Application Of Entomopathogenic Nematodes Research Articles

Application of Entomopathogenic nematodes Suppresses the Root Knot Nematodes, Agrotis ipsilon, Spodoptera litura in Tobacco

Application of Entomopathogenic nematodes (EPNs) is an efficient and novel alternative for management of plant-parasitic nematode and other insects to improve the productivity of tobacco and to protect the tobacco from the disturbing of underground and leaf chewing insects. In the present work, laboratory and field trials were conducted to control root-knot nematode (M. javanica) by using EPNs and the symbiotic bacterial, and the effect of the application was evaluated in tobacco plant. Approximately after inoculation of sixty days, egg masses and galls on tobacco root and agronomic characters of tobacco were calculated. Results showed that both EPNs and the symbiotic bacterium affected the reproduction of M. javanica population and the gall, egg masses and the root-knot nematodes in the tobacco root were significant reduced. EPNs also showed suppressive effect on S. litura larvae, and Agrotis ipsilon larvae as well. It might be the first study about the use of EPNs in the control of M. javanica in tobacco plant.

Damage to the host cadaver, simulating the effects of scavenging, differentially affects fitness of entomopathogenic nematode species

Insect cadavers infected by entomopathogenic nematodes (EPN) are defended against scavengers by chemical mechanisms and other means. Despite these defences, the cadaver may be bitten before being rejected. In this study, we investigated the effect of damage to the cadaver cuticle on the fitness of nematodes (Heterorhabditis downesi Stock, Griffin & Burnell or Steinernema feltiae Filipjev) developing inside. We first quantified the severity of scavenger damage to EPN-infected Galleria mellonella Linnaeus cadavers in the field, and separately, with crickets (Gryllus bimaculatus De Geer) in the laboratory. In both field and laboratory, EPN-infected cadavers suffered less damage than freeze-killed controls, and damage consisted mainly of small lesions to the cuticle. In further experiments, scavenging damage was simulated shortly after death of infected cadavers by piercing the cuticle 0, 1, 3 or 5 times and incubating in moist (100% relative humidity (RH)) or dry (60–70% RH) conditions. The greater the level of damage, the greater the loss of moisture from the cadaver (estimated by weight loss), and this was exacerbated in dry conditions. The number of infective juveniles (IJs) emerging from H. downesi-infected cadavers was significantly reduced by damage, especially in dry conditions. In addition, emerging IJs were progressively smaller with increasing damage. For this species, the number of IJs was negatively correlated with moisture loss, indicating that the reduction in fitness was mediated by desiccation. For S. feltiae, damage impacted IJ number to a lesser extent and size was not affected. The reduction in numbers was not explained by moisture loss, indicating that for S. feltiae, some factor other than desiccation (perhaps competition with opportunistic microbes) impacts the nematodes when the cuticle is damaged. The greater vulnerability of H. downesi, compared to S. feltiae, to scavenger damage to the host cadaver may be due to its longer developmental time in the host resulting in longer exposure to damaging conditions. In conclusion, damage simulating biting by scavengers impacts the fitness of EPN, with the effect depending on nematode species, environmental conditions and the extent of damage. These findings have implications for the success of field application of EPN in infected cadavers.

Evaluation of biocontrol agents along with pesticide against leopard moth, Zeuzera multistrigata moore (lepidoptera: cossidae) in apple

Leopard moth Zeuzera multistrigata (Lepidoptera: Cossidae) is a xylophagous insect whose larval stages are cryptic woodborers in apple and many other horticultural and forestry crops. The present study was carried out to test effectiveness of some biocontrol agents along with most effective pesticide against this pest on apple (cv. Royal Delicious) in Himachal Pradesh, India, for three consecutive years by injecting biocontrol agents/chemicals directly into galleries made by pest larvae. Investigations were conducted to observe the effect of Beauveria bassiana, Metarhizium anisopliae, Steinernemma feltiae, Heterorhabditis bacteriophora and azadirachtin along with a synthetic pesticide chlorpyriphos. The application of chlorpyriphos (0.04%) caused a 100%%larval mortality, whereas among the biocontrol agents H. bacteriophora (5000 IJs/gallery) exhibited the highest mortality of 66.7 to 80.0%% during these three years, which was significantly at par with application of azadirachtin (Neem baan) 1500 ppm @ 2 ml/Litre and S. feltiae @ 5000 IJs/gallery. The lowest mortality (33.3%) was observed with B. bassiana (5 g/Litre) for the first two years and with M. anisopliae (5 g/L) in the third year i.e. 40.0%. Application of entomopathogenic nematode H. bacteriophora (5000 IJs/gallery) is proven to be best among all biocontrol agents.

