Pathogen-microbiome interactions and the virulence of an entomopathogenic fungus.

Bacteria shape interactions between hosts and fungal pathogens. In some cases, bacteria associated with fungi are essential for pathogen virulence. In other systems, host-associated microbiomes confer resistance against fungal pathogens. We studied an aphid-specific entomopathogenic fungus called Pandora neoaphidis in the context of both host and pathogen microbiomes. Aphids host several species of heritable bacteria, some of which confer resistance against Pandora. We first found that spores that emerged from aphids that harbored protective bacteria were less virulent against subsequent hosts and did not grow on plate media. We then used 16S amplicon sequencing to study the bacterial microbiome of fungal mycelia and spores during plate culturing and host infection. We found that the bacterial community is remarkably stable in culture despite dramatic changes in pathogen virulence. Last, we used an experimentally transformed symbiont of aphids to show that Pandora can acquire host-associated bacteria during infection. Our results uncover new roles for bacteria in the dynamics of aphid-pathogen interactions and illustrate the importance of the broader microbiological context in studies of fungal pathogenesis. IMPORTANCE: Entomopathogenic fungi play important roles in the population dynamics of many insect species. Understanding the factors shaping entomopathogen virulence is critical for agricultural management and for the use of fungi in pest biocontrol. We show that heritable bacteria in aphids, which confer protection to their hosts against fungal entomopathogens, influence virulence against subsequent hosts. Aphids reproduce asexually and are typically surrounded by genetically identical offspring, and thus these effects likely shape the dynamics of fungal disease in aphid populations. Furthermore, fungal entomopathogens are known to rapidly lose virulence in lab culture, complicating their laboratory use. We show that this phenomenon is not driven by changes in the associated bacterial microbiome. These results contribute to our broader understanding of the aphid model system and shed light on the biology of the Entomophthorales-an important but understudied group of fungi.

Signatures of transposon-mediated genome inflation, host specialization, and photoentrainment in Entomophthora muscae and allied entomophthoralean fungi.

Despite over a century of observations, the obligate insect parasites within the order Entomophthorales remain poorly characterized at the genetic level. In this manuscript, we present a genome for a laboratory-tractable Entomophthora muscae isolate that infects fruit flies. Our E. muscae assembly is 1.03 Gb, consists of 7810 contigs and contains 81.3% complete fungal BUSCOs. Using a comparative approach with recent datasets from entomophthoralean fungi, we show that giant genomes are the norm within Entomophthoraceae owing to extensive, but not recent, Ty3 retrotransposon activity. In addition, we find that E. muscae and its closest allies possess genes that are likely homologs to the blue-light sensor white-collar 1, a Neurospora crassa gene that has a well-established role in maintaining circadian rhythms. We uncover evidence that E. muscae diverged from other entomophthoralean fungi by expansion of existing families, rather than loss of particular domains, and possesses a potentially unique suite of secreted catabolic enzymes, consistent with E. muscae's species-specific, biotrophic lifestyle. Finally, we offer a head-to-head comparison of morphological and molecular data for species within the E. muscae species complex that support the need for taxonomic revision within this group. Altogether, we provide a genetic and molecular foundation that we hope will provide a platform for the continued study of the unique biology of entomophthoralean fungi.

Entomophthoralean and hypocrealean fungal pathogens of the sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae), on sorghum in Georgia.

The sugarcane aphid, Melanaphis sacchari, is a widely distributed insect that attacks grasses in different genera including Miscanthus, Saccharum, and Sorghum. The invasive aphid superclone was first discovered in the U.S. attacking grain sorghum in Texas in 2013. Since then, it has been found in at least 25 states including Georgia. We conducted a survey of naturally occurring fungal pathogens of sugarcane aphids on five farms in Georgia, and identified a hypocrealean fungus, Akanthomyces dipterigenus, and two entomophthoralean fungi, Neoconidiobolus spp. From 2018 to 2020, fungal activity differed across farms but at one farm both major fungal species, A. dipterigenus and N. thromboides, were found each of the 3 years infecting sugarcane aphids, attacking adults, both alatae and apterae, and nymphs.

Disseminated Basidiobolomycosis Caused by Basidiobolus omanensis in a Child with Acute Lymphoblastic Leukemia (ALL). Case Report and Literature Review.

