Biological Control Strategies Research Articles

The species, density, and intra-plant distribution of mites on red raspberry (Rubus idaeus L.).

The adoption of the European Green Deal will limit acaricide use in high value crops like raspberry, to be replaced by biological control and other alternative strategies. More basic knowledge on mites in such crops is then necessary, like species, density, and their role as vectors of plant diseases. This study had four aims, focusing on raspberry leaves at northern altitude: (1) identify mite species; (2) study mite population densities; (3) investigate mite intra-plant distribution; (4) investigate co-occurrence of phytophagous mites, raspberry leaf blotch disorder and raspberry leaf blotch virus (RLBV). Four sites in south-eastern Norway were sampled five times. Floricanes from different parts of the sites were collected, taking one leaf from each of the upper, middle, and bottom zones of the cane. Mites were extracted with a washing technique and processed for species identification and RLBV detection. Mites and leaves were tested for RLBV by reverse transcription polymerase chain reaction (RT-PCR) with virus-specific primers. Phytophagous mites, Phyllocoptes gracilis, Tetranychus urticae, and Neotetranychus rubi, and predatory mites, Anystis baccarum and Typhlodromus (Typhlodromus) pyri were identified. All phytophagous mites in cultivated raspberry preferred the upper zone of floricanes, while in non-cultivated raspberry, they preferred the middle zone. The presence of phytophagous mites did not lead to raspberry leaf blotch disorder during this study. RLBV was detected in 1.3% of the sampled plants, none of them with leaf blotch symptoms, and in 4.3% of P. gracilis samples, and in some spider mite samples, implying that Tetranychids could also be vectors of RLBV.

Agent-Based Spatial Dynamic Modeling of Diatraea saccharalis and the Natural Parasites Cotesia flavipes and Trichogramma galloi in Sugarcane Crops

In recent years, sugarcane production areas in Brazil have experienced a slower evolution in productivity, and one of the reasons for this is related to the increase in phytosanitary problems, such as the presence of pests. Nevertheless, limited attention has been paid to the development of tools for simulating the spatial dynamics of pests, including their impact on production. This study aims to simulate the potential population growth and dispersal of Diatraea saccharalis (sugarcane borer) in sugarcane crop fields and its estimated impacts on this crop production and to simulate biological control strategies. We developed an agent-based model to simulate the pest population and its dispersal in a one-hectare sugarcane crop field in Pederneiras, São Paulo, Brazil, delimited with the aid of satellite imagery, considering two scenarios: the first without biological control and the second with biological control using the parasites Trichogramma galloi and Cotesia flavipes. The model was developed using the NetLogo 6.3.0 software. The results indicate that the model accurately reproduced the infestation rates reported in the literature. Additionally, it provided insights into expected pest dispersal, potential production losses, and how the use of T. galloi in association with C. flavipes could mitigate production losses. We believe that the model can be used to simulate different biological control strategies and the implementation of integrated pest management (IPM) to achieve adequate control levels and greater productivity in sugarcane production.

Three Ecological Models to Evaluate the Effectiveness of Trichoderma spp. for Suppressing Aflatoxigenic Aspergillus flavus and Aspergillus parasiticus.

Chemical pesticides help reduce crop loss during production and storage. However, the carbon footprints and ecological costs associated with this strategy are unsustainable. Here, we used three in vitro models to characterize how different Trichoderma species interact with two aflatoxin producers, Aspergillus flavus and Aspergillus parasiticus, to help develop a climate-resilient biological control strategy against aflatoxigenic Aspergillus species. The growth rate of Trichoderma species is a critical factor in suppressing aflatoxigenic strains via physical interactions. The dual plate assay suggests that Trichoderma mainly suppresses A. flavus via antibiosis, whereas the suppression of A. parasiticus occurs through mycoparasitism. Volatile organic compounds (VOCs) produced by Trichoderma inhibited the growth of A. parasiticus (34.6 ± 3.3%) and A. flavus (20.9 ± 1.6%). The VOCs released by T. asperellum BTU and T. harzianum OSK-34 were most effective in suppressing A. flavus growth. Metabolites secreted by T. asperellum OSK-38, T. asperellum BTU, T. virens OSK-13, and T. virens OSK-36 reduced the growth of both aflatoxigenic species. Overall, T. asperellum BTU was the most effective at suppressing the growth and aflatoxin B1 production of both species across all models. This work will guide efforts to screen for effective biological control agents to mitigate aflatoxin accumulation.

