carpocapsae, and 338.66 and 70.29 IJ.mL-1 for H. bacteriophora, respectively. Also, the median lethal time (LT50) values for each nematode species against the larvae and adults of X. luteola were 44.51 and 22.23 h for S. feltiae, 50.78 and 36.17 h for S. carpocapsae, and 67.64 and 34.71 h for H. bacteriophora, respectively. The S. feltiae nematode was the most effective species in controlling the larvae and adults of the elm leaf beetle, X. luteola. Based on these and other results, the research could be expanded on the prospects of using entomopathogenic nematodes, especially S. feltiae, in managing of the elm leaf beetle, X. luteola.

Many vector mosquito species have evolved resistance to chemical insecticides and the search for novel biological control strategies warrants further attention. Entomopathogenic nematodes (EPNs) (Heterorhabditis and Steinernema spp.) have been developed as biological control agents for use against agricultural pests but whether they could be used to control aquatic mosquito larvae warrants further research. We exposed Aedes aegypti and Ochlerotatus detritus larvae to commercially available (Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora) and wild isolated (S. affine and S. glaseri) EPNs and monitored survival over 7 days. We also exposed EPNs to water with a range of salinities and pHs found in the marshland habitats of British mosquitoes. Ae. aegypti and O. detritus were killed by commercial EPNs, but wild strains were unable to kill Ae. aegypti yet did kill O. detritus. All EPNs were capable of tolerating a wide range of pHs but showed variable tolerance to different salinities. EPNs could be used as an alternative to chemical insecticides but target species and habitat may influence choice of EPN strain in control operations. [ABSTRACT FROM AUTHOR]

Entomopathogenic Nematodes (EpNs) that serve as biological control agents include Steinernema spp and Heterorhabditis spp. EPNs Heterorhabditis indicus (Bromo Isolate) has a high toxicity against larvae Lepidoptera and Coleoptera and was successfully developed for mass production in Biological Control Laboratory of Jember University. These nematodes will be formulated as solid and liquid biopesticides. This research aims: to find EPNs local isolates from smallholder coffee plantations; to identify local and in vivo and in vitro cultured EPNs isolates; to determine the pathogenicity of EpNs local isolate against Coffee Berry Borrer (CBB) Hypothenemus hampei Ferr and to formulate EpNs in vitro culture as a liquid and solid formula. These formula were tested for the patogenicity and viability of EpNs to the larvae of H. hampei, Tenebrio molitor and Galleria melonella. The results showed that the pathogenecity of EpNs isolate to the larvae of CBB in Silo was 30% after 24 hours and 90% after 48 hours of in vivo inoculation. However, the mortality of CBB larvae was only 10% by liquid spraying on the coffee berry. The viability was 524 IJ (Infective Juvenile) on liquid formula packed on polyurethane sponge, and this was higher than that on solid formula (330 IJ).

The susceptibility of the elm leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae), 3rd instar larvae and adults to the entomopathogenic nematodes Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora was determined in laboratory assays. Larval mortality was assessed at 0, 16, 32, 48, 64, 80, 96, and 112 h after exposure of the larvae and adults to six concentrations (0, 100, 200, 300, 400, and 500) of infective juveniles (IJs) per mL. The median lethal concentration (LC50) values for each nematode species against the larvae and adults of X. luteola were 167.59 and 6.73 IJ·mL-1 for S. feltiae, 218.23 and 204.09 IJ·mL-1 for S. carpocapsae, and 338.66 and 70.29 IJ·mL-1 for H. bacteriophora, respectively. Also, the median lethal time (LT50) values for each nematode species against the larvae and adults of X. luteola were 44.51 and 22.23 h for S. feltiae, 50.78 and 36.17 h for S. carpocapsae, and 67.64 and 34.71 h for H. bacteriophora, respectively. The S. feltiae nematode was the most effective species in controlling the larvae and adults of the elm leaf beetle, X. luteola. Based on these and other results, the research could be expanded on the prospects of using entomopathogenic nematodes, especially S. feltiae, in managing of the elm leaf beetle, X. luteola. [ABSTRACT FROM AUTHOR]

In this study the occurrence of entomopathogenic nematodes (EPNs) was determined in three senatorial districts of Osun State in relation to soil texture, vegetation, moisture and pH. A total of 110 soil samples were randomly collected from various cultivated fields in different locations. The soil samples were baited twice using last instar larvae of the Galleria mellonella (greater wax moth) for presence of entomopathogenic nematodes. Four EPN isolates were recovered viz., Heterorhabditis indica, Heterorhabditis bacteriophora, Steinernema karii and Steinernema wesieri. Of a total of 110 soil samples examined, EPNs were found in 90.90% soil samples, they belonged to the genera Steinernema and Heterorhabditis. Steinernema spp. was found prevalent in both cultivated and undisturbed soils. Frequency of occurrence of EPNs in the sampled soils from the different senatorial zones was determined: soil samples from the Central zone recorded the lowest prevalence 87.50% while the soil samples from Western senatorial zone revealed 91.43% presence of the EPNs. The highest frequency of occurrence of EPNs- 94.29% was recorded in the soil samples from Eastern senatorial zone. Nematode distribution and frequency was found to be related to soil pH (pH<4.5 to pH>7.2) and soil moisture. This is the first report of these nematodes from Osun State, Nigeria. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Protection & Pathology is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chironomidae, or non-biting midges, are found worldwide in a wide variety of aquatic habitats. During periods of mass adult eclosion they can become a nuisance and health hazard. Current control methods target the aquatic larval stage and include the use of insect growth regulators or insecticides, which may be prohibited in certain environments or affect non-target organisms. The aim of this study was to investigate whether entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae, currently employed for control of terrestrial crop pests, could be used as a viable biocontrol for the aquatic larval stages of the Chrionomidae, offering an alternative to current chemical methods. We demonstrate that Steinernema feltiae (Filipjev, 1934), Steinernema carpocapsae (Weiser, 1955), Steinernema kraussei (Steiner, 1923) and Heterorhabditis bacteriophora (Poinar, 1975) are able to survive in water up to 96 h and are able to parasitize and kill Chironomus plumosus (Linnaeus, 1758) larvae, with mortality observed after just 24 h exposure and with < 20% survival after 4 days. We also show that following application to the water column, EPNs sink to the bottom of the lentic water body and can remain alive for more than 96 h. Taken together, we believe that several EPN species could be developed as a valid form of biocontrol for Chironomidae.