Basidiobolomycosis is an uncommon fungal infection caused by the genus Basidiobolus. In immunocompetent children, it usually causes cutaneous infection and rarely affects the gastrointestinal tract, and it is extremely rare for the disease to spread. The present study reports the first case of disseminated basidiobolomycosis caused by Basidiobolus omanensis in a child with acute lymphoblastic leukemia who died as a result of uncontrolled infection and multi-organ failure despite surgical and antifungal therapy with L-AMB and voriconazole. A review of the literature yielded 76 cases, including the current case with the majority of which were reported as invasive gastrointestinal infection. The median age was 4 years (61 male and 15 female) and the majority of these children were from the Middle East (80%), specifically Saudi Arabia (45%). Most patients were treated with systemic antifungal agents (mostly itraconazole and amphotericin B). Surgical intervention was done in 25% of these patients and the death rate was 12%.

Entomophthoralean fungi overwinter with the bird cherry-oat aphid on bird cherry trees.

In Scandinavia, the bird cherry-oat aphid Rhopalosiphum padi overwinter as eggs on the bird cherry tree Prunus padus. Branches of P. padus were collected at the late February / early March from 17 locations in Norway over a three-year period. We found 3599 overwintering aphid eggs, 59.5% of which were dead. Further, a total of 879 overwintering fungus-killed cadavers were observed. These cadavers were found close to bud axils, where overwintering eggs were also usually attached. Cadavers were infected with either Zoophthora cf. aphidis or Entomophthora planchoniana. All the fungal-killed cadavers were filled with overwintering structures of Z. cf. aphidis (as resting spores) or E. planchoniana (as modified hyphal bodies). We found a significant negative correlation between eggs and cadavers per branch. However, both numbers of eggs and cadavers varied greatly between years and among tree locations. This is the first report of E. planchoniana overwintering in R. padi cadavers as modified hyphal bodies. We discuss whether P. padus may act as an inoculum reservoir for fungi infecting aphids in cereals in spring.

The Changes in Mitochondrial Morphology and Physiology Accompanying Apoptosis in Galleria mellonella (Lepidoptera) Immunocompetent Cells during Conidiobolus coronatus (Entomophthorales) Infection.

Mitochondria have been shown to play an important role in apoptosis using mammalian cell lines. However, their role in insects is not fully understood; thus, more indepth studies of insect cell apoptosis are necessary. The present study investigates mitochondrial involvement during Conidiobolus coronatus-induced apoptosis in Galleria mellonella hemocytes. Previous research has shown that fungal infection could induce apoptosis in insect hemocytes. Our findings indicate that mitochondria undergo several morphological and physiological changes during fungal infection, e.g., loss of mitochondrial membrane potential, megachannel formation, disturbances in intracellular respiration, increased nonrespiratory oxygen consumption in mitochondria, decreased ATP-coupled oxygen consumption and increased non-ATP-coupled oxygen consumption, decreased extracellular and intracellular oxygen consumption, and increased extracellular pH. Our findings confirm that G. mellonella immunocompetent cells demonstrate Ca2+ overload in mitochondria, translocation of cytochrome c-like protein from mitochondrial to cytosol fraction, and higher activation of caspase-9-like protein after C. coronatus infection. Most importantly, several of the changes observed in insect mitochondria are similar to those accompanying apoptosis in mammalian cells, suggesting that the process is evolutionarily conserved.

Pandora cacopsyllae Eilenberg, Keller & Humber (Entomophthorales: Entomophthoraceae), a new species infecting pear psyllid Cacopsylla pyri L. (Hemiptera: Psyllidae).

The new species Pandora cacopsyllae Eilenberg, Keller & Humber (Entomophthorales) is described. The fungus was found on infected pear psyllids Cacopsylla pyri (Hemiptera: Psyllidae) in a pear orchard in Zealand, Denmark. Morphological structures (conidia, rhizoids, cystidia) were described on the designated type host C. pyri. In addition, conidia from an in vitro culture were described. Pandora cacopsyllae differs from other Pandora species by a) C. pyri is the natural host; b) conidia are different from other Pandora species infecting Psylloidea; c) ITS differs from other Pandora species infecting Hemiptera. The fungus has a high potential for future use in biological control of Cacopsylla pest species as well as other psyllids.

Histologic findings of Massospora cicadina infection in periodical cicadas (Magicicada septendecim).

