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Background: Fall armyworm (FAW), Spodopterafrugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is the new invasive pest of different economic crops, threatening the agricultural economy worldwide. Chemical insecticides are the main control management strategy applied by almost farmers. As the adverse effect of these chemicals on the environment and human health, improving alternative environmentally friendly control against this pest is urgently needed. In this response, the pathogenicity bioassays of 2 entomopathogenic nematode species (EPNs), Steinernemacarpocapsae (All) and Heterorhabditisindica (EGAZ2), on different FAW larval instars (2nd to 6th instars) were assessed under laboratory conditions. Results: The results cleared that FAW larval mortality rate was varied significantly related to nematode species, post-exposure times and developmental instar stages. S.carpocapsae application was more virulent and effective against all tested instars larvae, registering 100% mortality after 48–72 h post-exposure at different nematode concentrations (150–2400 IJs). However, H.indica caused 100% mortality in early instars only after 96 h, but late instars required a longer time extending to 120–188 h at tested concentrations. In this context, 2nd and 3rd instars were highly susceptible to Heterorhabditis species infection. Lower nematode concentrations (150–300 IJs) caused moderate mortality 33.33–50%, respectively, in 5th and 6th full-developed larvae only. All recovery larvae post-infection died in the pupal stage or adult emerged with wing malformation. Conclusion: The 2 EPN species were virulent against different FAW larval instars at different concentrations and exposure times. Thereby, they are recommended as biocontrol agents against this invasive pest, particularly S.carpocapsae after low-exposure time. This study provides essential information on EPNs, which will further help in the practical application of biological control against fall armyworm. [ABSTRACT FROM AUTHOR]

Background: The weevils Cosmopolites sordidus (Germar), Metamasius hemipterus (Linnaeus), and M. hebetatus (Gyllenhal) (Coleoptera: Curculionidae) form a complex of important pests of plantain crops, causing crop losses of over 60%. Using synthetic insecticides to control these insects has not been efficient; for this reason, the present study searched for using entomopathogenic fungi (EPF) and nematodes (EPN) as alternative control tools. Results: Compatibility of 74 combinations among 30 native fungal isolates and two EPNs (Steinernema feltiae and Heterorhabditis sp.) through inhibition tests was evaluated. It was found that the bacteria carried by Heterorhabditis sp. inhibited the growth of all fungi. In the biological test with EPF and EPN simultaneously against adults of C. sordidus, antagonistic interactions were observed when Heterorhabditis sp. was applied. Only the combination of the fungus strain B14 (Beauveria bassiana) + the EPN, S. feltiae had synergistic effects with a mortality rate of (93.3%). Conclusions: This study revealed that S. feltiae and B. bassiana (strain B14) showed a synergistic effect against adults of C. sordidus. This combination could be an excellent candidate for developing a highly efficient biopesticide prototype in further trials and, together with other strategies of integrated pest management has the potential to improve control of the banana weevil complex. [ABSTRACT FROM AUTHOR]

Simple Summary: Zabrus tenebrioides (cereal ground beetle) is one of the main pests of cereals worldwide and is predicted to cause serious damage to Polish crops in the near future. A potentially effective method of biological control of this pest is the parasitism of beetle larvae by entomopathogenic nematodes. This study assessed the effectiveness of local isolates of Steinernema feltiae against Z. tenebrioides larvae under Polish field conditions, with at least 90% persistence of infectivity after 60 days in the soil. The differences in biological activity among the isolates toward the host were evaluated in terms of morphometry through principal component analysis. One of the most dangerous pests of cereals is Zabrus tenebrioides and, in Poland, it is becoming a serious pest. Entomopathogenic nematodes (EPNs) seem to be a very promising, biological control agent for this pest. Native EPN populations are well adapted to local environmental conditions. The current study characterized three Polish isolates of the EPN Steinernema feltiae, which differed in their effectiveness against Z. tenebrioides. In the field, isolate iso1Lon reduced the pest population by 37%, compared with 30% by isolate iso1Dan and 0% by the iso1Obl isolate; the number of plants damaged by Z. tenebrioides in the presence of the different isolates reflected the results in terms of the decrease in pest population size. After incubation in the soil for 60 days, recovered EPN juveniles of all three isolates were able to infect 93–100% of the test insects, with isolate iso1Obl again showing the lowest effectiveness. The juveniles of isolate iso1Obl were also morphometrically distinct from the other two isolates, as revealed by principal component analysis (PCA), which helped to distinguish the EPN isolates. These findings showed the value of using locally adapted isolates of EPNs; two of the three isolates randomly selected from Polish soil outperformed a commercial population of S. feltiae. [ABSTRACT FROM AUTHOR]

The confused flour beetle, Tribolium confusum Jacquelin du Val, 1863 (Coleoptera: Tenebrionidae) is a major pest on stored grains. Chemical pesticides are usually used to control stored grain pests but insecticides residue and other negative effects on human and environmental health are the constrain ones in this concern. The biological control agents such as entomopathogenic nematodes (EPNs), which are used to control different harmful organisms, get attention in the alternative control methods. The aim of this study was carried out to determine biocontrol potential of local entomopathogenic nematode isolates, Steinernema carpocapsae (Tokat-Bakışlı05), S. feltiae (Tokat-Emir), Heterorhabditis bacteriophora (TOK-20), and H. bacteriophora (11KG) against adult beetles of confused flour beetle under controlled conditions. EPNs isolates were applied at four different concentrations i.e., 0.0, 25, 50 and 100 IJs/beetle in 1 ml of distilled water at 15 and 25 ± 1 °C temperatures. The highest mortality rates for H. bacteriophora (11KG) and H. bacteriophora (TOK-20) isolates at 25 ± 1 ºC were determined as 91.0 and 81.2%, respectively. H. bacteriophora (11KG) and H. bacteriophora (TOK-20) were found to be the most effective EPNs at a concentration of 100 IJs/beetle at 15 ºC with a mortality of 57.7 and 55.6%, respectively. Mortality rates for the adult confused flour beetle were increased with an increasing the concentration of all EPNs species and also the degrees of temperature. Results showed that local EPNs isolates may use as an alternative biological control agent for T. confusum. Efforts should be made to develop new formulations that will allow nematodes to survive until they find their hosts, and they also need to be tested under field conditions. [ABSTRACT FROM AUTHOR]

The objective of this research was to identify the most promising formulation variants for entomopathogenic nematodes (EPNs) through a systematic review of the literature and a meta-analysis. The focus was aimed at preformulating a nematode strain of the Heterorhabditis genus. Thus, 81,900 articles within the period 1985-2022 were processed and 404 were selected for the review, of which only 44 were included in the database for the meta-analysis. Two databases were created: VIABILITY and PATHOGENICITY, with 254 and 224 pairs of data, respectively, after purification. The data were processed by the nematode genus (Heterorhabditis or Steinernema) according to the result of a generalized linear model to Proc Mixed of SAS 9.0 and the contrast test of minimal significant difference. The statistical package RStudio version 1.1.463 2018 was used for the meta-analytic study. The statistics Q and I² were evaluated. The effect size and its 95% confidence interval were calculated and a forest-plot graph was used. The meta-analysis showed a high variability of the viability and pathogenicity data. The results confirmed that the solid formulations by using clays and other excipients, were adequate to for the entomopathogenic nematodes of the genus Heterorhabditis. [ABSTRACT FROM AUTHOR]

