Bassiana Strain Research Articles

Bazı Entomopatojen Fungusların Leptinotarsa decemlineata Say'nin Farklı Biyolojik Dönemleri Üzerindeki Ölümcül Etkilerinin Belirlenmesi

The lethal effects of Beauveria bassiana BIM-001 (1x106 spore mL-1, 1x107 spore mL-1, 1x108 spore mL-1), Fusarium subglutinans 12A (obtained from cotton aphid in Adana-Karataş) and the commercial preparation of 1.5% B. bassiana strain Bb-1 (250 mL da; 1x108 spore mL-1) (Nostalgist SL) on Leptinotarsa decemlineata were investigated. The isolates were applied to the eggs, larvae (1st, 2nd, 3rd, and 4th larval stages) and adults of L. decemlineata by spraying in laboratory conditions (25 ± 1°C, 60 ± 10% relative humidity and 16:8 [L: D] photoperiod). The observations to determine the lethal effect of isolates were performed up to 9 days for the eggs and larvae, and 21 days for the adults of L. decemlineata following the first spore suspension application. In the experiments conducted on the larval stages, it was determined that the mortality rates due to all entomopathogenic fungus isolates and at different concentrations were significantly different from the mortality rate of the control. The effect of all spore concentrations of B. bassiana BIM-001 was found significantly higher than other treatments and the mortality rates were 100% for all larval stages (P ˂0.05). In addition, the mortality rates were between 4 and 16% for adults across all treatment groups except for the control. Moreover, it has been determined that each three spore concentrations of B. bassiana BIM-001 also suppressed the egg hatching of L.decemlineata by 55 to 60%

Characterization and biological activity of two new entomopathogenic Beauveria bassiana strains isolated from Hyphantria cunea larvae in Turkey

In this study, two fungal strains (HC-Z1 and HC-Z2) from Hyphantria cunea (fall webworm) larvae were evaluated for their potential as biocontrol agents against the H. cunea larvae. Based on morphological and molecular (ITS1-5.8S-ITS2 region) characterization, the strains were identified as Beauveria bassiana (HC-Z1: OP415530 and HC-Z2: OP415531). To determine the biological activities of the two fungal strains, a concentration-response assay (1 × 104-8 conidia/ml) was performed against third stage H. cunea larvae. In addition, two B. bassiana strains were tested on five (1-5) larval stages at 1 × 107 conidia/ml concentration. Both isolates produced mortalities over 96% within 7 days for the first larval stage of H. cunea. The LC50 and LT50 of HC-Z1 and HC-Z2 strains against third instar H. cunea larvae were calculated as 0.6 × 104 and 1.2 × 104 conidia/ml, respectively. LT50 values were obtained in 2.82 and 3.44 days for HC-Z1 and HC-Z2 isolates, respectively. As a result, it can be concluded that HC-Z1 and HC-Z2 strains can potentially be used as biological control agents against H. cunea.

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.

The effect of spider mite-pathogenic strains of Beauveria bassiana and humidity on the survival and feeding behavior of Neoseiulus predatory mite species

Predatory mites and invertebrate-pathogenic fungi have been used as biological control agents in a complementary way to suppress two-spotted spider mite (TSM) populations, which are a key pest of horticultural crops worldwide. However, their performance can be lowered by both biotic (e.g., intraguild interactions) and abiotic stress (especially relative humidity - RH). The present study evaluated the susceptibility of three predatory phytoseiid mite species in the genus Neoseiulus – N. californicus, N. idaeus, and N. barkeri – to infection by selected spider mite-pathogenic Beauveria bassiana strains as well as their predation capacity and resilience under simulated drought conditions. The two selected B. bassiana strains induced TSM mortality above 70 %. All three Neoseiulus mite species also showed susceptibility to both strains; however, N. barkeri was less susceptible to fungal infections than the other Neoseiulus species (with mortality < 65 % and without reduction of oviposition). All three Neoseiulus species were negatively affected by low RH conditions. Neoseiulus barkeri was the most affected with a drastic reduction in TSM egg consumption (about 40 %) and preventing the deposition of eggs by females. The egg consumption by N. californicus and N. idaeus was not affected by low RH conditions; however, both predatory mites reduced the number of eggs laid per female. Thus, the efficiency of the conversion of food into egg biomass for all three Neoseiulus species decreased under low RH conditions, dropping to zero for N. barkeri. We showed that the simultaneous use of B. bassiana and Neoseiulus had a detrimental effect on predatory mite survival and progeny, indicating the need for further development of new strategies which combine these biological control agents.

