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The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), has invaded most Afro-Eurasian countries and is threatening worldwide tomato production. Various strategies have been developed and implemented to manage this pest. Here, we present a timely review on the up-to-date development and practical implementation of integrated pest management (IPM) programs for tomato crops across different world regions infested by T. absoluta. While insecticide resistance is a growing concern, biological control via releasing or conserving arthropod natural enemies and sex pheromone-based biotechnical control are the most successful management practices. Agronomic control-related research is an emerging area where the soil fertilization and/or irrigation, as well as breeding of resistant cultivars, has the potential to enhance IPM effectiveness. Grower survey responses in the native areas (i.e., South America), early-invaded areas (i.e., first report between 2006 and 2012) and newly invaded areas (i.e., first report after 2012) showed that the control programs evolved along with the areas and time since invasion. Growers in the early-invaded areas shifted more rapidly from chemical control to biological control compared to those from the native area. In all concerned regions, the pest control failure risk following chemical insecticide applications and the high cost associated with either biological or biotechnical control methods have been the greatest concerns for growers. The information gathered from the native and/or early-invaded areas may help achieve a more effective management in newly invaded areas. Lastly, researchers are expected to break the bottlenecks of some key issues that would enable lowering application cost of novel biorational alternative management options.

Background Ceratitis capitata Wiedemann (Diptera: Tephritidae) (Mediterranean fruit fly), is one of the important polyphagous pest species in the world that harms almost all fruits causing significant yields losses. Control of this pest which is on the quarantine list of many countries is highly important. Due to the negative effects of chemical control on the environment and human health, biological control approaches have gained importance. Entomopathogenic nematodes (EPNs) are a potential biological control agent that can be used for effectively controlling the Medfly. Results In this study, effects of four EPNs species on larvae, pupae and adults of Medfly were investigated under laboratory conditions. Four different concentrations of EPNs species were used against each stage of the pest. It pest showed different sensitivity to different concentrations of each of the tested EPNs. High mortality rate of 94% was caused by Heterorhabditis bacteriophora (11 KG),, followed by H. bacteriophora (TOK-20) with 91%, Steinernema carpocapsae (85%) and S. feltiae (Tokat-Emir) with 71% at highest concentration (200 IJ/larvae. The highest effect on adult mortality (100%) was recorded by the species S. feltiae (Tokat-Emir) at the highest concentration (200 IJ/adult) in the trials, followed by H. bacteriophora (11 KG) with 92%, H. bacteriophora (TOK-20) with 91% and S. carpocapsae (Tokat-Bakışlı05) with 87.37% mortality rates at the same concentrations. Conclusions It was determined that the EPNs tested in this study had insecticidal properties and they might be used in biological control programs against the Medfly.

Background Outbreak of the fall armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) occurred in Mizoram, North-Eastern India. The infestation spread in the entire state covering a total area of around 2840 hectares of maize cultivated land. Entomopathogenic nematodes (EPNs) represent potential candidates for the biological control of S. frugiperda. In the study, the susceptibility of the pest against 4 locally isolated EPN species Heterorhabditis indica, H. baujardi, Steinernema sangi and S. surkhetense was evaluated. Results The results indicated that all the isolated EPN species showed a high rate of larvicidal and pupicidal activities against the pest. Mortality between 43.75–100.00 and 25.00–100.00% of 3rd and 5th larval instars, respectively (at concentrations 10–800 IJs/larva), and 37.50–68.75% mortality of pupae (at concentrations 200–1600 IJs /pupa) were found after exposure to the EPN species. The mortality rate of the pest showed significant variations with life stages of the host insect, nematode concentrations and incubation time. Based on the median lethal concentration (LC50), H. indica was the most pathogenic species, followed by S. sangi, H. baujardi and S. surkhetense. The LC50 values of H. indica at 72 h post-incubation were 20.26 and 62.07 IJs/larva for the 3rd and 5th larval instars, respectively, and 913.34 IJs/pupa. The penetration assay showed that H. indica had the highest penetration rate into the hosts, 27.24, 21.30 and 20.00% in the 3rd, 5th larval instars and pupae, respectively. Furthermore, all the EPN isolates were capable of successful multiplication inside the cadaver of S. frugiperda that showed significant differences with the EPN isolates and life stages of the pest. Among the isolates, H. indica showed the highest multiplication rates, 17,692.25 ± 2103.59, 8345.63 ± 785.34 and 79,146.38 ± 5943.73 IJs per 3rd instar larva, 5th instar larva and pupa, respectively. Conclusions The study revealed that the 4 species of EPNs showed a high potency against S. frugiperda, thereby having the potential to be developed as a biological control agent against the pest. Moreover, the isolated EPN species could potentially serve as alternatives for chemical insecticides and could further be incorporated into the Integrated Pest Management (IPM).

