Beauveria Bassiana Isolates Research Articles

Acaricidal Efficacy of Abamectin against Tetranychus urticae Populations When Combined with Entomopathogenic Fungi

Tetranychus urticae (Acari: Tetranychidae) is a widespread and serious mite pest that infests tomato plants and causes economic losses worldwide. We investigated the acaricidal efficacy of two isolates of entomopathogenic fungi (EPF) Metarhizium robertsii (WG-7) and Beauveria bassiana (WG-12) alone and in combination with abamectin when applied topically to tomato leaf discs in the laboratory against T. urticae. We also evaluated the establishment and proliferation of T. urticae mite life stages on tomato plants in the greenhouse after application of each of the above treatments. The combination of abamectin with each EPF caused 100% mortality in T. urticae immatures after 2 days while each EPF or abamectin alone caused moderate mortality, not exceeding 74.2% 3 days post-exposure. Complete (100%) mortality of adults was observed after 5 days in leaf discs treated with M. robertsii plus abamectin whereas B. bassiana plus abamectin caused 100% mortality after 7 days. The mean number of eggs, emerged immatures, and adults were significantly reduced on both sides of the leaves (i.e., abaxial and adaxial sides) after using the combined application of M. robertsii or B. bassiana plus abamectin, compared to abamectin alone and controls. Our results reveal that the acaricidal efficacy of abamectin combined with either EPF was significantly better in managing the T. urticae life stages than either treatment alone under greenhouse conditions.

Isolation, morphological characterization, and screening virulence of Beauveria bassiana and Metarhizium robertsii fungal isolates on Galleria mellonella

Background Entomopathogenic fungi exists naturally in plants as an asymptote and have the potential to reduce the population of insect pests through indirect interactions. This study was conducted to detect and characterize the endophytic fungi Beauveria bassiana and Metarhizium robertsii from the rhizosphere soil of tomato plants and their virulence effect on Galleria melonella. Methods From the rhizosphere soil of 40 tomato fields, three Beauveria bassiana and seven Metarhizium robertsii isolates were isolated using the galleria bait method. All fungi isolate were morphologically characterized by their colony color, shape, and surface texture. Isolates with the highest percentages of germination, conidial yield, and radial growth were selected, and their virulence was evaluated on second instar larvae of Galleria melonella under laboratory conditions. Results In this study, Beauveria bassiana showed white colony color and aseptate hyphae, whereas Metarhizium robertsii showed dark green to light green colony color and septate hyphal structures. Maximum spore production and conidial length were obtained by Beauveria bassiana isolate APPRC-27 with 2.67x107 spores ml-1 and 3.24 µm, respectively. Colony radial growth rates ranged from 1.73 to 3.24 mm day-1. The results revealed that the highest mortality rate of Galleria melonella (100%) was obtained by Metarhizium robertsii isolates K-61 and K-102 at a concentration of 1x108 conidial ml-1 at 7 days post-inoculation. The lowest mortality rate was registered by Metarhizium robertsii isolate RST-11. Conclusions In the present study, isolates that produced the most spores and had the highest germination rates were the most virulent to Galleria mellonella second instar larvae. Therefore, virulent entomopathogenic fungi, Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of insect pests.

Evaluation of endophytic colonization and establishment of entomopathogenic fungi against Tuta absoluta (Lepidoptera: Gelechiidae) in tomato plants.

The tomato, Solanum lycopersicum L., is one of the most important horticultural crops that can be consumed fresh or after being processed worldwide. The tomato leaf miner (Tuta absoluta) is one of the most devastating pest to tomato plants due to its mine-feeding nature in the mesophyll tissue of the plant. Fungal entomopathogens can exist naturally in plants as an asymptote. This study aimed to detect the endophytic colonization of Beauveria bassiana and Metarhizium robertsii within tomato plants via artificial inoculation and their virulence effects on Tuta absoluta. Isolates with the highest percent germination and virulence against T. absoluta were selected for endophytic evaluation within tomato plants by different artificial inoculation techniques. This study revealed that, isolates with the highest percent germination and virulent to Tuta absoluta had the potential to colonize tomato plants. The result showed that, the maximum mortality rate (97.5%) of Tuta absoluta larvae was achieved by Metarhizium robertsii isolate K-61 at a concentration of 1x10 8conidial/ml at 7 days post inoculated. However, the highest cumulative mortality (100%) was recorded by Beauveria bassiana isolate APPRC-27 at 10 days post inoculated through the direct contact method. The highest endophytic colonization was registered by isolate APPRC-27 (76.67%) at 7 days post-inoculated using the leaf spray technique, but it declined to 11.67% after 28 days of inoculated. In the case of the seedling inoculation technique, the highest endophytic colonization was obtained in the root tissues of tomatoes at 28 days of inoculated by isolate K-61. This study revealed that the leaf spray inoculation technique was the most effective method, followed by seedling inoculation, for the deployment of Beauveria bassiana and Metarhizium robertsii endophytes in tomato plant tissues. Therefore, virulent Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of Tuta absoluta if deployed as endophytes.

