Arthropod-pathogenic Fungi Research Articles

Species diversity and major host/substrate associations of the genus Akanthomyces (Hypocreales, Cordycipitaceae).

Akanthomyces, a group of fungi with rich morphological and ecological diversity in Cordycipitaceae (Ascomycota, Hypocreales), has a wide distribution amongst diverse habitats. By surveying arthropod-pathogenic fungi in China and Southeast Asia over the last six years, nine Akanthomyces spp. were found and identified. Five of these were shown to represent four known species and an undetermined species of Akanthomyces. Four of these were new species and they were named A.kunmingensis and A.subaraneicola from China, A.laosensis from Laos and A.pseudonoctuidarum from Thailand. The new species were described and illustrated according to the morphological characteristics and molecular data. Akanthomycesaraneogenus, which was isolated from spiders from different regions in China, Thailand and Vietnam, was described as a newly-recorded species from Thailand and Vietnam. The phylogenetic positions of the nine species were evaluated, based on phylogenetic inferences according to five loci, namely, ITS, nrLSU, TEF, RPB1 and RPB2. In this study, we reviewed the research progress achieved for Akanthomyces regarding its taxonomy, species diversity, geographic distribution and major host/substrate associations. The morphological characteristics of 35 species in Akanthomyces, including four novel species and 31 known taxa, were also compared.

Patterns of Diversity, Structure and Local Ecology of Arthropod-Pathogenic Fungi in the Amazonian Forest of Cusco and Madre de Dios Regions, Southern Peru

The ecological role and potential management of arthropod-pathogenic fungi (APF) in neotropical forests are of great importance, but they are still little studied. The present study achieves a first estimation of diversity patterns, structure and local ecology of APF in the Amazonian forests of the Cusco and Madre de Dios regions in southern Peru. We sampled 39 localities in five basins, examining 277 specimens, four families and 20 genera with 82 species (40% morphospecies). The most diverse families were Cordycipitaceae with 51 species and Ophiocordicipitaceae (22). Cusco obtained a greater diversity: four families, 18 genera and 58 morphospecies, with the Urubamba and Amarumayu basins having greater diversity (31 and 20 species); for the Madre de Dios basin, there was 28 species. In both regions, the richness values were corroborated by Fisher’s Alpha and Chao-1 indexes, the latter identifies Amarumayu and Araza with maximum values. The NMDS analysis showed a good pattern of separation of the two APF communities, although an important group was shared. Elevation was identified as the environmental variable with the strongest influence on diversity and structure. The dominance analysis identified Ophiocordyceps australis and Paraisaria amazonica as hyperdominant, due to their density and distribution. The local ecological patterns in Pongo de Qoñec show that the richness of entomopathogens is largely favored by low understory light, associated with pristine or little-impacted habitats. We conclude that this first approximation of the knowledge of the high diversity of APF in southern Peru is still insufficient, but it demonstrates the importance of their conservation and represents enormous potential for sustainable management.

Phylogeny and species delimitations in the economically, medically, and ecologically important genus Samsoniella (Cordycipitaceae, Hypocreales).

Samsoniella is a ubiquitous genus of cosmopolitan arthropod-pathogenic fungi in the family Cordycipitaceae. The fungi have economic, medicinal, and ecological importance. Prior taxonomic studies of these fungi relied predominantly on phylogenetic inferences from five loci, namely, the nuclear ribosomal small and large subunits (nr SSU and nr LSU), the 3' portion of translation elongation factor 1 alpha (3P_TEF), and RNA polymerase II subunits 1 and 2 (RPB1 and RPB2). Despite many new species being described, not all of the recognized species inside this group formed well-supported clades. Thus, the search for new markers appropriate for molecular phylogenetic analysis of Samsoniella remains a challenging problem. In our study, we selected the internal transcribed spacer regions of the rDNA (ITS rDNA) and seven gene regions, namely, 3P_TEF, the 5' portion of translation elongation factor 1 alpha (5P_TEF), RPB1, RPB2, γ-actin (ACT), β-tubulin (TUB), and a gene encoding a minichromosome maintenance protein (MCM7), as candidate markers for species identification. Genetic divergence comparisons showed that the ITS, RPB2, ACT, and TUB sequences provided little valuable information with which to separate Samsoniella spp. In contrast, sequence data for 3P_TEF, 5P_TEF, RPB1, and MCM7 provided good resolution of Samsoniella species. The phylogenetic tree inferred from combined data (5P_TEF + 3P_TEF + RPB1 + MCM7) showed well-supported clades for Samsoniella and allowed for the delimitation of 26 species in this genus. The other two species (S.formicae and S.lepidopterorum) were not evaluated, as they had abundant missing data.

