Isolates Of Metarhizium Anisopliae Research Articles

Endophytic entomopathogenic fungi isolates as growth promoters of the grass Urochloa brizantha

This study evaluated the growth-promoting action of 16 isolates of the entomopathogenic fungal genus Metarhizium spp., representing 14 from the native pastures and two commercial isolates, on the forage grass Urochloa brizantha, via drench application to seeds. Multivariate analysis of plant height, length of the longest leaf and root, and dry and fresh weight of leaves and roots indicated the most promising isolates, five from native pastures (CEPAF_ENT25, CEPAF_ENT26, CEPAF_ENT27, CEPAF_ENT42, and CEPAF_ENT59) and one commercial (IBCB 425), all isolates of Metarhizium anisopliae. Except for isolate CEPAF_ENT59, there was a positive correlation between growth parameters of U. brizantha with the contents of chlorophyll a and b and carotenoids and with the contents of N, P, and Zn in the leaves. Endophytic colonization tests indicated the presence of Metarhizium spp. in all plant parts, most frequently in the stems. Furthermore, the selected isolates of Metarhizium spp. were recovered from the cultivation substrate and positively affected the germination and initial growth of U. brizantha. Thus, the most promising isolates have potential for application to seeds of U. brizantha.

The potency of fungal entomopathogens isolated from Spodoptera frugiperda as endophytic plant-growth promoter

Previous studies have identified endophytic fungi as plant growth promoters and insect pest management. In the current study, six fungal isolates of Metarhizium anisopliae and Beauveria bassiana were isolated from larval corpses of fall armyworm (Spodoptera frugiperda) and tested for their ability to colonize leaf tissue through root and leaf applications or foliar-spray and to promote the growth of young maize (Zea mays) plants. The maize growth attributes examined were germination rate, height, dry and fresh weight, and leaf area. The research was conducted in May until June 2023 in Universitas Sriwijaya, Indonesia. The results revealed that M. anisopliae and B. bassiana were isolated from the cadavers of S. frugiperda and confirmed to be endophytic fungi. Root application was more effective to enhance the fresh weight, plant height, and leaf area of maize compared to foliar-spray. The fungi could significantly enhance the fresh weight, plant height, and leaf area of the young maize plants. The best isolate that could enhance the maize growth was the B. bassiana WTTJC260521A isolate. These findings suggest that M. anisopliae and B. bassiana isolated from fall armyworm corpses that had the potential to enhance maize plant growth through root applicaton.

Genetic diversity of Metarhizium sp. isolated from various hosts in East Dumoga, North Sulawesi, Indonesia

Abstract. Siahaan P, Mangais RER, Kolondam B, Tangapo A, Mambu S. 2023. Genetic diversity of Metarhizium sp. isolated from various hosts in East Dumoga, North Sulawesi, Indonesia. Biodiversitas 24: 6888-6896. Metarhizium fungus is an entomopathogenic fungus known to kill many insect pests. This means that Metarhizium sp. has an important ecological role in the ecosystem, especially in controlling insect populations and recycling nutrients. Studying the genetic diversity of Metarhizium species and their relationships with insect hosts provides insight into pest management and the study of their taxonomy. The study aimed to investigate the genetic variability among Metarhizium fungi by examining their respective host types, which can be used as basic data for taxonomic studies, germplasm conservation efforts, and pest management. Exploration results showed that three insect species were infected with the Metarhizium sp fungus, namely Scotinophara coarctata, Nilaparvata lugens, and Recilia dorsalis. The results of a phylogenetic analysis has shown that the S. coarctata isolate was in the same group as four comparable Metarhizium anisopliae isolates from GenBank with a similarity level of 100%, while the N. lugens and R. dorsalis isolates were in the same group as four Metarhizium huainamdangense isolates with a similarity level. 99% and three isolates of Metarhizium flavoviride with 98% similarity. Molecular analysis confirmed that the Metarhizium isolated from S. coarctata was the M. anisopliae species, while those isolated from N. lugens and R. dorsalis were the M. huainamdangense species. Differences in host insects have been proven to provide genetic variation to the Metarhizium sp. fungus.