Characterization of Leclercia adecarboxylata isolated from field collected Anopheles subpictus, Berhampur, Odisha.

Malaria, a vector-borne diseases caused by Plasmodium species and transmitted by Anopheles species. Among them, Anopheles subpictus has emerged as a potent malarial vector in coastal areas of India. Numerous studies highlighted that bacterial communities within mosquito influence vector competence. The present study was designed to isolate and characterize bacterial microbiota from A. subpictus larvae. Isolation and purification of the predominant bacterial strain (AL1). Morphological, biochemical, antibiotic susceptibility and molecular characterization of the isolated bacteria. Bacterial isolate (AL1) was found to be rod, gram negative, catalase positive and oxidase negative. AL1 was identified as Leclercia adecarboxylata (Accession number: OR649235) through 16S rRNA ribotyping. Further, leaf extract of Nyctanthes arbortristis showed inhibitory effect against AL1. This is the first report on isolation of symbiotic bacteria (L. adecarboxylata) from A. subpictus and its control by leaf extract of Nyctanthes arbortristis. Isolated gram-negative bacterial strain might inhibit the development of mosquito vector and might use for various biological control strategies to combat malaria transmission.

Longevity of hymenopteran parasitoids in natural versus agricultural habitats and implications for biological control.

Agricultural habitats are frequently disturbed, and disturbances could have major effects on species in upper trophic levels such as hymenopteran parasitoids that are important for biological control. A strategy for conservation biological control is to provide a diversified agricultural landscape which increases the availability of resources such as sugar required by parasitoid biological control agents. Here, we ask whether parasitoids occurring in agriculture benefit from sugar resources more or less than parasitoids occurring in natural habitats surrounding agricultural fields. We collected parasitoids from agricultural alfalfa fields, field margins, and natural prairies, and in the lab we randomly divided them into two treatments: half were given a constant supply of a sugar source to test their residual lifespan, and half were given neither sugar nor water to test their hardiness. Collected individuals were monitored daily and their day of death recorded. Parasitoids receiving a sugar source lived substantially longer than those without. Parasitoids collected in prairies lived longer than those from alfalfa fields in both the residual lifespan and hardiness treatments, with parasitoids from field margins being intermediate between them. Furthermore, the benefits of a sugar source to increase longevity was lower for parasitoids collected in agriculture than in natural habitats. This suggests that, even though parasitoid biological control agents benefit from sugar resources, their short lifespans make the benefit of sugar resources small compared to parasitoids that occur in natural habitats and have longer lifespans, and are adapted to consistent sugar sources.

Population genetic diversity and structure of Tephritis angustipennis and Campiglossa loewiana (Diptera: Tephritidae) based on COI DNA barcodes in the three-river source region, China.