Metarhizium anisopliae E6 secretome reveals molecular players in host specificity and toxicity linked to cattle tick infection

Although Metarhizium anisopliae is one of the most studied fungal biocontrol agents, its infection mechanism is far from being completely understood. Using multidimensional protein identification technology (MudPIT), we evaluated the differential secretome of M. anisopliae E6 induced by the host Rhipicephalus microplus cuticle. The proteomic result showed changes in the expression of 194 proteins after exposure to host cuticle, such as proteins involved in adhesion, penetration, stress and fungal defense. Further, we performed a comparative genomic distribution of differentially expressed proteins of the M. anisopliae secretome against another arthropod pathogen, using the Beauveria bassiana ARSEF2860 protein repertory. Among 47 analyzed protein families, thirty were overexpressed in the M. anisopliae E6 predicted genome compared to B. bassiana. An in vivo toxicity assay using a Galleria mellonella model confirmed that the M. anisopliae E6 secretome was more toxic in cattle tick infections compared to other secretomes, including B. bassiana with cattle ticks and M. anisopliae E6 with the insect Dysdereus peruvianus, which our proteomic results had also suggested. These results help explain molecular aspects associated with host infection specificity due to genetic differences and gene expression control at the protein level in arthropod-pathogenic fungi.

Molecular Phylogeny and Morphology Reveal Cryptic Species in the Cordyceps militaris Complex from Vietnam.

The Cordyceps militaris complex, which is a special group in the genus Cordyceps, is rich in species diversity and is widely distributed in nature. Throughout the investigations of arthropod-pathogenic fungi in the national reserves and in Vietnam parks, collections of C. militaris attacking lepidopteran pupae or larvae were located in the soil and on the leaf litter. The phylogenetic analyses of the combined nrSSU, nrLSU, TEF, RPB1, and RPB2 sequence data indicated that the fungal materials collected in Vietnam belonged to C. militaris and two hidden species in the C. militaris complex. The phylogenetic analyses and morphological comparisons presented here strongly supported the descriptions of C. polystromata and C. sapaensis as new taxa as well as C. militaris as a known species. The morphological characteristics of 11 species in the C. militaris complex, which included two novel species and nine known taxa, were also compared.

First record of the interaction between the arthropod-pathogenic fungus Gibellula and a new species of harvestman Auranus (Stygnidae) narrowly endemic to the Brazilian rain forest.

Harvestmen are one of the largest groups of arachnids with more than 6,500 species distributed in 1,500 genera and 50 families. However, the interactions between harvestmen and arthropod-pathogenic fungi have rarely been studied. Certain previous studies report that fungal attack represents one of the most important factors for the mortality of harvestmen, but the fungus has rarely been identified, and most of the important information about the fungus-host interactions remains unrecorded. In the present study, we have described the new species Auranus quilombola sp. nov. and reported its interactions with the arthropod-pathogenic fungus Gibellula sp. Auranus quilombola sp. nov. belongs to the family Stygnidae, and it is endemic to the humid mountain forests of Cear state, Brazil in an area of endemism known as Brejos Cearenses. The species is related to five other species of Auranus, all of which have been recorded from the Amazon rainforest. A taxonomic description of this new species and its biogeographic implications have also been discussed in this paper.

Can colonization by an endophytic fungus transform a plant into a challenging host for insect herbivores?

Endophytic growth of arthropod pathogenic fungi can parasitize insect herbivores without causing damage to the crop. However, studies addressing this tritrophic interaction are absent. Here, the endophytic arthropod pathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordyciptaceae), the polyphagous two-spotted spider mite Tetranychus urticae Koch (Trombidiformes: Tetranychidae), and its preferred plant host Phaseolus vulgaris L. (Fabales: Fabaceae) were selected to study the multi-kingdom interactions among plants, arthropods, and entomopathogenic fungi. Real-Time PCR analysis of nine defense-related genes revealed that a broad range of plant defense mechanisms is activated in response to the endophytic growth of B. bassiana. Moreover, we studied the molecular mechanism adapted by the two-spotted spider mite that underlies resistance. The analysis of 41 detoxification genes revealed that relatively moderate, high, and few numbers of genes were changed in the adults, nymphs, and eggs stages of T. urticae, respectively, after inoculation on colonized tissues of P. vulgaris. The endophytic growth of B. bassiana can have a negative effect on the growth and performance of the pest, in a developmental stage-dependent manner, by priming plant defense pathways. In parallel, the herbivore induces a broad range of detoxification genes that could potentially be involved in adaptation to endophytically colonized plant tissues.