The current study aims to investigate the residual toxicity and nutritional indices of entomopathogenic nematodes (EPNs), as well as immunological response to an infection in Spodoptera littoralis. Compared to the individual impacts of Steinernema carpocapsae, Heterorhabditis indica and EPNs binary combinations showed a higher pathogenicity to S. littoralis according to mortality, physiological responses, and humoral immune. The anti-feedant activity percentages of H. indica and S. carpocapsae treated larvae had a more potent effect than their binary mixture at LC35, compared to full-feeding activity in the control. The biochemical characteristics of infected hemolymph showed a significant variation, not only in the total protein concentration, but also in the appearance of the new protein bands profile. An additional band, with a molecular weight of ~79 KDa was observed at immunized hemolymph, it has been postulated that it may be the phenoloxidase (PO), which is in close agreement with the significant induction of PO activity after infection. Interestingly, the immunised hemolymph of the larvae infected with binary combinations of EPNs showed a notably increased intensity of the major proteins and a rise in the number of antimicrobial peptides with molecular weights under 30 KDa. However, the significant reduction of total protein count and PO level, which ultimately resulting in larval death, is evidence that the binary mixture of the investigated nematodes is highly suppressed S. Littoralis larval immune system. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) are effective biopesticides used in insect control. There are several formulations of entomopathogenic nematodes which are commercially available, but their popularity is low because the requirement of periodic release of stored entomopathogenic nematodes in field has reduced infectivity and is a constraint in large-scale repeated application of entomopathogenic nematodes in field. So, in order to overcome this impediment, the current study focuses on storage of entomopathogenic nematodes for a longer period of time using encapsulating beads. In this study, three EPNs, namely, Steinernema carpocapsae, Steinernema monticolum, and Rhabditis blumi, were encapsulated with Arabic gum and sodium alginate gel beads at different concentrations. Bio-efficacy of stored EPNs at different concentrations (50, 100, 200, 500, and 1000 infective juveniles (IJs)) in varying time intervals of 3, 6, 9, and 12 weeks were tested against Culex quinquefasciatus larvae. The results show that, after 3 weeks of storage, these entomopathogenic nematode species showed survival up to 96%, and in 12-week storage, survival rate was 50%. The virulence of the progeny that emerged from these stored entomopathogenic nematodes was similar to the fresh infective juveniles. The results of the present study show that Arabic gum–sodium alginate combination is a promising approach toward storing entomopathogenic nematodes. Furthermore, semi-field trials showed 70–90% larval mortality at a concentration of 3000 IJs (encapsulated and stored entomopathogenic nematodes in S. monticolum, S. carpocapsae, and R. blumi) on C. quinquefasciatus larvae. Key points: • Increased survival of stored EPNs (S. carpocapsae, S. monticolum, and R. blumi) in encapsulated gel using Arabic gum, sodium alginate, and yeast cells was assessed. • The efficacy was greater in stored EPNs at different concentrations from 3 to 12 weeks. • Semi-field trials of stored encapsulated EPNs are efficient in mosquito larval control. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi 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.)

Field efficacy of three entomopathogenic nematodes (EPNs) viz., Steinernema carpocapsae (Weiser), Heterorhabditis indica Poinar, Karunakar & David, and H. pakistanensis was evaluated against third instar larvae of cabbage butterfly, Pieris brassicae (L.) and Diamondback moth, Plutella xylostella (L.) infesting kale, Brassica oleracea L. var. Khanyari during 2018 and 2019. Each EPN species was applied as a foliar spray. Heterorhabditis pakistanensis applied @ 3.0 lakh infective juveniles (IJs)/m² caused 57.6% mortality of P. brassicae, whereas at a similar concentration of IJs, H. indica and S. carpocapsae showed 43.2 and 21.2% larval mortality, respectively. Maximum larval mortality of diamondback moth was recorded with the application of H. pakistanensis (61.2%) followed by H. indica (47.2%) and S. carpocapsae (29.2 %). The difference in cumulative mortality as well as the cumulative reduction in mortality over control by the nematodes against both the pests were statistically significant (P £ 0.05). A strong positive correlation between EPN species and active IJs/plant (r= 0.85**; d.f.= 13) was also observed. The regression equation between EPN species vs. active IJs/plant indicated a best-fit model (Y = 2833 + 1450 x: R² = 0.73). The yield of IJs per insect cadaver was highest in the case of H. pakistanensis followed by H. indica and S. carpocapsae. Relationship between larval instars and the number of IJs/cadaver for both the test insect pests, P. brassicae (r= 0.95**; d.f.= 58) and P. xylostella (r= 0.97**; d.f.= 43) was positively correlated. [ABSTRACT FROM AUTHOR]

The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora infects a wide range of insect hosts with the aid of its mutualistic bacteria Photorhabdus luminescens. While the mutualistic relationship between H. bacteriophora and P. luminescens and the infectivity of the nematodebacteria complex have been characterized, how nematode fitness is affected by entomopathogenic bacteria existing in association with other EPN species remains poorly understood. In this study, the survival of H. bacteriophora infective juveniles containing or lacking P. luminescens was tested against the entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus asymbiotica as well as the non-pathogenic Escherichia coli. While X. nematophila and E. coli did not significantly affect the survival of H. bacteriophora, P. asymbiotica exerted a significant effect on nematode survival, particularly on those lacking P. luminescens. These results imply that P. asymbiotica encodes factors that are pathogenic to EPNs. Future efforts will focus on the identification of the bacterial molecular components that induce these effects. This study makes an important contribution to a growing body of research aimed at exploiting the full potential of nematodebacterial complexes for eliminating noxious insect pests and treating infectious diseases caused by parasitic nematodes. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi and entomopathogenic nematodes are globally distributed soil organisms capable of infecting and killing a vast variety of insects. Therefore, these organisms are frequently used as biocontrol agents in insect pest management. Both entomopathogenic fungi and nematodes share the soil environment and thus can infest and compete for the same insect host; however, natural co-infections are rarely found due to the cryptic soil environment. Our current knowledge on their interactions within hosts mainly comes from laboratory experiments. Because of the recent trend of combining biocontrol agents to increase their efficacy, many studies have focused on the co-application of different species of EPF and EPNs against various insect pests with variable outcomes ranging from synergistic effects and additive effects to antagonism. In addition, the effect on the development and reproduction of each pathogen varies from normal reproduction to exclusion, and generally the outcomes of the interactions are dependent on pathogen and host species, pathogen doses, and the timing of infection. The present review aims to summarize the current knowledge on the interactions of entomopathogenic fungi and nematodes within an insect host and to estimate the possible effects of the interactions on natural pathogen populations and on their use in biocontrol. [ABSTRACT FROM AUTHOR]

