Cordyceps Javanica Research Articles

Residual effect of commonly used insecticides on key predatory mites released for biocontrol in strawberry.

Florida is the second largest producer of strawberries in the United States. However, the production system faces numerous challenges, especially Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) infestations. Management of this pest involves applying insecticides and use of predatory mites, particularly Amblyseius swirskii Athias-Henriot, Neoseiulus cucumeris Oudemans, and Neoseiulus californicus McGregor (Mesostigmata: Phytoseiidae). Strawberry growers in Florida are concerned about the compatibility of the commercial formulations of insecticides used in strawberry pest management with predatory mites. This study assessed the residual effect of commercial insecticides used in strawberry production on the survival, feeding, and oviposition of the 3 predators. Using Munger cells, predators were exposed to commercial formulations of spinetoram, cyantraniliprole, azadirachtin + pyrethrin, Beauveria bassiana, Cordyceps javanica, capsicum, garlic, and canola oil extracts, and water control. There was a gradual decline in the survival and feeding of predatory mites when exposed to all insecticides. Spinetoram had the highest impact on the survival and feeding of all predators compared to other insecticides, while C. javanica had the lowest impact. Cyantraniliprole and azadirachtin + pyrethrin significantly reduced predator survival after 72h of exposure, whereas capsicum, garlic, and canola oil extracts caused a similar reduction after 96h. All predators consumed low proportions of S. dorsalis across all treatments. Oviposition was low in all treatments, with no discernable variation among treatments. These results highlight the potential of using entomopathogenic fungi in conjunction with A. swirskii, N. cucumeris, and N. californicus for the management of S. dorsalis and T. urticae in strawberries.

Exploration of three native strains of entomopathogenic fungi against rice yellow hairy caterpillar, <i>Psalis pennatula</i> (Lepidoptera: Lymantriidae): An emerging pest of rainfed rice in Assam

Rice yellow hairy caterpillar Psalis pennatula Fabricius (Lepidoptera: Lymantriidae) is an emerging pest of rice and an increased incidence is expected in different rice-growing areas of Assam in the coming years. The caterpillar is a voracious leaf feeder and can consume the whole leaves within a day. Keeping this in view, an attempt was made to evaluate the bio-efficacy of three important native isolates of entomopathogenic fungal strains viz. Beauveria bassiana (KR855715), Cordyceps javanica (OM321438) and Isaria fumosorosea (MH414514) against P. pennatula larvae under laboratory conditions during the Sali season of rice. All three EPF strains at different conidial dilutions (1x103, 1x105,1x107, 1x108 and1x109 conidia/ml) were found to be pathogenic to the 3rd instar larvae of P. pennatula. Among the tested fungal strains, the strain Isaria fumosorosea (MH414514) showed the highest mortality (100%) at 1x107 conidia/ml and Cordyceps javanica (OM321438) showed the lowest mortality (51%) at 1x107conidia/ml at 10th day of post-treatment. The tested fungal isolates could play a vital role as microbial biopesticides in suppressing the P. pennatula population in Assam and could be incorporated into IPM strategies.

Secondary metabolites in Cordyceps javanica with insecticidal potential

Cordyceps javanica has been registered as a fungal insecticide in several countries. However, little is known about whether metabolic toxins are involved in the insecticidal process. In this research, we assessed the insecticidal activity of the fermentation broth of C. javanica. Myzus persicae mortality differed when exposed to the metabolized C. javanica broths at 3 days post fermentation (DPF) and 5 DPF. Comparison of the metabolic fluid at 3 DPF and 5 DPF revealed a key alkaloid, heteratisine, which was found to have insecticidal activity and acetylcholinesterase (AChE) inhibitory activity. Heteratisine has high insecticidal activity against adult M. persicae, the absolute 50% lethal concentration (LC50) was only 0.2272 mg/L. Heteratisine showed high inhibitory activity on AChE with the 50% maximal inhibitory concentration (IC50) of 76.69 μM. Molecular docking and dynamic simulations showed that heteratisine conjugation occurs at the peripheral anionic site (PAS) of the AChE of M. persicae, leading to suppression of enzyme activity. Heteratisine was rarely found in fungal metabolites, which helps us to understand the complex and elaborate insecticidal mechanism of C. javanica.

