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Background: Entomopathogenic nematodes (EPNs) (Steinernematidae and Heterorhabditidae) and their symbiotic bacteria are pathogenic for a wide range of insect pests and have been used successfully as a biological control agent. Although EPNs are well studied against many agricultural insect pests, the efficacy of their symbiotic bacteria still remains unclear for many insect pests of agricultural importance. In the present study, the virulence of native EPN isolates and their cell-free supernatants of symbiotic bacteria were tested against the 3rd and 4th larval instars of Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae) under laboratory conditions (25 ± 1 °C and R.H. 60%). Results: The 4th instar larvae were more susceptible to infective juveniles (IJs) and mortalities over (95%) were achieved by all tested EPN isolates at the concentration of 100 IJs/cm2 after 72 hrs of exposure. The cell-free supernatants were more effective against the 3rd instar larvae and the highest mortalities were recorded as 42 and 60% in the contact and leaf disc bioassays, respectively. Conclusion: The results indicated that the cell-free supernatants can be an ideal application for young larval stages of A. segetum. However, further studies are required to test the effectiveness of both EPNs and the cell-free supernatants of their symbiotic bacteria in field conditions. [ABSTRACT FROM AUTHOR]

Background: Entomopathogens such as nematodes, bacteria and fungi are well recognized for their biocontrol potential. This study was carried out to examine the insecticidal properties of the Heterorhabditis bacteriophora Poinar, Beauveria bassiana Balsamo-Crivelli, Bacillus thuringiensis Berliner, individually and in combination against 3rd instar larvae of Spodoptera litura Fabricius (Noctuidae: Lepidoptera) under controlled laboratory and greenhouse conditions at Eternal University, Baru Sahib, Sirmaur, Himachal Pradesh. Results: The results demonstrated that the combined applications of the tested entomopathogens resulted in 100% insect mortality under the laboratory conditions. Among the individual concentrations, applications of 200 IJs/ml were noticed highly virulent with (98%) mortality, followed by B. thuringiensis (96%) and then by B. bassiana (92%). However, single treatments were also evaluated that further showed a highest mortality in the target pest by H. bacteriophora, followed by B. thuringiensis. Among the combined treatments by H. bacteriophora plus B. thuringiensis (200 IJs + 1 × 1012 CFU/cm2) more effective caused (100%) mortality were noticed in the laboratory and (28%) under the greenhouse conditions than H. bacteriophora plus B. bassiana (200 IJs + 1 × 1010 conidia/cm2) that caused (100%) mortality and (34%) damage under both, laboratory and greenhouse conditions. Conclusion: Laboratory bioassay and greenhouse evaluation tests demonstrated that the combined sprayed treatments showed reliable and fast synergism. This study could be recommended to the farmers to control the pest. [ABSTRACT FROM AUTHOR]

Background: Cabbage butterfly, Pieris brassicae Linnaeus (Lepidoptera: Pieridae), is a major insect pest affecting cole crops worldwide. Excessive applications of chemical-based insecticides have a devastating impression over the organisms and environment. Results: In this study, entomopathogenic nematode (EPN) Heterorhabditis bacteriophora Poinar strain EUPT-S26 (local isolate) was evaluated for Pieris brassicae control under polyhouse and field conditions. Under the polyhouse conditions, the highest insect mortality 91.6 and 94.0% was observed in the plots treated with the nematodes suspension 1500 IJs/ml and 2000 IJs/ml, respectively. Based on the highest cabbage plant protection under polyhouse conditions, H. bacteriophora EUPT-S26 was also applied for field assays in the course of the crop's productive phase. Data demonstrated from the field treatments signify the highest concentration (2000 IJs/ml) showed the maximum larval mortality and least damage percentage 45 ± 1.07% that remained constant until harvesting; this resulted in the highest productivity in polyhouse and under field conditions. Conclusion: According to assessed field conditions, it was suggested to perform 3 applications of EPNs during the vegetative phase and at the time of head formation to increase productivity and to reduce damage. The results approved that EPNs are an effective alternative of chemical-based insecticides to control the cabbage butterfly. [ABSTRACT FROM AUTHOR]

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

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

The cabbage butterfly (Pieris brassicae L.) is a major insect pest of cabbage in Pakistan. Heterorhabditis bacteriophora (at 1500 infective juvenile/ ml concentraction), Steinerma glaseri (at 1500 infective juvenile/ ml concentration), H. bacteriophora + S. glaseri (at 1500 infective juvenile/ ml concentration), Xenorhabdus spp., (at 4 × 1012 concentration) Photorhabdus spp., (at 4 × 1012 concentration) metabolites of Xenorhabdus spp. (at 50% concentration) and metabolites of Photorhabdus spp (at 50% concentration) were sprayed on cabbage hybrid CB-60 grown in pots placed in the greenhouse. After 7 days, the highest P. brassicae larval mortality (90.43%) was observed where H. bacteriophora + S. glaseri were sprayed. In field experiment, best-performing treatments from greenhouse experiment were selected i.e. H. bacteriophora + S. glaseri (at 1500 infective juvenile/ ml concentration), Xenorhabdus spp., (at 4 × 1012 concentration) and metabolites of Xenorhabdus spp. (at 50% concentration) were sprayed on a highly susceptible cabbage hybrid (CB-60). Heterorhabditis bacteriophora + Steinerma. glaseri @ 1500 infective juvenile/ ml was found to be more superior with maximum mortality (80.43) of cabbage butterfly larvae in comparison with other treatments. From the present study, it may be concluded that EPNs (H. bacteriophora and S. glaseri) application is more effective as compared to their symbiotic bacteria and metabolite for cabbage butterfly management. [ABSTRACT FROM AUTHOR]

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.

Abstract The study aimed to evaluate the efficacy of the EPNs against the larvae of Egyptian cotton leaf worm Spodoptera littoralis (Boisduval) and the black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) in vitro before in vivo study. The susceptibility of both larval species to the entomopathogenic nematode species, Steinernema monticolum and Heterorhabditis bacteriophora, was evaluated under laboratory conditions. The concentration of 400 IJs/dish for S. monticolum achieved up to 97.77 and 95.55% mortality rates of the 5 larval instars from 2nd to 6th instars of S. littoralis and A. ipsilon, respectively after 72 h. The concentration of 800 IJs/dish recorded larval mortality rates of 41.86 to 100% against 2nd to 6th instars of A. ipsilon larvae, after 72 h. At the lowest concentration (50 IJs/dish), the larvae of S. littoralis were more susceptible to H. bacteriophora than the larvae of A. ipsilon. The data indicated that 200 IJs/dish was the most effective concentration for all larval stages of both insect pests because the mortality percentage was 100%.