Background: The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a notorious polyphagous pest that has recently invaded India in 2018. Within a short period, this pest has spread throughout the country, causing a significant damage to maize. In order to manage this menace, farmers rely on chemical insecticides, but due to concealed feeding nature of this pest insecticides remain ineffective in reaching the target site. In this context, the present study aimed to isolate, characterize and evaluate the reproductive potential of the native strains of entomopathogenic nematode, Heterorhabditis indica against larval instars of S. frugiperda under laboratory conditions. Results: Two strains of H. indica isolated and characterized from the rhizosphere of mango and curry leaf trees were designated as CICR-HI-MN and CICR-HI-CL, respectively. Both strains, CICR-HI-CL and CICR-HI-MN showed differential mortality against 3rd (LC50 value of 21.65, 48.91 IJs/larva), 4th (LC50 value of 25.46, 52.36 IJs/larva) and 5th (LC50 value of 59.20, 71.04 IJs/larva) instar larvae of S. frugiperda, respectively. The instar-wise mortality of S. frugiperda showed that 3rd instar was relatively more susceptible compared to 4th and 5th instar larvae. In terms of efficacy, CICR-HI-CL was almost twice effective than CICR-HI-MN when LC50 and LC95 values of 3rd instar larvae were compared. However, the reproductive potential of both the strains was significantly higher against 5th instar than the 3rd and 4th instar larvae. Strain CICR-HI-CL was more effective in larval mortality, while nematode reproduction was higher in CICR-HI-MN. Conclusions: Native strains of H. indica evaluated in the present study were found effective against larval instars of fall armyworm, S. frugiperda. Higher reproduction on 5th instar larvae demonstrates the ability of these strains to multiply, sustain and perpetuate on late instars of this polyphagous pest and may serve as viable option in integrated pest management program. [ABSTRACT FROM AUTHOR]

Background: The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a major pest of tomato plants threatening global tomato production. The control of the pest is becoming increasingly difficult due to the rapid development of resistance to insecticides. Entomopathogenic nematodes (EPNs) of families Steinernematidae and Heterorhabditidae are successful biocontrol agents for many insect pests. Recently, their bacteria, Xenorhabdus spp. and Photorhabdus spp. have attracted great attention due to their major role in the pathogenicity of EPNs. In the present study, the pathogenicity of eleven EPNs isolates belonging to Steinernema feltiae and Heterorhabditis bacteriophora species was screened against the 1st/2nd and 3rd/4th instar larvae of T. absoluta. The cell-free supernatants and cell suspensions of the symbiotic bacteria from the most efficient isolates were further evaluated for their biocontrol potential in the oral and contact treatments on the larvae of T. absoluta. Results: KBC-4 and MCB-8 isolates of S. feltiae showed superior virulence relative to other EPNs species/isolates and induced 90% larval mortality against the 3rd/4th instar of T. absoluta larvae, whereas there were no clear differences in the efficacy of EPNs species/isolates against the 1st/2nd instar of T. absoluta. The 1st/2nd instar of T. absoluta larvae was more susceptible to cell-free supernatants and cell suspension of selected EPNs. The highest mortality (80%) was obtained from X. bovienii MCB-8 strain in the contact treatment of supernatants. In contact treatment of cell suspension, higher mortalities were obtained compared to oral treatments. Mortality rates ranged between 30 and 57.5% in the contact treatments of cell suspensions while the highest mortality did not exceed 20% in oral treatments. The antifeedant activity was observed in oral treatments of cell suspension and most of the larvae avoided feeding on treated leaves. Conclusion: The results indicated that symbiotic bacteria of EPNs had a great potential against T. absoluta larvae and contact treatment of cell-free supernatants against early instars of T. absoluta can be an ideal application. However, further studies are needed to investigate the field effectiveness of symbiotic bacteria. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi 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 rhabditid entomopathogenic nematode (EPN), Oscheius chongmingensis, has a stable symbiotic relationship with the bacterial strain Serratia nematodiphila S1 harbored in its intestines and drastically reduced viability when associated with a non-native strain (186) of the same bacterial species. This nematode is thus a good model for understanding the molecular mechanisms and interactions involved between a nematode host and a member of its intestinal microbiome. Transcriptome analysis and RNA-seq data indicated that expression levels of the majority (8797, 87.59%) of mRNAs in the non-native combination of O. chongmingensis and S. nematodiphila 186 were downregulated compared with the native combination, including strain S1. Accordingly, 88.84% of the total uniq-sRNAs mapped in the O. chongmingensis transcriptome were specific between the two combinations. Six DEGs, including two transcription factors (oc-daf-16 and oc-goa-1) and four kinases (oc-pdk-1, oc-akt-1, oc-rtk, and oc-fak), as well as an up-regulated micro-RNA, oc-miR-71, were found to demonstrate the regulatory mechanisms underlying diminished host viability induced by a non-native bacterial strain. Oc-rtk and oc-fak play key roles in the viability regulation of O. chongmingensis by positively mediating the expression of oc-daf-16 to indirectly impact its longevity and stress tolerances and by negatively regulating the expression of oc-goa-1 to affect the olfactory chemotaxis and fecundity. In response to the stress of invasion by the non-native strain, the expression of oc-miR-71 in the non-native combination was upregulated to downregulate the expression of its targeting oc-pdk-1, which might improve the localization and activation of the transcription factor DAF-16 in the nucleus to induce longevity extension and stress resistance enhancement to some extent. Our findings provide novel insight into comprehension of how nematodes deal with the stress of encountering novel potential bacterial symbionts at the physiological and molecular genetic levels and contribute to improved understanding of host–symbiont relationships generally. [ABSTRACT FROM AUTHOR]

Two families of entomopathogenic nematodes (EPNs), Steinernematidae and Heterorhabditidae, symbiotically associated with Xenorhabdus and Photorhabdus bacteria, are effective biological control agents of insect pests. Native isolates are likely to be better candidates for insect pest control than exotic specimens due to their adaptation to native environmental conditions. In this study, Steinernema feltiae isolate FUM221, was recovered from soil samples collected from the Ardabil Province, Iran. Morphological and morphometric investigations of the first and second-generation adults, infective juveniles, and molecular characterizations were conducted based on ITS and 18S rDNA genes. Molecular analysis based on the 16S rRNA region and phenetic data revealed Xenorhabdus bovienii as this isolate symbiont bacterium. The scanning electron microscopy (SEM) verified the identification of this isolate. The molecular characterization using two loci and phylogenetic analyses provided more evidence on the classification of this steinernematid and its distinction from same species from other countries. Moreover, molecular and phenetic characterizations of its symbiotic bacterium indicated minor variations compared to other isolates. Herein, the comprehensive taxonomic data of this steinernematid and its symbiont bacterium, is presented. [ABSTRACT FROM AUTHOR]