Effect of entomopathogenic Beauveria bassiana (Balls.) Vuill. isolates on Myzus persicae (Sulzer) (Hemiptera: Aphididae)

The aim of the study was to determine the lethal effect of 1 x 108 conidia mL-1 concentration of local Beauveria bassiana isolates (ET 10, BMAUM-M6-4, Bb 1) against M. persicae under laboratory conditions. For the spraying method, B. bassiana isolates was applied to M. persicae nymphs with a hand spray. In this context, the experiments were carried out in a randomized plots experimental design with ten replicates with ten nymphs in each Petri plate. After the applications, the number of live individuals was recorded by counting the 1st, 3rd, 5th and 7th days and the percentage mortality rate was calculated. On the third and fifth days of the experiment, the highest mortality rates of 64 and 95% were recorded for the Bb 1 isolate of B. bassiana, respectively. In the seventh day counts, 100% mortality rates were determined for Bb 1 and ET 10 isolates and 99% for the BMAUM-M6-4 isolate. In addition, the mortality date (LT50) values were calculated as 3.62 days for ET 10 isolate, 3.60 days for BMAUM M6-4 isolate, and 2.93 days for Bb 1 isolates, respectively. As a result, it is thought that B. bassiana isolates can be used in biological control practices within the scope of integrated pest management program against M. persicae.

Ability of Beauveria bassiana to suppress Colletotrichum truncatum and increase the growth of chili plants (Capsicum annuum)

Anthracnose is a disease caused by Colletotrichum sp., which can reduce the quality and yield of red chili by 45-60%. This study aimed to determine the ability of different Beauveria bassiana isolates to control anthracnose in chili. The research employed a Randomized Block Design (RBD) consisting of 6 treatments and 5 replications. The treatments included a control and 5 different B. bassiana isolates (PD114, TD312, WS, BbKo, KT2B21). The observed variables included incubation period, disease incidence and severity, plant height, number of leaves, flowering time, and chili fruit weight. The results showed that the application of different B. bassiana isolates have effectively inhibited the development of Colletotrichum truncatum, which caused anthracnose in chili. B. bassiana has demonstrated the ability to prolong the incubation period of C. truncatum (5.40 days) and reduce the percentage of disease incidence (16%). Furthermore, the application of B. bassiana increased the height of chili plants (40.40 cm) and the number of leaves (32 leaves), accelerated the flowering time (42.80 days), and boosted chili production (178.25 g). The WS and TD312 isolates revealed the most significant results. Although the severity of the disease was not impacted, the 2 isolates provided notable agronomic benefits to the chili plants.

Evaluation of virulence of isolates of certain species of entomopathogenic anamorphic ascomycetes (Fungi, Ascomycota) in relation to adult individuals of the tick <i>Ixodes Persulcatus</i>

In nature, entomopathogenic fungi (EPF) play an important role in the control of population density in many arthropods. The lethal effects of EPF on ixodid ticks (Ixodidae) have been, however, reported mainly in southern warm-loving species, which are mostly not found in Europe. The aim of this study was to evaluate in laboratory the virulence of nine selected psychrotolerant EPF isolates of Beauveria bassiana s. l. (6), Akanthomyces cf. muscarius (2) and Metarhizium anisopliae s. l. (1) at a moderate average daily temperature of +14°C in relation to overwintering adult taiga ticks (Ixodes persulcatus), collected at the end of May in the Kondopoga region of the Republic of Karelia. Under this temperature, the use of suspensions for infection with a concentration of infectious spores (conidia) of 3×107 per 1 ml, all isolates showed a lethal effect on ticks. Among these isolates, the most virulent and rapidly acting one was B. bassiana s. l. CCi-Ar (SI)14 from the Arkhangelsk Province, Bolshoy Solovetsky Island (N 65°, E 35°), that killed 70% of specimens after 9 days, and 95% after 11 days. At the same time, it was found that male ticks have a slightly higher death rate from fungal infections. However, the potential suitability of some EPF isolates for biological control of I. persulcatus populations at low temperatures, shown in this study, requires confirmation in further tests in real conditions of recreational areas actively visited by humans, where infection with dangerous pathogens (tick-borne encephalitis, Lyme borreliosis) transmitted by tick bites often occurs.