Immune Responses of Rhynchophorus ferrugineus to a New Strain of Beauveria bassiana

Evaluating a novel fungal strain’s pathogenicity to important pests and their involved immune responses may give crucial data on a broad scale for future use in pest management strategies. Date palms are mostly destroyed by invading populations of red palm weevils; thus, developing natural biopesticides for them requires a comprehensive screening program of plant secondary metabolites. In this research, we examined the pathogenicity of a new strain of Beauveria bassiana on an important agricultural pest, Rhynchophorus ferrugineus, by measuring the relative activity of defensive enzymes and detoxifying enzymes in certain larval instars. Our findings reveal that the B. bassiana strain may infect the instars of R. ferrugineus, and its pathogenicity to the larvae steadily increases as the spore concentration increases. Seven days after inoculation, the LC50 (the median lethal concentration) of B. bassiana was 490.42 × 105 and 2974.47 × 108 spores/mL for the second and fourth instar R. ferrugineus, respectively, and the LC50 of B. bassiana for each R. ferrugineus instar decreased with infection time, indicating a significant dose effect. Infected R. ferrugineus larvae of the second instars showed considerable changes in the activity of both protecting and detoxifying enzymes (peroxidase, catalase, superoxide dismutase, Cytochrome P450, glutathione S transferase (GST), and esterase) as infection time progressed. In addition, R. ferrugineus larvae that were infected with B. bassiana had enzyme activity that persisted from 24 to 48 h, which was much longer than in the control group. Lethality of B. bassiana resulted in elevated expressions of GST, Esterase, and Cytochrome P450 responsive genes. In conclusion, the results of this research indicate that B. bassiana may be utilized as a bio-insecticide to suppress young larvae of R. ferrugineus in an integrated pest management program.

Short- and Long-Term Evaluation of a Fixed Dose of Beauveria bassiana Strain MS-8 Diluted in Various Doses of Kaolin as a Powder Formulation Applied to Rice Grains to Control Almond Moth, Ephestia cautella Walker (Lepidoptera: Pyralidae).

Short-term and long-term evaluation studies were conducted against Ephestia cautella on rice grains, using Beauveria bassiana Strain MS-8 formulated in various doses of kaolin as an active carrier. In the short-term study (45 days), a fixed dose of 0.03 g conidia kg−1 of grain of Strain MS-8 was formulated in kaolin at doses of 0.3, 0.5, 1, and 2 g kg−1 of grain. These formulations were evaluated for their effects on larval mortality and the number of adults emerged. The highest level of larval mortality (90.0%) and the lowest numbers of adults emerged (1.6 insect/100 g of rice grain) were caused by Strain MS-8 in a kaolin dose of 2 g kg−1. However, Strain MS-8 in a kaolin dose of 1 g kg−1 performed well for the same parameters. In the long-term evaluation study (180 days), the same dose of Strain MS-8 was formulated in kaolin at doses of 0.5, 1, 2, and 3 g kg−1 of grain. These formulations were then evaluated against the levels of webbed grain, grain damage, and weight loss. The lowest levels of webbed grain (2.0%), grain damage (3.0%), and weight loss (1.8%) were caused by Strain MS-8 in kaolin at a dose of 3 g kg−1, although Strain MS-8 in kaolin doses of 1 g and 2 g kg−1 also performed well for the same parameters. The highest levels of webbed grain (15.0%), grain damage (30.0%), and weight loss (9.0%) were observed in the untreated control treatment (UCT).

Effect of Entomopathogenic Fungi, Beauveria bassiana (Cordycipitaceae), on the Bark Beetle, Ips typographus (L.), under Field Conditions.

