Strains Of Entomopathogenic Fungi Research Articles

Breeding of entomopathogenic fungi in different substrates

The issue of entomopathogenic fungi’s prodigious rate of reproduction plagues both academic research and clinical practice. Several production technologies and preparations based on them are currently available. These medications appear to be liquid, powdery, dry, and grainy. The selection of nutritional medium and substrates, as well as the identification of ideal breeding conditions, are crucial steps in the manufacturing of pesticide formulations. Making preparations based on fungus is successful when solid nutritional substrates are used. Because in solid nutritional medium, fungus develop more spores. This article presents the results of experiments on the selection of nutrient substrates EMV-71 for the cultivation of strains of P. varioti EMR-57 and B. bassiana, which have been found to be virulent against spider mites and aphids, for use against sucking pests of vegetable crops in greenhouses. Barley grain has been found to be the most effective food substrate for the cultivation of entomopathogenic fungal strains and obtaining large numbers of spores from them.

SUSCEPTIBILITY OF FOUR STORED-PRODUCT INSECT PESTS TO BEAUVERIA BASSIANA AND METARHIZIUM ANISOPLIAE STRAINS

Insect infestations are considered one of the major problems causing enormous economic losses in stored grains. Laboratory bioassays were performed to establish the mortality induced by the commercially available Beauveria bassiana strain ATCC74040 (formulated product: Naturalis®) and by Metarhizium anisopliae strain CIST8 against four stored products pests. Adults of four grain and legume pest species (Cathartus quadricollis, Callosobruchus maculatus, Sitophilus granarius, and Oryzaephilus surinamensis) were exposed in laboratory assays to three different concentrations (103, 105 and 107/mL) of each entomopathogenic fungal strain. For each insect species, fungal strain and concentration, the mortality was recorded daily over a period of 7 days. Mean survival time and final cumulative mortality were determined, and 7-day mortality curves were established. A significant effect of insect species, fungal strain, and conidial concentration was observed on the 7-day mortality curves and the final cumulative mortality. Also, the mean survival time varied significantly with the conidial concentration. In addition, a significant interaction between insect species and fungal strain was recorded for all three assessed parameters. In general, at all tested concentrations, B. bassiana strain ATCC 74040 caused higher mortality than M. anispliae strain CIST8 in all four insect species. Our results suggest that entomopathogenic fungi could be effectively used as part of an integrated pest management program for the control of legumes and grain pests. Key Words: Entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae, stored-products pests

Impact of Beauveria bassiana and Metarhizium anisopliae on the Metabolic Interactions between Cucumber (Cucumis sativus L.) and Cucumber Mosaic Virus (CMV)

In natural systems, plant–endophyte interactions are important for reducing abiotic and biotic stresses in plants by producing a variety of metabolites that protect plants from pathogens and herbivores. Biocontrol strategies are increasingly being used as a viable alternative to chemical pesticides. Entomopathogenic fungi (EPF) are one of them, and they have been touted as a successful method for biological pest control in plants. Because EPF strains are sensitive to environmental conditions when sprayed, the recently discovered endophytic behavior of several EPF strains has improved their management. Cucumber mosaic virus (CMV) is one of the most common and serious plant viruses worldwide, infecting over 1200 plant species and being spread by more than 80 aphid species. CMV control is directed towards the use of chemical insecticides to eradicate its insect vectors. Endophytic EPF is currently being studied to control plant virus infection, and antagonistic effects have been reported. Metabolomics is an emerging research field for plant metabolite profiling and is employed to study plant–endophyte interactions. In the present research, metabolomics approaches were conducted to gain information into mechanisms involved in defense against CMV in endophytes Beauveria bassiana and Metarhizium anisopliae (EPF)-treated diseased cucumber plants. In addition, CMV-induced metabolic changes in cucumber plants were investigated. Our analysis indicated large differences in cucumber metabolites due to endophytes application. In total, six hundred and thirty-one metabolites were differentially expressed in endophyte-treated CMV diseased cucumber plants. Regulation of different kinds of amino acids, organic acids, and phenylpropanoids metabolites could provide insight about plant defense mechanism against CMV pathogen. Important metabolites were found to be regulated in diseased cucumber plants due to fungal endophytes treatment that could possibly confer tolerance to CMV disease.