Molecular phylogeny and morphology reveal cryptic species in Blackwellomyces and Cordyceps (Cordycipitaceae) from Thailand

Nine species in Cordyceps sensu lato producing orange to red stromata were discovered during diversity surveys of arthropod-pathogenic fungi in Thailand. The phylogenetic analyses of combined ITS, LSU, RPB1, RPB2 and TEF1 sequence data indicated four novel species belonging to Blackwellomyces and five novel species of Cordyceps. All Blackwellomyces species produce filiform ascospores with septations. Blackwellomyces aurantiacus and Blackwellomyces roseostromatus occur on lepidopteran larvae, and both species produce an Evlachovaea-like conidial arrangement of the anamorph and produce a red pigment that diffuses across agar medium. Blackwellomyces calendulinus and Blackwellomyces minutus are found on coleopteran larvae producing Acremonium-like and Mariannaea-like conidial arrangements of their anamorphs and do not produce any pigment. Novel members of Cordyceps include the species Cordyceps brevistroma, Cordyceps inthanonensis, Cordyceps neopruinosa, and Cordyceps parvistroma that are pathogenic on lepidopteran larvae and cocoons, whereas C. araneae is pathogenic on spiders. All Cordyceps species produce bola-shaped, whole ascospores, except for C. inthanonensis that produces ascospores dissociating into part-spores. A common feature of the novel Cordyceps species presented herein is the production of Evlachovaea-like or Mariannaea-like conidial arrangement of the anamorphs.

Updating the application of Metarhizium anisopliae to control cattle tick Rhipicephalus microplus (Acari: Ixodidae)

The bovine tick, Rhipicephalus microplus, is the main ectoparasite of cattle and causes loss of billions of dollars worldwide in lost meat, milk, and leather production, as well as control expenses. In addition to systemically impacting the host during the parasitic act, this parasite is also an important disease vector. Traditionally, the main commercial control of the tick is achieved through application of chemical acaricides, which can leave residues in the meat and milk. Moreover, ticks can become resistant to these chemicals due to their massive and incorrect use. Many alternative methods have been tested including vaccines and natural products from plant origin. However, the efficacy of these treatments is variable and limited, especially when used alone. Arthropod-pathogenic fungi, such as Metarhizium anisopliae, are among the natural microbial agents with promising potential to be used alone or in association with other products, for example with chemical acaricides. This article discusses several aspects of bovine tick control related to the use of M. anisopliae, which is one of the most studied and viable alternative tools for effective tick control.

Entomopathogenic fungal conidia marginally affect the behavior of the predators Orius majusculus (Hemiptera: Anthocoridae) and Phytoseiulus persimilis (Acari: Phytoseiidae) foraging for healthy Tetranychus urticae (Acari: Tetranychidae).

We determined how conidia of arthropod-pathogenic fungi on leaves affected the behavior of two predators-Orius majusculus (Hemiptera: Anthocoridae) and Phytoseiulus persimilis (Acari: Phytoseiidae)-when offered a choice between preying on two-spotted spider mites, Tetranychus urticae (Acari: Tetranychidae), in the presence or absence of infective conidia of Metarhizium brunneum (Ascomycota: Hypocreales) and Neozygites floridana (Entomophthoromycota: Neozygitaceae). The results indicate no significant relation between the presence of conidia and predator behavior. The only indication of interference is between the generalists O. majusculus and M. brunneum, with a trend towards more time spent feeding and more prey encounters turning into feeding events on leaf discs without conidia than on leaf discs with conidia. Our results show that the presence of fungal conidia does not alter the preying behavior of the predators, and using predators and fungi together is not limited by any interference between organisms in the short term.

Phylogeny and species delimitations in the entomopathogenic genus Beauveria (Hypocreales, Ascomycota), including the description of B. peruviensis sp. nov.