Parasites of agricultural crops cause significant losses of quality and decrease in the profitability of agricultural production. Complex measures against pests are aimed both at termination of parasites and prevention of repeated infection of plants. One of the most progressive ways of protecting plants against harmful insects is the use of entomopathogenic nematodes. This method is most expedient in the conditions of organic arable farming. The results of our study reveal the impact of the fertilizers in various concentrations on the vitality of nematode larvae (L3) of four species (Steinernema feltiae, S. kraussei, S. carpocapsae and Heterorhabditis bacteriophora) and the possibility of their combined application for the treatment of plants. Mineral fertilizers and stimulators of growth of plants in 1% concentration insignificantly reduced the vitality of larvae, allowing them to be applied at the same time. We determined the tolerance of invasive larvae to pH for S. carpocapsae equaling рН = 0.9–13.4; optimum values of рН without reliable increase in the mortality during 24 h – рН = 1.3–12.8. Increase in the vitality of larvae (L3) of entomopathogenic nematodes was studied. The survivability of the cultures of larvae increased during the use of solutions of vitamins С, В1, В6, В12. We determined the influence of 21 pigment colourings on larvae (L3), the lowest effect on the vitality of nematode larvae was exerted by pigment bases Abrikos (7.0–10.8% mortality during 24 h), Zolotoi Pesok (6.0–11.8%), Pudra Ananasa (7.7–13.4%), and complex DMAE (7.6–17.4%). The results we obtained allow development of recommendations for agriculturalists for combined use of entomopathogenic nematodes with various substances and also improving the vitality of invasive nematodes.

Nematodes of the Meloidogyne genus affect to most of crops of an economic importance in Argentina. Researches related to new control strategies are needed to reduce the damage produced by these organisms. The objective of this work was to compare the effects of Galleria mellonella cadavers infected with the Argentine isolates Heterorhabditis bacteriophora Rama Caída and Steinernema rarum NOE, cadaver macerates and dead infective juveniles (IJs) on M. javanica suppression. Experiments were performed using 24-well plates and pepper plants grown in a growth chamber. The entomopathogenic nematodes-infected G. mellonella cadavers, their cadaver macerates and dead IJs were effective in suppressing M. javanica second-stage juveniles under laboratory conditions. The use of H. bacteriophora-infected cadavers caused a significant decrease in the number of galls and egg masses on pepper plants parasitized by M. javanica, in a growth-chamber.

Abstract In greenhouses, tomato plants are subject to attack by several pest species. The present study aimed to investigate the compatibility of releasing the egg parasitoid, Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae), and the entomopathogenic nematode, Heterorhabditis bacteriophora, strain HP88 against the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in commercial tomato greenhouses (Cherry and Bushra varieties) at winter plantation of 2018–2019 in Egypt. Three commercial plastic greenhouses were used. The first plastic greenhouses were treated by the two tested biological control agents (BCG), the second sprayed by certain recommended pesticides (PG), and the third used for control. Pheromone traps were used for monitoring the appearance of T. absoluta moths. The combined use of T. euproctidis and H. bacteriophora resulted to reduce the population density of the T. absoluta gradually until the end of the season in BCG. In the 17th week of treatments by T. euproctidis and H. bacteriophora, the population density of T. absoluta was estimated as leaf mines/plant (0.8 and 1.26 mines/leaf, in Cherry and Bushra varieties, respectively) in BCG. Also, in the 17th week of treatments by recommended pesticides, the population density of T. absoluta reached 12.73 mines/leaf and 18.33 mines/leaf, in CG. Early use of pesticides, by the appearance of T. absoluta infestation, could not suppress its population density that continued to increase until the end of the season in PG. Results revealed that the combination of the tested biological control agents against T. absoluta is recommended to be a main part in pest management practices in tomato greenhouses.

To improve the efficacy of entomopathogenic nematodes (EPNs) as biocontrol agents in the field, knowledge about the kinds of impact, which the physical nature of the agricultural soil environment may have on nematode survival, persistence, and host location is important. The study aimed to investigate the effects which the addition of organic soil amendments would have on the duration of infectivity and survivorship of infective juveniles (IJs) belonging to Heterorhabditis bacteriophora in soils undergoing progressive moisture loss. The soil amendments involved mixing commercially available organic compost such as mulch, organic compost, professional potting mix, organic lawn dressing with two soil textural classes, namely loamy soil, and coarse river sand. Using Petri dish-based assays, the mulch soil amendment resulted in the highest Galleria mellonella larval mortality rate across different organic compost application concentrations (mass: mass basis). The type of compost used based on its feedstock composition, the concentration of nutrients, and organic matter mixed with a specific type of soil texture had a significant effect on the tolerance of EPNs to different dehydration periods. Virulence and efficacy decreased over 7 days of progressive dehydration. The use of organic compost did not have any detrimental effect on EPNs. The knowledge obtained could be applied to increase the effectiveness of entomopathogenic nematodes as biocontrol agents. [ABSTRACT FROM AUTHOR]

Background: The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is a serious threat to date palms across the globe, causing heavy yield losses. The pest inflicts damage to palms stem and destroys vascular system; resultantly lower the vigor and affect the growth and yield. For ecological farming system, biological control of the pest is gaining increased interest due to hosts' specificity, safety to human, animal and non-target organisms, and their compatibility to environment. Results: In laboratory assay, Beauveria bassiana, Heterorhabditis bacteriophora and Bacillus thuringiensis var. kurstaki (Bt-k) alone and in combination against sixth instar larvae and adults of four distinct populations of RPW were applied. H. bacteriophora was more effective, followed by B. bassiana and Bt-k in alone treatments. While in combined treatments, the highest mortality was recorded for H. bacteriophora + B. bassiana combination (100% for both stages), followed by H. bacteriophora + Bt-k, (larvae 100%; adults 94.24%) and B. bassiana + Bt-k treatments (larvae: 87.01%; adults: 80.53%). Maximum rate of mycosis (larvae 85.74%; adults 69.07%), sporulation (larvae 189.22 conidia ml−1; adults 164.56 conidia ml−1), cadavers affected by nematodes (larvae 92.4%; adults 81.29%) and nematode production (larvae 178.78 IJs ml−1; adults 153.44 IJs ml−1) was observed where B. bassiana or H. bacteriophora was applied alone and the lowest (larvae 122.78 IJs ml−1; adults: 103.22 IJs ml−1) was recorded for H. bacteriophora + B. bassiana combination. Conclusions: Entomopathogens can be effectively used alone and/or in integration to control RPW populations. Natural capability of entomopathogens to infect and disseminate into other hosts makes them excellent biocontrol agents to be incorporated in the IPM plan of RPW and to make palm growers confident with the use of the most promising microbial control agents. [ABSTRACT FROM AUTHOR]