Histopathological Alterations in Nilaparvata lugens (Hemiptera: Delphacidae) after Exposure to Cordyceps javanica.

The brown planthopper (BPH), Nilaparvata lugens (Stål, 1854), is a pest of rice plants worldwide. Cordyceps javanica is a destructive entomopathogenic fungus known to attack leafhoppers or BPHs specifically. Live adult BPH samples were inoculated with isolated C. javanica PSUC002, and their interaction was morpho-histologically examined from 0 to 120 h post-inoculation (pi). We observed that the mortality of BPH continuously increased until 120 h pi (Day 5). Tissue alterations in the host were examined after infection using morphological and histological methods, including the Grocott Methenamine Silver stain test (GMS). Filamentous fungi were first found on the external integument at 12 h pi, and fungal conidia attached to the integument at 24 h pi. However, the initial degeneration of BPHs was identified by histology at 6 h pi especially in the integument and adipose tissue. We identified the degeneration and loss of integument and adipose tissue of infected BPHs at 12 h pi, and their necrosis was completed at 96 h pi. The enzymatic index of the sampled fungi (chitinase and protease) peaked at 7 days of incubation. This study demonstrated that C. javanica PSUC002 is useful to control the BPHs as an eco-friendly practice and will possibly be applied in agriculture.

Identification of a novel member of the genus Laulavirus (family Phenuiviridae) from the entomopathogenic ascomycete fungus Cordyceps javanica.

The virus family Phenuiviridae (order Hareavirales, comprising segmented negative-sense single stranded RNA viruses) has highly diverse members that are known to infect animals, plants, protozoans, and fungi. In this study, we identified a novel phenuivirus infecting a strain of the entomopathogenic fungus Cordyceps javanica isolated from a small brown plant hopper (Laodelphax striatellus), and this virus was tentatively named "Cordyceps javanica negative-strand RNA virus 1" (CjNRSV1). The CjNRSV1 genome consists of three negative-sense single stranded RNA segments (RNA1-3) with lengths of 7252, 2401, and 1117 nt, respectively. The 3'- and 5'-terminal regions of the RNA1, 2, and 3 segments have identical sequences, and the termini of the RNA segments are complementary to each other, reflecting a common characteristic of viruses in the order Hareavirales. RNA1 encodes a large protein (∼274 kDa) containing a conserved domain for the bunyavirus RNA-dependent RNA polymerase (RdRP) superfamily, with 57-80% identity to the RdRP encoded by phenuiviruses in the genus Laulavirus. RNA2 encodes a protein (∼79 kDa) showing sequence similarity (47-63% identity) to the movement protein (MP, a plant viral cell-to-cell movement protein)-like protein (MP-L) encoded by RNA2 of laulaviruses. RNA3 encodes a protein (∼28 kDa) with a conserved domain of the phenuivirid nucleocapsid protein superfamily. Phylogenetic analysis using the RdRPs of various phenuiviruses and other unclassified phenuiviruses showed CjNRSV1 to be grouped with established members of the genus Laulavirus. Our results suggest that CjNRSV1 is a novel fungus-infecting member of the genus Laulavirus in the family Phenuiviridae.

Fungi associated with the Asian citrus psyllid, Diaphorina citri Kuwayama, in northeastern Mexico