Stored-product commodities are attacked by numerous insect species. The adulticidal effects of entomopathogenic nematodes (EPNs) on grains remain uninvestigated. Thus, in the current study, seven doses of the EPNs Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), and Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) were inoculated on wheat kernels against adults of Trogoderma granarium Everts (Coleoptera: Dermestidae), Tenebrio molitor L. (Coleoptera: Tenebrionidae), and Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae). Complete mortality (100.0%) of T. granarium was recorded after exposure for eight days to the highest dose of 50,000 Infective Juveniles/mL (IJs/mL) of all tested EPN species. At the same exposure interval, 62.2%, 85.6%, and 76.7% of T. molitor were killed by 50,000 IJs/mL of H. bacteriophora, S. carpocapsae, and S. feltiae, respectively. The highest mortality of A. diaperinus (11.1%) was documented eight days post-exposure to 50,000 IJs/mL of H. bacteriophora. In general, T. granarium was highly susceptible, followed by T. molitor and A. diaperinus. Concerning EPN species, S. carpocapsae exhibited the highest insecticidal capacity, followed by S. feltiae and H. bacteriophora. Trogoderma granarium and T. molitor can be sufficiently managed by the highest dose of 50,000 IJs/mL of all three EPNs and by S. carpocapsae, respectively. However, A. diaperinus was not affected by any EPNs. [ABSTRACT FROM AUTHOR]

Abstract Background The cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), is an economic pest on various crops worldwide. Farmers generally used to apply chemical pesticides to control the pest. The bio-control potential of the entomopathogenic nematodes (EPNs) as alternatives to harmful synthetic pesticides was examined in this study. The study aimed to determine the efficacy of EPNs isolates against the different stages of larvae of the cotton leafworm S. littoralis and the effect of time on mortality rate under laboratory conditions. Results EPNs isolates were tested at 4 different concentrations (0, 250, 500 and 1000 IJs/ml) in 150 ml plastic containers on last instar larvae (sixth instar) of S. litorallis. Experiments for third, fourth and fifth instar larvae of S. litorallis were carried out in petri dishes at different concentrations (0, 50, 100 and 200 IJs/ml) at 25 °C temperature. Mortality rates of larvae were calculated at 3 different times (48, 72, 96 h) after inoculation. The high mortality rate of last instar larvae (98.81%) of S. littoralis was caused by Steinernema feltiae (Tokat-Emir), followed by S. carpocapsae (Tokat-Bakışlı05) (95.24%) and then H. bacteriophora (11 KG) with (90.47%) at the highest concentration (1000 IJ/ml). The highest mortality rate of fifth instar larvae was caused by S. feltiae (Tokat-Bakışlı05) and S. carpocapsae (Tokat-Emir) with (100%) and (92.12%). In addition, the highest mortality rate of the 4th instar larvae was determined S. feltiae (Tokat-Bakışlı05) and S. carpocapsae (Tokat-Emir) isolates (98.87%) and (97.74%), respectively. Additionally, the highest larval mortality rate in the third stage by S. feltiae (Tokat-Bakışlı05) and S. carpocapsae (Tokat-Emir) was (100%) and (97.74%) at the highest concentration. Mortality rates of larvae were calculated at 3 different times after inoculation. The highest mortality rate counted in all isolates was determined 96 and 72 h after inoculation of EPNs. Conclusions All indigenous EPN isolates were found to be effective at different rates against S. littoralis. The results showed that these nematode species could be used against S. littoralis biological control programs.

Abstract Background Cutworms (Agrotis spp.) are cosmopolitan and polyphagous pests distributed throughout world, which belong to the family Noctuidae, and about 26 species are found associated with agriculturally important crops in India and some other countries of world. The most prominent species belonging to genera Agrotis are Agrotis ipsilon, A. flammatra, A. plecta, A. spinifera and A. segetum. Cutworms cause substantial damage to many agricultural and horticultural crops particularly, at the seedling stage. This pest produces vitiating symptoms with a young stage (larvae) by feeding on the epidermis of leaves and eating away parts of the stem, tubers, etc. Results This review article is mainly focused on management of cutworm, which is very challenging due to larval hiding behaviour during the day time and feed actively at night. Efficient chemical control of cutworm may be obtained by adequately applying chemicals when young caterpillars are still on the leaves and therefore vulnerable. As per biology of cutworms, these pests remain hidden in cracks and crevices during most of life cycle so chemical control is often ineffective and economic. Sometimes, inadequate application of these chemicals is resulted into the development of resistance in these pests. Moreover, the adverse effects of the chemicals have led researchers to search for new control strategies. Recently, biological control has become a practical option for eco-friendly management of numerous insect pests. Among biological control, entomopathogenic nematodes (EPNs) have broad potential to kill the cutworms in soil itself. Conclusions Various species of EPNs like Steinernema spp. and Heterorhabditis spp. are found a quite effective and hold considerable potential to manage cutworms. So, the use of EPNs for the management of cutworms is a good alternate to chemical method.

Abstract Background Biotic and abiotic factors influence survival, infectivity, development, reproduction, and activity of the entomopathogenic nematodes (EPNs). EPNs have been used to suppress the soil-inhabitant insects, which applied as a successful biological control agent against the black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera/Noctuidae) larvae, and pupae. Results Studying the effect of different temperatures 20, 25, and 30°C ± 2, and the soil moisture content at 10, 15, and 25% on the susceptibility of two Heterorhabditis sp. strains, Egyptian strain (TAN5) and imported strain (Hb88) against the A. ipsilon 4th and 6th larval instars and 3-day-old pupae was carried out under laboratory conditions. The tested concentrations of the two strains were 30, 60, 120, 240, and 480 IJs/cm2 of soil surface. The mortality rate of 4th instar A. ipsilon larvae was high after Heterorhabditis strain TAN5 treatments at all concentrations, which ranged between (24 and 100%) and (6–100%) at 25°C and 30°C, respectively. At 20°C, Heterorhabditis strain Hb88 recorded higher mortality percentages for A. ipsilon 4th and 6th larval instars and pupae than the indigenous strain TAN5. The soil moisture content of 25% gave the highest mortality rates for the 4th instar larvae of A. ipsilon after treatments of the two strains. The Egyptian Heterorhabditis strain TAN5 was tolerant to the increase in temperature and more tolerant to the change in the water content of the soil than the imported strain Hb88 at all concentrations tested. In a semi-field experiment, Heterorhabditis strain TAN5 at concentrations between (1000–8000 IJs/cm2 of soil surface) showed mortality rates (27–95%) for 4th instar A. ipsilon larvae and (19–81%) for the 3-day-old pupae, respectively. Conclusions Heterorhabditis strains TAN5 can was utilized against the black cutworm of A. ipsilon at the temperatures 25 and 30°C. Heterorhabditis strains TAN5 and Hb88 can be utilized against the black cutworm of A. ipsilon at the soil moisture content from 15 to 25%. In the semi-field experiment, Heterorhabditis TAN5 and Hb88 strains were effective against larvae and pupae of A. ipsilon at high concentrations of the nematodes.