Virulence evaluation of entomopathogenic fungi against Panonychus citri (Acari: Tetranychidae) and its compatibility with acaricides and predatory mites

The citrus red mite, Panonychus citri (McGregor), is one of the most notoriously agricultural pests which can cause severe damage to over 100 species of plants. The species is difficult to control because of its short generation time and high reproductive rate. Owing to the reliance on chemical acaricides in pest management in the field, P. citri has evolved resistance to a number of chemical acaricides over the years. The emergence of pesticide resistant populations of P. citri is a significant concern worldwide. Thus, it is urgent to find alternative ways to keep the pest populations below the economic injury levels based on the IPM strategy. Nowadays, ecologically-sound control strategies have been sought for this pest and many biocontrol agents have been introduced into pest management such as the entomopathogenic fungi (EPF) and predatory insects. In our study, 5 EPF strains designated HL3, Bbzwn9, Bb0601, Bb07, and Bblh were tested for their efficacy against P. citri by spraying conidia suspension in the laboratory. Amongst these, the HL3 strain exhibited the highest pathogenicity against P. citri and was identified as Isaria cateniannulata using ITS sequences. Further bioassays of HL3 strain indicated the LC50 (3.093x104 conidia/mL) at 7 d post inoculation and the LT50 (3.356 d) at a concentration of 1x108 conidia/mL against P. citri. Subsequently, HL3 was evaluated for its compatibility with four commonly used chemical acaricides at their low dosages (gradient dilution of their labeled application rates for P. citri control) and its side effects on the predatory mite, Neoseiulus barkeri. Briefly, HL3 exhibited an ideal compatibility with avermectin compared to other three acaricides, with the lowest inhibition rate of colony growth, sporulation and spore germination in the PDA culture medium containing avermectin. Besides, the fungal strain was harmless to N. barkeri with only 9.167% mortality rate, and no significant impact was recorded on N. barkeri oviposition rates, although HL3 possessed a slightly negative effect on the predatory ability of N. barkeri. The analysis of functional response indicated that compared with the untreated P. citri, the handling time of predator increased on HL3-treated P. citri, while the attack rates decreased with the increase of the time after inoculation. In summary, in combination with avermectin or the natural enemy N. barkeri, HL3 exhibited a potential ability for sustainable control of the mite pest.

FIRST EVIDENCE OF THE TICKICIDE EFFECT OF ENTOMOPATHOGENIC FUNGI ISOLATED FROM MEXICAN CATTLE FARMS AGAINST AMBLYOMMA MIXTUM.

This is the first study to empirically evaluate the mortality of Amblyomma mixtum larvae caused by native entomopathogenic fungi (EPF) from cattle farm soils and the impact of the physicochemical conditions of those soils on the ability of EPF to kill ticks. The efficacy of 25 EPF strains isolated from cattle farms soils in Veracruz, Mexico, against A. mixtum ticks was evaluated using a larval immersion test. Physicochemical analyses of the soils where the EPF were isolated were carried out, and the results were correlated with the obtained mortality. The MaV25 strain showed a mortality of 36.55% (P < 0.05), followed by MaV57 with 27.30%, MaV08 with 26.21%, and MaV31 with 24.32% (P < 0.05). Nitrogen and potassium are nutritional components of soils that seem to be associated with mortality caused by the evaluated fungal strains. This is the first study in Mexico where the effect of EPF against A. mixtum is evaluated and also is the first study in the world that uses native strains from livestock soils against larvae of this tick. It is necessary to determine the virulence characteristics of EPF on A. mixtum to improve knowledge of fungus-tick interactions (Metarhizium anisopliae-A. mixtum).

High susceptibility of Tetranychus merganser (Acari: Tetranychidae), an emergent pest of the tropical crop Carica papaya, towards Metarhizium anisopliae s.l. and Beauveria bassiana strains.