Bermudagrass plants endophytically colonized with Metarhizium anisopliae isolates reduces the biological performance of fall armyworm

Bermudagrass plants endophytically colonized with Metarhizium anisopliae isolates reduces the biological performance of fall armyworm

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.

Virulence of Native Isolates of Metarhizium anisopliae (Metschnikoff) against Helicoverpa armigera (Lepidoptera: Noctuidae) in Western Uttar Pradesh, India

The chickpea pod borer Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is a destructive pest of chickpeas that is difficult to control using conventional methods. We isolated and evaluated the virulence of five isolates of Metarhizium anisopliae against larvae of H. armigera. All isolates of M. anisopliae, SVPUAT 1, SVPUAT 2, SVPUAT 3, SVPUAT 4, and SVPUAT 5, were most effective against the second instar H. armigera at 2 ×108 conidia/ml. Among all isolates, SVPUAT 1 Accession no. ON183248 had the highest virulence 100% mortality, whereas LT50 and LT90 were 3.16 and 5.16 days.

Isolation, Identification and Evaluation of the Effects of Native Entomopathogenic Fungi from Côte d'Ivoire on Galleria mellonella.

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a polyphagous pest highly damaging to maize and other food crops in Africa, particularly in Côte d'Ivoire. Chemical pesticides not only have often proved to be unsuccessful, but cause adverse effects on the environment and human health; therefore, entomopathogenic fungi could represent an alternative biocontrol solution. Against this background, fungi were isolated from soil samples collected in maize fields in three regions of Côte d'Ivoire, by the methods of soil dilution and baiting with Galleria mellonella. The resulting 86 fungal isolates were phenotypically and genetically identified. The pathogenicity of seven isolates of Metarhizium spp., three isolates of Beauveria bassiana and two isolates of Trichoderma sp. was evaluated on fifth instar larvae (L5) of G. mellonella. Larval mortality rates and the median lethal time (LT50) were determined seven days after inoculation for each of these selected isolates. The median lethal concentration (LC50) was determined for a selection of isolates. Beauveria bassiana isolate A214b was the most effective, causing 100% mortality, with an LT50 of 2.64 days and an LC50 of 1.12 × 104 conidia mL-1. Two other promising isolates, A211 and A214a, belonging to B. bassiana, caused 100% mortality with LT50 values of 3.44 and 4.04 days, respectively. Mortality caused by Metarhizium isolates varied from 65.38% to 100%, with Metarhizium anisopliae isolate T331 causing 100% mortality with an LT50 of 3.08 days at an LC50 of 3.33 × 104 conidia mL-1. Trichoderma sp. isolates were the least pathogenic ones. Beauveria bassiana and Metarhizium isolates showed to be virulent against the model Lepidopteran G. mellonella and will be tested on S. frugiperda.

Entomopathogenic fungi associated with cultivated honeybush, Cyclopia spp., in South Africa and their pathogenicity towards a leafhopper pest, Molopopterus sp. (Hemiptera: Cicadellidae)

The southern and eastern parts of the African Fynbos region favour the production of honeybush tea. Honeybush biomass and extracts are used to prepare a beverage both locally and internationally, mainly as herbal tea with health benefits. Honeybush tea is mostly grown organically requiring natural control measures for pests and diseases. The leafhopper, Molopopterus sp., is one of the most important pests of cultivated honeybush in South Africa, as its feeding compromises the quality and quantity of the yield through leaf discolouration and reduction of the photosynthetic area. Local entomopathogenic fungi (EPF) can provide a pool of potential biocontrol agents for this pest. Therefore, a total of 98 soil samples were collected from organically grown honeybush fields and vegetation surrounding the honeybush fields in the Western Cape province of South Africa. Entomopathogenic fungi were isolated using the insect bait method and were characterised using molecular techniques. Twenty fungal isolates of Metarhizium anisopliae and Fusarium oxysporum were recovered from soil samples, of which 70% were from honeybush fields and 30% were from surrounding vegetation. Fusarium oxysporum isolates comprised 20% of the recovered isolates; M. anisopliae the remainder. Laboratory bioassays of the recovered isolates against adults and nymphs of the leafhopper, showed that F. oxysporum isolates caused 10–45% mortality and M. anisopliae isolates 30–80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both nymphs and adults at a concentration of 1 × 107 conidia/ml.