Background The rust red flour beetle, Tribolium castaneum (Herbst.) (Coleoptera: Tenebrionidae) is a serious pest of stored grains and grain products across the world. This beetle is hold a significant place in Turkey by causing damages on stored products. T. castaneum primarily attacks milled grain and its derivates. Entomopathogenic nematodes (EPNs) are regarded as extremely an important biological control agent. EPNs kills their hosts within 48 h by the bacteria they carry. Results Efficacies of 4 isolates of EPNs Steinernema carpocapsae (Tokat Bakisli 05), S. feltiae (Tokat-Emir), Heterorhabditis bacteriophora (TOK-20) and H. bacteriophora (11-KG) against T. castaneum was investigated under laboratory conditions. The experiments were carried out thrice with 10 replicates at 2 different temperatures (15 and 25 ºC). EPNs isolates were tested at 3 different concentrations (250, 500 and 1000 IJs/ml) with a pure water as control. The overall mortality caused by H. bacteriophora (Kg11) was significantly higher than the other EPN species. At 25 ºC, H. bacteriophora (Kg11) at the highest concentration (1000 IJs/ml) caused 87.6% mortality after 120 h., followed by S. carpocapsae and S. feltiae with 79.22 and 75.3% mortality rates, respectively. The mortality percentages exhibited by all nematodes’ species at both temperatures were lowest at the concentration of (250 IJs/ml). At 15 °C, H. bacteriophora (Kg11) caused (55.2%) mortality rate at the highest concentration (1000 IJs / ml) after 120 h. Conclusion The study suggested that these nematodes were efficient and could be recommended to control T. castaneum in its biological control programs.

Background Entomopathogenic nematodes (EPNs) have more important role in biological control of economic insect pests. The effect of native EPNs on adults of the lucerne beetle, Gonioctena fornicata (Brüggemann, 1873) (Coleoptera: Chrysomelidae), and the alfalfa weevil, Hypera postica (Gyllenhal, 1813) (Coleoptera: Curculionidae), which are important alfalfa pests in Turkey and around the world, was investigated. Results Dose-mortality assays were carried out with 5 isolates [Steinernema carpocapsae (Weiser, 1955) (Nematoda: Steinernematidae) (Black sea isolate), S. feltiae Filipjev, 1934 (isolate 09-31), Heterorhabditis bacteriophora Poinar, 1976 (Nematoda: Heterorhabditidae) (isolate 09-43), H. bacteriophora Tokat-Songut, and S. carpocapsae Tokat-Ulas] using doses of 500, 1000, and 2000 IJs ml−1 under the laboratory conditions. Studies showed that all isolates had an effect 90% and more at 2000 IJs ml−1 and at the end of 112 h [except, H. bacteriophora (isolate 09-43) and H. bacteriophora Tokat-Songut isolates against H. postica]. In addition, LT30, LT50, and LT90 values at 1000 IJs ml−1 were determined. Conclusions According to the results, G. fornicata adults were susceptible to all isolates tested in the study and H. postica adults were susceptible to the isolates S. carpocapsae (Black sea isolate), S. feltiae (isolate 09-31), and S. carpocapsae Tokat-Ulas. This is the first study conducted in Turkey for the virulence of EPNs against G. fornicata and H. postica.

Background In this study, the virulances of 4 different concentrations of the entomopathogenic nematode, Steinernema feltiae (Filipjev) on adults of the rose weevil, Mecorhis ungarica (Herbst, 1784) (Coleoptera: Rhynchitidae) were tested under laboratory conditions. Results Ten replications for each concentration where 5 adults for each replicate were used. Suspensions prepared from each concentration, containing 3rd instar juveniles (infective juveniles) of S. feltiae, were sprayed on the pest adults for 20 s at 1 atm pressure. Deltamethrin was applied, at the recommended concentration (30 ml/ha), as a positive control, while pure water was used as negative control. Observations started 72 h after the applications and continued until the 15th day. The White Trap Method used for the re-isolation of nematodes from dead individuals obtained in observation days. As a result of the study, obtained mortality rates in concentration of S. feltiae (100, 150, 200, 250 million IJs/100 l water) were not different from each other but were found significant than control (P < 0.05). Additionally, among the number of re-isolated 3rd juveniles, the highest mean number was found on 200 million IJs concentration and the lowest mean was determined on 150 million IJs concentration. Tested concentrations of S. feltiae caused 80, 86, 82, and 92% death on adult individuals on the 15th day. Mortality rates caused by each concentration depending on the time were not significant between each other (P > 0.05). Conclusion In this study, it was determined that different concentrations of S. feltiae were effective on adults of rose weevil. It is thought that entomopathogenic nematodes may be an alternative and promising biological control strategy to reduce the risk of pesticide residues in oil-bearing rose production areas.