Massospora cicadina, an obligate fungal pathogen in the subphylum Entomophthoromycotina (Zoopagomycota), infects periodical cicadas (Magicicada spp.) during their adult emergence and modifies their sexual behavior to maximize fungal spore dissemination. In this study, 7 periodical cicadas from the Brood X emergence in 2021 infected by M. cicadina were histologically examined. In 7 of 7 cicadas, fungal masses replaced the posterior portion of the abdominal cavity, effacing portions of the body wall, reproductive organs, alimentary tract, and fat bodies. No appreciable inflammation was noted at the intersections of the fungal masses and host tissues. Fungal organisms were present in multiple morphologies including protoplasts, hyphal bodies, conidiophores, and mature conidia. Conidia were clustered into eosinophilic membrane-bound packets. These findings help uncover the pathogenesis of M. cicadina by suggesting there is evasion of the host immune response and by providing a more in-depth description of its relationship with Magicicada septendecim than previously documented.

Subcutaneous zygomycosis in an immunocompetent patient caused by Basidiobolus ranarum.

Zygomycosis is a fungal infection in humans caused by orders Mucorales and Entomophthorales. The incidence of Mucorales causing mucormycosis is on a rise and is well documented, whereas Entomophthorales is rare. Among Entomophthorales, infections caused by Conidiobolus are more common than Basidiobolus Here we present a case of subcutaneous basidiobolomycosis in a female patient. The patient had hyperpigmentation in the thigh region for 6 months and serous discharge for 4 months. All initial findings suggested the inflammatory stage of morphea. Differential diagnoses of granuloma annulare, malignant melanoma and morphea were considered radiologically. A good suspicion of fungal aetiology by the dermatologist led to an appropriate diagnosis of subcutaneous basidiobolomycosis based on fungal culture and histopathological examination. Based on macroscopic and microscopic findings, the causative organism was confirmed to be Basidiobolus ranarum The patient was started on oral potassium iodide and itraconazole and showed a good prognosis.

Batkoa major infecting the invasive planthopper Lycorma delicatula.

The entomopathogenic fungi Batkoa major and Beauveria bassiana caused co-epizootics in populations of invasive spotted lanternflies, Lycorma delicatula, in 2018 in northeastern North America. Although first described from North America in 1888, the biology and ecology of Batkoa major had not been studied since that time. This entomophthoralean fungus found infecting L. delicatula in 2018 produces conidia and rhizoids similar in appearance to the original description. We conducted laboratory bioassays to investigate infection of different ages and sexes of these planthoppers, inoculating via showered conidia. All nymphs, and male and female adults were susceptible, dying in 4.3-6.7 days. Adult males died more quickly than adult females or fourth instars. Batkoa major grew out of cadavers of adult males more frequently than adult females or fourth instar nymphs. Rhizoids that provide attachment of cadavers to substrates were produced from adult cadavers more frequently than conidia. Resting spores were not observed in vivo or in vitro in the lab, or in the field.

Strongwellsea selandia and Strongwellsea gefion (Entomophthorales: Entomophthoraceae), two new species infecting adult flies from genus Helina (Diptera: Muscidae).

Two new species from the genus Strongwellsea (Entomophthorales: Entomophthoraceae) that infect adult flies from the genus Helina (Muscidae) are described: Strongwellsea selandia Eilenberg & Humber infecting adult Helina evecta (Harris), and Strongwellsea gefion Eilenberg & Humber infecting adult Helina reversio (Harris). The descriptions are based on pathobiological, phenotypical and genotypical characters. The new species differ from other described members from the genus Strongwellsea by a) pathobiology as revealed by natural host species, b) morphology of primary conidia, c) color of resting spores, and d) genotypical clustering based on analysis of ITS2. The two new species have only been documented from North Zealand, Denmark.

Season-long infection of diverse hosts by the entomopathogenic fungus Batkoa major.

Populations of the entomopathogenic fungus Batkoa major were analyzed using sequences of four genomic regions and evaluated in relation to their genetic diversity, insect hosts and collection site. This entomophthoralean pathogen killed numerous insect species from 23 families and five orders in two remote locations during 2019. The host list of this biotrophic pathogen contains flies, true bugs, butterflies and moths, beetles, and barkflies. Among the infected bugs (Order Hemiptera), the spotted lanternfly (Lycorma delicatula) is a new invasive planthopper pest of various woody plants that was introduced to the USA from Eastern Asia. A high degree of clonality occurred in the studied populations and high gene flow was revealed using four molecular loci for the analysis of population structure. We did not detect any segregation in the population regarding host affiliation (by family or order), or collection site. This is the first description of population structure of a biotrophic fungus-generalist in the entomopathogenic Order Entomophthorales. This analysis aimed to better understand the potential populations of entomopathogen-generalists infecting emerging invasive hosts in new ecosystems.

A Very Rare Basidiobolomycosis Case Presented with Cecal Perforation and Concomitant Hepatic Involvement in an Elderly Male Patient: A Case Study.