Toxicity and physiological interruptions of a proteinaceous toxin from Metarhizium anisopliae against the olive fruit pest, Bacterocera oleae (Diptera: Tephritidae)

The use of natural bioactive compounds mainly proteinaceous secondary metabolites of fungi is one of the promising pest control methods because of their lethal effects on insects in low concentration, limited persistence in environment and easily decomposition into environmentally safe compounds. The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is a destructive pest of olive fruits around the world. In the current study, the proteinaceous compounds were extracted from the two isolates (MASA and MAAI) of Metarhizium anisopliae and their effects were evaluated on toxicity, feeding performance and antioxidant system of the adult's olive flies. Both extracts from MASA and MAAI showed entomotoxicity against the adults by 2.47 and 2.38 mg/mL as LC50 concentrations. Also, LT50 values were recorded 1.15 and 1.31 days for MASA and MAAI, respectively. No statistical differences were recorded in the consumption rate of the adults on control and secondary metabolite contained protein hydrolysate. In contrast, the adults fed on LC30 and LC50 concentrations of MASA and MAAI demonstrated significant reduction in the activities of digestive alpha-amylase, glucosidases, lipase, trypsin, chymotrypsin, elastase, amino- and carboxypeptidases. Activity of antioxidant enzymes changed in the adults of B. oleae fed on the fungal secondary metabolites. Catalase, Peroxidase and Superoxide dismutase elevated in the treated adults with the highest amounts of MAAI. Similar results were found in activity of ascorbate peroxidase and glucose-6-phosphate dehydrogenase except for malondialdehyde amount in which no statistical differences were recorded between treatments and control. Relative gene expression of caspase enzymes revealed the higher expression in the treated B. oleae compared to control with the highest level of caspase 8 for MASA and caspases 1 and 8 for MAAI. Results of our study showed that the secondary metabolites extracted from the two isolates of M. anisopliae caused mortality, interrupted digestion and induced oxidative stress in the adults of B. oleae.

Effectivity of Entomopathogen Fungus Metarhizium anisopliae (Metchnikoff) Sorokin to Mortality of Aedes aegypti Linnaeus, 1762 Larvae

The Aedes aegypti mosquito is the vector that causes the spread of the Dengue virus that causes Dengue Hemorrhagic Fever. Breaking the chain of spread of Dengue fever has been done a lot, but it can cause negative impacts to environment. It is necessary to use other alternative solutions. One of them uses natural bioinsecticides from entomopathogenic fungi. The entomopathogenic fungus that has been widely developed as a bioinsecticide is Metarhizium anisopliae. Metarhizium anisopliae is a fungus which has larvicidal activity. Isolates of Metarhizium anisopliae were obtained from the Center for Forecasting Plant Pest Organisms, Karawang, West Java and Aedes aegypti larvae were obtained from Parasitology Laboratory, Faculty of Medicine, Public Health, and Nursing, UGM. The research was conducted from November 2021-April 2022 at the Entomology Laboratory, Faculty of Biology and the Parasitology Laboratory, Faculty of Medicine, Public Health, and Nursing, UGM, Yogyakarta. The method in this research is the culture and manufacture of a suspension of the fungus Metarhizium anisopliae with an average conidia density 0,9 x 107, 0,57 x 106, 1,175 x 105, 5,25 x 104, 3 x 104, 12,5 x 103 of conidia/mL, rearing of Aedes aegypti, bioassay, and data analysis using Probit Test with SPSS software version 23 to determine LC50. The effective concentration to kill 50% of larvae was 0.9 x 107 conidia/ml. There was no significant effect between each different concentration in killing Aedes aegypti larvae. The LC50 value obtained was 1.4 x 107. Metarhizium anisopliae was effectively to control Aedes aegypti larvae.