BackgroundThe mite Tetranychus merganser is considered to be an emerging pest of various crops in tropical countries. It is one of the most detrimental pests in the papaya orchards of some regions of México. The current field control of Tetranychus spp. involves the extensive use of chemicals that have some degree of toxicity to humans or the environment and may cause selective resistance. The use of biological alternatives such as parasitoids and mite predators have limited effectiveness. In order to find effective but non-toxic alternatives for mite pest management, bio-products that are able to be mass produced and applied to large production areas have been sought, including the entomopathogen fungi. B. bassiana and M. anisopliae s.l. are the fungi most extensively used for the biological control of insect pests. Although they do not cause natural epizootic diseases in mites, there are reports that show that they infect T. urticae, and should be evaluated for use in the biological control of papaya’s mite pests.MethodsA T. merganser colony was established and the susceptibility of adult females to 30 entomopathogenic fungi strains was evaluated under laboratory conditions with an in vitro mass screening bioassay. Ten strains of Metarhizium anisopliae sensu lato (s.l.), eleven of Beauveria bassiana, nine of Lecanicillium sp. and one of Hirsutella thompsonii var. sinematosa were tested. The infectivity of adult females was evaluated calculating the percentage of mortality. To calculate the LC50 and LT50 of the most virulent strains, a bioassay was performed using serial concentrations (1×104–1×108 conidia/mL) for each strain. Strains showing ability to infect eggs laid were evaluated with a novel egg-infectivity bioassay. The internal transcribed spacer (ITS) region of the more lethal strains were sequenced.ResultsT. merganser and T. urticae were found in orchards of Carica papaya (Maradol variety and Tainung hybrid) in Campeche, México. All tested strains of M. anisopliae s.l. and B. bassiana were infectious to the adult female of T. merganser at a concentration of 1×108 conidia/mL. Six strains of M. anisopliae (Ma002, Ma003, Ma004, Ma005, Ma014 and Ma034) caused 100% mortality, and one of B. bassiana (Bb016) caused 95% mortality. The most virulent was Ma034, with an LC50 of 1.73×106 conidia/mL followed by Ma005 and Ma003. Ma005 and Ma034 were the fastest strains to reach LT50,achieving this in less than 3.7 days. Additionally, Ma034 and Ma014 strains were infectious to more than 70% of the eggs.ConclusionsT. merganser and T. urticae are present in the papaya orchards of Campeche, México. The high susceptibility of T. merganser adult females and eggs toward several M. anisopliae s.l. or B. bassiana strains suggests that these fungi are a viable alternative to control this emergent pest. The most virulent strain, Ma034, was also infective to eggs, and is the most promising to be tested in the field.

Selecting thermal tolerant strains of entomopathogenic fungi to control Ceratitis capitata (Wiedeman) in tropical semi-arid conditions

Although it is usual, using constant temperature to select thermo-tolerant entomopathogen (EF) strains could discard potentially efficient biocontrol agents (BCA). The objectives of this work were to select virulent EF against C. capitata and evaluate the effect of continual and fluctuating temperature on fungal development and virulence. Initial experiments compared the effect of constant temperatures (CT) (20, 25, 30, 35, and 38 °C) and simulated intraday temperature variation (SIV) (20–38 °C) over conidial germination, mycelial growth, and insect mortality. Temperatures ≥ 35 °C in the CT experiments significantly reduced conidial germination, and the strains of Beauveria bassiana BbLCB81 and BbLCB289 showed the highest conidial germination and mycelial growth. SIV also caused a significant effect, and M. anisopliae MaLCB62 showed the highest conidial germination and mycelial growth. Applying EF strains as toxic baits in CT showed that the highest mortality occurred at 30 °C, and BbLCB62 and BbLCB289 showed the largest insect mortality at 38 °C. Survival analysis showed a slight increase in the average survival time (ST50) at 30 °C. In SIV conditions, MaLCB56 and BbLCB289 were highly virulent. In a field cage experiment at a warmer temperature, BbLCB62 was the most virulent strain according to the M-C test comparing survival curves. However, confirmed accumulated mortality on the 10th day was similar to the moderately tolerant BbLCB289 (Tukey, p < 0.05). During winter, all EF strains showed similar mortality on 10th day (Tukey, p < 0.05), but a significant difference in the survival analysis. EF strains with mild temperature tolerance can be applied in seasons with high temperatures, and BbLCB62 and BbLCB289 were selected as potential biocontrol agents against C. capitata.

Entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae play roles of maize (Zea mays) growth promoter

Beauveria bassiana and Metarhizium anisopliae are two of the most important and widely used entomopathogenic fungi (EPFs) to control insect pests. Recent studies have revealed their function in promoting plant growth after artificial inoculation. To better assess fungal colonization and growth-promoting effects of B. bassiana and M. anisopliae on crops, maize Zea mays seedlings were treated separately with 13 B. bassiana and 73 M. anisopliae as rhizosphere fungi in a hydroponic cultural system. Plant growth indexes, including plant height, root length, fresh weight, etc., were traced recorded for 35 days to prove the growth promoting efficiency of the EPFs inoculation. Fungal recovery rate (FRR) verified that both B. bassiana and M. anisopliae could endophytically colonize in maize tissues. The recovery rates of B. bassiana in stems and leaves were 100% on the 7th day, but dropped to 11.1% in the stems and 22.2% in the leaves on the 28th day. Meanwhile, B. bassiana was not detected in the roots until the 28th day, reaching a recovery rate of 33.3%. M. anisopliae strains were isolated from the plant roots, stems and leaves throughout the tracing period with high recovery rates. The systematical colonization of B. bassiana and M. anisopliae in different tissues were further corroborated by PCR amplification of fungus-specified DNA band, which showed a higher detection sensitivity of 100% positive reaction. Fungal density comparing to the initial value in the hydroponic solution, dropped to be well below 1% on the 21st day. Thus, the two selected entomopathogenic fungal strains successfully established endophytic colonization rather than rhizospheric colonization in maize, and significantly promoted its growth in a hydroponic cultural system. Entomopathogenic fungi have great application potential in eco-agricultural fields including biopesticides and biofertilizers.

CHOOSING THE OPTIMAL CONCENTRATION OF INOCULUM FOR EFFECTIVE REDUCTION OF THE NUMBER OF ASIAN LOCUST LARVAE

The article presents the results of experiments to determine the dose-mortality relationships for 10 selected strains of the fungus B. bassiana (mountain and steppe) on younger larvae of natural populations of Asian locusts. Working suspensions with four different titers of conidia (1x106, 5x106, 1x107, 5x107) were used. All tested strains related to Asian locust larvae showed high toxicity on the titers of working suspensions 1x107 and 5x107.According to the mortality rate and the rate of death of the organism, the host had the best effect even at all concentrations, showing the specificity of BSc1-15, BSc2-15, BTr1-16, BPit-16, BCa3(m)-09 among the strains. And the maximum biological activity was observed in the BSc1-15 strain on the 15th day, and the mortality rate of test insects in all variants was 100%. The lowest activity was shown by the strain BHy-09 in the range of 47.5-82.5%. The remaining strains showed moderate biological activity. At the same time, the mortality rate of Asian locust larvae in the control variant (without treatment) for 17 days was 17.5±4.78%. As a result of the experiments, we selected strains BSc1-15, BCa3(m)-09 from one of the mountainous and steppe regions, which have high toxicity (75-100%) to Asian locust larvae at relatively low concentrations (1x106 and 5x106 conidia/ml), because when using low titers (1x106 and 5x106), the effect of entomopathogenic fungal strains showed that they stretch over time. Based on the data of this experiment, it was concluded that the optimal titers of the working suspension of the fungus for controlling the number of larvae of Asian locusts are 1x107 and 5x107.

Occurrence of entomopathogenic hypocrealean fungi in mosquitoes and their larval habitats in Central Brazil, and activity against Aedes aegypti

