Pathogenicity Of Entomopathogenic Fungi Research Articles

Altered Gene Expression of the Parasitoid Pteromalus puparum after Entomopathogenic Fungus Beauveria bassiana Infection

Both parasitoids and entomopathogenic fungi are becoming increasingly crucial for managing pest populations. Therefore, it is essential to carefully consider the potential impact of entomopathogenic fungi on parasitoids due to their widespread pathogenicity and the possible overlap between these biological control tools during field applications. However, despite their importance, little research has been conducted on the pathogenicity of entomopathogenic fungi on parasitoids. In our study, we aimed to address this knowledge gap by investigating the interaction between the well-known entomopathogenic fungus Beauveria bassiana, and the pupal endoparasitoid Pteromalus puparum. Our results demonstrated that the presence of B. bassiana significantly affected the survival rates of P. puparum under laboratory conditions. The pathogenicity of B. bassiana on P. puparum was dose- and time-dependent, as determined via through surface spraying or oral ingestion. RNA-Seq analysis revealed that the immune system plays a primary and crucial role in defending against B. bassiana. Notably, several upregulated differentially expressed genes (DEGs) involved in the Toll and IMD pathways, which are key components of the insect immune system, and antimicrobial peptides were rapidly induced during both the early and late stages of infection. In contrast, a majority of genes involved in the activation of prophenoloxidase and antioxidant mechanisms were downregulated. Additionally, we identified downregulated DEGs related to cuticle formation, olfactory mechanisms, and detoxification processes. In summary, our study provides valuable insights into the interactions between P. puparum and B. bassiana, shedding light on the changes in gene expression during fungal infection. These findings have significant implications for the development of more effective and sustainable strategies for pest management in agriculture.

The G-protein coupled receptor GPRK contributes to fungal development and full virulence in Metarhizium robertsii

G-protein-coupled receptor K (GPRK), which is a class VI fungal G-protein-coupled receptor (GPCR), plays a critical role in plant immunity against pathogens by mediating the endocytic pathway, influencing metabolism in response to environmental signals, and regulating asexual reproduction and pathogenic development. However, the function of these proteins in entomopathogenic fungi has rarely been investigated. Accordingly, we characterized MrGPRK, a GPCR in the entomopathogenic fungus Metarhizium robertsii containing a C-terminal seven-transmembrane and a conserved regulator of G protein signaling domain, and found that it localized to endosomes. Mutant phenotype assays showed that a ΔMrGprk strain displayed increased defects in radial growth (~28%) and decreased conidial production (~80%) compared with a wild-type strain. Decreased conidiation rates coincided well with the repression of conidiation-related regulatory genes, including three key conidial transcription factors: brlA, abaA, and wetA. MrGprk deficiency impaired full virulence (both topical and injectable inoculations). Further analysis demonstrated that deleting fungal MrGprk decreased the rates of appressorium formation and suppressed the transcription of several genes contributing to appressorial turgor pressure, cuticle penetration, and pH regulation. Additionally, the ΔMrGprk strain showed higher cyclic (cAMP) levels, suggesting that this GPCR is critical for cAMP signal transduction. In summary, MrGPRK was found to contribute to vegetative growth, conidial production, and full virulence of M. robertsii. These findings are conducive to a better understanding of the roles of GPCRs in the development and pathogenicity of entomopathogenic fungi.

Avaliação de fungos no controle da mosca-das-frutas na preservação do mercado brasileiro de frutas

O controle biológico, com a utilização de fungos entomopatogênicos, tem sido umas das promissoras alternativas no controle de moscas-das-frutas. Este estudo teve como objetivo avaliar a patogenicidade dos fungos entomopatogênicos das espécies Metarhizium anisopliae (Metsch.) Sorok. e Beauveria bassiana (Bals.) em larvas de 2º e 3º instar, pupas e adultos da mosca-das-frutas Ceratitis capitata Wiedemann (Diptera: Tephritidae). O experimento foi conduzido nos Laboratórios de Zoologia de Invertebrados e de Fitopatologia do Centro de Ciências Agrárias, Universidade Federal da Paraíba, no município de Areia - PB. Neste estudo foram utilizados dois isolados, Metarhizium anisopliae IDCB425 e Beauveria bassiana IDCB66, em diferentes concentrações. Verificou-se que o potencial de infecção de ambos isolados é maior em larvas de 2º e 3º ínstares e de adultos de C. capitata, do que em pupas. A taxa de mortalidade de C. capitata aumenta à medida que as suspensões se tornam mais concentradas. O isolado de IDCB66 de B. bassiana é mais eficiente à C. capitata, que o isolado IDCB425 de M. anisopliae.