Background Entomopathogenic nematodes (EPNs) are widely used in biological control for soil-dwelling stages of many insect pests that are characterized by their safety to most non-target organisms and to the environment. Results The objectives of the present study were isolation of EPNs from agricultural soil in Egypt for further use in biological control programs and study the genetic variation among them using the molecular marker inter-simple sequence repeats (ISSR). Three out of 25 soil samples collected from fields cultivated with strawberry, tangerine, and pumpkin were positive for the presence of EPNs, using the Galleria baiting technique. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong to Heterorhabditis sp. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under accession nos. MH553165, MH553168, and MH553169. Six ISSR primers were used. The numbers of polymorphic bands were 42 out of 56, and the polymorphism percentage was 75%. The highest number of bands was 12 bands generated by primer ISSR8 followed by UBC-809 (11 bands) while recorded the lowest band number (4 bands), the percentage of polymorphism ranged from 40% (ISSR1) to 100% (ISSR6). Conclusion ISSR marker can be considered a good marker to study genetic diversity and detecting the genetic polymorphism among the nematodes species.

Background The tobacco cutworm, Spodoptera litura [Fab.] (Lepidoptera: Noctuidae), is a devastating insect pest of several crops. Entomopathogenic nematodes (EPNs) of the families Heterorhabditidae and Steinernematidae are used as an alternative control measure in lieu of the hazardous synthetic chemical applications. Results A survey of naturally occurring EPNs was conducted across the province of Cotabato, Philippines, covering a total of 5 municipalities with 25 villages. Galleria-baiting technique was employed to recover nematodes from peanut and grassland soils. Out of 50 soil samples collected, only 5 samples harbored nematodes, indicating a recovery of 10%. Preliminary morphological data identified only one EPN under the genera Heterorhabditis (1 isolate), whereas 4 were facultative necromenic nematodes from the genera Metarhabditis (2 isolates) and Oscheius (2 isolates). Analysis of D2D3 segments of the 28S rDNA confirmed high sequence similarity to Heterorhabditis indica, Metarhabditis rainai, Oscheius insectivora, and Oscheius sp. This is the first record of H. indica and M. rainai in the entire region, whereas the first record for Oscheius spp. in the Philippines. Furthermore, the biocontrol potential of the local H. indica infective juvenile (IJ) populations (PIGCD1) isolated from peanut was assessed against the tobacco cutworm, S. litura, under laboratory conditions. The mean percentage mortality caused by H. indica on S. litura at 7 different concentrations ranged from 0-100% at 24 h post inoculation. The lethal concentration (LC50) required to kill 50% of the S. litura larvae population with H. indica was 7.13±1 (IJs/larva). Conclusions The use of Galleria-baiting method is a convenient approach to detect EPNs including other facultative necromenic nematodes from the soils. Obtained data indicated that the local H. indica isolate can be a promising alternative measure to suppress the economically important insect pest, S. litura, and this may provide significant outlook to establish the biocontrol program in the country.

Among the new contaminants relevant for environment, one of the most significant roles is played by pharmaceuticals like antibiotic products for either human or veterinary use. Their presence could cause serious damage to bacteria and microfauna, like nematodes. Within the widely investigated nematodes, very little is known about the interaction between antibiotics and entomopathogenic nematodes (EPN). EPNs have been used for biological control of crops, due to their ability to penetrate arthropod pests and kill their hosts thanks to a complex symbiotic mechanism with specific gram-negative bacteria. Tetracycline is an antibiotic used in human and veterinary medicine, both for therapeutic purposes and for the growth of livestock. Since its action against gram-negative bacteria is documented, we verified in this study the survival, growth and pathogenicity of two species of EPNs, Steinernema vulcanicum and S. feltiae. All tests were performed with tetracycline in 1% ethanol solution and up to 300 mg/L. Apparently, this incubation did not harm the vitality of EPNs. Both S. vulcanicum as S. feltiae recovered their vitality and entomopathogenic ability after 48 h. Moreover, the latter EPN species did not grow nor reproduce in the hemolymph of the Greater Wax Moth, Galleria mellonella, and their endosymbionts did not grow on MacConkey Agar. Our results suggest that the first EPN species has always retained all its abilities and that endosymbionts have acquired resistance to tetracycline, while experiments with the second EPN species provided some contrasting results in time that will require further investigations.

Background The complex including entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis and their mutualistic partner, i.e., Xenorhabdus and Photorhabdus bacteria, respectively possesses many attributes of ideal biological control agents against numerous insect pests as a third partner. Despite authenic opportunities for their practical use as biocontrol agents globally, they are challenged by major impediments especially their cost and reliability. Main body This review article presents major attributes of EPNs to familiarize growers and stakeholders with their careful application. As relatively high EPN costs and frequently low efficacy are still hindering them from reaching broader biopesticide markets, this is to review the latest findings on EPN strain/species enhancement, improvement of production, formulation and application technology, and achieving biological control of insects from the standpoint of facing these challenges. The conditions and practices that affected the use of EPNs for integrated pest management (IPM) are identified. Besides, efforts have been made to address such practices in various ways that grasp their effective approaches, identify research priority areas, and allow refined techniques. Additionally, sampling factors responsible for obtaining more EPN isolates with differential pathogenicity and better adaptation to control specific pest(s) are discussed. Conclusion Specific improvements of EPN production, formulation, and application technology are reviewed which may help in their broader use. Other diverse factors that optimize EPNs to constitute a cost-effective, value-added approach to IPM are also demonstrated.

Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are obligate parasites of soil inhibiting insects. EPNs are being widely researched as promising biocontrol agents for a wide range of agricultural pests. It is known that strains of EPNs isolated from different geographical regions differ in their attributes, such as host-finding ability, host range, infectivity, reproduction, and environmental stress tolerance. A precise knowledge of these factors is therefore an essential pre-requisite for devising successful strategies to use these nematodes in biological control programmes. Thus, ecological characterisation of the EPN Heterorhabditis indica (Rhabditida: Heterorhabditidae) newly isolated and representing the only species of EPN reported from the island of Viti Levu, Fiji was carried out using Galleria mellonella larvae (L) (Pyralidae: Galleriinae) as hosts to allow comparisons between bioassays conducted in different laboratories around the world. Temperature data showed that native isolates of H. indica are warm-adapted nematodes with thermal range for infectivity between 15˚C and 35˚C and can reproduce between 20˚C and 30˚C. They are highly virulent with LC50 values against G. mellonella ranging from 2.8 IJ to 3.8 IJ/larva. However, they showed poor desiccation tolerance and fail to infect hosts in soil with moisture levels below 8%. They showed a moderate level of hypoxic tolerance and can be stored at 15˚C for 4 months. Results also showed great variability within the selected native isolates of H. indica. Beneficial traits for selected isolates were added up to identify a superior candidate. The current study also suggested that the thermal niche breadth for infection can differ among conspecific strains of an EPN species. The results of this experimental study on ecological aspects of these native isolates of H. indica should form a basis for their potential use in biological control of insect pests in Fiji.

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 mellonellaL. (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 theGalleriabaiting technique. The positive soil samples were sandy clay loam. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong toHeterorhabditis indica. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under the accession nos. MH553167 andMK300683. The efficacy of the isolates was tested onG. mellonella, using different nematodes’ concentrations. Using 50 IJs/larvae fromH. indicaAborawash and ERSAG2 showed 100 and 86% mortality rate after 48 h, respectively. The penetration rate reported in deadG. mellonellawas 40% atH. indicaAborawash, while it was 35% in case of ERSAG2.

Entomopathogenic nematodes (EPNs) can provide a substantial control, especially of the root feeding larval pests. The objective of the present study was to examine beneficial traits of an indigenous entomopathogenic nematode species, Heterorhabditis bacteriophora Poinar (Hb-EG strain), and to identify superior biocontrol candidates for suppression of the scarab beetle Temnorhynchus baal (Reiche & Saulcy) (Coleoptera: Scarabaeidae: Dynastinae) larvae as serious pests of strawberry in Egypt. The nematodes were applied to infect the greater wax moth, Galleria mellonella L. cadavers, to represent natural emergence from the host in laboratory and under field conditions. Its average yield was 49604 infective juveniles (IJs) per G. mellonella larva. Overall averages of nematode-induced mortality in G. mellonella larvae were (4.63, 3.12, and 1.92) at 4, 8, and 12 weeks, respectively, after continuous weekly baiting with 5 cadavers. Nematode capability for infection and reproduction ranged from 72 to 26% one to five months, respectively, after field inoculation of the infected larvae into the strawberry rhizosphere. The number of IJs, moved to the North of the rhizosphere, was significantly (P ≤ 0.05) less than that moved to the South or the East as reflected by the numbers of infected insects. The factors that may have a marked influence on EPN foraging behavior, persistence, and movement direction with implications for harnessing them as biological pest control agents were discussed.

Two-year (2014-2015) study aimed to determine the effectiveness of entomopathogenic nematode (EPN) Heterorhabditis bacteriophora Poinar, 1976 (Nematoda: Heterorhabditidae) infective juveniles (IJs) on sugar beet weevil (Bothynoderes punctiventris Germar, 1824 (Coleoptera: Curculionidae)) larvae and to assess its potential for use in practice. In field experiments, three doses of nematodes were used and an untreated control. In the conditions of moderate larval attack (average infestation of 0.28 larvae per plant), EPNs showed clear dose response being highly effective (92.86% control) when applied in the highest dose. Although the results indicated that H. bacteriophora could have a satisfactory mortality effect on sugar beet weevil larvae, further investigations are needed in order to better determine the optimal dose and application timing. If effective, EPNs could be used as one of the tools in a strategy which aims to reduce sugar beet weevil population levels in a wider area.

