Seed priming with Metarhizium anisopliae (MetA1) improves physiology, growth and yield of wheat.

Microorganisms offer a sustainable way to increase crop production and promote eco-friendly farming. The endophytic fungus Metarhizium anisopliae is known for its multiple roles in plant ecosystems, including plant protection, symbiosis, and abiotic stress mitigation. In this study, we evaluated the potential of seed priming with M. anisopliae isolate MetA1 (MA) to enhance germination, photosynthetic efficiency, growth, and yield of two wheat varieties, BARI Gom 26 (BG26) and BARI Gom 33 (BG33) under field conditions. The study demonstrated that MA seed priming significantly improved wheat germination (by 13% and 26.04%) of BG26 and BG33, respectively. Overall, photosynthetic performance, indicated by increased leaf angle, leaf thickness, relative chlorophyll content, and linear electron flow (LEF), quantum yield of Photo System II (Phi2) was increased in MA primed wheat plants, while reducing non-photochemical quenching like NPQt, PhiNO, PhiNPQ of both varieties. These enhancements were attributed to increased shoot biomass (by 215.64% for BG26 and 280.38% for BG33), root biomass (by 141.79% for BG26 and 207.4% for BG33), effective tiller percentage (by 9.17% for BG26 and 5.7% for BG33), spike length (by 25.05% for BG26 and 25.42% for BG33), grain yield parameters such as filled grain percentage (by 23.8% for BG26 and 12.5% for BG33), and grain weight per plant (by 168.62% for BG26 and 119.62% for BG33). The findings of the research demonstrated the potential of M. anisopliae for field use in an agricultural setting, providing a sustainable means of increasing food production.

Effects of four potent entomopathogenic fungal isolates on the survival and performance of Telenomus remus, an egg parasitoid of fall armyworm.

Fall armyworm (FAW), Spodoptera frugiperda is a generalist pest known to feed on more than 300 plant species, including major staple crops such as rice, maize and sorghum. Biological control of FAW using a combination of a major indigenous egg parasitoid Telenomus remus and entomopathogenic fungi was explored in this study. Metarhizium anisopliae strains (ICIPE 7, ICIPE 41, and ICIPE 78) and Beauveria bassiana ICIPE 621 which demonstrated effectiveness to combat the pest, were evaluated through direct and indirect fungal infection to assess their pathogenicity and virulence against T. remus adults, S. frugiperda eggs and their effects on T. remus parasitism rates. Metarhizium anisopliae ICIPE 7 and ICIPE 78 exhibited the highest virulence against T. remus adults with LT50 values >2 days. ICIPE 7 induced the highest T. remus mortality rate (81.40 ± 4.17%) following direct infection with dry conidia. Direct fungal infection also had a significant impact on parasitoid emergence, with the highest emergence rate recorded in the M. anisopliae ICIPE 7 treatment (42.50 ± 5.55%), compared to the control ± (83.25 ± 5.94%). In the indirect infection, the highest concentration of 1 x 109 conidia ml-1 of ICIPE 78 induced the highest mortality (100 ± 0.00%) of T. remus adults, and the highest mortality (51.25%) of FAW eggs, whereas the least FAW egg mortality (15.25%) was recorded in the lowest concentration 1 x 105 conidia ml-1 of ICIPE 41. The number of parasitoids that emerged and their sex ratios were not affected by the different fungal strain concentrations except in ICIPE 7 at high dose. This study showed that potential combination of both M. anisopliae and B. bassiana with T. remus parasitoid can effectively suppress FAW populations.

Metarhizium caribense sp. nov., a Novel Species of Entomopathogenic Metarhizium Fungi Associated with Weevils Impairing Coffee, Sugar Cane and Sweet Potato Cultivation.