ABSTRACT Diaphorina citri Kuwayama (Asian citrus psyllid, ACP) is a devastating pest due to transmission of Liberibacter spp. to citrus plants. We identified presumed entomopathogenic fungi (EF) naturally associated with field-collected adult ACP, both killed (mycosed) and alive, at 14 field sites in the Gulf Coastal Plain of NE Mexico. On dead ACP, five species of EF (Hypocreales) were observed: Hirsutella citriformis Speare (Ophiocordycipitaceae), Cordyceps javanica (Frieder. & Bally) Kepler, Shrestha & Spatafora, Beauveria cf. bassiana (Bals.) Vuill., and Akanthomyces cf. lecanii (Cordycipitaceae); also, Niveomyces J.P.M. Araújo & C. de Bekker (Cordycipitaceae), a hyperparasite of Ophiocordycipitaceae, in this case H. citriformis. The most prevalent fungi on field ACP were H. citriformis and C. javanica, on dead and on live, incubated insects, respectively. In laboratory bioassays, C. javanica and H. citriformis conidia from cultures killed >60% of ACP adults. H. citriformis, C. javanica, and A. lecanii killed >60% nymphs. Niveomyces was observed only growing on H. citriformis fructifications on field-killed ACP; it was absent from live incubated insects, indicating Niveomyces is a mycoparasite on H. citriformis. Niveomyces cultures (ARSEF 10230) on agar grew as a Pleurodesmospora synanamorph; its LSU rRNA region D1–D2 sequences (Genbank OM780101) were 99.81% identical to Niveomyces sequences. Conidia from Niveomyces cultures were entomopathogenic on ACP nymphs and adults. These are the first reports of Niveomyces associated with H. citriformis; of the in vitro dimorphic growth (synanamorphs) Niveomyces/Pleurodesmospora; and of experimental verification of entomopathogenicity of Niveomyces. Understanding the interactions of these fungi will support sustainable ACP management.

Production of heat-resistant blastospores by Cordyceps javanica IF-1106 through optimizing metal ions composition

Heat tolerance of fungi is critical for field stability and efficacy of fungal insecticides. Components of the medium, such as carbon source, nitrogen source and metal ions, contribute to the thermotolerance of fungi. In this study, several metal ions were detected to establish their effects on the sporulation and thermotolerance of the blastospores of Cordyceps javanica IF-1106 when cultured in liquid medium. The results showed that metal ions play different roles in sporulation and thermotolerance of the fungi. Mn2+ greatly increased the thermotolerance of the blastospores, and Fe2+ increased the thermotolerance slightly. However, both has no or negative effects on sporulation of the fungi. In the case of Cu2+ and Fe3+, sporulation yield and thermotolerance of the blastospores increased significantly. In addition, intracellular trehalose and mannitol involved in thermotolerance of fungi were extracted and then quantified by ion chromatography. We find that the trehalose and mannitol are higher in the presence of Mn2+, implying that Mn2+ could adjust the intracellular trehalose and mannitol level confers the blastospores with higher tolerance to thermal stress. Further, Response Surface Methodology (RSM) was applied to screen the optimal composition of metal ions. When the formula was MnSO4·H2O 8 mg/L, CuSO4·5H2O 5 mg/L, FeSO4·7H2O 11 mg/L, FeCl3·6H2O 8 mg/L, maximum sporulation yield and GT50 were obtained. Lastly, the virulence of the blastospores to Acyrthosiphon pisum was validated, a higher virulence is achieved with decreased LT50 (2 d) and LC50 (2.37 × 104 blastospores mL−1). In conclusion, thermotolerant blastospores of C. javanica IF-1106 and higher sporulation yield could be achieved by optimizing the metal ions composition, which helps to determine the formula for larger scale fermentation process.