Evaluation of the effectiveness of spore suspension and fungal filtrate of Metarhizium anisopliae fungus in controlling Tribolium castaneum (Coleoptera: Tenebrionidae)

This study evaluated the effect of spore suspension and fungal filtrate against different developmental stages of Tribolium castaneum third and fifth larval instars and adults. Two isolates of entomopathogenic fungus Metarhizium anisopliae were used (commercially (Met 52 EC), and domesticly). For the two isolates, the effectiveness of various conidial concentrations were (1 × 104 ; 1 × 106 ; 1 × 108 conidia/ ml) and various concentrations of fungal filtrate (100,75,50%) were evaluated. It is observed that the fungal filtrate at a concentration of 75% and the conidial concentration of 1 x 108 conidia /ml for both isolates were the most effective in causing the highest mortality rates to the third and fifth instar larva and adults of T. castaneum. Additionally, it resulted in less eggs produced by females treated with conidial concentration and fungal filtrate compared to control treatment. The results of this study demonstrate that the fungus can be used as a biological control agent against T. castaneum, which infects stored products. However, further research studies under storage conditions are required.

Effect of Temperature on Germination, Radial Growth, and Sporulation of the New Isolates of Metarhizium anisopliae and their Virulence to Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

Metarhizium anisopliae is a potential entomopathogenic fungi (EPF) to control insect pests in Malaysia, yet little is known about the temperature influence on its growth and efficacy. The average daily temperature in Malaysia is between 21 °C and 32 °C, with some parts of Cameron Highland in Peninsular Malaysia experiencing temperatures as low as 14 °C. Therefore, for effective field application, the most effective EPF isolates should be tolerant to the temperature of the country. Here we conducted a laboratory experiment to determine the effects of average daily temperatures in Malaysia (15, 20, 25, and 30 °C) on conidial germination, radial growth, and conidial density of seven new isolates of M. anisopliae. However, at 25 and 30°C, the three isolates (Ma-2, Ma-9, and Ma-15) produced the highest number of conidia and were therefore selected for virulence test against the second instar of whitefly, Bemisia tabaci. The percentage mortality of the three isolates ranged between 36.1% and 97.7% across different temperatures for 7 days post-treatment. The isolates Ma-15 caused the highest percentage mortality of 97.7% and the shortest LT50 and LT90 values (1.68 and 3.98 days, respectively), at 30 °C incubation temperature. This study confirms that the growth and virulence of Malaysian isolates of M. anisopliae are strongly influenced by temperature and could be used as promising candidates for biocontrol of B. tabaci on vegetables planted in a tropical climate such as that of low land and highland in Malaysia, although extensive field and semi-field bioassays, as well as the development of ideal formulation, are still required.

Isolation, molecular characterization of indigenous Metarhizium anisopliae (Metchnikoff) isolate, using ITS-5.8s rDNA region, and its efficacy against the Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)

BackgroundAs a biological control agent, entomopathogenic fungus (EPF) can give an alternative to high-risk pesticides. Metarhizium anisopliae is one of the most promising pest controls EPF in the worldwide.ResultOn fungi-specific selective media, the EPF isolate SVPUAT was isolated from Western Uttar Pradesh, India. The isolate was identified as M. anisopliae (GenBank accession no. OP962431) after molecular screening utilizing PCR amplification with the internal transcribed spacer (ITS) region primer. In a contact toxicity experiment, the isolate SVPUAT was tested against the 4th instar larvae of Helicoverpa armigera (Hubner) at concentrations ranging from 103 to 1010 spores ml−1. The lethal time LT50 and LT90 values for the 4th instar larvae of H. armigera injected with 1 × 1010 spores ml−1 were 3.46 and 5.54 days, respectively.ConclusionsThe present M. anisopliae isolate SVPUAT was identified using the ITS-5.8s rDNA region from GenBank and has showed significant pathogenicity to H. armigera. More research is needed to prove the efficacy against various pests of economic important as a legitimate choice for an integrated pest management program.