Tephritis angustipennis (Diptera: Tephritidae)and Campiglossa loewiana (Diptera: Tephritidae) are phytophagous pests in China. Their damage has significantly impacted the collection and cultivation of germplasm resources of native Asteraceae plants. However, the genetic characteristics and structure of their population are unclear. This study focused on the highly damaging species of T. angustipennis and C. loewiana collected from the three-river source region (TRSR). We amplified the mitochondrial cytochrome C oxidase subunit I (mtCOI) gene sequences of these pests collected from this area and compared them with COI sequences from GenBank. We also analyzed their genetic diversity and structure. In T. angustipennis, 5 haplotypes were identified from 5 geographic locations; the genetic differentiation between France population FRPY (from Nylandia, Uusimaa) and China populations GLJZ (from Dehe Longwa Village, Maqin County), GLDR (from Zhique Village, Dari County), and GLMQ (from Rijin Village, Maqin County) was the strongest. GLJZ exhibited strong genetic differentiation from GLDR and GLMQ, with relatively low gene flow. For C. loewiana, 11 haplotypes were identified from 5 geographic locations; the genetic differentiation between the Chinese population GLMQ-YY (from Yangyu Forest Farm, Maqin County) and Finnish population FDNL (from Nylandia, Uusimaa) was the strongest, with relatively low gene flow, possibly due to geographical barriers in the Qinghai-Tibet plateau. Only 1 haplotype was identified across GLDR, GLMQ, and GLBM. High gene flow between distant locations indicates that human activities or wind dispersal may facilitate the dispersal of fruit flies and across different geographic. Geostatistical analysis suggested a recent population expansion of these 2 species in TRSR. Our findings provide technical references for identifying pests in the TRSR region and theoretical support for managing resistance, monitoring pest occurrences, analyzing environmental adaptability, and formulating biological control strategies for Tephritidae pests on Asteraceae plants.

Emerging pathogens and disease dynamics threatening avocado production in southern Türkiye

AbstractAvocado (Persea americana Milll.) holds a pivotal position in global fruit crops, contributing significantly to the economies of tropical and subtropical regions. However, the rising incidence of diseases poses a substantial risk to avocado production. This comprehensive study investigated the disease landscape in Antalya, the largest avocado cultivation area in the Türkiye. A survey of 2537 avocado trees across 11 regions from 2020 to 2021 revealed alarming disease incidences, particularly in the eastern regions of Gazipasa and Alanya. Dieback, branch canker, anthracnose, and soil-borne root rot were identified as the primary diseases affecting tree canopies, twigs, and branches. Morphological and molecular analyzes unveiled a spectrum of pathogens, with Colletotrichum gloeosporioides dominating in the Mediterranean region. Notably, Phytophthora cinnamomi emerged as a severe threat, causing root rot and decline in avocado trees. Fusarium solani and Fusarium oxysporum, known for their association with tropical fruit crops, were identified in the western parts of Antalya. Additionally, we have detected Neofusicoccum parvum, Lasiodiplodia theobromae, and Neopestalotiopsis rosae in collected samples from avocado trees. The identified pathogens exhibited varying levels of severity in branch canker and anthracnose on avocado branches and leaves. Furthermore, pathogenicity evaluations shed light on the potential of these pathogens to induce severe symptoms, emphasizing the urgency for effective control measures. The exploration of cultural and biological control strategies are crucial for mitigating the impact of branch canker, dieback, and anthracnose diseases, ensuring the sustainability of avocado cultivation in the region.

Morphological and molecular diagnosis of the pine processionary moth in Marmara University Göztepe Campus

Pine processionary moth are known as oligophagous forest pests, usually found in cocoons on Pinus trees. While these moths are found in the south of Europe and the north of Africa worldwide, in Turkey they are found in the Mediterranean, Aegean, Black Sea and Marmara regions. Thaumetopoea pityocampa (Den. & Schiff.) and Thaumetopoea wilkinsoni (Tams) species have been observed in the coastal regions of Turkey. Identification of the species is an important step in the development of biological control strategies. The starting point of this study is the desire to control the pine processionary moth in Marmara University Göztepe Campus. However, since both of these species are found in Turkey, especially in the Marmara Region, the main aim of this study is to determine which species the pine processionary moth in the campus belong to. Morphological and molecular methods were used. As a result of the study, based on both morphology and molecular data, it was determined that the species found on the campus was Thaumetopoea wilkinsoni.