Simple SummaryThe effect of B. bassiana fungal treatment on spruce bark beetle, Ips typographus (L.), was tested under field conditions. Altogether, it was detected that the effect of B. bassiana preparations on bark beetle infestations in terms of possible environmental effects is minimal compared to the severe damage and hence yield loss caused by this insect species worldwide. Even if the relatively low effects on I. typographus stages, including adults, larvae, pupae and even next-generation young adults, were reported, it remains clear that the present novel approach using a natural biological control agent rather than toxic synthetic insecticides is timely and may be potentially beneficial to the forestry industry as a rational control approach to combat this pest.The spruce bark beetle, Ips typographus (L.), attack progression (adult and larval galleries) and parental and offspring mortality rate were assessed in managed forests of the Poiana Ruscă and Bihor Mountains, along with Western Romanian Carpathians using fungal (Beauveria bassiana) treatments. The results show that the effect of B. bassiana on adult (maternal) gallery length was similar to the untreated variant and was less effective than the synthetic insecticide lambda-cyhalothrin applied at a dose of 50 g/L. Additionally, its effect on the mean larval gallery number per maternal gallery was low. B. bassiana did not have a significant influence on the attack progression. Significant correlations between log diameter and I. typographus attack progression were detected; such differences were higher than the effect of any treatment. Altogether, abiotic (low humidity, high temperature) and biotic factors (log diameter) influenced the bark beetles’ attack progression and reduced the entomopathogenic fungal effects. Considering the efficacy of the B. bassiana treatment on logs infested with I. typographus, the results showed that parents and offspring were infected, but even if the fungal treatment was applied in high concentrations, the mortality rate remained relatively low. Further research is necessary to test if different B. bassiana strains and their commercially recommended concentrations might be more effective under dry and warm climate conditions, respectively.

Volatiles released by Beauveria bassiana induce oviposition behavior in the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae).

Microbial volatile organic compounds may act as semiochemicals, inciting different behavioral responses in insects. Beauveria bassiana is an entomopathogenic fungus, and physiological and environmental factors are positively related to fungal virulence. In this study, we examined the volatile profiles produced by eight B. bassiana strains, isolated from soil plots and mycosed insect cadavers, with different speeds of kill and determined if these compounds induce oviposition behavior in Spodoptera frugiperda. Fungal volatilome analysis revealed differences between the isolates. Isolates from mycosed insects showed higher virulence, larger egg mass area and length, and a higher number of eggs by mass, than those obtained from soil. Furthermore, a dilution of the fungal odoriferous compounds increased the insect response, suggesting that S. frugiperda is highly susceptible to the fungal compound's fingerprint. Otherwise, the insect response to the natural blend of volatiles released by the fungus was different from that obtained with 3-methylbutanol, which was the most abundant compound in all isolates. The ability of an entomopathogen to produce volatiles that can induce olfactory stimulation of egg-laying behavior could represent an ecological adaptive advantage in which the entomopathogen stimulates the insect population growth.

Entomopathogenic fungi as biological control agents of Dactylopius opuntiae (Hemiptera: Dactylopiidae) under laboratory and greenhouse conditions

The cactus Opuntia ficus-indica L. is widly cultivated in Morocco and has a very an important economic role as a source of food, livestock feed and not forgetting that it is considered to be an income for people in rural communities. This crop is subject to the attack of a serious insect pest, the Dactylopius opuntiae (Cockerell), which sucks the sap from the plant causing huge production losses since its introduction to the country in 2014. The present study investigated the entomopathogenic effect of six fungal isolates {Beauveria bassiana [HASS; RFSL10; SPT 011(a)]; Akanthomyces lecanii [RFSLV; SPT R 215] and Cordyceps farinosa [SPSBI4]} for controlling of both nymphs and adult females of D. opuntiae in laboratory and greenhouse bioassays. Under laboratory conditions, the highest mortality of female D. opuntiae was registered by B. bassiana strain HASS at 108 conidia ml−1 with 100%, followed by B. bassiana strain RFSL10, A. lecanii RFSLV, and C. farinosa SPSBI4 isolates with 98%, respectively, 10 days after treatments. Similarly, the highest level of nymph mortality (100%) was recorded by B. bassiana RFSL10 and HASS isolates at 108 conidia ml1, respectively, 4 and 5 days after application. Under greenhouse conditions, B. bassiana (HASS and RFSL10) and A. lecanii (RFSLV) isolates sprayed alone expressed a higher toxicity on nymphs with 75, 68.5 and 58%, respectively, 12 days after treatments. However, no significant difference was observed in adult female's mortality between different fungal isolates, where B. bassiana (HASS) at 108 conidia ml−1 presented a moderate mortality rate with 55%, 12 days after application. In fact, the combination of black soap (60 g/L) with B. bassiana HASS and RFSL10 and A. lecanii (RFSLV) isolates at 108 conidia ml−1 caused the highest toxic activity on D. opuntiae adult females, with 70.5, 68.75 and 67.65%, respectively. These findings showed that entomopathogenic fungi are promising for developing a biopesticide formulation for the management of D. opuntiae as an adequate and safe alternative to chemical pesticides.