Photorhabdus luminescens subsp. akhurstii SL0708 (Enterobacteriaceae) is a symbiont of the entomopathogenic nematode (EPN), Heterorhabditis indica SL0708 (Nematoda: Rhabditida), used for insect pest biological control. In the present study, P. luminescens subsp. akhurstii SL0708 growth kinetic was evaluated considering growth and metabolic phases (phase I, intermediate phase, phase II), as well as pathogenicity. The study can be useful in determining bacterium feeding times in H. indica SL0708 production in liquid culture media. The logarithmic phase of the growth of bacterium was from 0 to 24 h, with a specific growth velocity of 0.21 h−1; during this phase, bacterium at metabolic phase I was detected. Maximum bioluminescence was registered at 24 h (3.437 luminescence AU). Finally, it was evidenced that the bacterial metabolic phase had an effect on the greater wax moth, Galleria mellonella L., larvae mortality rate. Moreover, biochemical tests were the same for all P. luminescens subsp. akhurstii SL0708 sampling times. This research is particularly relevant, since no reports are available on this bacterium isolate in Colombia. In the future, this will allow massive H. indica SL0708 production, because when pre-incubated with its symbiont, it provides essential nutrients for the EPNs development and reproduction.

Background Entomopathogenic nematodes (EPNs) are evidently a useful nematode group for the biocontrol of insect pests. It is well known that efficacy of different EPN strains, even belonging to the same species, can be significantly varied in different localities. Therefore, exploring EPNs and testing their efficacy in various ecological regions is of crucial importance to find out more efficient EPN strains. On the other hand, this practice is also needed to enhance the knowledge on diversity and distribution model of EPNs over the world. Results In this study, a species belonging to the genus Steinernema, S. surkhetense, has been characterized for the first time in Vietnam based on morphological and molecular characterizations. Morphological characterizations of infective juveniles, the first and second-generation adults, and molecular characterization of D2-D3 expansion segment of 28S rRNA region were given. Molecular phylogeny of the genus Steinernema was also provided. In addition, the study showed that the lethal efficacy of this local strain to larvae of Galleria mellonella L. was relatively higher than other reported EPN strains in Vietnam. Conclusions The Vietnamese EPN population found in this study was determined to be conspecific with S. surkhetense, revealed its new distribution in Vietnam. Besides, detailed morphological and molecular characterizations of it was provided with small variations compared to other populations in the world, and its relatively high lethal efficacy on larvae of G. mellonella implied that this strain can be potentially a useful strain for biological control of insect pests.

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae), is an important insect pest of maize in North America and Central and Eastern Europe. In Central Europe, the larvae emerge in May and its three instars feed intensively on maize roots in June, causing plant lodging that leads to a loss of economic yield. A three-year field experiment (2016&ndash, 2018) was conducted to compare the effectiveness i) of soil-applied granular insecticide based on the active ingredient tefluthrin, ii) of maize seeds dressed with thiacloprid, and iii) entomopathogenic nematodes Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae, product Dianem) against WCR larvae. An additional treatment with alcohol ethoxylate (i.e., soil conditioner) mixed with entomopathogenic nematodes was performed in 2017 and 2018 to check for any increase of entomopathogenic nematodes&rsquo, effectiveness. Field tests were carried out in two fields infested naturally with a WCR pest population, one in Bučečovci (Eastern Slovenia) and the other in &Scaron, martno pri Cerkljah (northern Slovenia), exhibiting dissimilar pedo-climatic conditions and soil pest densities. The treatments were performed in five replicates per experiment in each year. The efficacy of the treatments was very similar at both locations, despite the approximately five-fold lower WCR soil pest densities in northern than in eastern Slovenia, as well as being constant over time. The largest number of WCR beetles was observed in the negative control, followed by that of beetles subjected to thiacloprid treatment (insignificant decrease taking into account the entire three-year dataset). Treatments with tefluthrin (44.1 &plusmn, 11.7%), H. bacteriophora (46.2 &plusmn, 7.4%), and H. bacteriophora + alcohol ethoxylate (49.2 &plusmn, 1.8%) significantly decreased the numbers of emerging beetles. Treatments of thiacloprid, H. bacteriophora, and H. bacteriophora + alcohol ethoxylate additionally led to significantly increased maize plant weights. Furthermore, entomopathogenic nematodes were able to persist in maize fields for almost five months at both experimental locations in silty and sandy loam soils. It was concluded that the control of WCR larvae in maize using the entomopathogenic nematode H. bacteriophora is as effective as a tefluthrin treatment, and could thus offer a sustainable Diabrotica v. virgifera biological control management option in Europe.