Efficacy of entomopathogenic nematodes in laboratory and field conditions of Cicer arietinum against cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

BackgroundThe chickpea Cicer arietinum (Fabaceae) field has suffered significant economic losses due to the presence of cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Attempts to control the larval population through chemical pesticides led to some reduction but also resulted in the development of resistance among the larvae. Consequently, the H. armigera population experienced a rapid resurgence in the field. Given the substantial losses caused by Helicoverpa larvae, there is now a growing interest in adopting eco-friendly methods for management. The application of biocontrol agents has emerged as a promising solution for effectively managing the infestation.ResultsIn the laboratory experiment, the entomopathogenic nematodes (EPNs) Steinernema pakistanense NNRC-NB.14, S. balochiense NNRC-NB.23, and S. abbasi NNRC-NB.33 were evaluated for their infectivity and mortality effects on mature cotton bollworm at various concentrations. The study demonstrated that the highest mortality rates were achieved at a concentration of 250 infective juveniles (IJs) per larva after 72 h. Steinernema pakistanense and S. balochiense exhibited higher mortality rates (95–98%) compared to S. abbasi (77%) at higher application concentrations. The field trial results reinforced the laboratory findings, demonstrating a significant decrease in H. armigera larval populations when employing EPN strains, particularly NNRC-NB.14 and NNRC-NB.33, compared to NNRC-NB.23. Despite the initial applications showing relatively low mortality percentages, the most effective larval control occurred after the third application of EPNs. The field trials revealed that, following the third spray, mortality percentages significantly increased from the initial range of 20–32% to a more substantial 70–90%. This cumulative impact highlights the importance of multiple applications in achieving optimal pest control.ConclusionThe findings of these studies highlight the promising potential of EPN as an eco-friendly and sustainable method for controlling the cotton bollworm. However, the successful implementation of EPN-based control strategies in agricultural systems requires careful consideration of factors such as nematode species selection, application methods, environmental conditions, and integration with other pest management practices. Further research is needed to optimize the efficacy and practicality of using EPN on a larger scale, addressing issues such as nematode production, formulation, and compatibility with existing farming practice.

Preferences for livestock bedding as a development substrate of the stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), and potential application of entomopathogenic nematodes for controlling stable fly larvae.

The stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), is a significant insect pest with global veterinary implications due to its capacity to both cause nuisance and transmit disease-causing pathogens to livestock. This study aimed to determine the livestock bedding preferred for use as a development substrate by S. calcitrans larvae and field-collected adults. The result showed that S. calcitrans larvae exhibited a preference (26.7%) for 7-day-old cow manure. Gravid females displayed a pronounced preference (55.0%) for fresh cow manure. As there were eight choices, indifference would result in 12.5% for each bedding substrate. Furthermore, the efficacy of four entomopathogenic nematodes (EPNs), namely Heterorhabditis bacteriophora (Poinar), Heterorhabditis indica Poinar, Karunakar & David (Rhabditida: Heterorhabditidae), Steinernema siamkayai Poinar, Karunakar & David and Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), against S. calcitrans larvae and the persistence after application to livestock bedding substrates were evaluated under laboratory conditions. In filter paper bioassays, all four EPNs caused 76.7%-100.0% mortality in the second instar larvae of S. calcitrans when applied at 50 and 100 infective juveniles (IJs)/cm2 within 5 days after exposure. For the third instar larvae of S. calcitrans, only H. indica induced high mortalities of 86.6% when applied at 100 IJs/cm2 within 5 days after exposure, while the other EPNs resulted in mortalities of less than 70%. The data further demonstrated that H. bacteriophora, H. indica and S. siamkayai remained present in the substrates linked to S. calcitrans larvae for as long as 7 days after the application of EPNs. This study demonstrates the potential of EPNs as a biologically based control agent against larvae of S. calcitrans, a serious pest and significant vector for various livestock animals.