Endophytic Beauveria bassiana can protect the rice plant from sheath blight of rice caused by Rhizoctonia solani and enhance plant growth parameters.

Beauveria bassiana, a potential entomopathogenic biocontrol agent, has recently drawn attention worldwide for its other additional beneficial roles such as plant disease antagonist, beneficial rhizosphere colonizer, plant growth promoter and an endophyte. In the present study, endophytic colonizing behaviour of five (5) B. bassiana isolates viz., Bb4, Bb16, Bb25, Bb44 and Bb53 were studied in rice following three (3) artificial inoculation techniques viz., seed treatment, root inoculation and foliar spray and the endophytic colonizing ability were determined by culture-based assay. After B. bassiana inoculation, rice plants were challenged with Rhizoctonia solani and disease incidence and plant growth promotion were assessed. Per cent colonization of rice stems, leaves and roots were influenced by inoculation technique, post-inoculation time (7th, 14th, 21st and 28th dpi) and plant growth medium (sterile soil, non-sterile soil), recorded maximum on 14th-day post-inoculation (dpi) i.e., 96% in stems, 92% in leaves and 28% in roots, whereas, lower colonization was recorded on 7th, 21st and 28th dpi. Whereas, the foliar spray was found best as compared to seed and root inoculation techniques, and maximum fungal recovery was observed in stems and leaves and least in roots. Upon colonization, the physical presence of B. bassiana in rice was localized by light microscopy-based studies. Potential B. bassiana strains with endophytic ability were re-isolated and their identity was determined based on morphometric and PCR-based techniques. Further, the present study also identified several virulent genes viz., BbChit1, Cdep1, Bbhog1 and Bbjen1 and extracellular hydrolytic enzymes viz., α-amylase, cellulase, lipase, pectinase and xylanase secreted by endophytic B. bassiana strains as determinants responsible for establishing the endophytic association in rice. On the other hand, a significant reduction in disease incidence was observed in the endophytic B. bassiana Bb4-, Bb16- and Bb44-inoculated plants as compared to the non-endophytic B. bassiana Bb25- and Bb53-inoculated plants along with enhanced plant growth promotion. This is one of the few studies investigating the colonization of B. bassiana in rice and its promising role as a plant disease antagonist and plant growth promoter in rice.

Survey of Natural Enemies of the Invasive Boxwood Moth Cydalima perspectalis in Southwestern Mediterranean Europe and Biocontrol Potential of a Native Beauveria bassiana (Bals.-Criv.) Vuill. Strain.

Simple SummaryCydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia that feeds exclusively on Buxus spp., was first detected in Southwestern Germany and the Netherlands in 2007. Today, it is present in many countries in Europe. Since its detection, numerous researchers have studied the biology and the present or potential number of generations of C. perspectalis in European countries. However, less research has been devoted to detecting possible native biotic factors of mortality (predators, parasitoids, entomopathogenic microorganisms or nematodes) capable of reducing the pest populations. In this work, indigenous natural enemies in the boxwood of the southwest Mediterranean region were collected and identified. One of them, a native Beauveria bassiana strain from infected C. perspectalis larvae, showed potential for controlling this invasive crambid.Cydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia, has been especially devastating in the Mediterranean region and Catalonia, northeast Spain, where Buxus sempervirens is an essential component of the natural forest. As an invasive species, the lack of biotic mortality factors in the arrival region has been one of the main factors allowing its expansion. Therefore, this study aimed to collect and identify possible indigenous natural enemies adapting to the new species in the boxwood of the southwest Mediterranean region. Later, the efficacy of some of the collected species for controlling C. perspectalis larvae was tested in laboratory conditions. The larval collection was carried out in successive years in the boxwood of the region. Several collected larvae were infected with an entomopathogen, Beauveria bassiana, or parasitized by Compsilura concinnata, both common in native Lepidoptera caterpillars. The B. bassiana strain was found to be highly virulent against the developed larvae of C. perspectalis, which suggests that B. bassiana may be an effective treatment in parks and gardens when the first overwintering larvae are detected. The biology of the parasitoid identified is not very well known in Europe, which suggests the necessity of studying its biology and alternative hosts in the region in order to improve its population.