Enormous efforts have been made to understand the functions of bioluminescence; however, its relevance in soil ecosystems has barely been investigated. In addition, our understanding of the biological relevance of bioluminescence is hampered by the scarcity of tools to genetically manipulate this trait. Using the symbionts of entomopathogenic nematodes, Photorhabdus bacteria, we show that bioluminescence plays important regulatory roles in multitrophic interactions in the soil. Through genetic modifications and exploiting natural variability, we provide direct evidence for the multifunctional nature of bioluminescence. It regulates abiotic and biotic stress resistance, impacts other trophic levels, including nematodes, insects, and plants, and contributes to symbiosis. Our study contributes to understanding the factors that have driven the evolution and maintenance of this trait in belowground ecosystems. [Display omitted] • Plants respond to root bioluminescence exposure, which reduces biomass accumulation • Root, but not leaf, herbivores grow less on plants pre-exposed to bioluminescence • Bioluminescence repels scavengers, protecting developing nematodes inside cadavers • Bioluminescence modulates bacterial production of nematode growth factors Certain entomopathogenic nematodes infect soil-borne insects with bioluminescent bacteria, rendering insects bioluminescent. Muller et al. study if and how this type of bioluminescence impacts other soil-inhabiting organisms. Using genetic manipulation and phylogenetic comparative approaches, they provide evidence for the evolutionary significance and biological effects of bioluminescence in soil ecosystems. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPNs) are microscopic organisms that inhabit soil and plant tissues causing a significant challenge for farmers around the globe leading to substantial crop damage and losses. Major concern on the indiscriminate use of chemical nematicides has led to exploitation of safe alternatives to mitigate these losses. Entomopathogenic nematodes (EPNs) Steinernema spp. and Heterorhabditis spp. and their associated symbiotic bacteria, Xenorhabdus spp. and Photorhabdus spp. have gained attention as eco-friendly biocontrol agents against insect pests and nematodes. They have the ability to kill the insects by causing septicaemia disease in host insect by production of toxins. EPNs are soil inhabiting, free-living nematodes that also combat PPNs. The secondary metabolites produced by these bacteria exhibits antimicrobial, antifungal, nematicidal, insecticidal, and even anticancer properties. This current review explores the potential of EPNs and their symbiotic bacteria as nematode management strategies by targeting different stages of PPNs resulting in decreased egg production and nematode population. The EPNs and their associated bacteria suppress PPNs by three different ways viz., repulsion, competition and antagonism. Overall, EPNs and their symbiotic bacteria offer sustainable and effective alternatives to chemical pesticides, since application of hazardous chemical pesticides are harmful to environment and human health. This review gives an overview and idea for further research and development of EPN's and their symbiotic bacteria as commercial bioproducts towards PPNs control. [Display omitted] • Entomopathogenic nematodes belong to the genera Steinernema and Heterorhabditis. • Nematode associated bacteria produce toxins lethal to plant parasitic nematodes. • Plant-parasitic nematodes are suppressed by repulsion, competition, and antagonism. • Entomopathogenic nematodes are eco-friendly alternatives to chemical nematicides. [ABSTRACT FROM AUTHOR]

[Display omitted] • EPN symbiotic bacteria and their filtrates have insecticidal effects on T. absoluta. • The bacterium X. nematophila was the most effective against larvae of T. absoluta. • 1st/2nd instar larvae of T. absoluta were more susceptible than 3rd/4th instar. • The EPN, their bacteria and filtrates were also tested on the key predator N. tenuis. • The EPN symbiotic bacteria and their filtrates had low impact on N. tenuis. The use of biocontrol agents, such as predators and entomopathogenic nematodes, is a promising approach for the effective control of the tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidaean), an oligophagous insect feeding mainly on Solanaceae species and a major pest of field- and greenhouse-grown tomatoes globally. In this context, the effects of two entomopathogenic nematode species Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora (Poinar) (Rhabditida: Heterorhabditidae), as well as their respective bacterial symbionts, Xenorhabdus nematophila and Photorhabdus luminescens (Enterobacterales: Morganelaceae), which were applied as bacterial cell suspensions and as crude cell-free liquid filtrates on T. absoluta larvae, were investigated. The results showed that of all treatments, the nematodes S. carpocapsae and H. bacteriophora were the most effective, causing up to 98 % mortality of T. absoluta larvae. Regarding bacteria and their filtrates, the bacterium X. nematophila was the most effective (69 % mortality in young larvae), while P. luminescens and both bacterial filtrates showed similar potency (ca. 48–55 % mortality in young larvae). To achieve a holistic approach of controlling this important pest, the impact of these factors on the beneficial predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) was also studied. The results demonstrated that although nematodes and especially S. carpocapsae , caused significant mortality on N. tenuis (87 %), the bacterial cell suspensions of X. nematophila and P. luminescens and crude cell-free liquid filtrates had minimum impact on this beneficial predator (∼11–30 % mortality). [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes have been used in biological control for some time and are an alternative for the control of insect pests, but during their implementation, situations have arisen that can be improved. These vary with each species and include their production and storage. Oscheius myriophila, an entomopathogenic nematode (EPN), was monitored for its performance when produced in vivo, as well as its development using Galleria mellonella larvae, using the MC5-2014 strain isolated from soil samples in the municipality of Tepalcingo, Morelos, México. For a study with native strains of EPNs, a wide range of tests must be conducted because the required conditions can be very specific. In vivo production was quantified at initial infective juvenile (IJ) inocula of 50, 100 and 500, and we obtained the same production for the three inocula. The life cycle of the EPNs lasted 12 days, and two generations were observed in which adults were found at days 5 and 9. Both evaluations were performed at a temperature of 27 °C in G. mellonella larvae. In addition, the temperatures of 8, 12, 20 and 24 °C were evaluated for their storage, and we observed that the EPNs can be kept for at least 6 months, maintaining a survival rate of 58.67% and a good infective capacity at a temperature of 12 °C, remaining above 60%.

Abstract Background Entomopathogenic nematodes (EPNs) are promising alternatives since they have many characteristics as a biological control agent against insect pests. Results Among indigenous EPN isolated, adapted to local environmental conditions by employing the Galleria baiting strategy, only one sample was positive for the presence of EPNs. The new isolate was identified at the species level using DNA sequencing of the internal transcribed spacer region and the Basic Local Alignment Search Tool search of GenBank showed that the isolate had a high similarity (99%) with that sequence available for Heterorhabditis taysearae. The pathogenicity of the EPN isolate was tested against the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), using different concentrations (60, 90, 120 and 150 IJs/larvae). Data showed that 150 IJs/larvae caused 100% mortality rate, followed by 120 IJs/larvae (90%), while 60 IJs/larvae showed the lowest rate (60%) after 72 h. Conclusions The present study indicated that the native isolate of EPN could be recommended against S. littoralis as an efficient tool in its control programs.