Transcriptomic alterations in host parasitoid wasps resulting in extended lifespan due to PpNSRV-1 infection

The parasitoid wasp Pteromalus puparum, a pivotal agent in agricultural ecosystem balance, experiences significant alterations in lifespan due to infection by the negative-sense single-stranded RNA virus PpNSRV-1. This study utilized RNA sequencing (RNA-seq) to investigate the genetic mechanism(s) driving lifespan extension in response to this virus. Lifespan analysis, combined with RNA-seq of nearly isogenic lines of infected and uninfected wasps, yields a comprehensive temporal expression profile aligned with the P. puparum genome. Despite a modest overall impact of PpNSRV-1 on gene expression, notable effects were observed on specific gene families, such as the SPOP genes and the cytochrome P450 family. Through Weighted Gene Co-expression Network Analysis (WGCNA), we identified connections between the green and greenyellow modules to viral infection traits, with further functional analyses highlighting the pivotal roles of the Hedgehog, autophagy, AMPK, mTOR, p53, and PI3K-Akt signaling pathways. RNA interference experiment targeting the SPOP gene PPU06594-RA confirmed its role in lifespan modulation, underscoring the importance of Hedgehog pathway in the host’s adaptive response. These insights not only elucidate the complex genetic landscape of host-virus interactions but also open avenues for innovative biological pest control strategies.

Plants interfere with non-self recognition of a phytopathogenic fungus via proline accumulation to facilitate mycovirus transmission

Non-self recognition is a fundamental aspect of life, serving as a crucial mechanism for mitigating proliferation of molecular parasites within fungal populations. However, studies investigating the potential interference of plants with fungal non-self recognition mechanisms are limited. Here, we demonstrate a pronounced increase in the efficiency of horizontal mycovirus transmission between vegetatively incompatible Sclerotinia sclerotiorum strains in planta as compared to in vitro. This increased efficiency is associated with elevated proline concentration in plants following S. sclerotiorum infection. This surge in proline levels attenuates the non-self recognition reaction among fungi by inhibition of cell death, thereby facilitating mycovirus transmission. Furthermore, our field experiments reveal that the combined deployment of hypovirulent S. sclerotiorum strains harboring hypovirulence-associated mycoviruses (HAVs) together with exogenous proline confers substantial protection to oilseed rape plants against virulent S. sclerotiorum. This unprecedented discovery illuminates a novel pathway by which plants can counteract S. sclerotiorum infection, leveraging the weakening of fungal non-self recognition and promotion of HAVs spread. These promising insights provide an avenue to explore for developing innovative biological control strategies aimed at mitigating fungal diseases in plants by enhancing the efficacy of horizontal HAV transmission.

Environmental DNA assays for Laricobius beetles (Coleoptera: Derodontidae), biocontrol agents of the hemlock woolly adelgid in North America.

The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an invasive pest causing significant ecological and economic damage to certain hemlock tree (Tsuga (Endlicher) Carrière, Pinales:Pinaceae) species. In response to this invasive threat, biological control strategies have been implemented, introducing natural predators such as Laricobius nigrinus Fender (Coleoptera: Derodontidae) and, more recently, Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), as specialist predators against A. tsugae. However, the genetic and morphological similarities between L. osakensis and both L. nigrinus and the native beetle, Laricobius rubidus LeConte (Coleoptera: Derodontidae), pose challenges in their identification. Effective monitoring of released predators is integral to evaluating the success of biological control measures. Environmental DNA (eDNA) holds potential for various detection applications, including species monitoring. In this study, we developed specific primers and probes targeting the mitochondrial cytochrome oxidase 1 gene sequences, achieving high specificity despite their 95% sequence similarity. With an optimal annealing temperature of 60 °C, our tools effectively differentiated L. osakensis from the other 2 beetles and demonstrated eDNA detection sensitivity down to 2 copies/µl. This research underscores the potential of precise molecular tools for advancing biological control and biodiversity assessment against invasive threats like A. tsugae.

Phages enhance both phytopathogen density control and rhizosphere microbiome suppressiveness.

Ralstonia solanacearum is a highly destructive plant-pathogenic bacterium with the ability to cause bacterial wilt in several crucial crop plants. Given the limitations of conventional chemical control methods, the use of bacterial viruses (phages) has been explored as an alternative biological control strategy. In this study, we show that increasing the phage application frequency can improve the density control of R. solanacearum, leading to a significant reduction in bacterial wilt disease. Furthermore, we found that repeated phage application increased the diversity of rhizosphere microbiota and specifically enriched Actinobacterial taxa that showed synergistic pathogen suppression when combined with phages due to resource and interference competition. Together, our study unravels an undiscovered benefit of phages, where phages trigger a second line of defense by the pathogen-suppressing bacteria present in resident microbial communities. Phage therapies could, hence, potentially be tailored according to host microbiota composition to unlock the pre-existing benefits provided by resident microbiota.