(1) Background: Insect pathogenic fungi of the genus Metarhizium are under study and in application as highly solicited, more eco-system friendly substitutes for chemical insecticides in many countries and in different agricultural contexts. In Cuba and Florida, Metarhizium strains have previously been isolated from economically important coffee and sugar cane pests. (2) Methods: Unambiguous species delineation within the Metarhizium anisopliae species complex is methodologically challenging. Recently, a species-discriminating PCR approach has been developed based on ribosomal intergenic spacer (rIGS) sequences that covered the prominent four "PARB" species within the complex. This approach is combined here with further genetic markers and is extended to a further species. (3) Results: Metarhizium isolates from Cuba, found to be more naturally associated with the coffee berry borer, Hypothenemus hampei, were morphologically, microscopically and molecular taxonomically characterized. Multilocus sequence analysis based on 5TEF, MzIGS3 and rIGS markers delineated these weevil-associated strains from all previously established Metarhizium species. (4) Conclusions: The isolates under study represent a new fungal taxon proposed to be designated Metarhizium caribense. The rIGS-based species-discriminating diagnostic PCR is a suitable tool for the identification of new Metarhizium species and can be productively combined to approaches using further genetic markers.

Sgabd-2 plays specific role in immune response against biopesticide Metarhizium anisopliae in Aphis citricola.

Metarhizium anisopliae is an effective biopesticide for controlling Aphis citricola, which has developed resistance to many chemical pesticides. However, the powerful immune system of A. citricola has limited the insecticidal efficacy of M. anisopliae. The co-evolution between insects and entomogenous fungi has led to emergence of new antifungal immune genes, which remain incompletely understood. In this study, an important immune gene Sgabd-2 was identified from A. citricola through transcriptome analysis. Sgabd-2 gene showed high expression in the 4th instar nymph and adult stages, and was mainly distributed in the abdominal region of A. citricola. The recombinant protein (rSgabd-2) exhibited no antifungal activity but demonstrated clear agglutination activity towards the conidia of M. anisopliae. RNA interference of Sgabd-2 by dsRNA feeding resulted in decreased phenoloxidase (PO) activity and weakened defense for A. citricola against M. anisopliae. Simultaneous silence of GNBP-1 and Sgabd-2 effectively reduced the immunity of A. citricola against M. anisopliae more than the individual RNAi of GNBP-1 or Sgabd-2. Furthermore, a genetically engineered M. anisopliae expressing double-stranded RNA (dsSgabd-2) targeting Sgabd-2 in A. citricola successfully suppressed the expression of Sgabd-2 and demonstrated increased virulence against A. citricola. Our findings elucidated Sgabd-2 as a critical new antifungal immune gene and proposed a genetic engineering strategy to enhance the insecticidal virulence of entomogenous fungi through RNAi-mediated inhibition of pest immune genes.

Uncovering the function of insulin receptor substrate in termites' immunity through active immunization.

Insulin receptor substrate (IRS) proteins are key mediators in insulin signaling pathway. In social insect lives, IRS proteins played important roles in caste differentiation and foraging, but there function in disease defenses such as active immunization has not been reported yet. To investigate the issue, we successfully suppressed the IRS gene 3 days after dsRNA injection. Suppressing IRS gene increased the contents of glucose, trehalose, glycogen, and triglyceride and decreased the content of pyruvate in termites, and led to the metabolic disorder of glucose and lipids. IRS suppressing significantly enhanced grooming behaviors of nestmates of fungus-contaminated termites and hence increased the conidial load in the guts of the nestmates. Additionally, IRS suppressing led to significant downregulation of the immune genes Gram-negative bacteria-binding protein2 (GNBP2) and termicin and upregulation of the apoptotic gene caspase8, and hence diminished antifungal activity of nestmates of fungus-contaminated termites. The above abnormal behavioral and physiological responses significantly decreased the survival rate of dsIRS-injected nestmates of the fungus-contaminated termites. These findings suggest that IRS is involved in regulation of active immunization in termites, providing a better understanding of the link between insulin signaling and the social immunity of termites.

Efficacy of Metarhizium anisopliae, Isolate ICIPE 7, against Anopheles arabiensis, Glossina fuscipes, and Rhipicephalus spp.