The genus Beauveria is considered a cosmopolitan anamorphic and teleomorphic genus of soilborne necrotrophic arthropod-pathogenic fungi that includes ecologically and economically important species. Species identification in Beauveria is difficult because of its structural simplicity and the lack of distinctive phenotypic variation. Therefore, the use of multi-locus sequence data is essential to establish robust species boundaries in addition to DNA-based species delimitation methods using genetic distance, coalescent, and genealogical concordance approaches (polyphasic approaches). In this regard, our study used multilocus phylogeny and five DNA-based methods to delimit species in Beauveria using three molecular makers. These polyphasic analyses allowed for the delimitation of 20–28 species in Beauveria, confirming cryptic diversity in five species (i.e. B. amorpha, B. bassiana, B. diapheromeriphila, and B. pseudobassiana) and supporting the description of B. peruviensis as a new taxon from northeastern Peru. The other five species were not evaluated as they did not have enough data (i.e. B. araneola, B. gryllotalpidicola, B. loeiensis, B. medogensis, and B. rudraprayagi). Our results demonstrate that the congruence among different methods in a polyphasic approach (e.g. genetic distance and coalescence methods) is more likely to show reliably supported species boundaries. Among the methods applied in this study, genetic distance, coalescent approaches, and multilocus phylogeny are crucial when establishing species boundaries in Beauveria.

Sleeping Beauties: Horizontal Transmission via Resting Spores of Species in the Entomophthoromycotina

Many of the almost 300 species of arthropod-pathogenic fungi in the Entomophthoromycotina (Zoopagomycota) are known for being quite host-specific and are able to cause epizootics. Most species produce two main types of spores, conidia and resting spores. Here, we present a review of the epizootiology of species of Entomophthoromycotina, focusing on their resting spores, and how this stage leads to horizontal transmission and persistence. Cadavers in which resting spores are produced can often be found in different locations than cadavers of the same host producing conidia. Resting spores generally are dormant directly after production and require specific conditions for germination. Fungal reproduction resulting from infections initiated by Entomophaga maimaiga resting spores can differ from reproduction resulting from conidial infections, although we do not know how commonly this occurs. Reservoirs of resting spores can germinate for variable lengths of time, including up to several months, providing primary infections to initiate secondary cycling based on conidial infections, and not all resting spores germinate every year. Molecular methods have been developed to improve environmental quantification of resting spores, which can exist at high titers after epizootics. Ecological studies of biological communities have demonstrated that this source of these spores providing primary inoculum in the environment can decrease not only because of germination, but also because of the activity of mycopathogens.

Metabolomic profile and nucleoside composition of Cordyceps nidus sp. nov. (Cordycipitaceae): A new source of active compounds.

Cordyceps sensu lato is a genus of arthropod-pathogenic fungi, which have been used traditionally as medicinal in Asia. Within the genus, Ophiocordyceps sinensis is the most coveted and expensive species in China. Nevertheless, harvesting wild specimens has become a challenge given that natural populations of the fungus are decreasing and because large-scale culture of it has not yet been achieved. The worldwide demand for products derived from cultivable fungal species with medicinal properties has increased recently. In this study, we propose a new species, Cordyceps nidus, which parasitizes underground nests of trapdoor spiders. This species is phylogenetically related to Cordyceps militaris, Cordyceps pruinosa, and a sibling species of Cordyceps caloceroides. It is found in tropical rainforests from Bolivia, Brazil, Colombia and Ecuador. We also investigated the medicinal potential of this fungus based on its biochemical properties when grown on four different culture media. The metabolic profile particularly that of nucleosides, in polar and non-polar extracts was determined by UPLC, and then correlated to their antimicrobial activity and total phenolic content. The metabolome showed a high and significant dependency on the substrate used for fungal growth. The mass intensities of nucleosides and derivative compounds were higher in natural culture media in comparison to artificial culture media. Among these compounds, cordycepin was the predominant, showing the potential use of this species as an alternative to O. sinensis. Furthermore, methanol fractions showed antimicrobial activity against gram-positive bacteria, and less than 3.00 mg of gallic acid equivalents per g of dried extract were obtained when assessing its total phenolic content by modified Folin-Ciocalteu method. The presence of polyphenols opens the possibility of further exploring the antioxidant capacity and the conditions that may enhance this characteristic. The metabolic composition and biochemical activity indicate potential use of C. nidus in pharmaceutical applications.