Long-term suppression of turfgrass insect pests with native persistent entomopathogenic nematodes

Entomopathogenic nematodes (EPNs) can control several important turfgrass insect pests including white grubs, weevils, cutworms, and sod webworms. But most of the research has focused on inundative releases in a biopesticide strategy using EPN strains that may have lost some of their ability to persist effectively over years of lab maintenance and / or selection for virulence and efficient mass-production. Our study examined the potential of fresh field isolate mixes of endemic EPNs to provide multi-year suppression of turfgrass insect pests. In early June 2020, we applied isolate mixes from golf courses of the EPNs Steinernema carpocapsae, Heterorhabditis bacteriophora, and their combination to plots straddling fairway and rough on two golf courses in central New Jersey, USA. Populations of EPNs and insect pests were sampled on the fairway and rough side of the plots from just before EPN application until October 2022. EPN populations increased initially in plots treated with the respective species. Steinernema carpocapsae densities stayed high for most of the experiment. Heterorhabditis bacteriophora densities decreased after 6 months and stabilized at lower levels. Several insect pests were reduced across the entire experimental period. In the fairway, the combination treatment reduced annual bluegrass weevil larvae (59 % reduction) and adults (74 %); S. carpocapsae reduced only adults (42 %). White grubs were reduced by H. bacteriophora (67 %) and the combination (63 %). Black turfgrass ataenius adults were reduced in all EPN treatments (43–62 %) in rough and fairway. Sod webworm larvae were reduced by S. carpocapsae in the fairway (75 %) and the rough (100 %) and by H. bacteriophora in the rough (75 %). Cutworm larvae were reduced in the fairway by S. carpocapsae (88 %) and the combination (75 %). Overall, our observations suggest that inoculative applications of fresh field isolate mixes of endemic EPNs may be a feasible approach to long-term suppression of insect pests in turfgrass but may require periodic reapplications.

Standardization of Formulation and Application Approaches for Field Implementation of EPNs

Entomopathogenic nematodes (EPNs) live parasitically inside the infected insect host, and so they are termed as endoparasitic. They infect different types of insect living in the soil like the larval forms of moths, butterflies and beetles as well as adult forms of beetles, grasshoppers and crickets. The present experiment was conducted under both laboratory and field conditions at CCS Haryana Agriculture University, Hisar. Two most virulent strains of EPNs, Metarhabditis amsactae strain HAR-St-II and HAR-Ht-III were taken and their formulations were standardized using six different media i.e. cadaver based formulation, water, alginate gel, foam chips, clay chips and water dispersible granules. Among these formulations, cadaver based formulation was found to be best. Maximum numbers of active IJs after 90 days were obtained from this formulation were 3370 and 2728 /Petri plate in strain HAR-St-II and HAR- Ht-III of M. amsactae, respectively. Further this, experiment was conducted at field level for EPNs suspension was standardized using different size of nozzle opening i.e. 25 µm, 50 µm, 75 µm and 100 µm on knapsack sprayer. Spodoptera litura was selected as a test insect in okra crop for foliar application of EPNs and results revealed that 100 µm nozzle opening size gave maximum larval mortality of S. litura. Per cent mortality of S. litura was increased with increase in size of nozzle and period of observation

Effect of Mulching Manures and Use of Heterorhabditis Bacteriophora on Strawberry Fruit Yield Temnorhynchus baal and Meloidogyne javanica Under Field Conditions