Biological control potential of two Beauveria bassiana isolates against the stink bugs Nezara viridula L. and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae) in common bean

BackgroundThe stink bugs, Nezara viridula L. and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae) are the most important and widespread species of polyphagous stink bugs in the tropical and subtropical regions of Latin America, which affect the quality and yield of the common bean (Phaseolus vulgaris L.). The use of synthetic chemical insecticides is the major control strategy to manage stink bugs in common beans and alternatives are needed. In this study, mortality and median Lethal Time (LT50) of two Cuban isolates of the entomopathogenic fungus Beauveria bassiana (18 S-O-R and 96 P-O-E), as well as one commercial Cuban isolate (Bb-18), at a concentration of 1 × 108 conidia/ml were evaluated. These evaluations were conducted against both stink bug species using Petri dish bioassays and a semi-field experiment in common beans.ResultsIn Petri dish bioassays, the isolates 18 S-O-R and 96 P-O-E caused 100% mortality of both N. viridula and P. guildinii. This was significantly higher than for isolate Bb-18, which caused 86.3% N. viridula and 81.3% P. guildinii mortality. In the semi-field experiment, when pooling both stink bug species, total mortality after 14 days was 91.3% for 18 S-O-R, 80.0% for 96 P-O-E and 73.8% for Bb-18 isolates. LT50 value for isolate 18 S-O-R tested under laboratory conditions was 6.04 ± 0.18 days for N. viridula and 5.32 ± 0.14 days for P. guildinii at the same concentration of 1 × 108 conidia/ml. LT50 value for isolate 18 S-O-R in semi field was 6.79 ± 0.37 days for N. viridula and 7.71 ± 0.32 days for P. guildinii at 1 × 108 conidia/ml.ConclusionThe study highlights the potential of B. bassiana 18 S-O-R as a promising candidate for control of stink bugs in common bean under tropical conditions as an alternative to conventional chemical insecticides in integrated pest management (IPM) programs. Moving forward, further research should focus on validating the efficacy under diverse field conditions and integrating application methods into practical IPM approaches. Future use of B. bassiana will enhance sustainability and reduce environmental impacts associated with pesticide use.

Viability and virulence of freeze-dried Beauveria bassiana, Metarhizium acridum, and Hirsutella thompsonii isolates under non-refrigerated conditions in Ghana

ABSTRACT The necessity of cold storage for mycoinsecticides poses a logistical challenge in tropical Africa, where maintaining consistent refrigeration is a major obstacle. To investigate alternative preservation methods, our study evaluates conidial-based freeze-dried formulations of Beauveria bassiana (IMI 389521), Metarhizium acridum (IMI 330189), and mycelial-based freeze-dried formulations of Hirsutella thompsonii (IMI 327488 and IMI 391722). Propagules were cryoprotected with lactose, mannitol, and raffinose, encapsulated, and freeze-dried in plastic and glass vials. Bioformulations in glass vials were cryoprotected with mannitol only. Viability (CFU/g each day) of bioformulations, following 16-weeks-storage, and their virulence (at 1 × 107 conidia mL−1 in six days) against key pests of maize and cassava in Africa (larger grain borer, variegated grasshopper and cassava green mite) were determined under ambient laboratory conditions in Ghana. Our results show that non-freeze-dried conidia of B. bassiana and M. acridum had significantly higher viability and efficacy than freeze-dried versions, when stored under non-refrigerated conditions (averaging 27.7°C, 78.8% RH). Freeze-dried H. thompsonii mycelia were neither viable nor virulent against cassava green mite. Freeze-dried B. bassiana and M. acridum in plastic vials remained viable for 12 weeks, while in glass vials they were viable for seven weeks. Freeze-dried B. bassiana in both plastic and glass vials caused 38–43% mortality in larger grain borer, and M. acridum caused 45–82% mortality in variegated grasshopper. Further, conidia cryoprotected with lactose had significantly higher viability and mortality than raffinose and mannitol. Our research contributes to mycoinsecticide development, particularly in the context of storage and application challenges in tropical climates.