Distribution and survival of the predatory mite Blattisocius mali on cucumber leaves with the addition of bran, yeast and pollen

Biological control has a special position in sustainable agriculture that requires continuous exploration and diversification in bio-agents to cope with emerging crop pests. Blattisocius mali is a promising biological control agent against some acarid mites, nematodes and moth pests. This study aimed to examine factors that could increase survival and diminish dispersal of B. mali deprived of its prey, the mold mite Tyrophagus putrescentiae, from cucumber plants. The impact of the presence of males on starving females’ lifespans and the influence of different substrates, i.e., wheat bran, dry yeast pellets, and cattail pollen, on the distribution and survival of starving females in groups with males were examined. Experiments were performed on cucumber leaf platforms in Petri dishes filled with water. The results showed that females lived longer and a lower percentage drowned in water when accompanied by males. On the platforms with the addition of a substrate, the mites mainly stayed within the substrate, and eggs were only recorded in the substrate. They clearly preferred bran over pollen or pollen + yeast pellet aggregations. However, the quality of the substrate deteriorated within the first days, and some mites died of entrapment in the substrates. On the 3rd day, the lowest mean percentage of live individuals was observed on platforms with yeast + pollen (54.4%) followed by pollen (68.9%) alone. At that time, females also stopped laying eggs, and cannibalism towards hatched larvae and adults was observed. By the end of the experiment, 54.67% of the mites had been found dead on the leaf surface, and none of the substrates had significantly influenced their lifespan. The females lived on average 8.19 days and the males 5.06 days. The obtained results are discussed in the context of potential application of B. mali in biological control strategies.

Diversity of mosquito natural enemies and their feeding efficacy on Aedes vectors.

Mosquito-borne diseases are a major health issue among communities in Asia, and dengue has grown up as a serious public health concern in Sri Lanka with varying magnitude since 1960. With the realization of the failures and limitations of current vector control strategies, the authorities are moving towards simple, low-cost, and eco-friendly vector management methods. Thus, the present study was devised to evaluate the potential densities of mosquito natural enemies in natural water habitats in Galle district, Sri Lanka, and to investigate the feeding efficacy of prominent mosquito natural enemies on main dengue vectors (Aedes sp.) in a laboratory setting. The survey was carried out using eight sentinel sites in Galle district, and samples of mosquito natural enemies and mosquito larvae were collected, and then they were identified using taxonomic keys. Study records, the aquatic insects of Family Hydrometridae, Belostomatidae, Notonectidae, Nepidae, Ranatridae, and Corixidae as dominant mosquito natural enemies, and Libellulidae and Dytiscidae insects as sub-dominant families. The highest density of the family Hydrometridae was recorded in rural, natural inland, and rocky study sites. The order Hemiptera was recorded as the key order of the mosquitoes natural enemies in Galle district. The family Hydrometridae had the highest density of recorded mosquito natural enemies. Aedes aegypti and Ae. albopictus were recorded as abundant vector mosquitoes. Family Nepidae is the most effective natural mosquito predator on Ae. aegypti and Ae. albopictus, and this knowledge will be vital for implementing future biological control strategies for Aedes vectors in Sri Lanka.

The Function of Termicin from Odontotermes formosanus (Shiraki) in the Defense against Bacillus thuringiensis (Bt) and Beauveria bassiana (Bb) Infection.