Extended studies on the diversity of arthropod-pathogenic fungi in Austria and Poland

Results of studies on diversity of arthropod-pathogenic fungi in selected habitats in Austria and Poland carried out in the years 2006-2007 and 2009-2010 are discussed. In total 47 species of entomopathogenic fungi were found as pathogens of different arthropods in Austria. Twenty six entomophthoralean species from different insects and one species from mites were identified and 16 of them are recorded as new to Austria. From among 21 species of anamorphic Hypocreales (Ascomycota) affecting arthropods in Austria, 13 species so far have not been known from this country. In total 51 species of fungi affecting different arthropods in Poland were recorded, among them 28 species of Entomophthorales and 23 anamorphic Hypocreales (Ascomycota) were separated. The most frequent species of the entomopathogenic fungi both in agricultural and afforested areas in Austria were the common and usually worldwide distributed cordycipitaceous anamorphs <em>Beauveria bassiana, Isaria fumosorosea</em> and in areas of this study less numerous <em>I. farinosa</em>. The most frequent pathogens occurring in mite communities on plants and in wood infested by insects were <em>Hirsutella</em> species. Several entomophthoralean species developed epizootics that caused high reduction in host populations of different arthropods in both countries. Especially interesting is the first record of mycoses (up to 60% mortality), caused by <em>Zoophthora</em> spp. on <em>Phyllobius</em> beetles in a mixed forest near Białowieża. During our joint research, we found the first time in Poland and Europe, the presence of the fungus <em>Furia</em> cf. <em>shandongensis</em> on earwigs and <em>Hirsutella entomophila</em> on <em>Ips typographus</em> adults in forest habitats. From the feeding sites of the latter bark beetle and other subcortical species in oak bark (mostly <em>Dryocoetes villosus</em>) and D. alni in black alder over a dozen of various <em>Lecanicillium</em> strains - including few of the features not allowing to classify them to any of so far known species – were isolated both from the scolytids and from accompanying them mites, but these materials have now been successively elaborated. From the commonly occurring in these materials acaropathogenic species <em>Hirsutella cf. brownorum, H. minnesotensis, H. nodulosa and H. rostrata</em>, the two latter infected also adult bark beetles, whereas from the larvae and pupae some supposed nematophagous anamorphs were isolated, among them <em>Harposporium janus</em> and <em>Haptocillium</em> sp.

<i>Ophiocordyceps pulvinata</i> sp. nov., a pathogen with a reduced stroma

Ophiocordyceps pulvinata, a pathogen of ants, is formally described as a new species. Genus level designation of this species is difficult due to several apparently conflicting morphological and ecological characters. Affinity with Ophiocordyceps is suggested by the dark color stroma and ascospore morphology. However, the species was included in a book of entomopathogenic fungi of Japan as Torrubiella sp. due to the production of perithecia on an astipitate stroma. Phylogenetic analyses of molecular data support a close relationship with O. unilateralis, a finding consistent with morphological characteristics of the color, asci and ascospores and ecological traits of host affiliation. Thus, O. pulvinata represents another example of the loss of stipe for the hypocrealean arthropod pathogenic fungi and highlights the utility of asci and ascospore morphology as taxonomically informative characters of closely related taxa.

Ophiocordyceps pulvinata sp. nov., a pathogen with a reduced stroma

Ophiocordyceps pulvinata, a pathogen of ants, is formally described as a new species. Genus level designation of this species is difficult due to several apparently conflicting morphological and ecological characters. Affinity with Ophiocordyceps is suggested by the dark color stroma and ascospore morphology. However, the species was included in a book of entomopathogenic fungi of Japan as Torrubiella sp. due to the production of perithecia on an astipitate stroma. Phylogenetic analyses of molecular data support a close relationship with O. unilateralis, a finding consistent with morphological characteristics of the color, asci and ascospores and ecological traits of host affiliation. Thus, O. pulvinata represents another example of the loss of stipe for the hypocrealean arthropod pathogenic fungi and highlights the utility of asci and ascospore morphology as taxonomically informative characters of closely related taxa.

An Overview of Arthropod-Associated Fungi from Argentina and Brazil

Arthropod pests in forest and agricultural systems are affected by many pathogenic organisms. Among them, entomopathogenic fungi are the one most common control agents that regulate their populations. This review compiles the information available from Argentina and Brazil about the entomopathogenic fungi occurring in agricultural and natural environments. The scientific names of the fungi are listed according to the latest phylogenetically based classification of fungi. We present an updated list of arthropod-pathogenic fungi occurring in 15 of the 23 provinces of Argentina and 20 of the 27 states of Brazil based on published literature and our personal observations. The list includes a total of 114 fungal species from 53 genera: of Blastocladiomycetes (2 genera), Entomophthorales (8 genera), Harpellales (13 genera), and a diverse assortment of ascomycetes (primarily from Hypocreales) in 22 anamorphic and 5 teleomorphic genera. In the both countries, molecular studies on arthropod-pathogenic fungi are still in their early stages and have focused primarily on intraspecific variability and adequate generic assignment. This listing seeks to encourage more active collection and characterization of these fungi by both traditional and molecular approaches from the obviously rich but underexplored flora of fungi affecting arthropods throughout this large region of South America.