Native Entomopathogenic Fungi Isolated from Rhynchophorus palmarum (Linnaeus, 1758) in Northeast Brazil.

Both palm weevils, the South American (Rhynchophorus palmarum) (SAPW) and the red palm weevil (R. ferrugineus, RPW), are present in South America, affecting commercial, ornamental, and native palms. These pests oviposit and thrive on selected Arecaceae. R. palmarum mainly infests coconut (Cocos nucifera), oil palms (Elaeis guineensis), and other ornamental and native palms in America, causing a significant social impact on growers. The weevils fulfill a significant ectosymbiotic macro- and microorganism role in the first period of larval development, worsening the damage which, during this period, is not yet apparent. Palm protection in the Brazilian context suggests the use of indigenous agents for microbiological biocontrol. This research identifies three Brazilian Beauveria bassiana isolates: CVAD01, CVAD02, and CVAD06. The results suggest that the strain's impact on R. palmarum can also be compared with that of the commercial strain Beauveria bassiana. Phylogenetic analysis allowed the delimitation of species of Beauveria (Hypocreales). Pathogenicity tests caused significant mortality in R. palmarum. The isolates CVAD01, CVAD02, and CVADO6 showed high pathogenicity between 7 and 21 days, with mortality rates between 90 and 100%, suggesting that they may be effective biological control agents of R. palmarum in the field when used, within available means, to mitigate the impact of R. palmarum and R. ferrugineus in South America.

Isolation, morphological characterization, and screening virulence of Beauveria bassiana and Metarhizium robertsii fungal isolates in Galleria mellonella

Background Entomopathogenic fungi exists naturally in plants as an asymptote and have the potential to reduce the population of insect pests through indirect interactions. This study was conducted to detect and characterize the endophytic fungi Beauveria bassiana and Metarhizium robertsii from the rhizosphere soil of tomato plants and their virulence effect on Galleria melonella. Methods From the rhizosphere soil of 40 tomato fields, three Beauveria bassiana and seven Metarhizium robertsii isolates were isolated using the galleria bait method. All fungi isolate were morphologically characterized by their colony color, shape, and surface texture. Isolates with the highest percentages of germination, conidial yield, and radial growth were selected, and their virulence was evaluated on second instar larvae of Galleria melonella under laboratory conditions. Results In this study, Beauveria bassiana showed white colony color and aseptate hyphae, whereas Metarhizium robertsii showed dark green to light green colony color and septate hyphal structures. Maximum spore production and conidial length were obtained by Beauveria bassiana isolate APPRC-27 with 2.67x107 spores ml-1 and 3.24 µm, respectively. Colony radial growth rates ranged from 1.73 to 3.24 mm day-1. The results revealed that the highest mortality rate of Galleria melonella (100%) was obtained by Metarhizium robertsii isolates K-61 and K-102 at a concentration of 1x108 conidial ml-1 at 7 days post-inoculation. The lowest mortality rate was registered by Metarhizium robertsii isolate RST-11. Conclusions In the present study, isolates that produced the most spores and had the highest germination rates were the most virulent to Galleria mellonella second instar larvae. Therefore, virulent entomopathogenic fungi, Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of insect pests.

Entomopatojen fungus, Beauveria bassiana’nın Myzus persicae ve Trialeurodes vaporariorum üzerindeki etkisinin adipokinetik hormon ile arttırılması