Odontotermes formosanus (Shiraki) is a subterranean termite species known for causing severe damage to trees and structures such as dams. During the synergistic evolution of O. formosanus with pathogenic bacteria, the termite has developed a robust innate immunity. Termicin is a crucial antimicrobial peptide in termites, significantly contributing to the defense against external infections. Building upon the successful construction and expression of the dsRNA-HT115 engineering strains of dsOftermicin1 and dsOftermicin2 in our laboratory, this work employs the ultrasonic breaking method to establish an inactivated dsOftermicins-HT115 technological system capable of producing a substantial quantity of dsRNA. This approach also addresses the limitation of transgenic strains which cannot be directly applied. Treatment of O. formosanus with dsOftermicins produced by this method could enhance the virulence of both Bt and Bb to the termites. This study laid the theoretical groundwork for the development of novel termite immunosuppressants and for the advancement and application of termite biological control strategies.

Effector Cs02526 from Ciboria shiraiana induces cell death and modulates plant immunity.

Sclerotinia disease is one of the most devastating fungal diseases worldwide, as it reduces the yields of many economically important crops. Pathogen-secreted effectors play crucial roles in infection processes. However, key effectors of Ciboria shiraiana, the pathogen primarily responsible for sclerotinia disease in mulberry (Morus spp.), remain poorly understood. In this study, we identified and functionally characterized the effector Cs02526 in C. shiraiana and found that Cs02526 could induce cell deathin a variety of plants. Moreover, Cs02526-induced cell death was mediated by the central immune regulator BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1), dependent on a 67-amino acid fragment. Notably, Cs02526 homologues were widely distributed in hemibiotrophic and necrotrophic phytopathogenic fungi, but the homologues failed to induce cell death in plants. Pre-treatment of plants with recombinant Cs02526 protein enhanced resistance against both C. shiraiana and Sclerotinia sclerotiorum. Furthermore, the pathogenicity of C. shiraiana was diminished upon spraying plants with synthetic dsRNA-Cs02526. In conclusion, our findings highlight the cell death-inducing effector Cs02526 as a potential target for future biological control strategies against plant diseases.

Dual RNA sequencing during Trichoderma harzianum-Phytophthora capsici interaction reveals multiple biological processes involved in the inhibition and highlights the cell wall as a potential target.

Phytophthora capsici is a destructive oomycete pathogen, causing huge economic losses for agricultural production. The genus Trichoderma represents one of the most extensively researched categories of biocontrol agents, encompassing a diverse array of effective strains. The commercial biocontrol agent Trichoderma harzianum strain T-22 exhibits pronounced biocontrol effects against many plant pathogens, but its activity against P. capsici is not known. T. harzianum T-22 significantly inhibited the growth of P. capsici mycelia and the culture filtrate of T-22 induced lysis of P. capsici zoospores. Electron microscopic analyses indicated that T-22 significantly modulated the ultrastructural composition of P. capsici, with a severe impact on the cell wall integrity. Dual RNA sequencing revealed multiple biological processes involved in the inhibition during the interaction between these two microorganisms. In particular, a marked upregulation of genes was identified in T. harzianum that are implicated in cell wall degradation or disruption. Concurrently, the presence of T. harzianum appeared to potentiate the susceptibility of P. capsici to cell wall biosynthesis inhibitors such as mandipropamid and dimethomorph. Further investigations showed that mandipropamid and dimethomorph could strongly inhibit the growth and development of P. capsici but had no impact on T. harzianum even at high concentrations, demonstrating the feasibility of combining T. harzianum and these cell wall synthesis inhibitors to combat P. capsici. These findings provided enhanced insights into the biocontrol mechanisms against P. capsici with T. harzianum and evidenced compatibility between specific biological and chemical control strategies. © 2024 Society of Chemical Industry.