Systematics and evolution of the genus Torrubiella ( Hypocreales, Ascomycota)

Torrubiella is a genus of arthropod-pathogenic fungi that primarily attacks spiders and scale insects. Based on the morphology of the perithecia, asci, and ascospores, it is classified in Clavicipitaceae s. lat. ( Hypocreales), and is considered a close relative of Cordyceps s. 1., which was recently reclassified into three families ( Clavicipitaceae s. str., Cordycipitaceae, Ophiocordycipitaceae) and four genera ( Cordyceps s. str, Elaphocordyceps, Metacordyceps, and Ophiocordyceps). Torrubiella is distinguished morphologically from Cordyceps s. lat. mainly by the production of superficial perithecia and the absence of a well-developed stipitate stroma. To test and refine evolutionary hypotheses regarding the placement of Torrubiella and its relationship to Cordyceps s. lat., a multi-gene phylogeny was constructed by conducting ML and Bayesian analyses. The monophyly of Torrubiella was rejected by these analyses with species of the genus present in Clavicipitaceae, Cordycipitaceae, and Ophiocordycipitaceae, and often intermixed among species of Cordyceps s. lat. The morphological characters traditionally used to define the genus are, therefore, not phylogenetically informative, with the stipitate stromata being gained and/or lost several times among clavicipitaceous fungi. Two new genera ( Conoideocrella, Orbiocrella) are proposed to accommodate two separate lineages of torrubielloid fungi in the Clavicipitaceae s. str. In addition, one species is reclassified in Cordyceps s. str. and three are reclassified in Ophiocordyceps. The phylogenetic importance of anamorphic genera, host affiliation, and stipitate stromata is discussed.

Variability of the Mitochondrial SSU rDNA of Nomuraea Species and Other Entomopathogenic Fungi from Hypocreales

Hypocrealean arthropod pathogenic fungi have profound impact on the regulation of agricultural and medical pests. However, until now the genetic and phylogenetic relationships among species have not been clarified, such studies could clarify host specificity relationships and define species boundaries. Our purpose was to compare the sequences of the mitochondrial SSU rDNA fragments from several mitosporic entomopathogenic Hypocreales to infer relationships among them and to evaluate the possibility to use these sequences as species diagnostic tool in addition to the more commonly studied sequences of nuclear SSU rDNA. The SSU mt-rDNA proved to be useful to help in differentiation of species inside several genera. Clusters obtained with Parsimony, Bayesian, and Maximum Likelihood analyses were congruent with a new classification of the Clavicipitaceae (Sung et al. Stud Mycol. 2007;57:5-59) in which the anamorphic genera Nomuraea and Metarhizium species remain in the Clavicipitaceae and Isaria species sequenced here are assigned to the family Cordycipitaceae. Mitochondrial genomic information indicates the same general pattern of relationships demonstrated by nuclear gene sequences.

Comparison of peptidase activities in some fungi pathogenic to arthropods

Peptidases, highly specific toward several synthetic chromogenic peptides, were found in the mycelia of four arthropod pathogenic fungi: Aphanomyces astaci, Beauveria bassiana, Metarrhizium anisopliae, and Paecilomyces farinosus. A. astaci peptidases had high hydrolyzing activities toward most of the peptides, especially those with arginine in the P1 position, while those of B. bassiana and P. farinosus readily hydrolyzed peptides with valine and arginine, as well as proline and tyrosine in the P2 and P1 positions, respectively. The hydrolyzing capacities of M. anisopliae peptidases were similar to A. astaci, but showed lower specific activities. Casein or azocoll was only hydrolyzed by A. astaci peptidases. B. bassiana and M. anisopliae had a very low hydrolyzing capacity toward casein and could not degrade azocoll. P. farinosus had no hydrolyzing activity toward casein or azocoll. Only peptidases from the crayfish pathogen A. astaci could degrade the crayfish cuticle. The peptidase preparations of A. astaci and B. bassiana hydrolyzing MeO-Suc-Arg-Pro-Tyr-pNA or Bz-Phe-Val-Arg-pNA were of the serine type. The possible importance of peptidase activity of arthropod pathogenic fungi in the infection process is discussed.