The aim of this study was to investigate the effects of the co-application of entomopathogenic fungi (EMFs) and adipokinetic hormone (AKH) on the green peach aphid, Myzus persicae, and the greenhouse whitefly, Trialeurodes vaporariorum. Single and combined applications of two Beauveria bassiana isolates with AKH were tested. The green peach aphid was more susceptible to treatments than the greenhouse whitefly. Mortality rates of 58%, 67%, %95, and 95% were observed for the single and combined applications of BMAUM M6-4 and BMAUM LD 2016, respectively, against M. persicae. The application of these fungi singly and in combination with AKH against T. vaporariorum caused mortality rates of 44%, 68% and 45% and78%, respectively. The protein level measured at 595 nm with the standard, Bovine Serum Albumin (BSA), for M. persicae and T. vaporariorum revealed that the highest level of nutrient mobilization was for the BMAUM M6-4+AKH treatment. The level of carbohydrate (glucose) was slightly higher in the AKH treatments when compared to the control group. The lowest glucose level was measured for the entomopathogenic fungi application, and highest level was determined for the isolates combined with AKH. The mechanism of action of AKH applied with B. bassiana isolates is not fully understood. Therefore, more detailed studies are needed in this area to determine the potential of this promising approach for inclusion in IPM programs for the control of these insect pests.

Virulence of Local Isolates of The Entomopathogenic Fungus Beauveria bassiana on Egg and Adult Stages of Tomato Leaf Miner, Tuta absoluta

Hasan, A.H., M. Ahmad, O. Hamoudi and M. Moufleh. 2024. Virulence of Local Isolates of The Entomopathogenic Fungus Beauveria bassiana on Egg and Adult Stages of Tomato Leaf Miner, Tuta absoluta. Arab Journal of Plant Protection, 42(3): 340-348. https://doi.org/10.22268/AJPP-001252 The efficacy of four local isolates of the entomopathogenic fungus Beauveria bassiana (Ascomycota: Hypocreales), (b6 isolated from citrus orchard soil (Harisoon), b7 from greenhouse soil (Alkhrab), b8 from palm weevil pupae (Lattakia) and b10 from olive orchard soil (Mengella), were tested on the egg and adult stages of the tomato leafminer Tuta absoluta by direct spraying for each stage with three different concentrations of fungal spore suspensions 2×104 , 2×106 and 2×108 spores/ml. The results obtained showed that both insect stages were very sensitive to fungal infection to varying degrees and there were significant differences in the hatching rate and adult mortality rate caused by the four isolates in comparison with the control treatment. The b8 and b10 isolates were the most effective on both insect stages at all concentrations tested. Corrected mortality rates at the highest concentration (2×108 spore/ml) were 82.59% for b8 isolate and 86.30% for b10 isolate on eggs and LC50 was 1×106 spores/ml for b8 isolate and 8×105 spores/ml for b10 isolate, whereas the corrected mortality rate for both were 100% on adults, 8 days after treatment, and by using the highest spore concentration. The LT50 was 3.2 days for both isolates and the LC50 was 2×104 spores/ml for b8 isolate and 1×105 spores/ml for b10 isolate under laboratory conditions. Keywords: Biological control, Beauveria bassiana, Tuta absoluta, mortality, LT50, LC50

Control of Root-knot Nematodes (Meloidogyne spp.) on Tomato (Lycopersicum esculentum Mill.) using Antagonist Fungi

Nematodes Meloidogyne spp. is the most important phytonematode in the world, especially in agriculture in tropical areas. The level of root damage to tomato plants caused by the nematode Meloidogyne spp. can reach 68.3%. In general, control of plant parasitic nematodes is still carried out using pesticides in the form of insecticides which can also be used as nematicides. Continuous use of chemicals to control nematodes can cause environmental pollution, resurgence and nematode resistance to chemicals. One alternative control is biological. One of the biological agents that can be used to control Meloidogyne nematodes is the endophytic fungus Beauveria bassiana and Trichoderma asperellum. The research aims to obtain the best isolates of endophytic fungi for controlling rootknot nematodes (Meloidogyne spp.). The isolates tested were 2 Beauveria bassiana isolates and 2 Trichoderma asperellum isolates. The results showed that the fungus isolate Beauveria bassiana isolate TD312 had a higher ability to control Meloidogyne spp on tomatoes.