Abd-Elgawad, M.M.M., L.W. Duncan, M.M.A. Hammam, F. El-Borai and I.E. Shehata. 2024. Effect of Mulching Manures and Use of Heterorhabditis Bacteriophora on Strawberry Fruit Yield Temnorhynchus baal and Meloidogyne javanica Under Field Conditions. Arab Journal of Plant Protection, 42(3): 306-317. https://doi.org/10.22268/AJPP-001262 The importance of safe methods to manage strawberry pests has become more evident with increasing strawberry production and export in Egypt. Root damage by white grubs (Temnorhynchus baal larvae) and root-knot nematode (RKN), Meloidogyne javanica cause severe losses to strawberry fruit yield. Growers often rely on a few selective chemical pesticides to control these pests and to minimize pesticide residues in order to comply with maximum residue limits allowed for fruit export. Entomopathogenic nematodes (EPNs) that invade and kill grubs and reduce RKN population levels in the soil may be as effective as these insecticides in some cases. We evaluated the profitability of mulching strawberry with commonly used cow and/or chicken manure, with and without application of commercial Heterorhabditis bacteriophora in two farms for four consecutive years. All plots received chemical fertilizers. The designed drip irrigation system for EPN delivery in the farms insured efficient and even (P < 0.05) application of EPN in all treatments. Timing of EPN application varied due to import regulatory guidelines. All manure mulch treatments increased strawberry yield each year at a farm in Al-Qalyubia governorate, whereas yield remarkably increased in the fourth season at the farm in El-Beheira governorate. Compared to EPN-treated plots, 70% more (P = 0.06) insects were recovered in soil beneath dead plants in plots that did not receive EPNs. Heterorhabditis bacteriophora boosted fruit yield (P < 0.05) in the second and fourth years at El-Beheira and in all years at Al-Qalyubia. It reduced (P < 0.05) numbers of Meloidogyne javanica galls/egg masses on strawberry roots and juveniles in the soil in both farms. Mulches had no measurable effect on EPN performance, but suppressed pests and boosted plant productivity. The greatest yield enhancement by EPN occurred in the second year at El-Beheira farm when EPNs were applied shortly after planting (October), enabling early season control of the pests, but in the third year at Al-Qalyubia farm where the weather was generally warmer than that at El-Beheira, and therefore more suitable for EPN activity. Keywords: Strawberry yield, entomopathogenic nematodes, Meloidogyne, mulching, Egypt.

The application of entomopathogenic nematode modified microbial communities within nesting mounds of the red imported fire ants, Solenopsis invicta

Entomopathogenic microorganisms (e.g., fungi, bacteria, nematodes) have been widely used in biological control of soil-dwelling pests, including the red imported fire ant (RIFA), Solenopsis invicta, a notorious invasive pest worldwide. The application of large amounts of entomopathogenic microorganisms to soil may affect the indigenous soil microbial communities. However, reports about the effect of entomopathogenic nematodes (EPN) on soil microbial communities are very few. In this study, the effects of EPN on RIFA populations and microbial communities in mounds were investigated. Our results showed that the application of the EPN Steinernema carpocapsae. All strain on mounds efficaciously suppressed RIFA worker populations, without forming significantly more satellite mounds compared with the control treatment. The application of EPN did not impact the bacterial and fungal diversity in soils derived from the RIFA mounds. However, it slightly altered the taxonomic make-up of the bacterial communities, but significantly altered the taxonomic composition of fungal communities at the phylum, family, and genus levels. The abundances of some beneficial bacteria and fungi, such as Streptomyces, decreased, while those of plant and animal pathogenic bacteria and fungi, dramatically increased, after EPN treatment. On the other hand, the abundances of some entomopathogenic fungi, such as Fusicolla, Clonostachys, and Mortierella, increased. Redundancy analysis or canonical correspondence analysis revealed a positive correlation between the efficacious EPN control and the presence of the insect-resistant bacteria, Sinomonas, as well as entomopathogenic fungi Fusicolla and Mortierella. This suggests that the interactions between EPN and entomopathogenic fungi may play a role in the biological control of RIFA. Our discoveries shed light on the interactions among EPN, RIFA, and soil microbial communities, and emphasize a possible mutualistic relationship between EPN and entomopathogenic fungi in the biological control of RIFA.

Standardizing in-vivo mass production technique for entomopathogenic nematode Heterorhabditis bacteriophora (Nematoda: Heterorhabditidae)