Susceptibility of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), a Eucalyptus pest, to entomopathogenic fungi

ABSTRACT: Thaumastocoris peregrinus Carpintero and Dellape (Hemiptera: Thaumastocoridae) is a sap-sucking insect that has become a major pest of eucalypts. The entomopathogenic fungi Beauveria bassiana (Bals.-Criv.) Vuill. and Metarhizium anisopliae (Metsch.) Sorokin have the potential to control insect pests. This study evaluated the susceptibility of T. peregrinus to two commercial products based on conidia of B. bassiana and M. anisopliae. The fungi were sprayed onto adults of T. peregrinus at a concentration of 1 × 108 conidia mL−1 to evaluate their pathogenicity and conidial production on the insect cadavers. Beauveria bassiana caused 100 % mortality, while M. anisopliae caused more than 80 % mortality of T. peregrinus adults 11 days after fungi application. The fungi colonized the head and thorax regions and caused high mortality rates through conidial production. Pathogenicity of entomopathogenic fungi B. bassiana and M. anisopliae to T. peregrinus show potential to use these fungi in integrated pest management.

Diversity and characterization of entomopathogenic fungi from rhizosphere of maize plants as potential biological control agents

Abstract. Nelly N, Syahrawati MY, Hamid H, Habazar T, Gusnia DN. 2019. Diversity and characterization of entomopathogenic fungi from rhizosphere of maize plants as potential biological control agents. Biodiversitas 20: 1435-1441. The diversity and characters of entomopathogenic fungi in soil are influenced by cultivation techniques. This study aims at determining the characters and pathogenicity of entomopathogenic fungi in maize plant. Materials were extracted from maize plant rhizosphere at different planting system (monoculture, polyculture, and monoculture of corn on formerly oil palm plantation or replanting) in Nagari Koto Baru, Luhak Nan Duo Subdistrict, West Pasaman District, and West Sumatra Province. Insect bait and series dilution were used to carry out the isolation, while Tenebrio molitor larvae were used for the pathogenicity test. Parameters observed include macroscopic and microscopic characteristics, and pathogenicity of entomopathogenic fungi. The result shows that there are three types of entomopathogenic fungi with various features. After identification, it was known that Aspergillus and Metarizium were obtained from mono, polyculture and by replanting crops, while Beauveria was found from the rhizosphere of corn grown in polyculture with pathogenicity identified as one of the high causes of death to larvae T. molitor with LT50 ranging from 48.03-48.48 hours.
 Key words: Characterisation, diversity, entomopathogenic fungi, rhizosphere

The Herbivore-Induced Plant Volatiles Methyl Salicylate and Menthol Positively affect Growth and Pathogenicity of Entomopathogenic Fungi

Some herbivore-induced-plant volatiles (HIPVs) compounds are vital for the functioning of an ecosystem, by triggering multi-trophic interactions for natural enemies, plants and herbivores. However, the effect of these chemicals, which play a crucial role in regulating the multi-trophic interactions between plant-herbivore-entomopathogenic fungi, is still unknown. To fill this scientific gap, we therefore investigated how these chemicals influence the entomopathogenic fungi growth and efficacy. In this study, Lipaphis erysimi induced Arabidopsis thaliana HIPVs were collected using headspace system and detected with GC-MS, and then analyzed the effects of these HIPVs chemicals on Lecanicillium lecanii strain V3450. We found that the HIPVs menthol and methyl salicylate at 1 and 10 nmol·ml−1 improved many performance aspects of the fungus, such as germination, sporulation, appressorial formation as well as its pathogenicity and virulence. These findings are not only important for understanding the multi-trophic interactions in an ecosystem, but also would contribute for developing new and easier procedures for conidial mass production as well as improve the pathogenicity and virulence of entomopathogenic fungi in biological pest management strategies.

Pathogenicity of entomopathogenic fungi against white grub, Leucopholis lepidophora (Blanchard) infesting sugarcane under pot culture experiment

The pathogenicity of entomopathogenic fungi, Metarhizium anisopliae (Metsch.) Sorokin, Beauveria brongniartii (Sacc.) and Beauveria bassiana (Balsana) Vuillrmin, was done against white grub, Leucopholis lepidophora ( Blanchard) infesting sugarcane under pot culture experiment. In this investigation the virulence of different entomopathogenic fungi were determined by FYM enriched techniques against third instar grubs of Leucopholis lepidophora (Blanch.).An overall concentration range of 2x10 4 -2x10 8 conidia ml -1 of entomopathogenic fungi were used but among these, 2x10 8 conidia ml -1 concentration was the most promising for highest grub mortality in each entomopathogenic fungi. M. anisopliae was found to be most effective fungus as compared to other fungi. It was observed that 34.49-62.07 per cent grub mortality occurred on 45 DAT in M. anisopliae at different conidial concentrations. B. brongniartii recorded 31.03 to 58.62 per cent grub mortality while, B. bassiana caused 27.59 to 55.18 per cent grub mortality at different conidial concentration. The results showed that M. anisopliae was found to be more pathogenic than B. brongniartii and B. bassiana .