Arthropod vectors are responsible for a multitude of human and animal diseases affecting poor communities in sub-Saharan Africa. Their control still relies on chemical agents, despite growing evidence of insecticide resistance and environmental health concerns. Biorational agents, such as the entomopathogenic fungus Metarhizium anisopliae, might be an alternative for vector control. Recently, the M. anisopliae isolate ICIPE 7 has been developed into a commercial product in Kenya for control of ticks on cattle. We were interested in assessing the potential of controlling not only ticks but also disease-transmitting mosquitoes and tsetse flies using cattle as blood hosts, with the aim of developing a product for integrated vector management. Laboratory bioassays were carried out with M. anisopliae, isolate ICIPE 7 and isolate ICIPE 30, to compare efficacy against laboratory-reared Anopheles arabiensis. ICIPE 7 was further tested against wild Glossina fuscipes and Rhipicephalus spp. Dose-response tests were implemented, period of mosquito exposure was evaluated for effects on time to death, and the number of spores attached to exposed vectors was assessed. Exposure to 109 spores/mL of ICIPE 7 for 10 min resulted in a similar mortality of An. arabiensis as exposure to ICIPE 30, albeit at a slower rate (12 vs. 8 days). The same ICIPE 7 concentration also resulted in mortalities of tsetse flies (LT50: 16 days), tick nymphs (LT50: 11 days), and adult ticks (LT50: 20 days). Mosquito mortality was dose-dependent, with decreasing LT50 of 8 days at a concentration of 106 spores/mL to 6 days at 1010 spores/mL. Exposure period did not modulate the outcome, 1 min of exposure still resulted in mortality, and spore attachment to vectors was dose-dependent. The laboratory bioassays confirmed that ICIPE 7 has the potential to infect and cause mortality to the three exposed arthropods, though at slower rate, thus requiring further validation under field conditions.

Pathogenic fungi synergistically cooperate with Serratia marcescens to increase cockroach mortality.

The abuse of chemical insecticides has led to strong resistance in cockroaches, and biopesticides with active ingredients based on insect pathogens have good development prospects; however, their slow effect has limited their practical application, and improving their effectiveness has become an urgent problem. In this study, the interaction between Serratia marcescens and Metarhizium anisopliae enhanced their virulence against Blattella germanica and exhibited a synergistic effect. The combination of S. marcescens and M. anisopliae caused more severe tissue damage and accelerated the proliferation of the insect pathogen. The results of high-throughput sequencing demonstrated that the gut microbiota was dysbiotic, the abundance of the opportunistic pathogen Weissella cibaria increased, and entry into the hemocoel accelerated the death of the German cockroaches. In addition, the combination of these two agents strongly downregulated the expression of Imd and Akirin in the IMD pathway and ultimately inhibited the expression of antimicrobial peptides (AMPs). S. marcescens released prodigiosin to disrupted the gut homeostasis and structure, M. anisopliae released destruxin to damaged crucial organs, opportunistic pathogen Weissella cibaria overproliferated, broke the gut epithelium and entered the hemocoel, leading to the death of pests. These findings will allow us to optimize the use of insect pathogens for the management of pests and produce more effective biopesticides.

Exploration of the potential of a boosted sterile insect technique to control fruit flies in mango orchards.

BACKGROUND: An innovative version of the sterile insect technique (SIT) for pest control, called boosted SIT, relies on the use of sterile males coated with a biocide to control a target wild pest population of the same species. The objective of the present study was to assess the relevance of such technology to control the fruit fly Bactrocera dorsalis and fruit losses in mango orchards using. An agent-based simulation model named BOOSTIT was used to explore the reduction of fruit losses thank to sterile male fruit flies control and economic benefits according to different strategies of sterile male release. The simulation considered a landscape of 30.25 ha made up of four mango orchards. RESULTS: The SIT and the boosted SIT reduced fruit losses when releases were made before the mango fruiting period. According to model simulations, releases should be performed at least seven times at 2-week intervals and with a sterile/wild male ratio of at least 10:1. Considering the benefit/cost ratio (BCR), few releases should be done with a late start date. The BCR showed economic gains from the two control methods, the number of saved fruits and BCR being higher for SIT. CONCLUSION: Our simulations showed that SIT would have better results than the boosted SIT to contribute to an effective control of Bactrocera dorsalis at the scale of a small landscape. We highlight the need for laboratory studies of other types of pathogen to find a suitable one with higher incubation time and lower cost. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Managing Super Pests: Interplay between Pathogens and Symbionts Informs Biocontrol of Whiteflies.