How climate change will modify belowground tritrophic interactions is poorly understood, despite their importance for agricultural productivity. Here, we manipulated the three major abiotic factors associated with climate change (atmospheric CO2, temperature, and soil moisture) and investigated their individual and joint effects on the interaction between maize, the banded cucumber beetle (Diabrotica balteata), and the entomopathogenic nematode (EPN) Heterorhabditis bacteriophora. Changes in individual abiotic parameters had a strong influence on plant biomass, leaf wilting, sugar concentrations, protein levels, and benzoxazinoid contents. Yet, when combined to simulate a predicted climate scenario (Representative Concentration Pathway 8.5, RCP 8.5), their effects mostly counter-balanced each other. Only the sharp negative impact of drought on leaf wilting was not fully compensated. In both current and predicted scenarios, root damage resulted in increased leaf wilting, reduced root biomass, and reconfigured the plant sugar metabolism. Single climatic variables modulated the herbivore performance and survival in an additive manner, although slight interactions were also observed. Increased temperature and CO2 levels both enhanced the performance of the insect, but elevated temperature also decreased its survival. Elevated temperatures and CO2 further directly impeded the EPN infectivity potential, while lower moisture levels improved it through plant- and/or herbivore-mediated changes. In the RCP 8.5 scenario, temperature and CO2 showed interactive effects on EPN infectivity, which was overall decreased by 40%. We conclude that root pest problems may worsen with climate change due to increased herbivore performance and reduced top-down control by biological control agents.

Pieris rapae and Pentodon algerinus are considered a global threat to agricultural crops and food security, hence, their control is a critical issue. Heterorhabditid and Steinernematid nematodes, along with their symbiotic bacteria, can achieve the optimal biocontrol agent criterion. Therefore, this study aimed to evaluate the efficacy of Heterorhabditis bacteriophora, Steinernema riobravis, and their symbiotic bacteria (Xenorhabdus and Photorhabdus) against P. rapae and P. algerinus larvae. The virulence of entomopathogenic nematodes (EPNs) was determined at different infective juvenile concentrations and exposure times, while the symbiotic bacteria were applied at the concentration of 3 × 107 colony-forming units (CFU)/mL at different exposure times. Gas chromatography–mass spectrophotometry (GC-MS) analysis and the cytotoxic effect of Photorhabdus sp. and Xenorhabdus sp. were determined. The results indicated that H. bacteriophora, S. riobravis, and their symbiotic bacteria significantly (p ≤ 0.001) induced mortality in both insect species. However, H. bacteriophora and its symbiont, Photorhabdus sp., were more virulent. Moreover, the data clarified that both symbiotic bacteria outperformed EPNs against P. rapae but the opposite was true for P. algerinus. GC-MS analysis revealed the main active compounds that have insecticidal activity. However, the results revealed that there was no significant cytotoxic effect. In conclusion, H. bacteriophora, S. riobravis, and their symbiotic bacteria can be an optimal option for bio-controlling both insect species. Furthermore, both symbiotic bacteria can be utilized independently on EPNs for the management of both pests, and, hence, they can be safely incorporated into biocontrol programs and tested against other insect pests.

Background Entomopathogenic nematodes (EPNs) are one of the widely studied biological control agents. The present study was conducted to evaluate the efficacy of two EPNs species, Heterorhabditis bacteriophora (Poinar) (Rhabditida: Heterorhabditidae) and Steinernema aciari (Qui, Yan, Zhou, Nguyen and Pang) (Rhabditida: Steinernematidae), isolated locally from soils of Majuli river island, Assam, India against two important subterrenean pests; Odontotermes obesus (Rambur) (Isoptera: Termitidae) and Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) under laboratory conditions. Results In case of O. obesus, mortality percent was recorded by H. bacteriophora after 72 h. at 300 IJs/termite and by S. aciari at 250 and 300 IJs/termite after 96 h. The lowest LD50 and LT50 values obtained for H. bacteriophora were 13.054 IJs/termite and 26.639 h., respectively, while those of S. aciari were 42.040 IJs/termite and 31.761 h., respectively. With respect to A. ipsilon, H. bacteriophora registered a highest mortality rate at 300 IJs/larvae after 144 h. S. aciari showed 100 percent mortality at 300 IJs/larva after 168 h. The lowest values of LD50 and LT50 for H. bacteriophora were 35.711 IJs/larva and 83.050 h., respectively. The lowest values of LD50 and LT50 for S. aciari were 71.192 IJs/larvae and 97.921 h., respectively. Overall, H. bacteriophora displayed more virulence toward O. obesus and A. ipsilon than S. aciari. Conclusion Both native EPNs were found effective against O. obesus and A. ipsilon. However, H. bacteriophora was more virulent toward O. obesus and A. ipsilon than S. aciari under the laboratory conditions.

Colorado potato beetle (CPB) is an economic pest of potato that has developed resistance to all classes of chemical insecticides, thus requiring alternative control measures. As a potential solution, entomopathogenic nematodes (EPNs) have proven effective in suppressing this pest, but their efficacy against overwintering generations of CPB in Croatia has not been sufficiently researched. The aim of this two-year (2018–2019) field study was to determine the efficacy of Steinernema feltiae and Steinernema carpocapsae applied to overwintering CPB adults. EPNs were applied at three doses (7.5 mil./10 m2, 5.0 mil./10 m2 (the recommended dose) and 2.5 mil./10 m2) by watering the soil where the adults were overwintering. The first-year results were satisfactory for both EPNs: the efficacy of S. feltiae ranged from 79.03% to 100.00%, while the efficacy of S. carpocapsae ranged from 77.32% to 96.22%. In the second year, the highest efficacy (69.57%) was obtained using the recommended dose of S. feltiae. Although the results are not consistent across the two years of our study and suggest further research, they indicate that EPNs have great potential in controlling overwintering CPB generations to reduce first generation abundance and damage, and also to prevent the spread of new generations to surrounding potato growing areas.