Management of Bemisia tabaci on vegetable crops using entomopathogens

The sweetpotato whitefly, Bemisia tabaci Gennadius, is a devastating insect pest on vegetable crops around the world. This pest causes significant damage by directly feeding on vegetables, excreting honeydew, inducing plant physiological disorders, and transmitting plant viruses. The combined direct and indirect damage to vegetable crops has led to substantial economic losses. The heavy reliance on chemical insecticides for whitefly control has led to considerable resistance to many insecticides in whitefly populations. Therefore, integrated pest management (IPM) that includes entomopathogens is considered as a sustainable and effective approach against B. tabaci. This review focuses on biological control of B. tabaci using entomopathogens, including entomopathogenic fungi (EPF), entomopathogenic nematodes (EPN), and entomopathogenic bacteria (EPB). Among them, EPF is the mostly explored group of entomopathogens for B. tabaci control. In particular, Beauveria bassiana (Balsamo-Crivelli) Vuillemin, Akanthomyces lecanii (Zimm.) Spatafora, Kepler and B. Shrestha, Cordyceps javanica (Frieder. & Bally) Kepler, B. Shrestha & Spatafora, and C. fumosorosea (Wize) Kepler, B. Shrestha & Spatafora are the most commonly used EPF species for whitefly control. The control efficacy of EPN against B. tabaci varies with strains/species and concentrations of the EPN, whitefly nymphal instars, host plants, and environmental conditions. Most research on evaluating the virulence of various EPB isolates against whiteflies has been conducted in the laboratory. Entomopathogens offer a promising strategy for whitefly management in vegetables. This review discusses research updates on the three entomopathogen groups for whitefly control, barriers in broad adoption by vegetable growers, and future directions.

Improvement of the production and quality of Cordyceps javanica conidia for the control of Diaphorina citri adults.

This study aimed to evaluate the use of palm kernel meal (PKM) in the traditional solid-state fermentation system to improve the production and quality of Cordyceps javanica conidia. The impact of PKM was determined by measuring conidia yield, viability, hydrophobicity, shelf life, and conidia pathogenicity against Diaphorina citri adults. By supplementing rice grains with 5% palm kernel meal increased the conidial yield by up to 40%, without compromising conidia viability and hydrophobicity. In addition, conidia caused higher levels of mortality by mycosis against D. citri adults (90%), relative to conidia harvested from rice (52%). The conidia recovered from rice/palm kernel meal mixtures also retained viability greater than 90% after storage for 10months at 4°C, while the conidia produced on rice reached 80%. Thus, conidia produced in the presence of palm kernel meal can be consumed immediately or in the medium term. Some process advantages of the palm kernel meal as co-substrate in the traditional production system of C. javanica are also mentioned. These results are attractive for improving the mycoinsecticide production process, with excellent cost-benefit and minimal changes in infrastructure and process.

Structure and absolute configuration of natural fungal product beauveriolide I, isolated from Cordyceps javanica, determined by 3D electron diffraction.

Beauveriolides, including the main beauveriolide I {systematic name: (3R,6S,9S,13S)-9-benzyl-13-[(2S)-hexan-2-yl]-6-methyl-3-(2-methylpropyl)-1-oxa-4,7,10-triazacyclotridecane-2,5,8,11-tetrone, C27H41N3O5}, are a series of cyclodepsipeptides that have shown promising results in the treatment of Alzheimer's disease and in the prevention of foam cell formation in atherosclerosis. Their crystal structure studies have been difficult due to their tiny crystal size and fibre-like morphology, until now. Recent developments in 3D electron diffraction methodology have made it possible to accurately study the crystal structures of submicron crystals by overcoming the problems of beam sensitivity and dynamical scattering. In this study, the absolute structure of beauveriolide I was determined by 3D electron diffraction. The cyclodepsipeptide crystallizes in the space group I2 with lattice parameters a = 40.2744 (4), b = 5.0976 (5), c = 27.698 (4) Å and β = 105.729 (6)°. After dynamical refinement, its absolute structure was determined by comparing the R factors and calculating the z-scores of the two possible enantiomorphs of beauveriolide I.

Laboratory evaluation of 15 entomopathogenic fungal spore formulations on the mortality of Drosophila suzukii (Diptera: Drosophilidae), related drosophilids, and honeybees