Enzymatic Activity and Pathogenicity of Entomopathogenic Fungi from Central and Southeastern Mexico to Diaphorina citri (Hemiptera: Psyllidae)

Abstract. To understand the relationship between pathogenicity and enzymatic activity of fungal isolates associated with Diaphorina citri Kuwayama, three isolates of Beauveria bassiana (Bals.) Vuill. and six of Hirsutella citriformis Speare from southeastern and Central Mexico were characterized enzymatically. Pathogenicity against D. citri was evaluated in four of them. They killed >90%, and no differences among isolates were found; however, by the change rate (rL) of the logistic model, a trend of more mortality (1.12) was confirmed in the Bb-Ch isolate of B. bassiana obtained from adult D. citri from Quintana Roo State, while the Y-2 isolate of H. citriformis from Yucatan State resulted in least mortality (0.74). Enzymatic production, both intra and inter-specific, varied, but greatest variability was found in proteases, and there were strains without proteolytic activity. A positive relationship (r = 0.84 to 0.98) was found only between intracellular proteases versus pathogenicity; isolates with more ...

OCCURRENCE OF ENTOMOPATHOGENIC FUNGI IN SOILS FROM FESTUCA PRATENSIS HUDS. CROP

Entomopathogenic fungi are the largest group of microorganisms existing in the soil environment. Occurrence and pathogenicity of entomopathogenic fungi in soil is dependent on many factors affecting the soil environment. The aim of this study was to compare the species composition and the intensity of the occurrence of entomopathogenic fungi in soils from monoculture crops of Festuca pratensis Huds. The study material consisted of soil samples taken from the experiment conducted in two experimental stations of the Research Centre for Cultivars Study. The insecticides fungi were isolated from soil using a method of the selective substrate. Three species of entomopathogenic fungi Beauveria bassiana, Isaria fumosorosea and Metarhizium anisopliae were isolated from the study soils using the selective medium.

Pathogenicity of entomopathogenic fungi to eggs and larvae of Spodoptera litura, the common cutworm

The eggs and second instar larvae of Spodoptera litura were treated with different concentrations of conidial suspensions of six isolates of fungi belonging to five species, Metarhizium anisopliae var. anisopliae (Metschnikov) Sorokin (ARSEF 7487), Lecanicillium muscarium (Petch) Zare & W Gams (ARSEF 7037 and ARSEF 6118), Cordyceps cardinalis (ARSEF 7193), Fusarium lateritium Nees (ARSEF 8291/MTCC 9050) and Aspergillus sp. (ARSEF 8519). In bioassay with unscaled eggs, M. anisopliae, C. cardinalis, F. lateritium and Aspergillus sp. resulted in 100% mortality above 106 conidia/mL. However, with scaled egg masses, the highest hatching rate (56%) was observed with L. muscarium (ARSEF 6118) whereas the lowest hatchings were observed in the case of M. anisopliae followed by L. muscarium (ARSEF 7037), Aspergillus sp., F. lateritium, and C. cardinalis. The larvae were also found susceptible to all isolates in a dose dependent manner. Three promising isolates against larvae, viz. M. anisopliae, F. lateritium and L. muscarium (ARSEF 7037) resulted in average percent mortalities of 88, 89 and 77%, respectively at ≈108 conidia/mL. When both larvae and the leaves (provided as food) were treated with ≈108 conidia/mL, mortality further increased for these isolates. Based on the mortality data and the LC50 values, we suggest that M. anisopliae, F. lateritium and L. muscarium (ARSEF 7037) could be developed as potential biocontrol agents against rice cutworm in IPM programs.