Abstract Background Compatibility of entomopathogenic nematodes (EPNs) with insecticides is a crucial mainstay of integrated pest management (IPM) programs. This study was designed to evaluate the joint action of EPN species and insecticides when employed to deter 3rd and 4th larval instars of cabbage white butterfly, Pieris rapae L. (Lepidoptera: Pieridae) under laboratory conditions. EPNs [Steinernema carpocapsae (All strain), S. feltiae (Filipjev), Heterorhabditis bacteriophora (HP88), and H. bacteriophora (Ar-4)], at concentrations of 50, 100, and 125 IJs/larva, were tested with 3 insecticides (lambda-cyhalothrin, emamectin benzoate, and indoxacarb) at LC25 and LC50 values. Additionally, expression profiles of 2 detoxification genes (CYP6AE120 and PrGSTs1) when the 4th instar larvae were treated by H. bacteriophora (HP88) and lambda-cyhalothrin were examined. Results Data indicated that statistically significant mortality of 2 larval instars of P. rapae was observed in vitro among EPN species and pesticide concentrations. At concentration of 50 IJs/larva, LT50 values were 2.385 and 3.92 days for S. carpocapsae (All strain) and H. bacteriophora(Ar-4), respectively, on 3rd instar larvae; also, these values were 3.506 and 3.107 days for S. feltiae and H. bacteriophora (Ar-4), respectively, on 4th instar larvae Lambda-cyhalothrin was the most toxic insecticide, followed by emamectin benzoate and indoxacarb at LC25 and LC50, respectively. An additive effect was observed between EPN species with LC25 and LC50 of the tested insecticides, except for lambda-cyhalothrin at LC50 with H. bacteriophora (Ar-4), and indoxacarb, with all EPNs showing antagonistic effects on mortality of 3rd instar larvae after 3 days post-treatment. The interaction between the tested pesticides at LC25 and LC50 and EPN species, showed an additive effect, excluding lambda-cyhalothrin at LC25 with S. carpocapsae (All strain) and LC25 of indoxacarb with H. bacteriophora (Ar-4), which showed potentiation effects. The interaction of S. feltiae (Filipjev) with tested insecticides at LC50 exhibited an antagonistic effect on the mortality of 4th instar P. rapae larvae after 3 days post-treatment. The expression of both CYP6AE120 and PrGSTs1 was significantly up-regulated with lambda-cyhalothrin, followed by H. bacteriophora (HP88) compared to control. Conclusions The findings suggested that combining EPNs and the pesticide concentrations can be a practical strategy for managing P. rapae and could pave the way to using new control technologies in protecting organic farm vegetables from lepidopteran pests.

The peachtree borer, Synanthedon exitiosa (Say) (Lepidoptera: Sesiidae), is a major pest of stone fruits including the peach Prunus persica (L.) Batsch. The entomopathogenic nematode, Steinernema carpocapsae, was previously shown to be an effective tool for controlling S. exitiosa. In orchards where irrigation is not available, a sprayable gel (Barricade®) can be used to maintain soil moisture which can facilitate nematode efficacy. However, rates of nematode and Barricade® application had not been optimized for their maximum economic and biocontrol efficiency. Therefore, our objective was to compare rates of S. carpocapsae and Barricade® in field trials. Nematodes were tested at per-tree application rates of 1.5 million, 1 million and 0.5 million infective juveniles. The sprayable gel was used at two rates, 4% and 2%. A reduction in the used nematodes from 1.5 million to 0.5 million per tree showed no difference in efficacy. Similarly, using the gel at half rate also did not impact the efficacy, and treatments containing nematodes controlled the S. exitiosa better than the chlorpyrifos control in several of the tests (p < 0.05). As an added benefit, the nematode treatments were also able to reduce the prevalence of weevil (Coleoptera: Curculionidae) populations as secondary pests of the peach trees. The lower rates of grower inputs will reduce costs, making the nematode biocontrol of the peachtree borer more likely to be adopted by commercial growers of peach. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes are used as biological control agents against a broad range of insect pests. We ascribed the pathogenicity of these organisms to the excretory/secretory products (ESP) released by the infective nematode. Our group characterized different virulence factors produced by Steinernema carpocapsae that underlie its success as an insect pathogen. A novel ShK-like peptide (ScK1) from this nematode that presents high sequence similarity with the ShK peptide from a sea anemone was successfully produced recombinantly in Escherichia coli. The secondary structure of ScK1 appeared redox-sensitive, exhibiting a far-UV circular dichroism spectrum consistent with an alpha-helical secondary structure. Thermal denaturation of the ScK1 allowed estimating the melting temperature to 59.2 ± 0.1 °C. The results from toxicity assays using Drosophila melanogaster as a model show that injection of this peptide can kill insects in a dose-dependent manner with an LD50 of 16.9 µM per adult within 24 h. Oral administration of the fusion protein significantly reduced the locomotor activity of insects after 48 h (p < 0.05, Tukey's test). These data show that this nematode expresses insecticidal peptides with potential as next-generation insecticides. [ABSTRACT FROM AUTHOR]

The soil-dwelling nematode Steinernema feltiae is found across a wide range of environmental conditions. We asked if its only bacterial symbiont, Xenorhabdus bovienii, shows intraspecific variability in its thermal range, which may affect effectiveness of S. feltiae against host insects. We isolated X. bovienii from S. feltiae from six different natural locations with different mean annual temperatures and two laboratory cultures. We estimated X. bovienii thermal range and determined the specific growth rate based on optical density measurements and mathematical modeling using the Ratkowsky model. The minimal temperature (Tmin) of X. bovienii growth ranged from 0.9 ± 2.2 °C to 7.1 ± 1.4 °C. The optimal temperature (Topt) varied between 25.1 ± 0.2 °C and 30.5 ± 0.2 °C. The model showed that X. bovienii stops multiplying at around 36 °C. The calculated specific X. bovienii growth rate ranged from 2.0 ± 0.3 [h−1] to 3.6 ± 0.5 [h−1]. No differences in Tmin, Topt, and Tmax between the isolated bacteria were found. Additionally, X. bovieniiTopt did not correlate with the mean annual temperature of S. feltiae origin. However, the obtained growth curves suggested that the analyzed X. bovienii may show some variability when comparing the growth curves characteristics. [ABSTRACT FROM AUTHOR]