Entomopathogenic Fungi as a Potential Management Tool for the Control of Urban Malaria Vector, Anopheles stephensi (Diptera: Culicidae).

Anopheles stephensi (Diptera: Culicidae) is the vector of urban malaria in India and has a significant impact in transmitting infection in cities and towns. Further, WHO has also alarmed its invasive nature as a threat to African countries. Entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae have been found to be highly effective in controlling vector mosquito populations and therefore could be used in integrated vector control programs. Before employing the entomopathogenic fungi into the control programs, an effective isolate must be selected. Two separate experiments were conducted to evaluate the efficacy of Beauveria bassiana (Bb5a and Bb-NBAIR) and Metarhizium anisopliae (Ma4 and Ma-NBAIR) isolates against An. stephensi. Cement and mud panels were treated with fungal conidia with the concentration of 1 × 107 conidia/mL and adult An. stephensi mosquitoes were exposed to the treated panels (24 h after conidia were applied) by conducting WHO cone bioassay tests. The survival of the mosquitoes was monitored daily until the 10th day. In the second experiment, second instar larvae of An. stephensi were treated with fungal (Bb5a, Bb-NBAIR, Ma4 and Ma-NBAIR) conidia and blastospores with the spore concentration of 1 × 107 spores/mL. The survival of larvae was monitored until pupation. All the fungal isolates tested caused mortality in the adult mosquitoes, with varying median survival times. The Bb5a isolate reported lesser median survival times on both cement and mud panels (6 days). The treated mosquitoes showed similar survival rates for each fungal isolate irrespective of the panel type. There was no mortality in the treated larvae; however, a delay in larval development to pupae was observed compared with the untreated control larvae. Ma4-treated larvae took 11 days (95% CI = 10.7-11.2) to become pupae when compared with the untreated control larvae (6 days [95% CI = 5.6-6.3]). The findings of this study will be useful to consider EPF as a tool for the management of vector mosquitoes.

Effect of temperature and pH on growth and sporulation of both Local isolates of biological control fungi Metarhizium anisopliae and Beauveria bassiana

A laboratory study was conducted by using two local isolates of biological control fungi M. anisopliae and B.bassiana that isolated from the soil of citrus orchards that infested with Mediterranean fruit fly Capitata ceratiris in Baghdad to know the effect of four different temperatures included 15, 20, 25 and 30 ° C and four levels of the pH, including 5, 6, 7 and 8 on the growth and sporulation of two local isolates on liquid medium. Results showed that the highest growth of the fungus M. anisopliae was at 20° C, average dry weight was1.19 gm and best sporulation of the fungus at 25°C ,it was 10.3×104 spore/g, while was higher growth and sporulation for B. bassiana at 20 °C , they were 1.11 gm and 2.7 × 104 spore / g, respectively, the results showed that the highest dry weight for M. anisopliae and B.bassiana was at /pH 7,they were 5.9 and 3.38 gm respectively, and the best sporulation for them when the pH5 ,they were 3.9×104 and 3.8×104 spore /g respectively, the isolated fungus B. bassiana surpass in the production of both chitinase and proteinase enzymes depending on decomposition aureole diameter, they were 15.76 and 11.37 cm, respectively, compared to M.anisopliae which amounted 14.17 and 4.36 cm respectively.