Abstract The drosophilids Drosophila suzukii (Matsumura), Drosophila melanogaster Meigen and Zaprionus indianus Gupta (Diptera: Drosophilidae), are common pests of Mexican berry plantations. Attract-and-infect-based application strategies using entomopathogenic fungi (EPF), which are more environmentally friendly than synthetic chemical pesticides, are currently under evaluation for their potential at controlling insect pests, as compared to synthetic pesticides. In this study, we evaluated 15 EPF formulations against D. suzukii adults to determine which formulations would work best in an attract-and-infect device in terms of spore accumulation, pathogenicity, and mortality. Formulations of Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae), Cordyceps javanica (Friederichs & Bally) (Hypocreales: Cordycipitaceae), and Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) spores exhibited the highest levels of conidia attachment, pathogenicity, and virulence, making them effective against D. suzukii. In a subsequent experiment, these formulations were evaluated against D. melanogaster, Z. indianus, and the honey bee, Apis mellifera L. (Hymenoptera: Apidae). Our results revealed that the formulations containing C. javanica and M. anisopliae were highly virulent not only against D. suzukii, but also against D. melanogaster and Z. indianus, with minimal impact on honey bees. Our results showed that spore formulations of M. anisopliae and C. javanica were the most promising entomopathogens for further testing of attract-and-infect devices to manage D. suzukii, D. melanogaster and Z. indianus in berry crops.

Isolamento e caracterização molecular de Cordyceps sp. de Bemisia tabaci e patogênico para Glycaspis brimblecombei (Hemiptera: Aphalaridae)

The Brazilian forestry sector stands out for its technology, forestry management practices, social and environmental responsibility and, mainly, for its high productivity and exotic pests can reduce it. The red gum lerp psyllid Glycaspis brimblecombei (Moore, 1964) (Hemiptera: Aphalaridae) is an important pest in Eucalyptus plantations. The parasitoid Psyllaephagus bliteus (Riek, 1962) (Hymenoptera: Encyrtidae), predatory bugs and entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae are the natural enemies and used in the biological control of the red gum lerp psyllid. The use of entomopathogenic fungi against exotic pests is increasing in the forestry sector and the prospecting and identification of fungus isolates is important for integrated pest management. The objective of this work was the isolation and molecular identification of Cordyceps spp. And to evaluate the pathogenicity of isolates, obtained from Bemisia tabaci (Gennadius, 1889) (Hemiptera: Aleyrodidae) adults, against to the red gum lerp psyllid G. brimblecombei. The fungi were isolated from B. tabaci adults found in soybean and tomato crops and molecularly identified. The conidia obtained were suspended in solution with Tween 80 (0.1%) at a concentration of 1.0 × 108 conidia/mL and sprayed on ten G. brimblecombei nymphs per Eucalyptus leaf cut and placed on a hydroretentive gel inside per Petri dishes as a replication. The number of dead insects was quantified, daily, for seven days, and transferred to humid chambers. Cordyceps javanica (LCBPF 11) and C. fumosorosea (LCBPF 12 and LCBPF 63) were identified with a molecular analysis and all isolates were pathogenic to the insects and indicates that they could be used to manage G. brimblecombei and adds to reports that, normally, fungi cause greater mortality on insects of the same order as that from which they were isolated.

DC-electrical penetration graph waveforms for Dalbulus maidis (Hemiptera: Cicadellidae) and the effects of entomopathogenic fungi on its probing behavior

The corn leafhopper Dalbulus maidis is an important transmitter of viruses and bacteria to maize plants. Data on the stylet probing and ingestion behavior of D. maidis, gathered using the DC-electrical penetration graph (DC-EPG) technique, are limited. The increasing prevalence of this pest and the diseases that it transmits in maize crops heighten the importance of studying how control tools affect the probing behavior of these insects, to reduce or prevent the chances of pathogen transmission and the damage from feeding. Our study recorded stylet activities of D. maidis, using a DC-EPG system and compared the appearances of waveforms with those from published AC and AC-DC EPG studies. All types of systems produced similar waveform appearances; therefore, we used the waveform nomenclature previously published. We also determined the effects of the entomopathogenic fungus Cordyceps javanica on the probing behavior of D. maidis at different time points after the fungus was applied by spraying. Forty-eight hours after the insects were sprayed, the effects were pronounced, with significant disruption of the stylet activities in phloem and non-phloem phases. Our study indicated that this commercial microbiological product, with the active ingredient C. javanica, can alter the probing behavior of D. maidis and may be helpful in management of the vector.