This is a case report of Basidiobolomycosis in a 65-year-old male patient from Jizan presenting with colonic perforation and concomitant liver involvement from February 2021 to July 2021. To control the infection, the patient underwent colonic resection and segmental liver resection, as well as three antifungal drugs. The treatment was successful, and the condition was completely resolved.

Encapsulation of the psyllid-pathogenic fungus Pandora sp. nov. inedit. and experimental infection of target insects.

BACKGROUND: Pandora sp. nov. inedit. (Entomophthorales: Entomophthoraceae) (ARSEF 13372) is a recently isolated entomophthoralean fungus with potential for psyllid pest control. This study aimed to develop a formulation based on biocompatible hydrogel beads in order to transfer the fungus into an easily applicable form and to test the effects on psyllids. RESULTS: After encapsulation in calcium alginate beads, Pandora sp. nov. grew from the beads and discharged conidia over 12 days under optimal humidity conditions at 18 °C. Conidial number was increased 2.95-fold by the addition of skimmed milk as nutritional formulation adjuvant to the beads. The virulence of the encapsulated fungus was assessed with the two target psyllid species; the summer apple psyllid, Cacopsylla picta and the pear psyllid, Cacopsylla pyri. Beads containing skimmed milk as nutritional adjuvant led to the highest mortalities (48.3% on C. picta and 75.0% on C. pyri). In a second bioassay, survival time of C. pyri exposed to beads containing different concentration (10%, 20% or 40%) of Pandora sp. nov. was tested. The survival time of C. pyri was significantly reduced when exposed to beads containing 10% or 20% Pandora sp. nov. The median survival time was reached after 5-6 days past inoculation and the cumulative mortality for C. pyri treated with Pandora sp. nov. beads showed up to 89% mortality. CONCLUSION: The promising results of this study will ease the way for large-scale field application of a novel Pandora species in biological psyllid pest control.

Strongwellsea crypta (Entomophthorales: Entomophthoraceae), a new species infecting Botanophila fugax (Diptera: Anthomyiidae).

A new species from the genus Strongwellsea (Entomophthorales: Entomophthoraceae) is described: Strongwellsea crypta Eilenberg & Humber from adult Botanophila fugax (Meigen) (Diptera: Anthomyiidae). The description is based on pathobiological, phenotypical and genotypical characters. The abdominal holes in infected hosts develop rapidly and become strikingly large and edgy, almost rhomboid in shape. The new species S. crypta differs from S. castrans, the only described species infecting flies from Anthomyiidae, by: (a) naturally infecting another host species, (b) by having significantly longer primary conidia, and (c) by genotypical clustering separately from that species when sequencing ITS2.

Mechanisms behind the Madness: How Do Zombie-Making Fungal Entomopathogens Affect Host Behavior To Increase Transmission?

Transmission is a crucial step in all pathogen life cycles. As such, certain species have evolved complex traits that increase their chances to find and invade new hosts. Fungal species that hijack insect behaviors are evident examples. Many of these "zombie-making" entomopathogens cause their hosts to exhibit heightened activity, seek out elevated positions, and display body postures that promote spore dispersal, all with specific circadian timing. Answering how fungal entomopathogens manipulate their hosts will increase our understanding of molecular aspects underlying fungus-insect interactions, pathogen-host coevolution, and the regulation of animal behavior. It may also lead to the discovery of novel bioactive compounds, given that the fungi involved have traditionally been understudied. This minireview summarizes and discusses recent work on zombie-making fungi of the orders Hypocreales and Entomophthorales that has resulted in hypotheses regarding the mechanisms that drive fungal manipulation of insect behavior. We discuss mechanical processes, host chemical signaling pathways, and fungal secreted effectors proposed to be involved in establishing pathogen-adaptive behaviors. Additionally, we touch on effectors' possible modes of action and how the convergent evolution of host manipulation could have given rise to the many parallels in observed behaviors across fungus-insect systems and beyond. However, the hypothesized mechanisms of behavior manipulation have yet to be proven. We, therefore, also suggest avenues of research that would move the field toward a more quantitative future.

Inoculative Releases and Natural Spread of the Fungal Pathogen Entomophaga maimaiga (Entomophthorales: Entomophthoraceae) into U.S. Populations of Gypsy Moth, Lymantria dispar (Lepidoptera: Erebidae).