Assessing the Endophytic Potential of a Commercially Available Entomopathogenic Beauveria bassiana Strain in Various Citrus Rootstocks

The citrus industry is challenged by numerous arthropods, yet extensive research has not been conducted to determine the potential use of entomopathogenic fungi as endophytes in pest management strategies. Two inoculation methods (i.e., soil drench and foliar spray) using a suspension of Beauveria bassiana (strain PPRI 5339 contained in Velifer®) containing 4 × 107 conidia mL−1 in 0.01% Tween 80 were conducted on three commercially available citrus rootstocks (i.e., ‘US-942’, ‘US-812’, ‘Swingle’). Seedlings were grown under greenhouse-controlled conditions over a 7-week observation period. Similarly, a third inoculation method (seed soaking) was conducted using seeds from the same three rootstocks. The fungus was re-isolated post-inoculation from ‘US-942’ and ‘US-812’ in the foliar spray and seed soaking treatments. In addition, the fungus was recovered from root tissue in the foliar-sprayed seedlings, suggesting possible systemic movement from leaves to roots. The fungus was not recovered from soil-drench-treated seedlings, nor from any of the ‘Swingle’ cultivars. This study assessed the potential of B. bassiana to endophytically colonize certain citrus rootstocks in planta.

TEMPERATURE EFFECTS ON THE ENTOMOPATHOGENIC FUNGI BEAUVERIA BASSIANA STRAIN CNMN-FE-01: VEGETATIVE GROWTH, SPORULATION, GERMINATION RATE

As part of an approach for selecting potential mycoinsecticides for biocontrol control of weevils, the physiological properties of the strains are to be considered. The paper aimed to investigate the temperature effects on the vegetative growth, conidia germination, and viability of the fungal strains Beauveria bassiana CNMN-FE-01. As a result of the provided analyses, it was shown that the radial growth of the investigated strain follows a linear model. Based on the rate of average radial growth data, the optimum temperature growth at 25°C was determined, while at 35°C, the growth stops. Furthermore, it was found that the maximum rate of sporulation and germination of B. bassiana strain CNMN-FE-01 are at 25°C. At this temperature, the strain maintains the viability of the spores in a proportion of 86% for 90 days. However, temperatures above 25°C significantly reduce the viability of spores. The inhibition in growth of the investigated strain Beauveria bassiana CNMN-FE-01 at 30°C and higher and considerable reduction of its spore viability after extended exposure to 30°C testify to the need for repeated application when used as a biological control agent.

Virulence analysis of novel Beauveria bassiana strains isolated from three different climatic zones against Locusta migratoria

Virulence analysis of novel Beauveria bassiana strains isolated from three different climatic zones against Locusta migratoria

Natural occurrence of Beauveria caledonica, pathogenicity to Cosmopolites sordidus and antifungal activity against Fusarium oxysporum f. sp. cubense

Entomopathogenic fungi can provide a set of ecological services, such as suppressing arthropod pests and plant pathogens. In this study, novel indigenous Beauveria caledonica (Bc) strains were isolated from naturally infected banana weevils (Cosmopolites sordidus) occurring in commercial banana plantations in Brazil. The prevalence of infection by Bc strains on field-caught C. sordidus ranged from 1.3% to 12.9%. Similar to the Beauveria bassiana strains tested, none of the Bc strains caused more than 50% weevil mortality at a concentration of 1 × 108 conidia ml-1 . Bc strain CMAA1810 caused the highest mortality in C. sordidus and had enhanced insecticidal activity when formulated with an emulsifiable oil. In paired co-culture assays, this same strain showed a significant growth-inhibitory effect on the causal agent of Fusarium banana wilt (Fusarium oxysporum f. sp. cubense, Foc) of twofold magnitude compared with the control. Cell-free crude filtrates derived from the red-pigmented culture broth of Bc (CMAA1810) strongly reduced Foc conidial viability, and this inhibitory activity was inversely related to the age of the Bc culture. Crude concentrated filtrates from 4-day-old cultures exhibited the strongest antifungal activity (13-fold) compared with untreated Foc conidia. The abundant compound identified in the crude filtrate of Bc was oosporein (1,4-dibenzoquinone) present at a concentration of 0.829 ± 0.018 mg g-1 dry matter, and the antifungal activity of the filtrate was demonstrated. These results indicated that Bc strains might have the potential to manage both C. sordidus and Foc, two of the major phytosanitary problems in banana crops worldwide. Further research under field conditions using suitable formulations of virulent Bc strains in combination with the metabolite oosporein is needed to evaluate their efficacy in the management of C. sordidus and Foc in banana plantations. © 2022 Society of Chemical Industry.