Background: Entomopathogenic nematodes (EPNs) have the potential to supersede larvicidal activity for the management of various insect pests. Result: Lab experiments were conducted to test the pathogenicity of 2 EPNs local species; Steinernema feltiae and Heterorhabditis bacteriophora at different (IJs/cm2) concentrations against the cabbage butterfly, Pieris brassicae (L.). The native isolate was obtained from soil samples, collected from Rajgarh, Hamachi Pradesh, India. Petri dish bioassay used the EPNs species (S. feltiae HR1 and H. bacteriophora HR2) at the concentrations (0, 10, 20, 40, 80, 160 IJs/cm2). Based on the pathogenicity of the strains, only 2 isolates effectively showed larvicidal activity. The highest (%) (72.08 and 67.42%), at the 2nd instar larval mortality was recorded in the treatments with H. bacteriophora and S. feltiae at160 IJs/cm2, respectively. At the 4th instar larvae, respective larval mortality (85.38, 69.50%) was recorded in treatment with H. bacteriophora, and S. feltiae, respectively, at160 IJs/cm2. In case of pupae, the mortality rates were (62.12, 58.58%) for H. bacteriophora and S. feltiae, respectively, at 160 IJs/cm2; (74 and 12%) for both the tested EPNs, respectively, at 80 IJs/cm2. Percent of P. brassicae larval mortality treated with the tested EPN isolates was significantly higher than the untreated control. Results revealed that the percent of larval mortality significantly increased with the increase in time periods, being maximum at 72 h. S. feltiae and H. bacteriophora, strains showed potent larvicidal activity at low concentration even at 48 and 72 h of exposure. Conclusion: This study revealed that the local strains of EPNs (S. feltiae HR1 and H. bacteriophora HR2) were found as a biocontrol agent against P. brassicae. [ABSTRACT FROM AUTHOR]

We present the first report of Heterorhabditis bacteriophora entomopathogenic nematodes isolated from sandy loam soil obtained from Walkerville, South of Johannesburg, Gauteng province, South Africa. A survey was conducted to collect soil samples and isolate entomopathogenic nematodes between 2012 and 2016. Entomopathogenic nematodes are insect-killing microscopic worms found in soil and have a symbiotic relationship with insect pathogenic bacteria. Molecular and morphological techniques including genomic DNA extractions, polymerase chain reaction and sequencing of the 18S rDNA, phylogenetic analysis, light microscopy and scanning electron microscopy were used to identify entomopathogenic nematodes from the collected soil samples. H. bacteriophora was recovered in one out of 80 soil samples from an uncultivated grassland and the frequency of its isolation from soil samples in our study was 2%. Phylogenetic tree analysis revealed that the South African isolate was grouped with the strain H. bacteriophora strain 56-C. H. bacteriophora. The body length, body width and tail of the isolate are slightly shorter than the previously described H. bacteriophora. This is the first H. bacteriophora species to be isolated and reported from South African soil and future studies will explore its potential as a biological control agent of problematic insect pests in agricultural industries. [ABSTRACT FROM AUTHOR]

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

BACKGROUND Entomopathogenic nematodes (EPN) show potential in controlling larvae of the Mediterranean fruit fly (medfly) Ceratitis capitate, but previous studies mainly concern species and strains that are not commercially available. The use of EPN for control of Mediterranean fruit fly is further hampered by the cost of using nematodes. In this study, the efficacy and residual activity of commercial strains of three EPN species, Steinernema carpοcapsae, S. feltiae and Heterοrhabditis bacteriοphοra medfly) C. capitata, in the soil substrate and inside fruits were evaluated. RESULTS: Suspensions of these species were applied at a dose of 1.5 mi m−2 on a soil substrate wherein medfly larvae were added sequentially for a period of 4 weeks post application at 20 °C. S. feltiae provided the highest suppression up to 50% as assessed by adult medfly emergence because it had the highest immediate activity and long residual activity. Furthermore, S. feltiae, and to a lesser degree S. carpocapsae, were able to move and infect medfly larvae inside infested apples and oranges left in the surface of the substrate wherein EPN were applied, reducing significantly adult medfly emergence (60–78%). CONCLUSION: These results support the efficacy and feasibility of applying a single, relatively low dose of S. feltiae in autumn, off‐season, targeting overwintering medfly larvae with the scope of reducing the number of adult medflies emerging later in the new season. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

South African entomopathogenic nematodes (EPNs), Steinernema australe and Heterorhabditis bacteriophora were used for studying the responses of infective juveniles (IJs) to soil desiccation and soil rehydration. The capacity to infect larvae of Galleria mellonella was used to assess the viability of EPNs after their exposure to desiccation. All the samples were initially hydrated to 10% moisture and moisture loss was recorded daily before rehydrating the soil. Desiccation tolerance results revealed that both species were able to withstand desiccated conditions or continuous dehydration for 20 days in sandy loam soil. H. bacteriophora caused 80% larval mortality after day 15 on rehydration of soil, whereas S. australe caused only 60% larval mortality. All the controls, with coarse river sand, gave zero larval mortality by day 21, indicating that the soil texture is also important for EPNs recovery from dehydrated soils. It may be concluded that coarse sand is not ideal for survival and effectiveness of EPNs, because of its incompetence to retain water. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) are widely used as a biological control agent in pest management. The purpose of this study was to determine the effectiveness and penetration rates of certain EPNs. Three different EPN species were utilized in the study: Heterorhabditis bacteriophora HBH hybrid strain, Steinernema carpocapsae TUR-S4 isolate, Steinernema feltiae TUR-S3 and S-Bilecik isolates. These isolates were applied at different doses (50, 100, 150, 200, 250, 300, 350, and 400 Infective Juveniles (IJs)/Petri) on larvae of Tenebrio molitor and adults of Rhyzopertha dominica. Additionally, the penetration rates of the mentioned EPN species on T. molitor larvae and R. dominica adults were determined. As a result, the highest mortality rate observed in R. dominica adults was 93.33% when treated with the HBH isolate at the dose of 400 IJs/Petri dishes. For T. molitor larvae, the highest mortality rate was 100% at doses of 8.85 IJs/cm2, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for HBH and TUR-S3, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for TUR-S4, and 7.10 IJs/cm2, 8.85 IJs/cm2, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for S-Bilecik. When examining the penetration rates, the highest rate of 23.33% was observed in R. dominica adults treated with HBH, while for T. molitor , this rate was 22.67% in individuals treated with HBH. These findings underscore the importance of continued investigation into the potential of these EPNs for sustainable pest management strategies. • Entomopathogenic nematodes (EPNs) play a crucial role as biological control agents in controlling agricultural pests. • The HBH isolate of Heterorhabditis bacteriophora showed high mortality rates of 93.33% in Rhyzopertha dominica adults. • Specific doses for each EPN species resulted in a 100% mortality rate for Tenebrio molitor larvae. • The HBH isolate demonstrated the highest penetration rates, with 23.33% observed in R. dominica and 22.67% in T. molitor. [ABSTRACT FROM AUTHOR]