Bemisia tabaci is distributed globally and incurs considerable economic and ecological costs as an agricultural pest and viral vector. The entomopathogenic fungus Metarhizium anisopliae has been known for its insecticidal activity, but its impacts on whiteflies are understudied. We investigated how infection with the semi-persistently transmitted Cucurbit chlorotic yellows virus (CCYV) affects whitefly susceptibility to M. anisopliae exposure. We discovered that viruliferous whiteflies exhibited increased mortality when fungus infection was present compared to non-viruliferous insects. High throughput 16S rRNA sequencing also revealed significant alterations of the whitefly bacterial microbiome diversity and structure due to both CCYV and fungal presence. Specifically, the obligate symbiont Portiera decreased in relative abundance in viruliferous whiteflies exposed to M. anisopliae. Facultative Hamiltonella and Rickettsia symbionts exhibited variability across groups but dominated in fungus-treated non-viruliferous whiteflies. Our results illuminate triangular interplay between pest insects, their pathogens, and symbionts-dynamics which can inform integrated management strategies leveraging biopesticides This work underscores the promise of M. anisopliae for sustainable whitefly control while laying the groundwork for elucidating mechanisms behind microbe-mediated shifts in vector competence.

Characterization of Bacillus velezensis TJS119 and its biocontrol potential against insect pathogens.

Introduction: The white-spotted flower chafer (Protaetia brevitarsis seulensis), which is widely distributed in Asian countries, is traditionally used in oriental medicine. However, its larvae are prone to severe damage by green muscardine disease (caused by Metarhizium anisopliae) during breeding. The aim of this study was to characterize Bacillus velezensis TJS119, which has been isolated from freshwater, and investigate its potential as a biocontrol agent against M. anisopliae in insects. Methods: TJS119 was obtained from freshwater samples in the Republic of Korea and was classified as B. velezensis. We evaluated its in vitro antifungal effect, sequenced the bacterial whole genome, mined genes responsible for the synthesis of secondary metabolites, performed secondary metabolite analysis Ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS), and conducted bioassays for determining green muscardine disease control ability. Results: Bacillus velezensis TJS119 inhibited the mycelial growth of M. anisopliae in vitro. The size of the B. velezensis TJS119 genome was estimated to be 3,890,913 bp with a GC content of 46.67% and 3,750 coding sequences. Biosynthetic gene clusters for secondary metabolites with antifungal activity were identified in the genome. Lipopeptides, including fengycin secreted by TJS119 exhibit antifungal activity. Application of TJS119 for the biocontrol against green muscardine disease increased the viability of white-spotted flower chafer by 94.7% compared to the control. Discussion: These results indicate that B. velezensis TJS119 is a potential biocontrol agent for insect pathogens.

Efficacy of entomopathogenic fungi against Philaenus spumarius, the vector of Xylella fastidosa.

BACKGROUND: Xylella fastidiosa is an important causative agent of Olive Quick Decline Syndrome in the Apulia region of Italy. The current study evaluated the bioefficacy of three entomopathogenic fungal strains: Beauveria bassiana SGB7004, Metarhizium robertsii SGB1K, and Akanthomyces lecanii SGB4711 against Philaenus spumarius the main vector of this pathogen, under laboratory conditions. Pathogenicity bioassays were performed by dipping nymphs and adults of P. spumarius in an aqueous suspension of powdered fungal culture (PFC) or conidial suspension (CS) of the three fungal strains. RESULTS: Both B. bassiana SGB7004 and M. robertsii SGB1K affected the viability of nymphs, resulting in more than 80% mortality at 48 h post treatment, while the effect of A. lecanii SGB4711 was not statistically significant. On adults, all three biocontrol strains were effective in a time- and concentration-dependent manner. The PFCs of B. bassiana SGB7004, M. robertsii SGB1K, and A. lecanii SGB4711 at the highest concentration tested (120 mg mL-1) resulted in 97%, 83% and 27% mortality at the trial endpoint (120 h), respectively. Mycelial growth was observed on 38.5%, 37.0% and 61.5% of dead insects treated with B. bassiana SGB7004 (2.3 × 108 CFU mL-1), M. robertsii SGB1K (3.8 × 106 CFU mL-1) and A. lecanii SGB4711 (5.4 × 108 CFU mL-1), respectively. None of the PFCs of the tested strains was pathogenic when injected into nymph spittle. CONCLUSIONS: Beauveria bassiana SGB7004 and M. robertsii SGB1K significantly affected the survival of P. spumarius nymphs and adults, while A. lecanii SGB4711 was not effective on nymphs and only slightly effective against adults. © 2024 Society of Chemical Industry.

Combined application of entomopathogenic fungi and predatory mites for biological control of Tetranychus urticae on chrysanthemum.