Chironomidae, or non-biting midges, are found worldwide in a wide variety of aquatic habitats. During periods of mass adult eclosion they can become a nuisance and health hazard. Current control methods target the aquatic larval stage and include the use of insect growth regulators or insecticides, which may be prohibited in certain environments or affect non-target organisms. The aim of this study was to investigate whether entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae, currently employed for control of terrestrial crop pests, could be used as a viable biocontrol for the aquatic larval stages of the Chrionomidae, offering an alternative to current chemical methods. We demonstrate that Steinernema feltiae (Filipjev, 1934), Steinernema carpocapsae (Weiser, 1955), Steinernema kraussei (Steiner, 1923) and Heterorhabditis bacteriophora (Poinar, 1975) are able to survive in water up to 96 h and are able to parasitize and kill Chironomus plumosus (Linnaeus, 1758) larvae, with mortality observed after just 24 h exposure and with < 20% survival after 4 days. We also show that following application to the water column, EPNs sink to the bottom of the lentic water body and can remain alive for more than 96 h. Taken together, we believe that several EPN species could be developed as a valid form of biocontrol for Chironomidae. [ABSTRACT FROM AUTHOR]

This paper presents an improved way of applying Monte Carlo simulation using the crossentropy method to calculate the risk of capacity deficit of a composite power system. By applying importance sampling for load states in addition to the generation and transmission states in a systematic manner, the proposed method is many orders of magnitude more efficient than the crude Monte Carlo simulation and considerably more efficient than other crossentropy-based algorithms that apply other ways of estimating the importance sampling distributions. An effective performance metric of system states is applied in order to find optimal importance sampling distributions during presimulation that significantly reduces the required computational effort. Simulations, using well-known IEEE reliability test systems, show that even problems that are nearly intractable using crude Monte Carlo simulation become very manageable using the proposed method. [ABSTRACT FROM AUTHOR]

The influence of different temperature ranges on the reproductive potential of native and exotic species of entomopathogenic nematodes (EPNs) was checked on Galleria mellonella larvae. The native species included Steinernema asiaticum and Heterorhabditis indica whereas exotic species were S. feltiae and H. bacteriophora. G. mellonella larvae were exposed to 300 IJs of each species. After inoculation at different temperatures, the reproductive potential of EPNs increased with increasing temperature and was found to be the best at 25°C. No EPNs species could reproduce at 5°C. S. feltiae started reproduction at 10°C, while all remaining species reproduced at 15°C or higher temperatures. Maximum numbers of IJs were recovered from H. bacteriophora. Time taken for first emergence of IJs from the host was shortest at 25°C i.e. 7-8 days in case of S. asiaticum and S. feltiae, while 11-13 days for H. bacteriophora and H. indica. Maximum emergence time was taken by S. feltiae at 10°C. [ABSTRACT FROM AUTHOR]

The entomopathogenic nematode (EPN) Steinernema feltiae , which carries the symbiotic bacterium Xenorhabdus bovienii in its gut, is an important biocontrol agent. This EPN could produce a suite of complex metabolites and toxin proteins and lead to the death of host insects within 24-48 h. However, few studies have been performed on the key biomarkers released by EPNs to kill host insects. The objective of this study was to examine what substances produced by EPNs cause the death of host insects. We found that all densities of nematode suspensions exhibited insecticidal activities after hemocoelic injection into Galleria mellonella larvae. EPN infection 9 h later led to immunosuppression by activating insect esterase activity, but eventually, the host insect darkened and died. Before insect immunity was activated, we applied a high-resolution mass spectrometry-based metabolomics approach to determine the hemolymph of the wax moth G. mellonella infected by EPNs. The results indicated that the tryptophan (Trp) pathway of G. mellonella was significantly activated, and the contents of kynurenine (Kyn) and 3-hydroxyanthranilic acid (3-HAA) were markedly increased. Additionally, 3-HAA was highly toxic to G. mellonella and resulted in corrected mortalities of 62.50%. Tryptophan metabolites produced by EPNs are a potential marker to kill insects, opening up a novel line of inquiry into exploring the infestation mechanism of EPNs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhang, Wang and Zhao.)