Isolation, morphological characterization, and screening a virulence of Beauveria bassiana and Metarhizium robertsii as bioagents

Background: Entomopathogenic fungi exists naturally in plants as an asymptote and has the potential to reduce the population of insect pests through indirect interactions. This study was conducted to detect and characterize the endophytic fungi Beauveria bassiana and Metarhizium robertsii from the rhizosphere soil of tomato plants and their virulence effect on Galleria melonella. Methods: From the rhizosphere soil of 40 tomato fields, three Beauveria bassiana and seven Metarhizium robertsii isolates were identified using the galleria bait method. All fungi isolates were morphologically characterized by their colony color, shape, and surface texture. Isolates with the highest percentages of germination, conidial yield, and radial growth were selected, and their pathogenicity was evaluated on second instar larvae of Galleria melonella under laboratory conditions. Results: In this study, Beauveria bassiana showed white colony color and aseptate hyphae, whereas Metarhizium robertsii showed dark green to light green colony color and septate hyphal structures. Maximum spore production and conidial length were obtained by Beauveria bassiana isolate APPRC-27 with 2.67x107 spores ml-1 and 3.24 µm, respectively. Colony radial growth rates ranged from 1.73 to 3.24 mm day-1. The results revealed that the highest mortality rate of Galleria melonella (100%) was obtained by Metarhizium robertsii isolates K-61 and K-102 at a concentration of 1x108 conidial ml-1 at 7 days post-inoculation. The lowest mortality rate was registered by Metarhizium robertsii isolate RST-11. Conclusions: In the present study, isolates that produced the most spores and had the highest germination rates were the most virulent to Galleria mellonella second instar larvae. Therefore, virulent entomopathogenic fungi, Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of pests.

The effect of two isolates of Beauveria bassiana (Bals.) Vull. on the larvae of confused flour beetle [Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)

The confused flour beetle cause economic losses in stored products, especially in products obtained from wheat. Although using insecticides against storage pests is an effective method, their frequent and continuous use can lead to resistance and toxicity issues in non-target organisms. In this study, the effect of local Beauveria bassiana isolates (BMAUM LD.2016 and BMAUM M6-4) on the 3rd instar larvae of confused flour beetle (Tribolium confusum) was determined under laboratory conditions. As a result of the experiment, both isolates of B. bassiana were found to be more effective on the larvae in the spraying method compared to the dipping method. In the spraying method, mortality rates on the 9th day were 72% in BMAUM LD.2016 isolate, 34% in the dipping method, respectively. Mortality rates of BMAUM M6-4 isolate were recorded as 96% in the spraying method and 8% in the dipping method. In the spraying method, the mortality date (LT50) was determined as 6.09 days for BMAUM LD.2016 isolate and 3.90 days for BMAUM M6-4 isolate. The LT50 value could not be calculated in the dipping method, since the mortality rates were below 50% for both isolates. BMAUM M6-4 isolate caused higher mortality in larvae than BMAUM LD.2016 isolate. As a result, B. bassiana isolates have shown a high level of effectiveness against T. confusum, demonstrating that they can be used as isolates for insect control.

Detection of a PCR‐based mating type for native intraspecific Beauveria bassiana isolates

AbstractThis study developed a PCR‐based mating‐type analysis of 30 intraspecific Beauveria bassiana isolates after ITS phylogenetic analysis. Out of 30 isolates, only 11 B. bassiana isolates, viz., Bb4, Bb5, Bb11, Bb18, Bb19, Bb20, Bb23, Bb25, Bb27, Bb28, and Bb29, exhibited amplification of the mating‐type loci and were thought to be heterothallic. All of these isolates, with the exception of Bb20, had MAT1 mating‐type amplification. All these 11 isolates were clustered together with the MAT1‐ and MAT2‐specific reference strains of B. bassiana in the maximum likelihood phylogenetic analysis of mating‐type genes (IFO 31953 and IFO 31676, respectively). Although the PCR products obtained by the mating‐type assay were short, the phylogenetic trees of the mating‐type genes gave better resolution than that of the ITS region. Understanding the mating type of fungi can clarify the biological species concept and the identification of sex‐related genes in fungi without the presence of teleomorphs. So, combining phylogenetic, developmental, and mating research on each teleomorph specimen has the potential to clarify the systematics of Beauveria species.

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.

Isolation, morphological characterization, and screening virulence of Beauveria bassiana and Metarhizium robertsii fungal isolates on Galleria mellonella.