Effective biological control of chickpea rabies (Ascochyta rabiei) through systemic phytochemical defenses activation by Trichoderma roots colonization: From strain characterization to seed coating

Chickpea (Cicer arietinum) is a legume of great economic and agricultural importance worldwide, whose crop is severely affected by rust or Ascochyta blight, caused by the fungus Ascochyta rabiei. The fungal genus Trichoderma includes several species widely characterized as effective biological control agents against crop pathogens. First, this work characterized several species of the genus Trichoderma as potential biological control agents of A. rabiei directly (in vitro confrontation) or indirectly in chickpea plants (activation of systemic resistance), selecting T. harzianum EN1 as the most efficient strain. Subsequently, different materials were tested as coatings to apply the T. harzianum conidia on chickpea seeds, determining that gum arabic at 1 % concentration was the one that most promoted the germination of conidia and seeds. The third phase of the study was based on the application of the coating and T. harzianum conidia on chickpea seeds and to study plant survival after infection with the pathogen A. rabiei, characterizing root colonization by Trichoderma and systemic hormonal and metabolic changes related to the induction of systemic defenses. The treatment of chickpea seeds with gum arabic and T. harzianum conidia was found to increase Trichoderma-root colonization and to improve plant survival. The induction of systemic ethylene- and melatonin-mediated resistance, which led to the accumulation of nicotinic acid in plant tissues, was considered the cause of such a protection. Therefore, T. harzianum applied as seed coating with gum arabic could be a good biological control strategy against A. rabiei on chickpea, due to the induction of systemic resistance.

DETERMINATION OF ENTOMOPATHOGENIC NEMATODE FAUNA IN ŞIRNAK, TURKIYE

This study focuses on the isolation, identification, and characterization of entomopathogenic nematodes (EPNs) in Şırnak Province, Turkey. Between July and September 2023, we collected 256 soil samples, from which 11 EPN isolates were successfully recovered,representing a 4.3% of the samples. These isolates were identified using morphological examinations and molecular diagnostics, including mitochondrial COI and 18S rDNA gene regions. Our findings revealed a diverse population of EPNs, predominantly Heterorhabditis bacteriophora with five isolates, alongside four Steinernema species (one Steinernema carpocapsae, one Steinernema affine, and two Steinernema sp.). Phylogenetic analysis, employing the mitochondrial cytochrome oxidase subunit I (COXI) and the 18S rDNA gene regions, indicated low genetic variability within H. bacteriophora and greater diversity among Steinernema species. The study contributes significant insights into the EPN biodiversity in Şırnak Province and underscores the potential of these nematodes in biological pest control, offering a sustainable alternative to chemical pesticides. The results highlight the importance of local EPN isolates in the development of effective biological control strategies and the conservation of agricultural biodiversity.

Determination of Antagonistic Activities of Endophytic Bacteria Isolated from Different Wheat Genotypes Against Fusarium culmorum

This study aimed to evaluate the physiological and biochemical properties and enzyme activities of endophytic bacteria obtained from different wheat genotypes, as well as their effectiveness against Fusarium culmorum, which causes root and crown rot in wheat. The results obtained from double culture tests of isolates against F. culmorum showed that the inhibition rate varied between 80.56% and 13.90%. The inhibition rate against F. culmorum was 80.59% for Bacillus subtilis (MM11), 69.41% for Stenotrophomonas maltophilia (EY5), and 61.10% for Enterobacter sp. (MY3) under in vitro conditions, the most effective isolates. Pseudomonas putida (EM9) and Pseudomonas orientalis (MM21) isolates gave positive results in all tests in the production of amylase, cellulase, phosphatase, ACC deaminase, and siderophore. To identify six promising isolates, 16S rRNA gene-based sequence analysis was utilized. The efficacy of bacterial strains against F. culmorum, pot experiments were conducted in a growth room (in vivo). The results demonstrated that the combination of S. maltophilia, Enterobacter sp., and B. subtilis (MY3+EY5+MM11) yielded the most favorable outcomes in terms of disease severity, plant height, wet weight, dry weight, root wet weight, and root dry weight. The combination of Stenotrophomonas rhizophila, P. putida, and P. orientalis (EY1+EM9+MM21) exhibited promising results. Utilizing effective bacterial strains is anticipated to reduce the dependence on and costs associated with chemical fertilizers and pesticides while minimizing their environmental impact. Furthermore, these strains show potential for commercial applications pending further validation procedures. The findings from this study significantly contribute to the field of biological control strategies against F. culmorum by leveraging the diverse capabilities of endophytic bacteria.