Akanthomyces dipterigenus acts as a potential biocontrol agent by causing mortality and inhibiting population growth of Bemisia tabaci

Bemisia tabaci is a worldwide pest, and has developed severe resistance to many insecticide. Therefore, it is great significance to find new substitute for chemical insecticide to control B. tabaci. In this study, selected efficient strains by comparing the virulence of Akanthomyces dipterigenus, Cordyceps javanica, Purpureocillium lilacinum, Penicillium camemberti, Metarhizium anisopliae, and Beauveria bassiana against 2nd-instar nymphs of B. tabaci and bioassays were conducted on various developmental stages of B. tabaci using highly pathogenic strain. Additionally, the effects of medium lethal concentration of high-efficiency strains on the biological parameters of B. tabaci were also studied. The bioassay showed that six entomopathogenic fungi have significant effects on the 2nd-instar nymphs of B. tabaci, the median lethal concentration (LC50) of A. dipterigenus against 2nd-instar nymphs of B. tabaci was only 6.54 × 103 (3.35 × 103–1.13 × 104) conidia mL−1, which was lower than that of the other five fungi, and the median lethal time (LT50) was the shortest. In addition, A. dipterigenus also had lethal effects on eggs, nymphs and adults of B. tabaci, among which the mortality rate of 2nd-instar nymphs was the highest. The fungal treatment affected the population parameters of B. tabaci, R0, r, and λ were significantly reduced, T was significantly prolonged, and had higher preadult mortality and shorter adult longevity, but had no significant effect on the total fecundity. These findings highlight the potential of using A. dipterigenus as a sustainable and eco-friendly alternative to chemical insecticides for controlling B. tabaci populations in agricultural settings.

Pathogens are an important driving force for the rapid spread of symbionts in an insect host.

One of the biggest challenges for pathogens invading hosts is microbial symbionts but the role of pathogens in symbionts in nature is unknown. By tracking the dynamics of the entomopathogenic fungal Cordyceps javanica and symbionts in natural populations of the whitefly Bemisia tabaci from 2016 to 2021 across China, we reveal that Rickettsia, a newly invaded symbiont, is positively correlated with the pathogen in both frequency and density. We confirm that applying pathogen pressure can selectively drive Rickettsia to sudden fixation in whiteflies both in the laboratory and in the field. Furthermore, the driving force is elucidated by the Rickettsia-conferred suppression of pathogen infection quantity, proliferation and sporulation, acting as a potential barrier of onward transmission of the pathogen. These results show that pathogens are an important driving force for rapid shifts in host symbionts in the natural niche.

Post-Application Field Persistence and Efficacy of Cordyceps javanica against Bemisia tabaci.

Previously, Cordyceps javanica Wf GA17, a causing agent of whitefly epizootics in southern Georgia, demonstrated superior temperature tolerance and higher virulence against the whitefly Bemisia tabaci than commercial strains in the laboratory. The post-application persistence and efficacy of this fungus against B. tabaci were compared with that of the commercially available C. javanica Apopka97 strain over a two-year field study in cotton and vegetable crops. When blastospores of both strains were applied alone, whitefly populations were not effectively suppressed. Thus, JMS stylet oil was added to fungal treatments for enhancing efficacy and persistence. For 0-day samples, all fungal treatments caused similar but significant levels of immature mortality regardless of fungal strain, propagule form (conidia vs. blastospores), and application method (alone or mixed with JMS). In follow-up samplings, Wf GA17 blastospores + JMS achieved higher control levels than other treatments in some trials, but the efficacy did not last long. The JMS oil alone caused significant mortality and suppressed whiteflies. Over 90% of spores lost viability 24 h after treatment in all fungal treatments. Across evaluation times, there was no difference between the two fungal strains (conidia or blastospores, alone or combined with JMS), but conidia persisted better than blastospores for both strains. Overall, the field persistence and efficacy of C. javanica did not last long; therefore, improved delivery methods and formulations are needed for enhancement.