Entomopathogenic fungi exists naturally in plants as an asymptote and have the potential to reduce the population of insect pests through indirect interactions. This study was conducted to detect and characterize the endophytic fungi Beauveria bassiana and Metarhizium robertsii from the rhizosphere soil of tomato plants and their virulence effect on Galleria melonella. From the rhizosphere soil of 40 tomato fields, three Beauveria bassiana and seven Metarhizium robertsii isolates were isolated using the galleria bait method. All fungi isolate were morphologically characterized by their colony color, shape, and surface texture. Isolates with the highest percentages of germination, conidial yield, and radial growth were selected, and their virulence was evaluated on second instar larvae of Galleria melonella under laboratory conditions. In this study, Beauveria bassiana showed white colony color and aseptate hyphae, whereas Metarhizium robertsii showed dark green to light green colony color and septate hyphal structures. Maximum spore production and conidial length were obtained by Beauveria bassiana isolate APPRC-27 with 2.67x10 7 spores ml -1 and 3.24 µm, respectively. Colony radial growth rates ranged from 1.73 to 3.24 mm day -1. The results revealed that the highest mortality rate of Galleria melonella (100%) was obtained by Metarhizium robertsii isolates K-61 and K-102 at a concentration of 1x10 8 conidial ml -1 at 7 days post-inoculation. The lowest mortality rate was registered by Metarhizium robertsii isolate RST-11. In the present study, isolates that produced the most spores and had the highest germination rates were the most virulent to Galleria mellonella second instar larvae. Therefore, virulent entomopathogenic fungi, Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of insect pests.

Isolation, morphological characterization, and screening a virulence of Beauveria bassiana and Metarhizium robertsii as bioagents

Background: Entomopathogenic fungi exists naturally in plants as an asymptote and has the potential to reduce the population of insect pests through indirect interactions. This study was conducted to detect and characterize the endophytic fungi Beauveria bassiana and Metarhizium robertsii from the rhizosphere soil of tomato plants and their virulence effect on Galleria melonella. Methods: From the rhizosphere soil of 40 tomato fields, three Beauveria bassiana and seven Metarhizium robertsii isolates were identified using the galleria bait method. All fungi isolates were morphologically characterized by their colony color, shape, and surface texture. Isolates with the highest percentages of germination, conidial yield, and radial growth were selected, and their pathogenicity was evaluated on second instar larvae of Galleria melonella under laboratory conditions. Results: In this study, Beauveria bassiana showed white colony color and aseptate hyphae, whereas Metarhizium robertsii showed dark green to light green colony color and septate hyphal structures. Maximum spore production and conidial length were obtained by Beauveria bassiana isolate APPRC-27 with 2.67x107 spores ml-1 and 3.24 µm, respectively. Colony radial growth rates ranged from 1.73 to 3.24 mm day-1. The results revealed that the highest mortality rate of Galleria melonella (100%) was obtained by Metarhizium robertsii isolates K-61 and K-102 at a concentration of 1x108 conidial ml-1 at 7 days post-inoculation. The lowest mortality rate was registered by Metarhizium robertsii isolate RST-11. Conclusions: In the present study, isolates that produced the most spores and had the highest germination rates were the most virulent to Galleria mellonella second instar larvae. Therefore, virulent entomopathogenic fungi, Beauveria bassiana and Metarhizium robertsii, are promising bioagents for the control of pests.

Growth of Zea mays in response to artificial inoculation with endophytic Beauveria bassiana compared to Trichoderma sp. “atroviride B”

ABSTRACT Demand for sustainable crop production is putting pressure on growers to improve yield while using environmentally friendly solutions. Recently, entomopathogenic fungi have been reported to promote plant growth under certain conditions; however, colonisation of plants as endophytes may be inconsistent or persistence within plant tissues brief. We studied the effects of inoculating three Beauveria bassiana isolates in comparison with a known plant-growth-promoting isolate of Trichoderma sp. “atroviride B” as a positive control, on the growth of maize (Zea mays L.). We tested the plant response by measuring multiple parameters including biomass, length, chlorophyll content and root architecture following inoculation, to identify even subtle plant growth effects. Fungal isolates were inoculated by inserting hyphae through a small wound made in the stem of emerging seedlings, a technique that has not been previously used for B. bassiana. Results showed neutral effects on biomass, but plants exhibited root architecture changes because of inoculation with B. bassiana isolate (FRh2), which increased fine root length and because of T. sp. “atroviride B” which increased larger diameter root length. A higher chlorophyll content was observed for plants inoculated with B. bassiana isolate (J18), although this did not correlate with biomass differences. The inoculation technique enabled the comparison of systemic effects to the plants and may have affected subtle but important root-trait modifications. Changes to root architecture can impact resource acquisition in plants, therefore this study highlights the importance of measuring various physiological changes in the plant host when assessing for potential growth effects.