Fungal consortium of two Beauveria bassiana strains increases their virulence, growth, and resistance to stress: A metabolomic approach.

The use of two or more microorganisms in a microbial consortium has been increasingly applied in the biological control of diseases and pests. Beauveria bassiana is one of the most widely studied fungal species in biological control, yet little is known about its role in fungal consortiums. In a previous study, our group found that a consortium formed by two strains of B. bassiana had significantly greater biocontrol potential against the polyphagous caterpillars Duponchelia fovealis (Lepidoptera: Crambidae) than either strain on its own. In this study, we use GC-MS and LC-MS/MS to evaluate and discuss the metabolomics of the consortium. A total of 21 consortium biomarkers were identified, corresponding to 14 detected by LC-MS/MS and seven by GC-MS. Antioxidant and anti-inflammatory mechanisms are the main properties of the metabolites produced by the consortium. These metabolites can depress the insect’s immune system, increasing its vulnerability and, hence, the fungal virulence of the consortium. In light of these results, we propose an action model of insect mortality due to the metabolites secreted by the consortium. The model includes the inhibition of defense mechanisms such as pro-inflammatory interleukin secretion, cell migration, cell aggregation, Dif, Dorsal and Relish gene transcription, and JAK/STAT and JNK signaling pathways. It also promotes the cleaning of oxidative molecules, like ROS, NOS, and H2O2, and the induction of virulence factors.

Efficacy of single and combined applications of entomopathogenic fungi and nematodes against the pupae of colorado potato beetle (Leptinotarsa decemlineata [Say]), (Coleoptera: Chrysomelidae)

BackgroundThe lethal effects of different entomopathogenic fungi (EPF) and nematodes (EPN) on the pupae of the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) were investigated in a two-step study when used separately or together. In the first step, Nostalgist (Beauveria bassiana strain Bb-1, Agrobest Co.), Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae), Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) (Bioglobal Co.), 2 Turkish isolates of Beauveria bassiana BIM-001 and BY2 were applied separately to the pupal stage of pest in the soil. In the experiments, 3 different concentrations (150, 200, and 250 million infective juveniles (IJs)/100 l water) of EPN and a single concentration (1x108 spores/ml for and maximum recommended field dose 1 × 108 CFU/ml) of EPF were used. In the second step, BIM-001 and BY2 isolates of B. bassiana were combined with both EPN species; S. feltiae + B. bassiana BIM-001, S. feltiae + B. bassiana BY2, H. bacteriophora + B. bassiana BIM-001, H. bacteriophora +B. bassiana BY2 were applied to pupae. At this stage, 150 million IJs/100 l water which was the maximum recommended field concentration for EPN and 1 × 108 spores/ml for local EPF isolates were used.ResultsAccording to the study results, pupae deaths were significantly higher in Nostalgist (74%) than those of B. bassiana BIM-001, B. bassiana BY2, S. feltiae, and H. bacteriophora (P<0.05). While both EPN caused higher mortality than B. bassiana BY2, B. bassiana BIM-001 had the highest mortality rates. The combination of S. feltiae + B. bassiana BIM-001 at the highest mortality rate (80%) was found statistically different and significant from other EPF + EPN treatments on pupae. Moreover, there were non-statistical differences between the other EPF and EPN combinations.ConclusionIt was found that the combined use of EPF and EPN was more effective on the pupae of L. decemlineata than a single application. According to the results of the study, it may be promising to use EPN and EPF together for the control of the Colorado Potato Beetle pupae.

Isolation and identification of two Beauveria bassiana strains from silkworm, Bombyx mori.