Pathogenicity of three commercial products of entomopathogenic fungi, Beauveria bassiana, Metarhizum anisopilae and Lecanicillium lecanii against adults of olive fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae) in the laboratory

The pathogenicity of entomopathogenic fungi, <I>Beauveria bassiana, Metarhizum anisopilae</I> and <I>Lecanicillium lecanii</I>, was evaluated against adults of the olive fly <I>Bactrocera oleae</I> (Gmelin) under laboratory conditions by two ways, contact bioassays and oral bioassays. The results showed that oral bioassays caused higher mortality after four treatments than the used contact bioassays. Moreover, the virulence of<I>L. lecanii</I> was higher than the virulence of <I>B. bassiana</I> and<I> M. anisopilae</I> in both ways of experiment. Lethal time (LT<sub>50</sub>) was shorter in oral bioassays than in contact bioassays in all treatments. It was 14.67, 8.30 and 5.43 days for <I>B. bassiana, M. anisopilae</I> and<I> L. lecanii</I> with oral treatment while it was 16.6, 26.07 and 12.59 days for <I>B. bassiana, M. anisopilae</I> and<I> L. lecanii</I>, respectively, with contact treatment. The slope values were 2.41, 2.55 and 2.37 for contact bioassays and 1.64, 1.69 and 1.61 for oral bioassays of <I>B. bassiana, M. anisopilae</I>and<I> L. lecanii</I>, respectively. The mortality response to the interaction between <I>B. bassiana</I> and <I>M. anisopilae</I> was synergistic while the interaction between <I>B. bassiana + L. lecanii</I> and <I>M. anisopilae + L. lecanii </I>showed an antagonistic response.

Control of Pyrethroid-Resistant Chagas Disease Vectors with Entomopathogenic Fungi

Background Triatoma infestans-mediated transmission of Tripanosoma cruzi, the causative agent of Chagas disease, remains as a major health issue in southern South America. Key factors of T. infestans prevalence in specific areas of the geographic Gran Chaco region—which extends through northern Argentina, Bolivia, and Paraguay—are both recurrent reinfestations after insecticide spraying and emerging pyrethroid-resistance over the past ten years. Among alternative control tools, the pathogenicity of entomopathogenic fungi against triatomines is already known; furthermore, these fungi have the ability to fully degrade hydrocarbons from T. infestans cuticle and to utilize them as fuel and for incorporation into cellular components.Methodology and FindingsHere we provide evidence of resistance-related cuticle differences; capillary gas chromatography coupled to mass spectrometry analyses revealed that pyrethroid-resistant bugs have significantly larger amounts of surface hydrocarbons, peaking 56.2±6.4% higher than susceptible specimens. Also, a thicker cuticle was detected by scanning electron microscopy (32.1±5.9 µm and 17.8±5.4 µm for pyrethroid-resistant and pyrethroid-susceptible, respectively). In laboratory bioassays, we showed that the virulence of the entomopathogenic fungi Beauveria bassiana against T. infestans was significantly enhanced after fungal adaptation to grow on a medium containing insect-like hydrocarbons as the carbon source, regardless of bug susceptibility to pyrethroids. We designed an attraction-infection trap based on manipulating T. infestans behavior in order to facilitate close contact with B. bassiana. Field assays performed in rural village houses infested with pyrethroid-resistant insects showed 52.4% bug mortality. Using available mathematical models, we predicted that further fungal applications could eventually halt infection transmission.ConclusionsThis low cost, low tech, ecologically friendly methodology could help in controlling the spread of pyrethroid-resistant bugs.

Pathogenicity of entomopathogenic fungi on three species of coffee plant mites

Brevipalpus phoenicis (Geijskes, 1939) and Oligonychus ilicis (McGregor, 1917) (Acari: Tenuipalpidae, Tetranychidae) are considered the main pest mites of coffee plants ( Coffea spp.), causing damages such as leaf fall and reduction of the photosynthetic foliar area. Among their main natural enemies, the entomopathogenic fungi and predatory mites have great potential for biological control. However, the entomopathogenic fungi can, occasionally, also infect the predatory mites. The objective of this work was to evaluate the pathogenicity of entomopathogenic fungi to the pest mites B. phoenicis and O. ilicis and to the predatory mite Iphiseiodes zuluagai Denmark & Muma, 1972 (Acari: Phytoseiidae). The experiments were carried out in a laboratory, using four strains of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill. and one of the Lecanicillium sp. The mites were exposed to the fungi by spraying the pathogen in a Potter tower. For the B. phoenicis mite, the Lecanicillium sp. UFLA 70 strain caused 100% mortality in three days of exposure. For the O. ilicis species, the most effective treatments were UFLA 13 ( B. bassiana ) and UFLA 70 ( Lecanicillium sp.) strains, which caused 70% of mortality. Most of the tested fungi strains were not pathogenic to the predator I. zuluagai , causing low mortality. Of all the fungi tested in this experiment, the most effective for B. phoenicis and O. ilicis was UFLA 70 of Lecanicillium sp., which caused high mortality of these pests, but did not cause a high mortality rate of the predatory mite I. zuluagai .