Commercial-scale field studies were conducted in citrus orchards to test the efficacy of entomopathogenic nematodes (EPNs) in controlling the soil-dwelling life stages of the key pest, Thaumatotibia leucotreta. Trials were conducted in three provinces of South Africa from 2011 to 2013. Two EPN species were tested: Heterorhabditis bacteriophora and Steinernema feltiae. Both EPN species were applied underneath citrus tree canopies, either with a spray machine or through the microsprinkler irrigation system. The concentration of nematodes and frequency of application varied. Efficacy of these treatments was measured by evaluation of EPN infection of sentinel T. leucotreta larvae in the soil at various intervals after application and by T. leucotreta infestation of fruit. Successful control was recorded in several trials, with EPN infection of larvae frequently reaching 80 %. However, in a few trials, this level of infection was assisted by naturally occurring EPNs. Fruit infestation by T. leucotreta larvae was reduced by up to 88 %. Efficacy appeared to be limited by suboptimal soil moisture and temperature. The former was influenced mainly by mode and relative thoroughness of irrigation before and after EPN application. This was best obtained through microsprinkler application. Nematode species and concentration also influenced efficacy. Both EPN species survived and persisted in the soil of the treated orchards for up to 4 months. Promising results support their potential for use in an integrated pest management programme in citrus in South Africa. • Thaumatotibia leucotreta is an important pest of citrus in sub-Saharan Africa. • Heterorhabditis bacteriophora and Steinernema feltiae are virulent to T. leucotreta. • In field trials, more than 80 % of T. leucotreta larvae were infected with nematodes. • Fruit infestation with T. leucotreta larvae was reduced by up to 88 %. • Best results were achieved with monthly applications of EPNs for four months. [ABSTRACT FROM AUTHOR]

• Allium sativum EO increased EPN mortality and reduced their infective capacity. • Satureja montana EO caused low mortality rates but exhibited repellency towards EPNs. • Mentha suaveolens EO minimally affected EPNs survival, infectivity and reproduction. • M. suaveolens EO is suggested as the most compatible oil for field use with EPNs. • Field validation is essential to confirm the practical applicability of these findings. The European truffle beetle, Leiodes cinnamomeus , is the most important pest in black truffle (Tuber melanosporum) plantations. Entomopathogenic nematodes (EPNs) are promising biological control agents against L. cinnamomeus. Essential oils (EOs) are also recently being investigated for the control of the adults of this pest. Therefore, both control methods could be combined in Integrated Pest Management (IPM) programs to enhance their efficacy. However, limited information exists regarding the effects of the EOs on EPNs and so their compatibility. The aims of our work were to study the effects of three previously described insecticidal and nematicidal essential oils, Allium sativum , Mentha suaveolens , and Satureja montana, on the survival, infectivity, reproduction, and attraction behaviour of three EPN species: Steinernema feltiae , Steinernema carpocapsae and Heterorhabditis bacteriophora. Therefore, we conducted three experiments under laboratory conditions to observe the lethal and sublethal effects by direct contact, the lethal effect by fumigation, and the chemotaxis response. Allium sativum caused the highest mortality rates in all three EPN species at 24 and 72 h post application whether by direct contact (97–99%) or fumigation (40–42%), and it also reduced their infective capacity on Galleria mellonella. Satureja montana EO caused low mortality rates compared to A. sativum , but it was significantly more lethal (6–8%) than the control (0–3%) at 72 h in the direct contact assay. It also displayed repellent properties against S. feltiae and H. bacteriohora in the chemotaxis assay. In contrast, M. suaveolens EO exhibited minimal impact on the survival, infectivity and reproduction of all three EPN species. Therefore, our results suggest M. suaveolens oil may be the most compatible EO for use integrated with EPNs. Further validation under field conditions and in the presence of L. cinnamomeus is necessary to confirm the practical applicability of these findings. [ABSTRACT FROM AUTHOR]

Abstract A survey for naturally occurring entomopathogenic nematodes (EPNs) was conducted in various agricultural fields in central Turkey, Nevsehir, between 2015 and 2016 years. EPNs were recovered from 20 of 112 soil samples (17.9%). Seventeen isolates were identified as Steinernema feltiae (Rhabditida: Steinernematidae). One was unknown Steinernema sp. (Rhabditida: Steinernematidae), and two were Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae). The most common species was S. feltiae, which was recovered from 5 out of 8 sites. The pathogenicity of these isolates was evaluated on the last larval instar of Galleria mellonella L. (Lepidoptera: Pyralidae) at different concentrations (25, 50, 100 IJs) in the laboratory at 25 ± 1 °C. Maximum mortality rate (87%) was achieved from the H. bacteriophora AVB-15 isolate at the lowest concentration after 48 h post-inoculation, while the only isolate that caused maximum mortality of (100%) at the concentration of 50 IJs/ml, 24 h post-inoculation was S. feltiae DDKB-17 isolate. All isolates showed high pathogenicity on G. mellonella last instar ranging from 63 to 100% at the concentration of 100 IJs/ml, 48 h post-inoculation. The present survey revealed that these EPNs are commonly present at Nevsehir, and they might have a good potential in biological control of insect pests.