Collecting entomopathogenic fungi associated with mosquitoes and studies on their activity against mosquito developmental stages will improve the understanding of their potential as agents to control important mosquito vectors. Twenty-one strains of entomopathogenic fungi affecting mosquitoes in Central Brazil were studied: 7 of Beauveria bassiana, 7 of Metarhizium humberi, 3 of M. anisopliae, 2 of Cordyceps sp. and one each of Akanthomyces saksenae and Simplicillium lamellicola. These fungi were isolated from field-collected mosquito adults (3 strains) or larvae (a single strain); the other 17 strains were isolated from laboratory-reared Aedes aegypti sentinel larvae set out in partially immersed cages placed in diverse small- to middle-sized aquatic mosquito habitats in or close to areas with secondary tropical forest. The frequent recovery of normally soil-borne Metarhizium spp. and B. bassiana from aquatic habitats is notable. Our laboratory findings indicated that M. anisopliae IP 429 and IP 438 and M. humberi IP 421 and IP 478 were highly active against immature stages and, together with M. anisopliae IP 432, also against adults. These strains appear to be the most promising candidates to develop effective control strategies targeting the different developmental stages of A. aegypti, the most important vector of viral diseases in humans in the tropics.

Soil isolation, identification, and virulence testing of Turkish entomopathogenic fungal strains: a potential native isolate of Beauveria bassiana for the control of Leptinotarsa decemlineata

Soil isolation, identification, and virulence testing of Turkish entomopathogenic fungal strains: a potential native isolate of Beauveria bassiana for the control of Leptinotarsa decemlineata

The effect of UV radiation on entomopathogenic fungal strains beauveria bassiana CNMN- FE-01 and Cordyceps fumosorosea CNMN-FE-02

The paper aimed to investigate the influence of UV radiation on the conidia germination and vegetative growth of the fungal strains Beauveria bassiana CNMN-FE-01 and Cordyceps fumosorosea CNMN-FE-02, potential biological control agents of weevils. It was established that UV-B radiation (λ = 312 nm) significantly reduces the viability of conidia, the highest decrease being attested after 30 min. of exposure. However, the radial growth rate of the investigated fungal strains was not significantly affected by exposure of conidia to UV-B rays (p = 0,443 and 0,349, respectively).

Assessment of entomopathogenic nematodes and fungi against Eubulus cf. elongatus Hustache (Coleoptera: Curculionidae), a destructive cassava pest in Brazil

ABSTRACT Eubulus cf. elongatus was recently recorded as one of the most destructive pests of cassava in the Brazilian Cerrado. In this study, we evaluate the susceptibility of E. cf. elongatus to entomopathogenic fungi and nematodes in laboratory. Adults and larvae of E. cf. elongatus were first collected in the field to assess the natural occurrence of fungi and nematodes. Seven nematode species within Heterorhabditis and Steinernema genera were tested in direct applications onto the larvae or indirectly through soil inoculation (2000 infective juveniles per group of 10 larvae). Bioassays with 16 strains of entomopathogenic fungi (beauveria and metarhizium species) were conducted by immersion (108 conidia per mL), direct spray or by exposing adults to soil sprayed with conidial suspensions (6 × 104 conidia per cm2). In all bioassays insects were kept at 24–25 °C and 75-90% RH for 16 days. Nematodes were not found naturally occurring in E. cf. elongatus larvae collected in field. Of the adults collected, 1.76% and 0.04% were infected with B. bassiana and Metarhizium sp., respectively. In the laboratory trials, the highest mortality of larvae was caused by H. bacteriophora (95.0% for application on larvae and 60% for soil application). Entomopathogenic fungi caused low mortality rates in adults of E. cf. elongatus, being less than 11% in direct and soil applications and reaching a maximum of 16.07% when insects were treated by immersion. Our results show the potential of nematodes, such as H. bacteriophora, in controlling the larvae of E. cf. elongatus in soil.

Biological control potential of entomopathogenic fungal strains against peach Fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae).