BACKGROUND: Most studies on efficacy of fungal pathogens and predatory mites against Tetranychus urticae have been done on individual species in the laboratory. We evaluated fungi and predatory mites separately and together against glasshouse populations of T. urticae on chrysanthemum plants. First, effectiveness of the fungal pathogens Beauveria bassiana (Bb88) and Metarhizium anisopliae (Ma129) was compared; then, effectiveness of the predatory mites Phytoseiulus persimilis and Neoseiulus californicus. Based on the results, N. californicus and isolate Ma129 were selected and evaluated in combination. In all experiments, treatment effects were assessed for eggs and motile stages of T. urticae. RESULTS: The first experiment showed no significant effect of either fungal isolate on T. urticae populations, except on plants initially infested with 20 mites, where more eggs were found in the control compared to the fungal treatments. In the second experiment, both predatory mites were equally effective at reducing T. urticae populations compared with the control, regardless of initial T. urticae population density. The last experiment demonstrated that populations of T. urticae were reduced most when M. anisopliae (Ma129) and N. californicus were applied together, compared with the control and when each natural enemy was applied separately. CONCLUSIONS: Metarhizium anisopliae (Ma129) and B. bassiana (Bb88) isolates did not have a significant effect on reducing T. urticae populations. Both predatory mites reduced T. urticae populations, regardless of T. urticae density. Combined application of M. anisopliae (Ma129) and N. californicus were more effective against T. urticae than the control or when each agent was applied separately. © 2024 Society of Chemical Industry.

Molecular identification and related functional characterization of the FKBP52 gene in immunity of Locusta migratoria manilensis (Orthoptera: Oedipodidae).

Metarhizium anisopliae is an important class of entomopathogenic fungi used for the biocontrol of insects, but its virulence is affected by insect immunity. We identified a novel FK506 binding protein gene that was differentially expressed between control and Metarhizium-treated Locusta migratoria manilensis. We hypothesized that this protein played an important role in Metarhizium infection of L. migratoria and could provide new insights for developing highly efficient entomopathogenic fungi. We, therefore, cloned the specific gene and obtained its purified protein. The gene was then named FKBP52, and its dsRNA (dsFKBP52) was synthesized and used for gene interference. Bioassay results showed that the mortality of L. migratoria treated with dsFKBP52 + Metarhizium was significantly lower than that of other treatments. Furthermore, immune-related genes (MyD88, Dorsal, Cactus, and Defensin) in L. migratoria treated with dsFKBP52 + Metarhizium showed significant upregulation compared to that treated with Metarhizium only. However, the activities of peroxidase (POD), superoxide dismutase (SOD), and calcineurin (CaN) showed fluctuations. These results suggest that the FKBP52 gene may play a crucial role in the innate immunity of L. migratoria. The effect of its silencing indicated that this immunity-related protein might be a potential target for insect biocontrol.

Entomopathogenic fungi-based silver nanoparticles: a potential substitute of synthetic insecticides to counter behavioral and physiological immunity in Aedes aegypti mosquito (Diptera: Culicidae).

Excessive use of synthetic insecticides has resulted in environmental contamination and adverse effects on humans and other non-target organisms. Entomopathogenic fungi offer eco-friendly alternatives; however, their application for pest control requires significant advancement owing to limitations like slow killing time and effectiveness only when applied in higher amounts, whereas exposure to UV radiation, high temperature, and humidity can also reduce their viability and shelf-life. The nanoparticles synthesized using fungal extracellular extracts provide a new approach to use fungal pathogens. Our study focused on the synthesis of Metarhizium anisopliae-based silver nanoparticles (AgNPs) and evaluation of their efficiency on various physiological and behavioral parameters of the mosquito Aedes aegypti. The synthesis, size (27.6 d.nm, PDI = 0.209), zeta potential (- 24.3 mV), and shape of the AgNPs were determined through dynamic light scattering, scanning and transmission electron microscopic, and UV-visual spectroscopic analyses (432 nm). Our results showed significantly reduced survival (100% decrease in case of 3.2 and 1.8 µL/cm2 volumes, and 60% decrease in case of 0.8 µL/cm2 volume), phenoloxidase activity (t = 39.91; p = 0.0001), and gut microbiota, with increased oxidative stress and cell apoptosis in AgNPs-challenged mosquitoes. Furthermore, the AgNPs-exposed mosquitoes presented a concentration-specific decrease in flight locomotor activity (F = 17.312; p < 0.0001), whereas no significant changes in antifungal activity, self-grooming frequencies, or time spent were found. These findings enhance our understanding of mosquito responses to AgNPs exposure, and offer a more efficient mosquito control strategy using entomopathogenic fungi.