Background: The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an endemic destructive pest for several cultivars in America and recently in Africa and Asia. Due to the development of pesticide resistance as well as environmental contamination, chemical control of the fall armyworm is ineffective. Alternatively, entomopathogenic nematodes (EPNs) provide a successful biological control tool sustainably. This study was designed to estimate the virulence of 2 isolates (Steinernema carpocapsae (All) and Heterorhabditis bacteriophora (HP88)) on 3rd and 5th larval instars of FAW under laboratory conditions. As well, the effect of gamma radiation (with 2 Gy) on the nematodes' pathogenicity was studied. Results: The results revealed that S. frugiperda larvae were sensitive to the 2 tested nematodes which were more apparent to S. carpocapsae. The mortality rates presented a significant elevation with the increase in un-irradiated and irradiated nematode concentrations. The highest recorded mortality for the 3rd and 5th larval instars was 100% after 3 and 4 days of treatment at concentration (80 IJs/ml) irradiated S. carpocapsae and the recorded death rate for un-irradiated S. carpocapsae was 72.2 and 77.8% for the two treated larval instars, respectively, after 4 days of the treatment with the same concentration. However, H. bacteriophora caused mortality of 88.9 and 61.1% at irradiated concentration (80 IJs/ml) and 66.7 and 50% at un-irradiated concentration (80 IJs/ml) for the 3rd and 5th larval instars, respectively, after 6 days of treatment. Based on the LC50 values, the 3rd instar larvae was more susceptible than the 5th instar larvae. In addition, juveniles' irradiation increased their virulence. Conclusions: Laboratory studies indicated that S. carpocapsae had a high potency among S. frugiperda larvae, especially the irradiated juveniles. Therefore, they have the potential to be developed as a biological control agent for S. frugiperda after further field studies. [ABSTRACT FROM AUTHOR]

Colorado Potato Beetle [Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)] (CPB) is one of the most destructive pests of potatoes. CPB is a polyphagous pest that damages every stage of the potato. Although entomopathogenic nematodes (EPNs) in the world have been demonstrated by many laboratories and field/garden studies activity against many harmful groups, very few studies have been conducted on CPB in our country (Türkiye). In the scope of work intended to be used EPNs against CPB. The main objective of the study is to reveal greenhouse-pot applications (soil, green limbs, and cadaver applications) of EPN [Steinernema feltiae (isolate 09-31) and Heterorhabditis bacteriophora (isolate 09-43)], which are present in our laboratories in our stocks. For the first time in Türkiye, greenhouse-pot applications studies have been carried out against this harmful group. There is also a lot of work in the world about the use of aqueous concentrations of EPNs against harmful effects. In recent years, efforts have been made to use EPNs in cadavers instead of aqueous concentrates. This application (cadaver applications) against CPB is the first working. The results revealed that EPNs performed better in soil applications, and the highest mortality rate was obtained from S. feltiae (65.23±4.45 and 77.33±2.59). Other applications (green limbs and cadaver applications) are seen to have a low level of efficacy. In trials, the mortality rate in cadaver applications did not exceed 40%, and the lowest mortality rate in H.bacteriophora was 37,40±8,88%. In the case of green devices, the mortality rate did not exceed 30%, and the highest mortality rate was 29.14±6.09 in H.bacteriophora. According to EPN greenhouse-pot experiments results, soil applications of S. feltiae (isolate 09-31) should be included within the scope of field trials. [ABSTRACT FROM AUTHOR]

Spodoptera frugiperda has caused serious economic damage to various crops. Entomopathogenic nematodes (EPNs) can be used as biological control agents for many pests, including lepidopteran insects. In this study, 218 soil samples were collected from 46 sites in Guangxi, and EPNs were detected in 15 samples. The ITS region of the rDNA gene was used for the molecular identification of isolated nematodes. In total, four and eleven identified populations belonged to Heterorhabditis and Oscheius, respectively. A series of bioassays were conducted to examine the virulence of EPN isolates from Guangxi to control the larvae and pupae of S. frugiperda. The mortality of the third-instar larvae caused by EPNs was concentration dependent. The same dose of EPNs was used to control the third and sixth-instar larvae of S. frugiperda, and the virulence was lower in the sixth-instar larvae. S. frugiperda pupae were treated with different EPNs strains, and the adult eclosion rate of the treated group was significantly lower than that of the sterile water control group (93.3%). Therefore, EPNs could significantly inhibit the eclosion of S. frugiperda pupae. This study provides important information for the biological control of S. frugiperda with EPNs. [ABSTRACT FROM AUTHOR]

The contributions of soil arthropods to entomopathogenic nematode (EPN) food webs are mainly studied in artificial conditions. We investigated changes in arthropod communities in a citrus orchard following soil inundation with Steinernema feltiae or Heterorhabditis bacteriophora. We hypothesized that arthropod taxa, which decline or increase in response to EPN augmentation, represent potential prey or predators of EPN, respectively. Soil was sampled periodically after nematodes were applied, DNA was extracted from organisms recovered by sucrose centrifugation, libraries were prepared, and the ITS2 and CO1 genes were sequenced using Illumina protocol. Species from 107 microarthropod (mites and collembola) families and 121 insect families were identified. Amplicon sequence variant (ASV) reads for H. bacteriophora were less than 10% of those for S. feltiae three days after inundation, whereas microarthropod ASVs were double in plots with H. bacteriophora compared to those with S. feltiae. Significantly fewer microarthropod and insect reads in S. feltiae compared to untreated plots suggest the possibility that S. feltiae preyed on mites and Collembola in addition to insects. The responses over time of the individual microarthropod species (MOTU) suggest that regulation (up or down) of these EPN resulted from a cumulative response by many species, rather than by a few key species. [ABSTRACT FROM AUTHOR]

Chemical insecticides are intensively used in agriculture which cause negative effects on environmental sustainability by increasing pest tolerance and continuous action on local fauna. In contrast to chemical insecticides, biological insecticides target specific pests, minimizing their impact on the surrounding environment. However, most of the natural insecticides available in the market are expensive for farmers in the Central Asian region. This study is the first evidence of the effectiveness of local entomopathogenic nematodes (EPN) from the arid zone of northern Kazakhstan that can be used as an alternative to export EPN products. The laboratory experiment is conducted with two local and two commercial Steinernema feltiae and Steinernema carpocapsae, which are applied to larvae of Tenebrionidae. The experiment design is randomized with four doses of EPN (100, 200, 300, and 400 IJ/cm2) and a control (without EPN). According to the experiment results, one out of two local EPNs (AF29 at dose 100 IJ/cm2) caused a high mortality rate (67%) among larvae. This finding confirms that local EPNs can compete with commercial EPNs and potentially be used as insecticidal agents. [ABSTRACT FROM AUTHOR]

The potential of a radio-sterilized host, Spodoptera litura (Fabr.), an established noctuid pest, was ascertained for in vivo transport of the viable entomopathogenic nematodes (EPNs), Steinernema thermophilum. Radiosterilization (70 Gy) of the host (pest) was done to avoid any pest population build-up from the host larvae that could inadvertently miss EPN infection. The infective juveniles (IJs) derived from a radio-sterilized host took 67.3 h to induce host mortality, 132 h for incubation, and showed 87.8% parasitization with 98.9 IJs harvesting per mg host body wt, indicating almost similar parasitizing behaviour of these IJs as control. The findings indicated the suitability of the radio-sterilized host, S. litura, for carrying the IJs (in vivo) in a safe mode, that could retain a substantial degree of infectivity to be utilized in the field for managing this serious noctuid pest using biocontrol measures. [ABSTRACT FROM AUTHOR]