PATHOGENICITY OF ISOLATES OF ENTOMOPATHOGENIC FUNGI TO WORKERS OF Acromyrmex heyeri (Forel, 1899) (HYMENOPTERA: FORMICIDAE)

Leaf-cutting ants stand out among the main pests of agricultural and forestry crops. Chemical control is the most used method to control these insect pests, requiring the development of techniques that are less harmful to the environment. The present study aimed at verifying the action of Beauveria bassiana (Bals.) Vuill, Cordyceps fumosorosea (Wize), and Metarhizium anisopliae (Metsch.) Sorokin isolates on the in vitro mortality of Acromyrmex heyeri (Forel). Seven isolates of entomopathogenic fungi were used: three isolates of Beauveria bassiana (IBCB 66, IBCB 170, and IBCB 632), one isolate of Cordyceps fumosorosea (IBCB 130), and three isolates of Metarhizium anisopliae (IBCB 348, IBCB 383, and IBCB 425), and five concentrations of spores (1.0×104, 1.0×105, 1.0×106, 1.0×107, and 1.0×108 spores mL-1) for each fungal isolate. The control treatment consisted of autoclaved distilled water and 0.01% Tween 40, without fungal pathogens. The experiments were carried out in a completely randomized design with five replications. Estimation of lethal concentrations of LC50 and LC90 was performed using Probit analysis. The isolates of B. bassiana, C. fumosorosea, and M. anisopliae were pathogenic to leaf-cutting ants with the five tested concentrations of spores. Higher mortality of the specimens was reached with increasing concentration. The entomopathogenic fungi evaluated in this study proved to be efficient agents for the biological control of Acromyrmex heyeri.

Seleção de fungos entomopatogênicos para controle de percevejos e bicudo-do-algodoeiro

ABSTRACT Entomopathogenic fungi stand out in the biological control of several agriculturally important insects. Six isolates of Metarhizium anisopliae, Cordyceps javanica, Beauveria sp. and B. bassiana were screened to control Anthonomus grandis, Euschistus heros, Oebalus poecilus, O. ypsilongriseus and Thyanta perditor, important insect pests of soybean, cotton and rice. The bioassays were conducted in a completely randomized design, with four replications (10 insects/replication). Significant differences for virulence were observed between the tested fungal species and isolates. For A. grandis, the most virulent isolate was M. anisopliae BRM 2335, followed by Beauveria BRM 14527 and BRM 67744 [82.5 to 97.5 % of mortality; average lethal time (LT50) of 5.9 to 7.8 days]. M. anisopliae BRM 2335 was also highly virulent to the four stink bug species (75 to 97.5 % of mortality; LT50 of 5.2 to 9.7 days). For the stink bugs, Beauveria sp. BRM 67744 was infectious to O. poecilus (75 % of mortality), but failed to control E. heros (16.9 % of mortality). C. javanica BRM 27666 and BRM 14526 showed average virulence to the stink bugs and A. grandis (17.5 to 57.3 % of mortality; LT50 of 6.0 to 9.7 days). M. anisopliae was consistently more virulent to the stink bugs than the other fungi. Therefore, M. anisopliae BRM 2335 was selected for further studies under screenhouse and field conditions to control A. grandis and other stink bug species, especially E. heros.

Bioefficacy of Isolates of Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) (Ascomycota: Hypocreales) as field Protectants of Citrullus lanatus (Thunb.) Matsum. and Nakai against Fruit Flies

The efficacy of field application of two isolates of Metarhizium anisopliae (MaD and ICIPE-69) and two isolates of Beauveria bassiana (Bb337, Bb338) was compared to that of synthetic insecticide, K-Optimal (Lambda-Cyhalothrin and Acetamiprid), for the control of major pests infesting watermelon (Citrullus lanatus), Zeugodacus cucurbitae and Dacus vertebratus. Both biopesticides and chemicals were applied twice a week from 3 weeks after sowing to 2 weeks before harvest. Experiments were conducted during the dry and rainy seasons at the garden of the International Institute of Tropical Agriculture (IITA) in Benin Republic. Significant damage was caused to watermelon, primarily in young and immature stages. During the dry season, the highest infestation rate (63.62 pupae/kg) was recorded in the control, with the lowest on plots treated with MaD (11.88 pupae/kg). However, infestation rate was not significantly different among treatments. The tendency of infestation load (number of pupae per kilogram of fruit) significantly varied during the rainy season. Thus, plots treated with ICIPE-69 had the highest number of pupae per kilogram (120.20 pupae/kg), and the lowest was on plots treated with Bb337 (44.48 pupae/kg). Marketable yields were 148.75 t/ha (MaD), 145.83 t/ha (K-optimal), 136.67 t/ha (Bb337), and 119.17 t/ha (Bb338). Beauveria bassiana (Bb337) and M. anisopliae (ICIPE-69) applied at 0.012 × 108 CFU/mL have a great potential to be used against both Z. cucurbitae and D. vertebratus infesting watermelon and have a little effect on nontarget organisms such as spiders, lady beetles, and ants.