BACKGROUND: Carrot weevil is an important pest throughout carrot‐producing regions in Canada. Pesticides to control carrot weevil adults require application when the majority of adults have emerged and often this occurs after oviposition has already commenced and damage will be realized. One alternative to conventional pesticides are entomopathogenic nematodes. We studied four commercially available entomopathogenic nematode products (Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora) for efficacy against carrot weevil in Nova Scotia and Ontario carrot fields in 2017 and 2018. The longevity and infectivity of the products in fine sandy loam soil (Ontario) and sandy loam soil (Nova Scotia) were evaluated using Galleria mellonella larvae. RESULTS: In Nova Scotia soils, only S. kraussei when applied twice, showed some efficacy to reduce damage from carrot weevil in 2017. In Ontario, an early application of H. bacteriophora and S. feltiae significantly reduced the percentage of carrots with weevil damage in 2018. Longevity and infectivity of S. carpocapsae and S. feltiae (against G. mellonella) was obtained up to 6 weeks post application in Nova Scotia in 2017. Similarly, S. feltiae showed infectivity up to 9 weeks post application in Ontario and Nova Scotia in 2018. CONCLUSION: Entomopathogenic products showed an ability to survive and remain infective for up to 9 weeks in soils without irrigation. Timing of application to effect control of carrot weevil requires further study. The influence of soil moisture on the longevity and infectivity of these products is discussed. © 2021 Her Majesty the Queen in Right of Canada International Pest Management Science © 2021 Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri‐Food Canada. [ABSTRACT FROM AUTHOR]

Drosophila suzukii is a global pest of ripening fruit, and its immature stages developing in fallen fruit are susceptible to entomopathogenic nematodes. In this study, Steinernema riobrave, was as effective as other tested nematodes, killing 80–100% of D. suzukii larvae in sand at 24 and 28°C. Combining Heterorhabditis bacteriophora with S. riobrave did not increase mortality rates compared to using H. bacteriophora alone. All nematode species infected D. suzukii adult cadavers at high rates, but S. riobrave produced the fewest infective juveniles from second-instar cadavers. Steinernema riobrave may be a suitable biological control agent for D. suzukii in warm climates. [ABSTRACT FROM AUTHOR]

Under laboratory conditions, the virulence of the Kashmir isolate of EPN, Heterorhabditis bacteriophora (SKUASTK-EPN- Hr 01) to Galeria mellonella, Corcyra cephalonica and Bombyx mori showed that after 48-72 h, 100% mortality was recorded in all the test insects. Considering 48 h time and 20 IJs/larva as standard against G. mellonella, C. cephalonica and B. mori, the LC50 and LT50 values for the EPN were 10.17, 28.72 and 23.81 IJs/larva, and 38.64, 53.04 and 49.20 h after exposure, respectively. Again its virulence to the larvae of three different sizes of these insects, viz., small (0.12g, 0.04g, 0.17g), medium (0.18g, 0.05g, 0.59g) and large (0.22g, 0.07g, 2.58g) sized larvae showed that all the three sizes of G. mellonella were more susceptible than that of B. mori and C. cephalonica. Considering 20 IJs/ larva as standard against small, medium and large sized larvae, the LT50 value for the EPN was 25.00, 26.45 and 27.21 h; 47.73, 48.92 and 53.16 h, and 46.04, 47.48 and 48.92 h for G. mellonella, C. cephalonica and B. mori, respectively. The production of nematode infective juveniles per larvae was directly proportional to the size and/or body weight of the insect species tested. The average production of nematode infective juveniles per gram of host body weight ranged from 1557.79 to 1933.55 x 10³, 217.38 to 335.43 x 10³ and 71.03 to 128.00 x 10³ in G. mellonella, C. cephalonica and B. mori, respectively. The total time period between the larval mortality and the initiation of emergence, and between larval mortality and the cessation of emergence of nematode infective juveniles from the cadavers ranged from 7-10, 6-8 and 9-12 days, and 19-28, 16-24 and 23-41 days in G. mellonella, C. cephalonica and B. mori, respectively. [ABSTRACT FROM AUTHOR]

The virulence of a cold tolerant indigenous Kashmir isolate of Heterorhabditis bacteriophora (SKUASTK-EPN-Hr 01) tested against 1st, 2nd and 3rd instars of white grub, Heteronychus sp. @ 0, 100, 150, 200, 250, 500, 750 and 1000 IJs/grub using Petri dish bioassay method, revealed large differences in the virulence of H. bacteriophora towards the different stages of Heteronychus sp. However, there was a positive correlation between nematode concentration and the insect mortality. The 3rd instar grubs succumbed to nematode infection later (LT50 = 6.47 days at 250 IJs/grub) than the grubs of 2nd (LT50 = 3.23 days at 250 IJs/grub) and 1st instars (LT50 = 2.44 days at 250 IJs/grub). When grubs were in 1st instar, relatively shorter exposure periods and low nematode concentrations (LC50 = 126.72 IJs/grub at 5 DAE) were needed for achieving lethal nematode infections as compared to 2nd (LC50 = 176.02 IJs/grub at 5 DAE) and 3rd (LC50 = 456.35 IJs/grub at 5 DAE) instar grubs where longer exposure periods and high nematode concentrations were required. The recovery of nematode infective juveniles per grub ranged from 47.47-51.32 x 10³, 89.19-92.85 x 10³ and 260.36-263.95 x 10³ IJs in 1st, 2nd and 3rd larval instars of Heteronychus sp., respectively. The total time period between the grub mortality and the initiation of emergence and between grub mortality and the cessation of emergence of nematode infective juveniles from the cadavers ranged from 6-8, 14-16 and 22-24 days, and 21-26, 31-36 and 42-45 days in case of 1st, 2nd and 3rd larval instars of white grub, Heteronychus sp., respectively. [ABSTRACT FROM AUTHOR]

A laboratory investigation was carried out to assess the bioefficacy and mass culturing of Kashmir isolate of entomopathogenic nematode (EPN), Heterorhabditis bacteriophora on cabbage butterfly, Pieris brassicae in Srinagar. The pathogenicity of H. bacteriophora against 3rd, 4th and 5th larval instars of P. brassicae showed cent per cent mortality of the pest in all the three larval instars at the dosages of 20 IJs/larva and above. The LC50 values of H. bacteriophora against 3rd, 4th and 5th larval instars of P. brassicae ranged from 46.61 to 9.32, 76.33 to 9.82 and 91.36 to 10.08 IJs/larva at 24 to 96 h and that the LT50 values from 65.15 to 23.12, 84.54 to 29.20 and 105.36 to 33.52 h at 10 to 60 IJs/larva, respectively. The average production of nematode infective juveniles per larvae was found to be 7.02 x 10³, 25.74 x 10³ and 58.45 x 10³ and that from per gram of host body weight was 91.49 x 10³, 151.30 x 10³ and 233.78 x 10³ in 3rd, 4th and 5th larval instars of P. brassicae, respectively. The total time period between the larval mortality and the initiation of emergence of the infective juveniles from the cadavers ranged from 7-8, 9-10 and 10-11 days and the peak period of emergence of infective juveniles ranged from 10-13, 14-19, 16-21 days after mortality from the cadavers of 3rd, 4th and 5th larval instars of P. brassicae, respectively. The total duration of nematode emergence recorded during the period between larval mortality and cessation of emergence of infective juveniles from the cadavers ranged 17-19, 23-25 and 26-29 days after mortality in case of 3rd, 4th and 5th larval instars of P. brassicae, respectively. [ABSTRACT FROM AUTHOR]