Biological control is a need of hour to protect crops in a sustainable manner without disturbing ecological balance. Entomopathogenic nematodes (EPNs) have a potential to be used effectively and selectively as inoculative agents for classical biological control. EPNs production can be done in both in vivo and in vitro. In vivo method was preferred during present studies aimed at standardizing mass production technology for Heterorhabditis bacteriophora that can easily be adopted at small scale farms. Different cost-effective diets used for rearing Galleria mellonella (GWM) (Lepidoptera: Pyralidae) were standardized to show their effect on development and production of in vivo mass production of EPNs on GWM larvae. Diet consisting of maize flour (400 g), wheat flour, wheat bran, milk powder (200 g each), yeast (100 g), glycerol (350 ml) and honey (350 ml) was found best among all the diets tested for rearing GWM with 93.5 percent larvae surviving to cocoon formation stage and average larval weight of ca 300 mg for inoculating 5 GWM larvae in 50 mm diameter inoculation arena, 0.5 ml of formalin solution (0.1 percent) was found to create optimum moisture in the arena to give quick mortality of GWM. The inoculation dose (200 ± 2.1 IJs/larva) of EPNs and temperature of 20 °C were found to give highest harvest of infective juveniles (IJs/larva) from the host. Enhanced effectiveness of EPN application can be assisted through advanced diet which is most significant factor influencing consistent development of GWM in turn affecting EPNs maximum harvest.

Exploring entomopathogenic nematodes for the management of Lobesia botrana (Lepidoptera: Tortricidae) in vineyards: Fine-tuning of application, target area, and timing

Lobesia botrana (Lepidoptera: Tortricidae) is a crucial grapevine pest worldwide. Expanding the available biocontrol agents can provide new management strategies compatible with organic viticulture. Entomopathogenic nematode (EPN) potential as a biocontrol agent was demonstrated against various developmental stages of L. botrana. For its field application, we hypothesised that by selecting the best combination of EPN-adjuvant and identifying the best area/timing for their application, we will secure their effective implementation against L. botrana. The aim of this study was to determine the best ecological scenarios for their use against L. botrana. We investigate three EPN species naturally occurring in Riojan vineyards: Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora. We evaluated (i) EPN viability, infectivity, and adherence on leaves combined with adjuvants (Multi-Us, Maximix, Dash HC, Nu-Film-17, and Adrex), (ii) EPN biocontrol against L. botrana larva on leaves and grapes and damage reduction, and (iii) EPN efficacy against L. botrana at 22°, 15°, and 10 °C. Overall, all the adjuvants were compatible with the EPN, except Adrex with Heterorhabditis bacteriophora. Compared with the no application, EPNs (steinernematids) alone or with Maximix increased L.botrana L3 mortality on grapes and leaves, thereby reducing the damage. Pupal mortality caused by steinernematids EPN (alone or with Maximix) decreased with temperature, from ∼60% at 22 °C to <30% at 10 °C. Overall, steinernematids EPN (alone or with Maximix) applied against L. botrana on leaves, grapes, or trunks reduced the damage and increased insect mortality. This study suggests the best-case scenario for the application of EPNs is at sunset during late spring/early autumn at mid-temperatures (22 °C-15 °C). Further field validation is necessary for their full implementation.

Sensitivity of Yponomeuta padella and Yponomeuta cagnagella (Lepidoptera: Yponomeutidae) to a Native Strain of Steinernema feltiae (Filipjev, 1934)

The larvae of ermine moths from the Yponomeutidae family (Lepidoptera) feed on a range of species and varieties of fruit and ornamental trees. Some species of this family pose a serious threat to the environment, mainly because of the significant defoliation they cause but also due to the widespread use of insecticides used to control them. This study was designed to assess the sensitivity of Yponomeuta padella and Yponomeuta cagnagella larvae and pupae to a native strain of Steinernema feltiae ZAG15 nematodes under laboratory conditions and to test the biological activity of these nematodes against the larvae and pupae of these species in field studies. The following doses were used in the laboratory tests: 50 IJs/insect (Petri dish tests) and 100 IJs/insect (container tests). Petri dish and container tests were performed at 20 °C and 60% humidity. Mortality of two stages (larvae and pupae) was determined 3 days after treatment. In the field trials, the nematodes were applied at the following doses: 4000 IJs/web for the caterpillars of Y. padella and Y. cagnagella and 1000 IJs/web for the pupae of Y. padella and Y. cagnagella (this corresponded to approximately 200 IJs/insect). Nematodes were applied using a 1 L hand sprayer and a lance. The efficacy of the application was assessed after seven days. The results of our study showed that the larvae (81.7%) and pupae (88.3%) of Y. padella had a greater susceptibility to entomopathogenic nematodes (EPNs) than those of Y. cagnagella (50% and 33.3%, respectively). However, our promising laboratory results did not translate into results in field trials, where the application of EPNs proved to be ineffective.