The peachfruit fly, Bactrocera zonata (Saunders) is a polyphagous pest in nature, belonging to order, Diptera and their respective family is Tephritidae. It mostly feeds on different crops, vegetables and fruits. Different traditional chemical insecticides have been used to control this notorious pest. Excessive consumption of pesticides has become a major threat to the fresh fruits trade since many importing countries refused to accept the shipments due to public health and environmental concerns. There is a growing trend to control these pests using the most effective biological control methods and other preventive measures have been adopted for reducing their attacks. Fungal agents have been used as biological agents to manage the attack of different insects pest through biological means. The present study was conducted to assess the virulence of three entomopathogenic fungi, Metarhizium anisopliae, Beauveria bassiana and Verticillium lecanii, against Bactrocera zonata stages under different laboratory conditions. The results showed that B. bassiana and M. anisopliae were more effective in pathogenicity and potentially kill at all stages of B. zonata as compared to V. lecanii. The highest mortality rate for the third larval instar and the pupal stage were recorded after exposure to the 1 × 1010 conidia/ml concentrations, B. bassiana, with 68.67% and 89.67%, respectively. Adult B. zonata flies were the most susceptible to all entomopathogenic fungi. However, M. anisopliae was more virulent against B. zonata adult flies than B. bassiana and V. lecanii at 1 × 1010 conidial concentration. Therefore, the entomopathogenic fungi B. bassiana and M. anisopliae can be used as an cost effective bio-insecticide in the integrated pest management programs to control B. zonata. This study will be helpful to overcome this pest through biological control means.

Molecular Identification and Virulence of Four Strains of Entomopathogenic Fungi Against the Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae).

The whitefly, Bemisia tabaci (Gennadius), is a key pest of many economically important crops grown in the field and in greenhouses throughout the world. Because entomopathogenic fungi (EPF) are potential biological control agents for B. tabaci, however, minimal research has been conducted on using fungal strains to control B. tabaci. In this study, four EPF strains were isolated and identified as Lecanicillium attenuatum (Zare & Gams) JL-003, Beauveria bassiana Balsamo (Vuillemin) JL-005, Lecanicillium longisporum (Petch) JL-006, and Akanthomyces lecanii (Zimmerman) JL-007, based on rDNA-ITS sequence analysis. In comparing the virulence of the four fungi against the different life stages (i.e., eggs, 1st-, 2nd-, 3rd-, 4th-instar nymphs, and adults) of B. tabaci the mortality of B. tabaci decreased and LT50 values increased as the conidia concentration decreased in a series of conidia concentrations (1×105, 106, 107, and 108 conidia/mL). The fungal strains L. attenuatum JL-003 (LC50: 1.31×106) and B. bassiana JL-005 (LC50: 0.92×106) were found to be more effective than L. longisporum JL-006 (LC50: 4.97×107) and A. lecanii JL-007 (LC50: 6.46×106). Fourth-instar nymphs, eggs, and adult stages of B. tabaci were less susceptible to all fungal strains compared to 1st-, 2nd-, and 3rd-instar nymphs. The virulence of L. attenuatum, which was tested for the first time on B. tabaci, was found to be more toxic to early-stage nymphs. Our data will be useful in biological control programs that are considering using EPF against B. tabaci.

Efficacy of Beauveria bassiana and Cordyceps javanica mycoinsecticides against spotted lanternflies, Lycorma delicatula, in laboratory bioassays

ABSTRACT The invasive spotted lanternfly, Lycorma delicatula (White), was first detected in southeastern Pennsylvania in 2014 and has since expanded its range to ten more states. Since fall 2017, we have found L. delicatula killed by Beauveria bassiana in multiple counties in southeastern Pennsylvania. Mycoinsecticides containing strains of entomopathogenic fungi are commercialised worldwide and could be a tool for managing L. delicatula populations. In 2020 we conducted laboratory bioassays on L. delicatula using five mycoinsecticides, including four strains of B. bassiana and one strain of Cordyceps javanica. Mycoinsecticides were directly applied to all L. delicatula nymphal instars and adults at three different stages of reproductive maturity. All B. bassiana mycoinsecticides were effective at killing L. delicatula under optimal conditions in the laboratory. Lycorma delicatula nymphs exposed to B. bassiana mycoinsecticides displayed mean survival times of 6.3–6.9 days and 90–93% mortality after 14 days, and adults displayed mean survival times of 7.2–9.8 days with 82–99% mortality after 14 days. PFR-97 killed L. delicatula at a slower rate than all B. bassiana mycoinsecticides tested with 43–57% mortality after 14 days. Adult L. delicatula males died significantly faster than females for all treatments except BioCeres.