Parasites and pathogens can follow different patterns of infection depending on the host developmental stage or sex. In fact, immune function is energetically costly for hosts and trade‐offs exist between immune defenses and life history traits as growth, development and reproduction and organisms should thus optimize immune defense through their life cycle according to their developmental stage. Identifying the most susceptible target and the most virulent pathogen is particularly important in the case of insect pests, in order to develop effective control strategies targeting the most vulnerable individuals with the most effective control agent. Here, we carried out laboratory tests to identify the most susceptible target of infection by infecting different stages of the red palm weevil Rhynchophorus ferrugineus (larvae, pupae, male, and female adults) with both a generic pathogen, antibiotic‐resistant Gram‐negative bacteria Escherichia coli XL1‐Blue, and two specific strains of entomopathogenic nematodes (EPNs), Steinernema carpocapsae ItS‐CAO1 and Heterorhabditis bacteriophora ItH‐LU1. By evaluating bacterial clearance, host mortality and parasite progeny release, we demonstrate that larvae are more resistant than adults to bacterial challenge and they release less EPNs progeny after infection despite a higher mortality compared to adults. Considering the two EPN strains, S. carpocapsae was more virulent than H. bacteriophora both in terms of host mortality and more abundant progeny released by hosts after death. The outcomes attained with unspecific and specific pathogens provide useful information for a more efficient and sustainable management of this invasive pest. [ABSTRACT FROM AUTHOR]

Summary: The invasive red palm weevil (RPW) (Rhynchophorus ferrugineus) (Coleoptera: Curculionidae) is one of the most destructive palm pests in the world. More options are needed for its management, including optimised use of microbial entomopathogens (EP). The sub-lethal effects of an entomopathogenic fungus (EPF) Beauveria bassiana (isolate WG-11) (Ascomycota: Hypocreales) (at 1 × 104 spores ml−1) and two entomopathogenic nematode (EPN) species, Heterorhabditis bacteriophora (at 100 infective juveniles (IJ) ml−1) and Steinernema carpocapsae (at 50 IJ ml−1) were evaluated in various combinations against laboratory-reared 3rd, 5th and 8th instar larvae of RPW in bioassays. Individual and combined effects of both EP were observed after the pre-application of B. bassiana fungus at 0-, 1- and 2-week intervals. Combined treatments were tested for antagonistic, additive and synergistic effects. Additive and synergistic effects were observed in B. bassiana / S. carpocapsae and in B. bassiana / H. bacteriophora combined treatments. Early instar larvae of RPW were more susceptible than older instars. Sole and combined EP treatments decreased pupation, subsequent emergence of RPW adults and hatching. Sub-lethal effects of EP were observed in R. ferrugineus following application at the above-mentioned rates to 3rd, 5th and 8th instar larvae, including reduced larval weights, increased larval, pre-pupal and pupal durations, reduced adult weights and life spans. Simultaneous combined applications of B. bassiana / S. carpocapsae and B. bassiana / H. bacteriophora at the above-mentioned rates against last instar (9th) larvae of R. ferrugineus reduced food consumption, frass production and affected weight gains. [ABSTRACT FROM AUTHOR]

Summary: Anomala corpulenta is one of the major white grubs that cause serious damages in peanut production. To develop an environmentally friendly method to control A. corpulenta larvae, the efficacy of species of entomopathogenic nematodes (EPN), application rate and larval stage against A. corpulenta were determined. Results showed that Steinernema longicaudum X-7 and S. glaseri B-4-1 were the most virulent species, which caused 77.8 and 84.4% corrected mortalities of the 2nd instar larvae at 25°C 14 days after treatments. Corrected mortalities of A. corpulenta caused by EPN were significantly affected by EPN application rate. A decrease but no significant difference in susceptibility from the 2nd to the 3rd instar was observed for the test EPN species S. longicaudum , S. glaseri and Heterorhabditis bacteriophora. The field experiments indicated that S. longicaudum and S. glaseri applied at a relatively high rate (⩾5.0 × 103 infective juveniles (IJ) plant−1, i.e. , 7.5 × 108 IJ ha−1) were able to provide not only control efficacy against A. corpulenta with ⩾92.7% reduction of larvae and ⩽5.06% of damaged pods, and the peanut yield increase was as good as phoxim, but also gave better control persistency compared to phoxim. Our findings indicated that EPN could be an effective strategy for the management of A. corpulenta in peanut fields. [ABSTRACT FROM AUTHOR]

Compatibility of the Turkish entomopathogenic nematode isolates Steinernema feltiae (Filipjev) and Heterorhabditis bacteriophora (Poinar) with six chemical pesticides registered for vegetable crops in Turkey was investigated. Mortality, infectivity, and reproduction capacity of pesticide-treated EPNs have been assessed. Our study indicated that imidacloprid and cyflumetofen showed no adverse effect on the survival, infectivity, and reproduction rates of EPNs and can be considered as the most compatible pesticides. The fungicides, fluxapyroxad + difenoconazole and ametoctradin + dimethomorph, caused significantly higher mortality on S. feltiae; however, only fluxapyroxad + difenoconazole showed the negative effect on the survival of H. bacteriophora. Although spiromesifen, spinosad and fluxapyroxad + difenoconazole treated H. bacteriophora had significantly lower reproduction capacity, no negative effect has been observed on the progeny production of S. feltiae among the tested pesticides. In this study, compatibility of cyflumetofen, fluxapyroxad + difenoconazole and ametoctradin + dimethomorph with EPNs have been reported for the first time. The results of the present study will contribute to cost-effective and sustainable management of vegetable pests. [ABSTRACT FROM AUTHOR]