While emphasis with entomopathogens has often been on inundative releases, we describe here historic widespread inoculative releases of a fungal entomopathogen. Several U.S. states and municipalities conducted inoculative releases of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), pathogen Entomophaga maimaiga Humber, Shimazu et Soper (Entomophthorales: Entomophthoraceae) after 1993, as gypsy moth populations spread into the Midwest and North Carolina. This Japanese pathogen first caused epizootics in northeastern North America in 1989 and methods for its inoculative release were tested and proven to be effective from 1991 to 1993. After 1993, spores in soil or in late instar cadavers were collected during or after epizootics and were released inoculatively into newly established populations of this spreading invasive; the goal was that spores would overwinter and germinate the next spring to infect larvae, thus speeding pathogen spread and hastening the development of epizootics in newly established populations. The fungus was released in gypsy moth populations that were separated from areas where the fungus was already established. In particular, extensive releases by natural resource managers in Wisconsin and Michigan aided the spread of E. maimaiga throughout these states. Where it has become established, this acute pathogen has become the dominant natural enemy and has exerted considerable influence in reducing gypsy moth damage. While this pathogen most likely would have invaded these new regions eventually, releases accelerated the spread of E. maimaiga and helped to reduce impacts of initial outbreaks, while further outbreaks were reduced by the pathogen's subsequent persistence and activity in those areas.

Factors Influencing the Population Fluctuations of Euproctis chrysorrhoea (Lepidoptera: Erebidae) in Maine.

The browntail moth (Euproctis chrysorrhoea (L.)) is a forest pest that was accidentally introduced in the late 1800's and spread throughout New England in the early part of the 20th Century. At its peak range expansion in 1915 it encompassed an area of 150,000 km2 after which populations declined. By the 1960s, its distribution had receded to relic populations on outer Cape Cod, MA, and islands in Casco Bay, ME. In 1989 browntail moth resurged in Maine, with periodic, moderate outbreaks before a dramatic increase of the population occurred in 2016. We examined the pattern of annual defoliation by browntail moth since its resurgence in the 1990s as well as variation in populations throughout infested areas in Maine during three years of the recent outbreak, 2016-2018, relative to differences in weather, parasitism and habitat characteristics. Levels of defoliation over 24 yr were predicted by the preceding spring precipitation (-, negative effect) and the year's previous late summer and early fall temperatures (+, positive effect) when first to third instar larvae feed and then construct winter hibernacula. Late summer temperatures predicted the abundance of hibernacula across outbreak areas (+). Early spring temperatures (+) and early and late spring precipitation (-) predicted early summer larval and pupal nest abundance. Warmer fall temperatures result in more mature populations coming out of winter hibernacula in the spring, whereas spring precipitation drives epizootic outbreaks of Entomophaga aulicae (Reichardt in Bail) Humber (Entomophthorales: Entomophthoraceae). with parasitoids playing a lesser role. Climate trends indicate continued increases in fall temperatures since browntail moth resurgence.

Pathogenicity against hemipteran vector insects of a novel insect pathogenic fungus from Entomophthorales (Pandora sp. nov. inedit.) with potential for biological control.

A new but still unpublished entomopathogenic fungus (ARSEF13372) in the genus Pandora (Entomophthorales: Entomophthoraceae) was originally isolated from Cacopsylla sp. (Hemiptera: Psyllidae). Several species of the genus Cacopsylla vector phloem-borne bacteria of the genus 'Candidatus Phytoplasma', which cause diseases in fruit crops such as apple proliferation, pear decline and European stone fruit yellows. To determine Pandora's host range and biocontrol potential we conducted laboratory infection bioassays; Hemipteran phloem-feeding insects were exposed to conidia actively discharged from in vitro produced mycelial mats of standardized area. We documented the pathogenicity of Pandora sp. nov. to species of the insect families Psyllidae and Triozidae, namely Cacopsyllapyri L., C.pyricola (Foerster), C.picta (Foerster, 1848), C.pruni (Scopoli), C.peregrina (Foerster), and Trioza apicalis Foerster. The occurrence of postmortem signs of infection on cadavers within 10 days post inoculation proved that Pandora sp. nov. was infective to the tested insect species under laboratory conditions and significantly reduced mean survival time for C.pyri (summer form and nymph), C.pyricola, C.picta, C.pruni, C.peregrina and T.apicalis. Assessing a potential interaction between phytoplasma, fungus and insect host revealed that phytoplasma infection ('Candidatus Phytoplasma mali') of the vector C.picta and/or its host plant apple Malus domestica Borkh. did not significantly impact the survival of C.picta after Pandora sp. nov. infection. The results from infection bioassays were discussed in relation to Pandora sp. nov. host range and its suitability as biocontrol agent in integrated pest management strategies of psyllid pests, including vector species, in orchards.