Background: Atrijuglans hetaohei (Yang) (Lepidoptera, Heliodinidae) is a major pest of walnut in China. Larvae feed on the seeds of walnut fruit. Damaged fruits turned black and fallen prematurely. Current management relies upon broad-spectrum of chemical insecticides applied in the late spring or early summer. However, due to missed applications or poor application timing, high levels of A. hetaohei infestation may still occur. Entomopathogenic nematodes (EPNs) have been long used for suppressing the soil-dwelling and fruit-boring pest, but few were done on the control of A. hetaohei. The present study was conducted to determine the virulence of seven EPN strains against A. hetaohei under laboratory conditions. Results: Among the seven EPN strains, Steinernema glaseri (Sgib strain) (Rhabditida: Steinernematidae) had good potentials in the management of A. hetaohei because of the better desiccation tolerance and pathogenicity than other strains. The cocooned and mature larvae of A. hetaohei all could be infected by the nematodes of Sgib strain. Sgib strain had the best efficiency to A. hetaohei under the infection condition of 24 °C and 100 IJs per larva. At 48-h exposure to 24 °C, the highest mortality rate of A. hetaohei treated with Sgib strain was 96.67%. Sgib strain of 100 IJs/larva caused 100% mortality after 72-h post-application. Conclusion: Sgib strain from Steinernematidae was the favorable to control A. hetaohei larvae which inhabit in the soil surface effectively. Sgib strain may be a contribution to the biological control of A. hetaohei in China. Highlights: Steinernema glaseri (Sgib strain) could be used as biocontrol agent for A. hetaohei larvae because of the better anti-desiccation ability and pathogenicity. Sgib strain showed high infectivity to the cocooned larvae as well as the mature larval A. hetaohei. Sgib strain had the optimum infecting effect with 100 IJs per larva at 24 ℃ and still maintained high pathogenicity after spraying into the field for 96 h. The results suggested that some potential for Sgib strain from Steinernematidae as one tool in controlling A.hetaohei larvae, which is the main fruit-boring pest of walnut in China [ABSTRACT FROM AUTHOR]

Background: Entomopathogenic nematodes (EPNs) have been regarded as the most convenient strategy for insect pest management. The native strains of EPNs: Heterorhabditis bacteriophora EUPT-SD, H. bacteriophora EUPT-R, H. bacteriophora EUPT-KN, H. bacteriophora EUPT-K and H. bacteriophora EUPT-H isolated from mid-Himalayan region of Himachal Pradesh were tested in laboratory for their multiplication and virulence against 3rd and 4th larval instars of the tobacco cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae), the serious polyphagous pest affecting a wide range of agricultural crops worldwide. Results: All the EPN strains were effective against 3rd and 4th larval instars of S. litura. Insect mortality reached 90–96% after 96 h at nematode concentrations of 150 infective juveniles (IJs)/ml. The insect mortality was also recorded at low concentrations of IJs, but the most exposure period was required. High virulence was shown by H. bacteriophora EUPT-SD 96 and 94%, followed by H. bacteriophora EUPT-R 92 and 90%, H. bacteriophora EUPT-KN 92 and 90%, H. bacteriophora EUPT-K 92 and 90% and H. bacteriophora EUPT-H 92 and 90%, respectively, against 3rd and 4th larval instars in terms of reproductive potential and killing. All the insects were alive in the absolute control. Conclusion: Utilization of EPNs for the management of S. litura may be the best method to overcome the insect resistance problems and to manage the population of this insect pest. It may be an effective method and may be a partial substitute of synthetic insecticides, thus minimizing the excessive use of synthetic chemicals. The results demonstrated the potential of indigenous EPNs isolates against S. litura, but before further recommendation, multiplication field trials need to be conducted to confirm their efficacy at farm level. [ABSTRACT FROM AUTHOR]

The present study on pathogenicity of entomopathogenic nematodes against Spodoptera litura in laboratory conditions was undertaken during 2020-21, with the aim to ascertain the effectiveness of entomopathogenic nematodes, against an obnoxious cosmopolitan pest S. litura. Experiments were conducted by using entomopathogenic nematode (EPN) isolate Heterorhabditis indica (CICRGuava), on filter paper, against Galleria mellonella and S. litura at the treatment dose of 10, 20, 30, 40, 60, 80 and 100 IJs/100µl along with control (Sterile distilled water). The results of our study revealed that, EPN isolate H. indica (CICR-Guava) caused 100% mortality at the treatment dose of 40 IJs/100µl within 72 h of infection in 5th instar larvae of G. mellonella and in case of S. litura, 100% mortality was recorded within 72 h of infection at the treatment dose of 100 IJs/100µl in 3rd instar larvae, which was found more susceptible. The median lethal concentration of H. indica (CICR-Guava) for 5th instar larvae was 2.29 IJs/100µl. The result of reproductive potential of isolates of entomopathogenic nematodes revealed that the highest yield was obtained from 5th instar larvae of G. mellonella at treatment dose of 100 IJs/100µl 278667 IJs per larva. In case of S. litura, the highest yield obtained was 152533 IJs. It could be concluded that, there was a positive correlation between nematode treatment concentration, time of exposure and the insect mortality of the tobacco cut worm and multiplication rate of IJs increased with increase of exposure time and size of larvae. This EPN isolate, H. indica (CICR-Guava) can be suggested as biocontrol agents for the control of S. litura in the Vidarbha region. [ABSTRACT FROM AUTHOR]

Drosophila suzukii is a pest of global concern due to its great impact on several crops. The entomopathogenic nematode Steinernema carpocapsae was highly virulent to the larvae of the fly although some immune mechanisms were triggered along the infection course. Thus, to understand the gene activation profile we performed a comparative transcriptome of D. suzukii larvae infected with S. carpocapsae and Xenorhabdus nematophila to map the differentially expressed genes involved in the defence response. The analysis exposed the induction of genes involved in the humoral response such as the antimicrobial peptides and pattern-recognition receptors while there was a suppression of the cellular defence. Besides, genes involved in melanisation, and clot formation were downregulated hindering the encapsulation response and wound healing. After the infection, larvae were in a stress condition with an enrichment of metabolic and transport functionalities. Concerning the stress response, we observed variations of the heat-shock proteins, detoxification, and peroxidase enzymes. These findings set a genetical comprehensive knowledge of the host-pathogen relation of D. suzukii challenged with S. carpocapsae which could support further comparative studies with entomopathogenic nematodes.

Abstract 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.

Insect problem has been one of the most severe problems in agriculture and forestry, which causes great economic losses to the primary industry in China. For a long time, the use of chemical insecticides for insect control has led to many issues, such as pollution, insect resistance, etc. Therefore, in recent years, the research and application on biological pesticides of broad spectrum, high efficiency and low toxicity is increasing. Insecticidal proteins, especially those of microbial source, as an important branch of biological insecticides, have been continuously developed and applied due to their excellent insecticidal potential. This paper aims to classify the information on insecticidal proteins from microorganism over the world, and to provide fresh opinions for the application of insecticidal proteins in agriculture, forestry and other industries in China.

Abstract 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.