METARHIZIUM ANISOPLIAE SENSU LATO NATIVE TO LIVESTOCK SOILS CAUSES HIGH MORTALITY ON RHIPICEPHALUS MICROPLUS LARVAE, ADULTS AND AFFECTS THEIR REPRODUCTION.

The acaricidal effect of 14 strains of Metarhizium anisopliae sensu lato isolated from soil of livestock farms in the Mexican tropics was evaluated against larvae and engorged females, and during the laying and hatching of eggs of Rhipicephalus microplus (Ixodida: Ixodidae). For each fungal strain, the larvae mortality percentage was evaluated through a larval immersion test, while the reproductive efficiency indices in engorged females were measured using adult immersion tests at a dose of 1 × 108 conidia/ml. All strains of M. anisopliae (s.l.) proved to be highly effective against R. microplus larvae (66-100%) and engorged females (100%). The strains also showed a good effect in inhibiting egg laying (16.45-56.38%) and a moderate effect in decreasing egg hatching (5.24-32.68%). Two strains demonstrated to be effective against all development phases of R. microplus in an integrated manner.

Evaluation of farmers friendly IPM modules for the management of fall armyworm, Spodoptera frugiperda (JE Smith) in maize in the hot semiarid region of India.

Invasive alien species (IAS) pose a severe threat to global agriculture, with their impact projected to escalate due to climate change and expanding international trade. The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), a native of the Americas, has rapidly spread across various continents, causing significant damage to several food crops, especially maize. Integrated pest management (IPM) programs are vital for sustainable FAW control, combining multiple strategies for sustainable results. Over three consecutive years, 2019-20, 2020-21 and 2021-22, the field demonstrations were conducted in semiarid regions of India, testing a four-component IPM approach viz., pheromone traps, microbial, botanicals and ETL based applications of insecticides against farmers' practices (sole insecticide application). IPM implementation led to substantial reductions in FAW infestation. Furthermore, egg mass and larvae infestations were significantly lower in IPM-adopted villages compared to conventional practices. Pheromone-based monitoring demonstrated a consistent reduction in adult moth populations. The lowest technology gap (10.42), extension gap (8.33) and technology index (12.25) was recorded during 2020-21. The adoption of IPM led to increased maize yields (17.49, 12.62 and 24.87% over control), higher net returns (919, 906.20 and 992.93 USD), and favourable benefit-cost ratios (2.74, 2.39 and 2.33) compared to conventional practices respectively during 2019-20, 2020-21 and 2021-22. The economic viability of IPM strategies was evident across three consecutive years, confirming their potential for sustainable FAW management in the semiarid region of India. These strategies hold promise for adoption in other parts of the world sharing similar climatic conditions.

The fungal endophyte Metarhizium anisopliae (MetA1) coordinates salt tolerance mechanisms of rice to enhance growth and yield.

The implementation of salt stress mitigation strategies aided by microorganisms has the potential to improve crop growth and yield. The endophytic fungus Metarhizium anisopliae shows the ability to enhance plant growth and mitigate diverse forms of abiotic stress. We examined the functions of M. anisopliae isolate MetA1 (MA) in promoting salinity resistance by investigating several morphological, physiological, biochemical, and yield features in rice plants. In vitro evaluation demonstrated that rice seeds primed with MA enhanced the growth features of rice plants exposed to 4, 8, and 12 dS/m of salinity for 15 days in an agar medium. A pot experiment was carried out to evaluate the growth and development of MA-primed rice seeds after exposing them to similar levels of salinity. Results indicated MA priming in rice improved shoot and root biomass, photosynthetic pigment contents, leaf succulence, and leaf relative water content. It also significantly decreased Na+/K+ ratios in both shoots and roots and the levels of electrolyte leakage, malondialdehyde, and hydrogen peroxide, while significantly increasing proline content in the leaves. The antioxidant enzymes catalase, glutathione S-transferase, ascorbate peroxidase, and peroxidase, as well as the non-enzymatic antioxidants phenol and flavonoids, were significantly enhanced in MA-colonized plants when compared with MA-unprimed plants under salt stress. The MA-mediated restriction of salt accumulation and improvement in physiological and biochemical mechanisms ultimately contributed to the yield improvement in salt-exposed rice plants. Our findings suggest the potential use of the MA seed priming strategy to improve salt tolerance in rice and perhaps in other crop plants.