Diversity of anamorphic Cordyceps (formerly Isaria) isolated from Brazilian agricultural sites

A total of 53 anamorphic strains of Brazilian Cordyceps species currently maintained in a government-owned culture collection, were reassessed for diversity and species identity using multi-loci-based phylogenetic methods. The strains used in this study were originally obtained from soil samples or were isolated from insects of the orders Hemiptera, Lepidoptera, Coleoptera and Diptera, mostly from agricultural sites. A Bayesian phylogenetic tree was constructed based on a concatenation of five loci (ITS, LSU, RPB1, RPB2 and TEF). In a few cases of ambiguity, morphological traits were also considered for species delimitations. Considerable variability within the set of strains was detected and six Cordyceps species were identified: C. amoenerosea, C. fumosorosea, C. javanica, C. tenuipes and, for the first time, C. brevistroma and C. spegazzinii are reported in Brazil. Four other taxonomically equivocal groups, closely related to other known taxa (C. amoenerosea, C. cateniannulata, C. polyarthra and C. spegazzinii), were also recognized, although further studies will be required to confirm their identifications or their descriptions as new species. Cordyceps javanica was the most common species in our dataset, originally isolated from soil and several different insect orders, and includes 17 strains from the whitefly, Bemisia tabaci. Interestingly, strains previously identified as C. fumosorosea based on morphology and growth characteristics, were shown to be C. javanica, including the active ingredients of some commercial mycoinsecticides. Cordyceps farinosa, usually mentioned in the literature as occurring in Brazil, was not found in our study. Since most strains were from insect crop pests, further studies with hosts from non-agricultural settings or from environmental samples would be advisable for a deeper understanding of the occurrence of anamorphic Cordyceps in Brazil.

Impacts of repeated liquid culture on entomopathogenic fungi

ABSTRACT Production of entomopathogenic fungi (EPF) for biopesticides relies on in vitro production of fungal propagules as the active ingredients. Repeated culturing or sub culturing may select for fungi with reduced spore production and virulence. We completed 60 cycles of repeated liquid culture on six isolates representing four genera of EPF. Measurements of the spent media recorded at T2, T15, T30, T45 and T60 cycles included blastospore concentrations, dry matter accumulation as hyphae, glucose concentration remaining, and final pH. Insecticidal activity (LC50 of Trichoplusia ni neonates) was compared between initial and final cultures for conidia grown on nutrient agar. Virulence of Beauveria bassiana GHA was 3× lower at T60 (LC50 ratio = 0.308) and consumption of glucose increased with additional culture cycles. Two Cordyceps javanica (MBC 177 and Apopka 97) had fewer blastospores, higher pH, and altered mycelia dry weight at the T15 sample, but maintained similar values from T15 through T60. MBC 177 and Apopka 97 lost virulence with LC50 ratios of 0.345 and 0.016, respectively. Metarhizium robertsii and M. brunneum F52 isolates failed to produce conidia by plating T30, T45, and T60 cultures on nutrient agar. When comparing T0 with T15 cultures, M. robertsii conidia had increased virulence while M. brunneum had decreased virulence (LC50 ratios of 1.746 and 0.740, respectively). These differences between the two Metarhizium species demonstrate that the direction and level of impact imposed by repeated culture is at least species dependent.

Role of the Subtilisin-like Serine Protease CJPRB from Cordyceps javanica in Eliciting an Immune Response in Hyphantria cunea

Hyphantria cunea is a globally distributed quarantine plant pest. In a previous study, the Cordyceps javanica strain BE01 with a strong pathogenic effect on H. cunea was identified, and overexpression of the subtilisin-like serine protease CJPRB of this strain was found to accelerate the death of H. cunea (previous research results). In this study, the active recombinant CJPRB protein was obtained through the Pichia pastoris expression system. It was found that CJPRB protein administration to H. cunea via infectation, feeding and injection was able to induce changes in protective enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO), and the expression of immune defense-related genes in H. cunea. In particular, CJPRB protein injection induced a more rapid, widespread and intense immune response in H. cunea compared to the other two treatment methods. The results suggest that the CJPRB protein may play a role in eliciting a host immune response during infectation by C. javanica.

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

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