Biocontrol potential of entomopathogenic nematodes against invasive fall armyworm, Spodoptera frugiperda in India

The invasion of fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), has threatened the researchers to develop an effective biological control strategy at the global level. Larval stage remains in maize whorl, and precise placement of entomopathogenic nematodes (EPNs) opens up wide opportunity for biological control. The study evaluated the virulence of Heterorhabditis indica (Poinar) and Steinernema carpocapsae (Weiser) against all the developmental stages of S. frugiperda. The results revealed that both the tested EPNs had a high rate of ovicidal, larvicidal and pupicidal effects on S. frugiperda. The EPNs also significantly affected the adults, resulting in the deformation and death. The invasion efficiency and reproduction assays of EPNs revealed that H. indica had higher invasion efficiency and reproduction rates compared to S. carpocapsae on different larval stages and pupae. EPNs also reproduced in the adult cadavers of S. frugiperda emerged from the EPN-treated pupa. A preliminary study on the effect of EPN application on S. frugiperda was carried out under semi-field conditions by pre-releasing third instar larvae to whorl of corn plants. Application of H. indica and S. carpocapsae @ 500 IJs mixed with five gram of sand was applied manually to whorl led to mortality of 86.67 and 83.33%, respectively. The study demonstrated that both the EPN species tested showed high puissance as bio-control agents against S. frugiperda, having the potential for its successful management.

Entomopathogenic Nematodes for Field Control of Onion Maggot (Delia antiqua) and Compatibility with Seed Treatments.

Onion maggot (Delia antiqua) is a prominent pest of allium crops in temperate zones worldwide. Management of this pest relies on prophylactic insecticide applications at planting that target the first generation. Because effective options are limited, growers are interested in novel tactics such as deployment of entomopathogenic nematodes. We surveyed muck soils where onions are typically grown to determine if entomopathogenic nematode species were present, and then evaluated the compatibility of entomopathogenic nematode species with the insecticides commonly used to manage D. antiqua. We also evaluated the efficacy of these entomopathogenic nematodes for reducing D. antiqua infestations in the field. No endemic entomopathogenic nematodes were detected in surveys of muck fields in New York. Compatibility assays indicated that, although insecticides such as spinosad and, to some extent, cyromazine did cause mortality of entomopathogenic nematodes, these insecticides did not affect infectivity of the entomopathogenic nematodes. Field trials indicated that applications of entomopathogenic nematodes can reduce the percentage of onion plants killed by D. antiqua from 6% to 30%. Entomopathogenic nematodes reduced D. antiqua damage and increased end of season yield over two field seasons. Applications of entomopathogenic nematodes may be a viable option for reducing D. antiqua populations in conventional and organic systems. Together with other management tactics, like insecticide seed treatments, applications of entomopathogenic nematodes can provide a yield boost and a commercially acceptable level of D. antiqua control.

Combined effect of entomopathogenic nematode, Heterorhabditis indica with entomopathogenic fungi, Metarhizium pinghaense and M. robertsii against the obscure mealybug, Pseudococcus viburni

In this study, we evaluated the combined application of entomopathogenic nematodes (EPN), Heterorhabditis indica, with entomopathogenic fungi (EPF), Metarhizium pinghaense or M. robertsii, against Pseudococcus viburni (Signoret), in laboratory trials. Three EPF-EPN combinations were used, where P. viburni was either exposed to the EPF and EPN isolates simultaneously or sequentially, at different time intervals. The combined application of H. indica with each of the two EPF isolates resulted in higher mortality of P. viburni, under laboratory conditions, relative to when applied individually. With sequential application, the H. indica and M. robertsii combination was shown to be more effective, resulting in 85 ± 3.1% and 88.8 ± 3.9% mortality after four and three days, respectively. Heterorhabditis indica combined with M. pinghaense was more effective for simultaneous application of the entomopathogens, resulting in 95 ± 6.5% mortality after five days. Insect mortality was mostly due to EPN infection. The single application of H. indica against P. viburni resulted in 76.3 ± 2.9% after 48 h, while M. pinghaense and M. robertsii resulted in 73.8 ± 7.9% and 82.5 ± 3.3% respectively, after a week. Interactions between H. indica and the two EPF isolates were shown to have an additive effect, when used simultaneously and sequentially. The results from the study indicate that the combined application of EPF and EPN could potentially be used as an alternative strategy for management of P. viburni in fruit production areas.