Screening and evaluation of entomopathogenic fungi against the bean bug, Riptortus pedestris using multiple tools

AbstractThe bean bug Riptortus pedestris causes major damage to soybean and has become a serious problem due to its high resistance to insecticides. To address this problem, this study aimed to select the most effective entomopathogenic fungi for the control of R. pedestris. Selection was performed through the evaluation of virulence, thermotolerance, and UV‐B tolerance of fungal isolates against R. pedestris and conidial production on grain medium. The pathogenicity of 30 Beauveria bassiana isolates and 30 Metarhizium anisopliae isolates was evaluated, and pathogenicity was confirmed in all but 3 isolates of B. bassiana. Among the 57 isolates, 11 exhibited high virulence. Of these 11 isolates, B. bassiana JB13G1W1 and M. anisopliae CB6T1G1 and JB12R3G1 showed the highest virulence of more than 80%. The conidial production of all fungal isolates in millet grain medium was good, ranging from 108 to 109 conidia/g. The UV‐B tolerance and thermotolerance of the 57 isolates varied according to the isolate, and those of M. anisopliae isolates were slightly higher than those of B. bassiana. As a result of comparative evaluation of the virulence, conidial production, thermotolerance, and UV‐B tolerance of fungal isolates, B. bassiana JB13G1W1 and M. anisopliae CB6T1G1 and JB12R3G1 were selected as excellent fungal isolates for the control of R. pedestris. Among them, B. bassiana JB13G1W1 showed the highest virulence, with LC50 and LT50 values of 7.86 × 105 conidia/mL and 5.24 days at 108 conidia/mL, respectively. The most effective growth stage to control R. pedestris with B. bassiana JB13G1W1 was 2nd‐instar nymphs.

Entomopathogenic Fungi-Mediated AgNPs: Synthesis and Insecticidal Effect against Plutella xylostella (Lepidoptera: Plutellidae).

The insect Plutella xylostella is known worldwide to cause severe damage to brassica plantations because of its resistance against several groups of chemicals and pesticides. Efforts have been conducted to overcome the barrier of P. xylostella genetic resistance. Because of their easy production and effective insecticidal activity against different insect orders, silver nanoparticles are proposed as an alternative for agricultural pest control. The use of entomopathogenic fungi for nanoparticle production may offer additional advantages since fungal biomolecules may synergistically improve the nanoparticle's effectiveness. The present study aimed to synthesize silver nanoparticles using aqueous extracts of Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea isolates and to evaluate their insecticidal activity against P. xylostella, as innovative nano-ecofriendly pest control. The produced silver nanoparticles were evaluated by measuring the UV-vis spectrum and the mean particle size by dynamic light scattering (DLS). I. fumosorosea aqueous extract with 3-mM silver nitrate solution showed the most promising results (86-nm mean diameter and 0.37 of polydispersity). Scanning electron microscopy showed spherical nanoparticles and Fourier-Transform Infrared Spectroscopy revealed the presence of amine and amide groups, possibly responsible for nanoparticles' reduction and stabilization. The CL50 value of 0.691 mg mL-1 was determined at 72-h for the second-instar larvae of the P. xylostella, promoting a 78% of cumulative mortality rate after the entire larval stage. From our results, the synthesis of silver nanoparticles mediated by entomopathogenic fungi was successful in obtaining an efficient product for insect pest control. The I. fumosorosea was the most suitable isolate for the synthesis of silver nanoparticles contributing to the development of a green nanoproduct and the potential control of P. xylostella.