Silkworm diseases caused by fungi infection occur frequently in sericulture and brought huge economic loss to sericulture. However, on the other hand, some fungi such as Beauveria bassiana, as an important entomological fungus, play an important role in biological control of insect pests. Here, two fungal pathogens causing yellow muscardine were isolated from the silkworm and named as SZY1 and SZY2. These two strains showed almost the same conidial morphology which were smooth, near-spherical, spherical, or ovoid and 2.7 ± 0.6µm × 2.5 ± 0.9µm in size, and the hyphal growth rate was also similar. However, the conidia production of SZY2 was almost twice as many as that of SZY1. The complete ribosomal RNA gene was sequenced and analyzed. As a result, the gene sequences of internal transcript space 1 (ITS1)-5.8S rRNA-internal transcript space 2 (ITS2) of SZY1 and SZY2 were identical in sequence and size, and for 18S rRNA, 28S rRNA, and intergenic spacer (IGS), the gene identity of SZY1 to SZY2 was 99%, 99%, and 98%, respectively. Results of phylogenetic analysis based on either ITS1-5.8S rRNA-ITS2 or 18S rRNA showed that both SZY1 and SZY2 were closely related to Beauveria bassiana. These results revealed that the pathogens of yellow muscardine SZY1 and SZY2 were identified as two different strains of Beauveria bassiana, which could provide diagnostic evidence for silkworm muscardine and was helpful for the research and development of novel Bombyx batryticatus and fungal biological insecticide.

Mortality of various-age larval winter ticks, Dermacentor albipictus, following surface contact with entomopathogenic fungi

The larval stage of the one-host tick, Dermacentor albipictus Packard (Acari: Ixodidae), the winter tick, is spent aggregated on the ground in summer until they quest for hosts in the autumn. Metarhizium brunneum (Petch) and Beauveria bassiana (Balsamo-Crivelli) Vuillemin are promising fungal biocontrol agents of ticks. The success of tick biocontrol using entomopathogenic fungi relies on infective propagule contact with a susceptible host at the right time within their life cycle and stage. The susceptibility of various-age D. albipictus larvae to commercial isolates of M. brunneum strain F52 (Mb-F52) and B. bassiana strain GHA (Bb-GHA) was assessed over a three-week period after contact with surfaces treated with 1.3 × 106 conidia/cm2. Larvae of four ages were examined (a) upon eclosion from eggs, (b) 2-weeks, (c) 1.5-months and (d) 3-months-old. Mortality of larvae exposed to fungus-treated surfaces ranged from 4 to 51% for Bb-GHA and 64–100% for Mb-F52 after three weeks. Significantly greater mortality was observed when larvae were exposed to Mb-F52 than Bb-GHA. Larval susceptibility was significantly greater within 2 weeks of eclosion from eggs and after 3 months of age. These results demonstrate the varying susceptibility of larvae to mycoacaricides at different times within their non-parasitic larval life stage.

Early-Stage Defense Mechanism of the Cotton Aphid Aphis gossypii Against Infection With the Insect-Killing Fungus Beauveria bassiana JEF-544.

Aphis gossypii, commonly known as the cotton aphid, is a widely distributed pest of agricultural crops and acts as a vector for many serious plant viruses. Cotton aphid shows high resistance to chemical insecticides due to rapid rates of genetic diversity as a result of its short life cycle, seasonal migration, and host alteration. As an alternative, entomopathogenic fungi can be used to control cotton aphids in an environmentally sound manner. However, little is known about how cotton aphids respond to fungal infection. In this work, a new Beauveria bassiana strain JEF-544 (Bb JEF-544) was selected and isolated through bioassays with high virulence against cotton aphid. Early response of cotton aphid to Bb JEF-544 infection was analyzed at the transcriptome level. Infected aphids were collected two days after treatment at 25% lethal time (LT25), and total RNA of non-infected and Bb JEF-544-infected aphids was independently subjected to sequencing. Infected aphids showed significant up-regulation of the insect hormone biosynthesis pathway. Bursicon (Burs) and crustacean cardioactive peptide (CCAP) receptors involved in molting along with ecdysone synthesis were also strongly up-regulated in the aphid response to the fungal infection. In the immune response, melanization in the hemocoel was significantly up-regulated, while phagocytosis was less actively transcribed. In conclusion, cotton aphids protect themselves from Bb JEF-544 infection by activating the immune response including melanization and insect molting hormones to shed infected cuticles. In addition to describing the initial stages of Bb JEF-544 infection at the transcriptome level, this work provides potential treatment targets and insight into how fungal isolates can effectively be used to control this serious aphid species.