Background The codling moth (CM), Cydia pomonella (L). (Lepidoptera: Tortricidae), is an important pest of apple in Turkey and other apple producing countries in the world. Several control methods are available for reducing the pest populations. Entomopathogenic nematode (EPNs), for example, can be used as a potential alternative to chemical insecticides to control codling moth larvae in the soil as eco-friendly management their hosts that can actively find them in cryptic locations. Results Efficacy of 4 EPN isolates, Steinernema carpocapsae (Bakışlı), S. feltiae (ES-3), Heterorhabditis bacteriophora (TOK-20) and H. bacteriophora (11-KG) for controlling the 1st instar larvae of the codling moth (Cydia pomonella L.) was investigated under controlled laboratory conditions. Codling moth was susceptible to different rates to all the 4 EPN isolates. All nematode trials were more effective than the control (water). The overall mortality caused by S. carpocapsae (Bakışlı 05) was significantly higher than the other EPN species. S. carpocapsae was the most effective with the highest tested concentration (100 IJs/larva), killing 82.63% of codling moth larvae, followed by S. feltilae (ES-3), with a mortality rate of 71.5%. H. bacteriophora (TOK-20) exhibited the least mortality at 25 IJs/larva concentration in all experiments. Conclusion The study proved that these nematodes were very efficient and could be used to control codling moth in biological control programs.

In Brazil, countless insect species attack and damage sugarcane (Saccharum officinarum L.), which is an extremely important crop since it is planted on more than 10 million hectares. Among these insects, the sugarcane billbug, Sphenophorus levis (Coleoptera: Curculionidae), is of great importance as the larvae open tunnels in the rhizome of the plant, causing high damage and losses. This insect is attracted mainly to vinasse, which is the liquid fraction generated from the alcohol production and discarded onto the sugarcane fields for fertigation. Toward a novel control method for S. levis, the native entomopathogenic nematode Steinernema rarum (Pam 25) was compared with S. carpocapsae (IL 1) and Heterorhabditis bacteriophora (HBEN01) in respect to their ability to search for larvae of two insect hosts (Galleria mellonella and S. levis) within the cane rhizome. The selected nematode S. rarum was also assessed for rate effects, its survival in vinasse and field efficacy to control sugarcane pests S. levis, Hyponeuma taltula (Lepidoptera, Erebidae) and Leucothyreus alvarengai (Coleoptera: Melolonthidae). Steinernema rarum exhibited superior virulence to G. mellonella and S. levis larvae inserted into the cane rhizomes (75–78% mortality) compared to S. carpocapsae (30–53%) and H. bacteriophora (18–28%). Vinasse affected S. rarum when infective juveniles were suspended in the liquid compost for more than 6 h but did not affect the nematode when kept on the straw and soil treated with the compost. Steinernema rarum tested at 1–3 × 108 infective juveniles/ha on the sugarcane field caused 74.1, 56.3 and 50.6% control of S. levis, L. alvarengai and H. taltula, respectively.

Background Stored grain products suffer a considerable economic loss due to insect infestations. The resistance of pests to insecticide, and residues on crops are produced by the application of insecticide. Nowadays, incremental necessity has been occurred to find out alternatives to chemicals. As biological control agents, entomopathogenic nematodes (EPNs) attract attention increasingly in the research area recently. Results The aim of the study was to evaluate the pathogenicity of Pakistani isolates Steinernema bifurcatum and S. affine against the stored grain pests, Tribolium castaneum and Lasioderma serricorne, under laboratory conditions. Suspensions of nematodes were applied at 4 different concentrations 0, 50, 100, and 200 IJs/ml and 3 variable temperatures 15, 30, and 45°C. Pathogenicity rate was recorded after 48 h of application. The larval stage is found more susceptible than the adult. At 200 IJs, S. bifurcatum showed high mortality of L. serricorne larva (92%) and T. castaneum larva (93%), whereas S. affine showed 90 and 95% mortality of L. serricorne and T. castaneum larva, respectively, at 200 IJs. The results revealed that both species of EPN were able to control and reproduce on L. serricorne and T. castaneum. Maximum mortality was recorded at 45 °C from S. bifurcatum whereas S. affine at 15 °C. Conclusions Therefore, S. bifurcatum and S. affine could be suggested as a biological control agent for hot and cold climatic zones, respectively.