Effectiveness of entomopathogenic fungal strains against poplar/willow weevil (Cryptorhynchus lapathi L.) larvae

Effectiveness of entomopathogenic fungal strains against poplar/willow weevil (Cryptorhynchus lapathi L.) larvae

Comparison of Methods for Isolating Entomopathogenic Fungi from Soil Samples

The goal of the present study is to compare the effectiveness of using insect baits versus artificial selective medium for isolating entomopathogenic fungi (EPF) from soil samples. The soil is a rich habitat for microorganisms, including EPF particularly belonging to the genera Metarhizium and Beauveria, which can regulate arthropod pests. Biological products based on fungi are available in the market mainly for agricultural arthropod pest control. Nevertheless, despite the high endemic biodiversity, only a few strains are used in commercial bioproducts worldwide. In the present study, 524 soil samples were cultured on potato dextrose agar enriched with yeast extract supplemented with chloramphenicol, thiabendazole, and cycloheximide (CTC medium). The growth of fungal colonies was observed for 3 weeks. All Metarhizium and Beauveria EPF were morphologically identified at the genus level. Additionally, some isolates were molecularly identified at the species level. Twenty-four out of these 524 soil samples were also surveyed for EPF occurrence using the insect bait method (Galleria mellonella and Tenebrio molitor). A total of 51 EPF strains were isolated (41 Metarhizium spp. and 10 Beauveria spp.) from the 524 soil samples. All fungal strains were isolated either from croplands or grasslands. Of the 24 samples selected for comparison, 91.7% were positive for EPF using Galleria bait, 62.5% using Tenebrio bait, and 41.7% using CTC. Our results suggested that using insect baits to isolate the EPF from the soil is more efficient than using the CTC medium. The comparison of isolation methods in addition to the identification and conservation of EPF has a positive impact on the knowledge about biodiversity. The improvement of EPF collection supports scientific development and technological innovation.

Genomic Determinants of Entomopathogenic Fungi and Their Involvement in Pathogenesis.

Entomopathogenic fungi offer an effective and eco-friendly alternative to curb insect populations in biocontrol strategy. The evolutionary history of selected entomopathogenic fungi indicates their ancestral relationship with plant endophytes. During this host shifting, entomopathogenic fungi must have acquired multiple mechanisms, including a combination of various biomolecules that make them distinguishable from other fungi. In this review, we focus on understanding various biochemical and molecular mechanisms involved in entomopathogenesis. In particular, we attempt to explain the indispensable role of enlarged gene families of various virulent factors, viz. chitinases, proteases, lipases, specialized metabolites, and cytochrome P450, in entomopathogenesis. Our analysis suggests that entomopathogenic fungi recruit a different set of gene products during the progression of pathogenesis. Knowledge of these bio-molecular interactions between fungi and insect hosts will allow researchers to execute pointed efforts towards the development of improved entomopathogenic fungal strains.

Supplementing artificial diet with antimicrobial compounds increases the resistance of sterile males of Ceratitis capitata (Diptera: Tephritidae) applied as vectors of virulent fungi

ABSTRACT Sterile males (SMs) of C. capitata have been proposed as vectors of entomopathogenic fungi (EF). However, they are also susceptible to virulent strains. This work evaluates the effects of supplementing the artificial diet with antimicrobial compounds on the larvae and adults of C. capitata tsl Vienna-8 and their resistance to virulent EF strains. Even a lower dose of methylparaben (MPB) (0.5 g kg-1) inhibited the mycelial growth of Metarhizium anisopliae LCB255 and Beauveria bassiana LCB289. Sodium benzoate (BNZ) at 2.5 g kg-1 reduced mycelial growth of both strains by 50%, while citric acid did not interfere with fungi development. Supplementing the larval and adult diets with MPB (2.0 g kg-1) plus BNZ (2.5 g kg-1) or only MPB significantly reduced the mortality of pupae and adults treated with LCB255 or LCB289. Feeding larvae and adults with diets amended with the antimicrobials significantly reduced SMs’ mortality and its mortality curve (p <0.05). SMs fed with the supplemented diet showed a significantly higher median survival time (8 days) than the control group (3–4 days) (p <0.05). As a result, there was an efficient transference of EF conidia to females during mating and mating attempts, thus increasing female mortality. The results were confirmed in a field-cage experiment when SMs were fed diets supplemented with antifungal compounds, which showed a higher median survival time.