Plum sawflies are among the most damaging pests of European plum. Current control strategy implies insecticide application. Three species of entomopathogenic nematodes (EPN), Steinernema feltiae Filipjev, S. carpocapsae Weiser and Heterorhabditis bacteriophora Poinar were tested under laboratory and field conditions to assess effectiveness against larval and adult stages. Laboratory tests resulted in up to 100% mortality of last instar larvae before construction of a cocoon. However, the nematodes were not able to penetrate the cocoon. Foliar application did not result in plum sawflies larvae infestation by EPNs. Under field conditions, the nematodes reduced the number of emerging adults by application against sawfly larvae in the previous year before migration into the soil for overwintering by 62%–92%. Application of the nematodes against adults just before their anticipated emergence resulted in reduction of fruit infestation up to 100%. Mean results of 5 trials using caged trees were 47.8% with S. feltiae, 56.3% with S. carpocapsae and 62.9% with H. bacteriophora. In open field trails, control of adults obtained with S. feltiae at 0.5 million nematodes/m2 was 98.2 and 67.8% and at 0.25 million m−2 41.7 and 41.2%. Forecasting adult emergence and optimal soil moisture conditions are essential for success of the nematode application. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the efficacy of the EPNs against the larvae of Egyptian cotton leaf worm Spodoptera littoralis (Boisduval) and the black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) in vitro before in vivo study. The susceptibility of both larval species to the entomopathogenic nematode species, Steinernema monticolum and Heterorhabditis bacteriophora, was evaluated under laboratory conditions. The concentration of 400 IJs/dish for S. monticolum achieved up to 97.77 and 95.55% mortality rates of the 5 larval instars from 2nd to 6th instars of S. littoralis and A. ipsilon, respectively after 72 h. The concentration of 800 IJs/dish recorded larval mortality rates of 41.86 to 100% against 2nd to 6th instars of A. ipsilon larvae, after 72 h. At the lowest concentration (50 IJs/dish), the larvae of S. littoralis were more susceptible to H. bacteriophora than the larvae of A. ipsilon. The data indicated that 200 IJs/dish was the most effective concentration for all larval stages of both insect pests because the mortality percentage was 100%. [ABSTRACT FROM AUTHOR]

Control methods for the larvae of the maize pest Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) are known to produce inconsistent results under field conditions. To better understand the effects of plant protection products on the root-feeding larvae, we looked for changes in efficacy of the granular soil insecticides chlorpyrifos, cypermethrin, and tefluthrin during a cropping season, as well as a fluid-applied entomopathogenic nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae). Twelve field-scale experiments carried out in Hungary between 2010 and 2018 revealed that treatments, whether chemical or biological, are able to reduce D. v. virgifera. However, results were variable with failures in about a quarter of the experiments. Unexpectedly, our findings indicated only limited effect of time on treatments, meaning all products appeared capable of continuously reducing larvae during their time in the soil. Only chlorpyrifos seemed to slightly lose and tefluthrin to slightly increase efficacy over time. Nevertheless, there is no major evidence that failure of treatments is due to temporal effects. Other factors may play a larger role and merit investigation under field conditions. [ABSTRACT FROM AUTHOR]

In greenhouses, tomato plants are subject to attack by several pest species. The present study aimed to investigate the compatibility of releasing the egg parasitoid, Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae), and the entomopathogenic nematode, Heterorhabditis bacteriophora, strain HP88 against the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in commercial tomato greenhouses (Cherry and Bushra varieties) at winter plantation of 2018–2019 in Egypt. Three commercial plastic greenhouses were used. The first plastic greenhouses were treated by the two tested biological control agents (BCG), the second sprayed by certain recommended pesticides (PG), and the third used for control. Pheromone traps were used for monitoring the appearance of T. absoluta moths. The combined use of T. euproctidis and H. bacteriophora resulted to reduce the population density of the T. absoluta gradually until the end of the season in BCG. In the 17th week of treatments by T. euproctidis and H. bacteriophora, the population density of T. absoluta was estimated as leaf mines/plant (0.8 and 1.26 mines/leaf, in Cherry and Bushra varieties, respectively) in BCG. Also, in the 17th week of treatments by recommended pesticides, the population density of T. absoluta reached 12.73 mines/leaf and 18.33 mines/leaf, in CG. Early use of pesticides, by the appearance of T. absoluta infestation, could not suppress its population density that continued to increase until the end of the season in PG. Results revealed that the combination of the tested biological control agents against T. absoluta is recommended to be a main part in pest management practices in tomato greenhouses. [ABSTRACT FROM AUTHOR]

Popillia japonica Newman (Japanese beetle) is an invasive, polyphagous pest in North America, as adults feed on plant foliage and larvae on roots. Management in crops relies on foliar and soil applications of insecticides, but entomopathogenic nematodes (EPN) are effective biocontrol agents. In highbush blueberry, mulches (composts, woodshavings, sawdust, bark) are used for weed control and fertility. Therefore, our objective was to determine the effects of Heterorhabditis bacteriophora and Steinernema scarabaei on third-instar P. japonica in substrates commonly used as mulches in blueberry. In containers in the laboratory, larval mortality was 90–100% with H. bacteriophora for all substrates, but rates with S. scarabaei were lower and variable among substrates. A mixture of municipal compost + woodchips/sawdust resulted in 60% larval mortality without adding EPN, but few nematodes were recovered, indicating other causes of death. In a field microplot experiment in October, larval mortality rates were 50% at most for all EPN and substrate type combinations, likely due to lower than optimal soil and substrate temperatures for EPN survival and infectivity. Overall, a compost and woodchip/sawdust mulch should help suppress P. japonica populations in blueberry, and applying H. bacteriophora when temperatures are optimal to mulches can provide excellent larval control.

Pieris brassicae L. is one of the most important pests of Brassicaceae. The insecticidal effect of two entomopathogenic nematodes (EPNs), Heterorhabditis bacteriophora and Steinernema feltiae, was determined through their interaction with Beauveria bassiana and Bacillus thuringiensis subsp. kurstaki (Btk) against P. brassicae. In the interaction tests, the EPNs were applied at LC50 level 0, 12 or 24h after treating the larvae with LC10 or LC25 of the B. bassiana or Btk. The interaction between the EPNs and B. bassiana was entirely different from the interaction of the EPNs and Btk. The interaction with B. bassiana was dependant on time intervals, while the interaction of the EPNs with Btk was almost additive or synergistic. An antagonistic effect was seen when the EPNs were applied immediately after the B. bassiana. However, the application of the EPNs 24h after their treatment with B. bassiana caused additive or synergistic effects. The results also showed the best mortality effect when the EPNs were used with Btk at 12 h and 24 h time intervals. Based on the results, a simultaneous use of the EPNs and B. bassiana is not recommended against P. brassica. However, the EPNs could be used simultaneously after Btk but it is better to allow a time interval to increase mortality.