Evaluation of the effectiveness of two Iranian su-strains of Metarhizium anisopliae (ascomycota: hypocreales) on the mortality rate of American cockroach.

The cockroach is one of the most important disease vectors in world. Entomopathogenic fungi, as three concentrations of spores were taken 1.1 × 105, 1.1 × 107, and 1.1 × 109 conidia/mL from two isolates of Nour and Saravan-Iranian. In this study, the immersion method caused about 13% mortality only in isolation (1 × 109 conidia/mL) of Saravan isolates. Inoculation of isolates below the pronotum did not significantly differ the mortality rate between the two genera (P = 0.8), compared to the pathogenicity of three isolates of M. anisopliae (1.1 × 105, 1.1 × 107, and 1.1 × 109 conidia/mL). In total, Saravan and Nour isolates were 66%, 73%, and 93%, respectively, indicating a significant difference (P < 0.001). Mortality of male and female cockroaches with Saravan isolates respectively occurred 3 and 4 days after inoculation (LT50 = 4.3d), while for Nour isolates, in both sexes, mortality was observed within four days after the test (LT50 = 5.5d). Considering the results M. anisopliae can be one benefit methods for control American cockroach in the future. .

An updated and validated model for predicting the performance of a biological control agent for the oriental migratory locust.

BACKGROUND: The oriental migratory locust is a major crop pest across eastern and south-eastern Asia. Metarhizium anisopliae is an effective biopesticide agent used for locust control, but its performance is temperature dependent, and thus can be more variable than chemical pesticide performance. To predict biopesticide performance for the control of the oriental migratory locust, we adapted a previous temperature-dependent model and validated it using field trial data. To increase the applicability of this model, we explored the use of readily available temperature variables, as well as our own satellite-derived canopy temperature variable, to run the model. RESULTS: Compared to collected in situ temperature data, our canopy temperature variable most accurately represented the ambient temperature experienced by the locust. When the biopesticide performance model was run using this canopy temperature and compared to field trials results, the model predictions were more accurate than when the model was run with the other temperature variables. The accuracy of the biopesticide performance model was impacted by vegetation cover, but across the areas most associated with locust oviposition, growth and migration, the model predictions were satisfactorily accurate to guide biopesticide operational use. CONCLUSION: We validated the model in six provinces in China, representing the three agro-ecological zones largely representative of the oriental migratory locust problem areas in China, Thailand, Cambodia and Vietnam. Whilst further validation work is needed, this model could be used in these countries to assess, at a fine spatial scale, the appropriateness of M. anisopliae for controlling the oriental migratory locust. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Immunological responses and gut microbial shifts in Phthorimaea absoluta exposed to Metarhizium anisopliae isolates under different temperature regimes.

The invasive tomato leaf miner, Phthorimaea absoluta, is conventionally controlled through chemical insecticides. However, the rise of insecticide resistance has necessitated sustainable and eco-friendly alternatives. Entomopathogenic fungi (EPF) have shown potential due to their ability to overcome resistance and have minimal impact on non-target organisms. Despite this potential, the precise physiological mechanisms by which EPF acts on insect pests remain poorly understood. To attain a comprehensive understanding of the complex physiological processes that drive the successful control of P. absoluta adults through EPF, we investigated the impacts of different Metarhizium anisopliae isolates (ICIPE 665, ICIPE 20, ICIPE 18) on the pest's survival, cellular immune responses, and gut microbiota under varying temperatures. The study unveiled that ICIPE 18 caused the highest mortality rate among P. absoluta moths, while ICIPE 20 exhibited the highest significant reduction in total hemocyte counts after 10 days at 25°C. Moreover, both isolates elicited notable shifts in P. absoluta's gut microbiota. Our findings revealed that ICIPE 18 and ICIPE 20 compromised the pest's defense and physiological functions, demonstrating their potential as biocontrol agents against P. absoluta in tomato production systems.