Background Entomopathogenic nematodes (EPNs) are a group of nematode families, have the ability to search for their hosts, and are considered as promising biological control candidates for insect pests, providing protection to non-target organisms and the environment. Results This study was conducted to isolate indigenous EPN isolates from Egyptian agricultural soils for further use in biological control programs and study their genetic polymorphism among the previously isolated isolates under accession no. MH553167 and MK300683 and the new isolate (MH496627), using the start codon targeted (SCoT) marker. One out of 15 soil samples obtained from a banana cultivated field was positive for the presence of EPNs, using the Galleria baiting method. Morphological analysis and sequencing of the internal transcribed spacer (ITS) region suggested that the isolate obtained belongs to Heterorhabditis indica. The sequence of the ITS was submitted to the National Center for Biotechnology Information (NCBI) and registered under accession no. MH496627. Ten SCoT primers were used in the study; the polymorphic bands were 68 out of 76 with 89% as polymorphism percentage. The highest numbers of bands were 10 bands generated by SCoT 1 and SCoT 18 while SCoT 48 and SCoT 60 recorded the lowest band number (5 bands). Conclusions The present study is considered as a preliminary study to demonstrate the effectiveness of the SCoT marker for the first time in assessing genetic relationships in EPNs.

The strength of sequence-related amplified polymorphism (SRAP) in comparison to random amplified polymorphic DNA (RAPD) in determining the genetic polymorphism among seven species of entomopathogenic nematodes (Steinernematidae) was tested. Nine RAPD and 12 SRAP primer pair’s combinations were used. The number of polymorphic bands and the polymorphism percentages was high in SRAP analysis (97 out of 107 bands were polymorphic (90.6%)) compared to RAPD (65 out of 89 bands were polymorphic (73%)). The highest number of RAPD bands was recorded for OPE-A-07 primer (14 band) while OPE-D-20 was scored the lowest band number (7 bands). The SRAP primers Me3-em2 registered the highest number of bands (13 bands) while Me3-em3and Me2-em2 showed the lowest band number (6 bands). The genotype-specific SRAP and RAPD markers for the different ENP species were recorded. The highest number of SRAP specific markers (7 markers) was scored for Steinernema glaseri, then 4 markers for S. abbasi 2 followed by S. riobrave (3 markers), 1 marker for S. abbasi 1, S. riobrave recorded the highest number of specific RAPD marker (4 specific markers) followed by S. carpocapsae DD 136 and S. glaseri (two specific markers), then only 1 specific marker for S. abbasi 1. Based on the data obtained from RAPD and SRAP analysis, the dendrogram was created to clarify the genetic distances among different species of the studied entomopathogenic nematodes. The present study indicated that SRAP was more powerful than RAPD analysis for detecting the genetic polymorphism among closely related species of nematodes. The genotype-specific markers detected from both RAPD and SRAP can be used in future biological control programs.

Background Entomopathogenic nematodes (EPNs), as biological control agents, have been isolated from many regions throughout the world. Local isolates of EPNs are usually more effective for controlling indigenous insect pests as they are adapted to the local environmental conditions and the insect pest species. Results In the present work, EPN isolates were searched in the soil under citrus and guava trees, and Egyptian clover at Noubaria region, Elbhaira governorate, Egypt, within two consecutive years. The EPNs were isolated from two positive soil samples of Egyptian clover (Trifolium alexandrinum) (TAN5) and guava trees (Psidium guajava) (PGN6), while the EPNs were not existent in the soil samples under citrus. Laboratory applications of the two EPNs isolates against the cotton leafworm, Spodoptera littoralis(Boisd.), and the black cutworm, Agrotis ipsilon (Hufn.) (Lepidoptera: Noctuidae), were recorded. Nematodes naturally occurring in the soil were trapped by full-grown larvae of the greater wax moth (Galleria mellonella L.). Infected larvae turned from whitish beige to dark reddish color, proofed that these isolates belong to the genus Heterorhabditis. Laboratory results revealed that the mortality rate ranges from 24 to 100% with TAN5 while from 18 to 96% with PGN6 at A. ipsilon larvae. The LC50 values of TAN5 against A. ipsilon were 1285.527 and 1560.747 IJs/cup, while those values for S. littoralis were 1339.099 and 2531.605 IJs/cup in larvae and pupae, respectively. The 3rd instar larvae of A. ipsilon and S. littoralis were more sensitive than the pupae. Production of Heterorhabditis sp. strain TAN5 was the highest in the reproduction of infective juveniles than the strain PGN6 at all concentrations. Conclusions The EPNs isolated from the soil samples belonged to the genus Heterorhabditis. Heterorhabditis sp. strain (TAN5) collected from the soil under Egyptian clover at Noubaria region was the highest reproduction and the most effective against both tested pests, A. ipsilon and S. littoralis larvae and pupae. EPN species would serve as an alternative to chemical pesticides and fit well in an integrated pest management program against larvae as well as adults and pupae of many economic insect pests which inhabit the soil.