Field application of encapsulated entomopathogenic nematodes using a precision planter

The use of entomopathogenic nematodes (EPNs) as a biological control agent in agriculture has shown efficacy against various soil-dwelling pests. Despite its potential, high production costs and inconsistent field efficiency remain significant challenges. Although EPNs can be applied using irrigation systems and spraying equipment, optimized applications are required. This study aimed to evaluate the feasibility of applying EPNs in gelatin capsules and planting with a precision planter. It was hypothesized that this method would lead to more controlled and uniform EPN application. The effects of EPN encapsulation on dispersal and field persistence in the soil were also investigated. Larval mortality for capsule applications was between 53 and 67% under field conditions, with no statistical difference compared to the drip irrigation applications. Dispersal trials were carried out using custom steel olfactometers, and capsule application did not have any adverse effects on the dispersal of infective juveniles for 24, 48 and 72 h. Persistence trials revealed no significant differences between the capsule and control groups, with a maximum persistence of 50 days. The results suggest that the capsule technique could be a promising option for large-scale EPN applications, and further optimization may lead to improved results.

Direct antagonistic effect of entomopathogenic nematodes and their symbiotic bacteria on root-knot nematodes migration toward tomato roots

AimsNegative interactions in the rhizosphere between entomopathogenic nematodes (EPNs) and plant-parasitic nematodes, such as root-knot nematodes (RKNs), have been documented over the past two decades but the mechanisms and dynamics of such interactions remain largely elusive.MethodsHere, we evaluated the effect of the inoculation position of two EPN species, Steinernema feltiae and Heterorhabditis bacteriophora, as well as different facets of the EPN-bacterial symbiont complex on the migration of RKNs toward tomato roots, both in sand and in Pluronic gel conditions.ResultsWhen EPNs were placed between the position of the RKNs and the roots, the movement of RKNs toward the roots was inhibited. We observed this same pattern both in sand and in Pluronic F-127 (PF-127) gel for two species of EPNs. We also observed that different components of the EPNs/bacterial symbiont complex (bacteria separate from the nematodes vs. the nematode-bacterium complex), and particularly the cell-free supernatant produced by the bacterial culture, displayed inhibitory effects on RKNs.ConclusionTherefore, the EPNs/bacterial complex, by slowing down the movement of RKNs toward the host plant roots, could partially contribute to RKN control. By screening for the most repulsive strains of EPNs that are also effective against insect pests, the combined target approach should alleviate EPNs application costs in integrated pest management practices.

Entomopathogenic nematodes for the control of oriental fruit fly Bacterocera dorsalis (Diptera: Tephritidae)

BackgroundFruit fly species are most damaging pests around the globe which reduced the commercial value of fruits at maturity. Entomopathogenic nematodes (EPNs) from genera Heterorhabditis and Steinernema cause death by inducing septicimia in insect pests in the soil, moreover, endemic nearly all soils. Current study was planned to manage the oriental fruit fly, Bacterocera dorsalis (Hendel.) (Diptera: Tephritidae) hazards by using indigenous EPNs (Heterorhabditis bacteriophora, H. indica, Steinernema asiticum, S. corpocapsae and S. glasseri) as they have host finding ability and recognise as potential eco-friendly biocontrol agent over synthetic chemicals. MethodsStudy for the assessment of EPNs concentrations, various temperatures, soil type and soil moisture levels against mortality (%) of fruit fly (B. dorsalis) larvae was conducted in completely randomized design (CRD) under factorial arrangements. ResultsEPNs concentrations (70 IJs/ml, 110 IJs/ml, 150 IJs/ml) showed that S. asiaticum (150 IJs/ml) showed maximum mortality (94.97 %) of B. dorsalis as compared to other used EPNs along with their respective concentrations. Impact of various temperatures (20 °C, 24 °C, 28 °C, 32 °C, 36 °C) with respect to used EPNs exhibited that H. indica (36 °C) showed maximum mortality (94.33 %) of B. dorsalis as compared to all other treatment. Various soil types (Sandy, Sandy loam, Loam, Clay) impacted the infectivity of EPNs against fruit fly, In case of sandy loam soil, S. asiaticum showed maximum mortality (98.05 %) of B. dorsalis followed by all used treatments. Soil moisture level (12 %, 18 %, 24 %, 30 %) also significantly influenced the infectivity of EPNs against mortality of fruit fly. In case of 12% moisture level, S. asiaticum showed maximum mortality (99.06 %) of B. dorsalis over all the applied treatments along with respective moisture levels. ConclusionIn crux, Steinernema asiaticum higher concentration exhibited efficient control of fruit fly larvae in sandy loam soil with 12 % moisture level at 36 °C over the used EPN species. While application of EPNs against fruit fly is most suitable strategy to manage the fruit fly hazards and it should be included as a part of integrated pest management control programme.