The humoral immune responses of the nipa palm hispid beetle Octodonta nipae involves the inducible expression of the genes coding for antimicrobial peptides (AMPs) which are mediated by immune deficiency signaling pathways. In insects, the nuclear factor-κB (NF−κB) transcription factor, Relish, has been shown to regulate AMP gene expressions upon microbial infections. Here, we dissect the expression patterns of some AMPs in O. nipae during infections by entomopathogenic nematodes (EPNs) and their symbionts, before and after Relish knock down. Our results indicate that, prior to gene silencing, the AMPs attacin C1, attacin C2, and defensin 2B were especially expressed to great extents in the insects challenged with the nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora as well as with their respective symbionts Xenorhabdus nematophila and Photorhabdus luminescens. The study also established the partial sequence of OnRelish/NF-κB p110 subunit in O. nipae, with an open reading frame coding for a protein with 102 amino acid residues. A typical Death domain-containing protein was detected (as seen in Drosophila) at the C-terminus of the protein. Phylogenetic analysis revealed that in O. nipae, Relish is clustered with registered Relish/NF-κB p110 proteins from other species of insect especially Leptinotarsa decemlineata from the same order Coleoptera. Injection of OnRelish dsRNA remarkably brought down the expression of OnRelish and also reduced the magnitude of transcription of attacin C1 and defensin 2B upon S. carpocapsae and H. bacteriophora and their symbionts infections. Altogether, our data unveil the expression pattern of OnRelish as well as that of some AMP genes it influences during immune responses of O. nipae against EPNs and their symbionts.

Herbivore natural enemies protect plants by regulating herbivore populations. Whether they can alter the behavior of their prey to increase predation success is unknown. We investigate if and how infection by the entomopathogenic nematode Heterorhabditis bacteriophora changes the behavior of healthy larvae of the western corn rootworm (Diabrotica virgifera), a major pest of maize. We found that nematode-infected rootworm cadavers are attractive to rootworm larvae, and that this behavior increases nematode reproductive success. Nematode-infected rootworms release distinct volatile bouquets, including the unusual volatile butylated hydroxytoluene (BHT). BHT alone attracts rootworms, and increases nematode reproductive success. A screen of different nematode and herbivore species shows that attraction of healthy hosts to nematode-infected cadavers is widespread and likely involves species-specific volatile cues. This study reveals a new facet of the biology of herbivore natural enemies that boosts their predation success by increasing the probability of host encounters.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most damaging insect pests of onions, Allium cepa L., which is an economically important agricultural crop cultivated worldwide. In this study, the combined application of entomopathogenic nematodes with entomopathogenic fungi against different soil dwelling stages of T. tabaci was evaluated. The nematodes included Heterorhabditis bacteriophora (VS strain) and Steinernema feltiae (SN strain), and fungi included Beauveria bassiana (WG-11) and Metarhizium anisopliae (WG-02); all four paired combinations (nematode + fungus) were included. In a small cup bioassay, only the combined application of H. bacteriophora and B. bassiana (WG-11) caused a synergistic interaction against pre-pupae, while all other combinations were compatible in an additive manner against pupae and late second instars. In a larger arena, a potted soil bioassay, again, combined applications of both pathogens produced greater mortality compared to single applications of each pathogen; all the combinations exhibited additive interactions, with the highest mortality observed in pre-pupae, followed by pupae and late second instar larvae using H. bacteriophora and B. bassiana (WG-11). Additionally, in the potted plant bioassay, lower adult emergence was observed from treated groups compared to control groups. Under field conditions, lower numbers of adults and larvae were found in treated groups relative to controls. Overall, the pre-pupal stage was more susceptible to the pathogen treatments, followed by pupae and late second instar larvae, and also combined applications of both pathogens suppressed the adult population. Combined application of entomopathogenic nematodes and fungi could be used for integrated pest management (IPM) of T. tabaci in onion production systems.

The humoral immune responses of the nipa palm hispid beetle Octodonta nipae involves the inducible expression of the genes coding for antimicrobial peptides (AMPs) which are mediated by immune deficiency signaling pathways. In insects, the nuclear factor-κB (NF−κB) transcription factor, Relish, has been shown to regulate AMP gene expressions upon microbial infections. Here, we dissect the expression patterns of some AMPs in O. nipae during infections by entomopathogenic nematodes (EPNs) and their symbionts, before and after Relish knock down. Our results indicate that, prior to gene silencing, the AMPs attacin C1, attacin C2, and defensin 2B were especially expressed to great extents in the insects challenged with the nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora as well as with their respective symbionts Xenorhabdus nematophila and Photorhabdus luminescens. The study also established the partial sequence of OnRelish/NF-κB p110 subunit in O. nipae , with an open reading frame coding for a protein with 102 amino acid residues. A typical Death domain-containing protein was detected (as seen in Drosophila) at the C-terminus of the protein. Phylogenetic analysis revealed that in O. nipae , Relish is clustered with registered Relish/NF-κB p110 proteins from other species of insect especially Leptinotarsa decemlineata from the same order Coleoptera. Injection of OnRelish dsRNA remarkably brought down the expression of OnRelish and also reduced the magnitude of transcription of attacin C1 and defensin 2B upon S. carpocapsae and H. bacteriophora and their symbionts infections. Altogether, our data unveil the expression pattern of OnRelish as well as that of some AMP genes it influences during immune responses of O. nipae against EPNs and their symbionts. [ABSTRACT FROM AUTHOR]

Large-scale use of entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae) as biological control agents is impaired by their short shelf life. Three local South African EPN species, including Steinernema yirgalemense, S. jeffreyense and Heterorhabditis bacteriophora, were investigated for their role in formulations. Encapsulation of the infective juveniles (IJs) in alginate beads and diatomaceous earth (DE) was investigated. Survival of the IJs in the formulations was determined at 6 °C, 14 °C and 25 °C for four weeks. Of the IJs, 10-20% were observed to escape from the beads, depending on temperature, and readily survived the encapsulation process. DE did not cause the desiccation of the nematodes, with there still being a lower mortality rate by the 4th week of the study. In both formulations, the survival and virulence rates differed significantly at 6 °C, as compared to at 14 °C and 25 °C, with a drastic decrease over time for S. yirgalemense. The EPN species revealed poor survival and loss of virulence at low temperatures in both formulations. The alginate beads successfully retained most of the IJs and can be stored for a longer time. [ABSTRACT FROM AUTHOR]

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