Efficacy of entomopathogenic nematode isolates from Turkey against wheat stink bug, Aelia rostrata Boheman (Hemiptera: Pentatomidae) adults under laboratory conditions

BackgroundThe wheat stink bug, Aelia rostrata Boheman (Hemiptera: Pentatomidae), is one of the harmful insects that caused significant product losses in cereals due to outbreaks. Entomopathogenic nematodes (EPNs) are natural enemies of soil insect pests whose effects as a biocontrol agent against many harmful pests have been demonstrated by many laboratories and field/garden studies in the world. The present laboratory studies, using native EPNs [Steinernema carpocapsae (Black sea isolate), S. feltiae (isolate 09-31) (Aydin isolate) and Heterorhabditis bacteriophora (isolate 09-43) (Aydin isolate)] against the wheat stink bug adults, were carried out.ResultsIn the application of EPNs to the soil in plastic cups, the highest mortality rates (75 and 70%) on wheat stink bug occurred at 200 IJs cm−2 concentration of S. carpocapsae isolate at 15 and 12 °C, respectively. In other tested nematode species, the highest insect mortality was observed at 200 IJs cm−2 concentration of S. feltiae and H. bacteriophora isolates, with mortality rates of 65–35% and 55–25%, at 15 and 12 °C, respectively. S. carpocapsae (Black sea isolate) was the most pathogenic among the three nematodes tested.ConclusionsIt was concluded that S. carpocapsae had the potential as a biocontrol agent against the wheat stink bug, A. rostrata. The applications of S. carpocapsae were the great potential for the management of the pest. Effective use of EPNs should be evaluated in integrated pest management strategies between other biological control agents. According to EPNs laboratory experiments results, field trials should be conducted in future studies.

Evaluation of the entomopathogenic nematode, Steinernema asiaticum against the diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) under screen house and field conditions

BackgroundThe experiments were conducted at Research Farm, Chaudhary Charan Singh Haryana Agricultural University, Hisar, India. Infectivity and effectiveness of entomopathogenic nematode (EPN), Steinernema asiaticum infective juveniles (IJs) were evaluated against the diamondback moth (DBM), Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) as foliar spray on cabbage plants in screen house with single (30,000 IJs per plant), two (15,000 + 15,000 IJs per plant) or three (10,000 + 10,000 + 10,000 IJs per plant) applications. In the field trial, S. asiaticum (25,000 or 50,000 IJs per plant) and Malathion 50 EC (0.05%) singly or in combination at half the concentrations were used.ResultsIn screen house trial, all the treatments resulted in significantly high larval mortality than untreated plants. Split concentration application (15,000 + 15,000 IJs per plant) gave better DBM larval mortality (48.33%) compared to single application (36.00% at 30,000 IJs per plant). Comparing the two and three split applications, 15,000 IJs was significantly better (23.33% mortality) than 10,000 IJs (13.33%). In the field trial, S. asiaticum alone at 50,000 IJs resulted in 28.8% insect mortality compared to 18.0% in Malathion at 0.05%. Best results (37.5% mortality) were obtained by using nematode IJs at 25,000 per plant in combination with half the recommended concentration of Malathion (0.025%) leading to synergistic effect.ConclusionsThe study revealed that split application (15,000 + 15,000 IJs) of EPN S. asiaticum IJs proved better than single application of IJs at the same concentration (30,000 IJs) in the management of P. xylostella larvae in the screen house conditions. In the field experiment, the best effectiveness was obtained in combination of half the concentrations of EPN and insecticide (S. asiaticum IJs @ 25,000 per plant + Malathion @ 0.025%).