Evaluating the tradeoffs of a generalist parasitoid fungus, Ophiocordyceps unilateralis, on different sympatric ant hosts

Unique Bioactives from Zombie Fungus (Cordyceps) as Promising Multitargeted Neuroprotective Agents

Cordyceps, also known as "zombie fungus", is a non-poisonous mushroom that parasitizes insects for growth and development by manipulating the host system in a way that makes the victim behave like a "zombie". These species produce promising bioactive metabolites, like adenosine, β-glucans, cordycepin, and ergosterol. Cordyceps has been used in traditional medicine due to its immense health benefits, as it boosts stamina, appetite, immunity, longevity, libido, memory, and sleep. Neuronal loss is the typical feature of neurodegenerative diseases (NDs) (Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS)) and neurotrauma. Both these conditions share common pathophysiological features, like oxidative stress, neuroinflammation, and glutamatergic excitotoxicity. Cordyceps bioactives (adenosine, N6-(2-hydroxyethyl)-adenosine, ergosta-7, 9 (11), 22-trien-3β-ol, active peptides, and polysaccharides) exert potential antioxidant, anti-inflammatory, and anti-apoptotic activities and display beneficial effects in the management and/or treatment of neurodegenerative disorders in vitro and in vivo. Although a considerable list of compounds is available from Cordyceps, only a few have been evaluated for their neuroprotective potential and still lack information for clinical trials. In this review, the neuroprotective mechanisms and safety profile of Cordyceps extracts/bioactives have been discussed, which might be helpful in the identification of novel potential therapeutic entities in the future.

Morphology, phylogeny and host specificity of two new Ophiocordyceps species belonging to the "zombie-ant fungi" clade (Ophiocordycipitaceae, Hypocreales)

Species of the genus Ophiocordyceps, which include species able to manipulate the behaviour of ants, are known as the "zombie-ant fungi" and have attracted much attention over the last decade. They are widespread within tropical, subtropical and even temperate forests worldwide, with relatively few reports from subtropical monsoon evergreen broad-leaved forest. Fungal specimens have been collected from China, occurring on ants and producing hirsutella-like anamorphs. Based on a combination of morphological characters, phylogenetic analyses (LSU, SSU, TEF1a, RPB1 and RPB2) and ecological data, two new species, Ophiocordycepstortuosa and O.ansiformis, are identified and proposed herein. Ophiocordycepstortuosa and O.ansiformis are recorded on the same species of Colobopsis ant, based on phylogenetic analyses (COI), which may be sharing the same host. Ophiocordycepstortuosa and O.ansiformis share the morphological character of producing lanceolate ascospores. They have typical characteristics distinguished from other species. The ascospore of O.tortuosa are tortuously arranged in the ascus and the ascospore of O.ansiformis have a structure like a handle-shape in the middle. Our molecular data also indicate that O.tortuosa and O.ansiformis are clearly distinct from other species.

Six new species of zombie-ant fungi from Yunnan in China

Some Ophiocordyceps species infecting ants are able to manipulate the host behavior. The hosts are manipulated in order to move to location that are advantageous for fungal spore transmission. Ophiocordyceps species that are able to manipulate the ant's behavior are called "zombie-ant fungi". They are widespread within tropical forests worldwide, with relatively few reports from subtropical monsoon evergreen broad-leaf forest. Zombie-ant fungi have been described and reported in different countries worldwide. However, there were a few reports from China. This study proposed six new species of zombie-ant fungi from China based on multi-gene (SSU, LSU, TEF, RPB1 and RPB2) phylogenetic analyses and morphological characteristics. Six novel species of Ophiocordyceps from China were identified as the Ophiocordyceps unilateralis core clade, forming a separate lineage with other species. Six novel species of Ophiocordyceps with hirsutella-like asexual morphs exclusively infecting ants were presented herein, namely, Ophiocordyceps acroasca, Ophiocordyceps bifertilis, Ophiocordyceps subtiliphialida, Ophiocordyceps basiasca, Ophiocordyceps nuozhaduensis and Ophiocordyceps contiispora. Descriptions and illustrations for six taxon were provided. Five of these species were collected from the subtropical monsoon evergreen broad-leaf forest, and one was collected from the rainforest and subtropical monsoon evergreen broad-leaf forest. This work proposes that the same host of Camponotus can be infected by multiple ant pathogenic fungi, while multiple ants of Polyrhachis can be infected by the same pathogenic fungi at the same time. This study contributes towards a better understanding of the evolutionary relationship between hosts and fungi, and provides novel insights into the morphology, distribution, parasitism, and ecology of Ophiocordyceps unilateralis sensu lato. We have provided a method for obtaining living cultures of Ophiocordyceps unilateralis complex species and their asexual morphs based on the living cultures, which is of significant value for further studies of Ophiocordyceps unilateralis complex species in the future.

Ecological and Molecular Interactions between Insects and Fungi

Insects and fungi represent two of the most widespread groupings of organisms in nature, occurring in every kind of ecological context and impacting agriculture and other human activities in various ways. Moreover, they can be observed to reciprocally interact, establishing a wide range of symbiotic relationships, from mutualism to antagonism. The outcome of these relationships can in turn affect the extent at which species of both organisms can exert their noxious effects, as well as the management practices which are to be adopted to counter them. In conjunction with the launch of a Special Issue of Microorganisms with the same title, this article offers a general overview of the manifold aspects related to such interactions from the perspective of implementing our capacity to regulate them in a direction more favorable for the environment, crop production and human health.

Possible impacts of the predominant Bacillus bacteria on the Ophiocordyceps unilateralis s. l. in its infected ant cadavers

Animal hosts infected and killed by parasitoid fungi become nutrient-rich cadavers for saprophytes. Bacteria adapted to colonization of parasitoid fungi can be selected and can predominate in the cadavers, actions that consequently impact the fitness of the parasitoid fungi. In Taiwan, the zombie fungus, Ophiocordyceps unilateralis sensu lato (Clavicipitaceae: Hypocreales), was found to parasitize eight ant species, with preference for a principal host, Polyrhachis moesta. In this study, ant cadavers grew a fungal stroma that was predominated by Bacillus cereus/thuringiensis. The bacterial diversity in the principal ant host was found to be lower than the bacterial diversity in alternative hosts, a situation that might enhance the impact of B. cereus/thuringiensis on the sympatric fungus. The B. cereus/thuringiensis isolates from fungal stroma displayed higher resistance to a specific naphthoquinone (plumbagin) than sympatric bacteria from the environment. Naphthoquinones are known to be produced by O. unilateralis s. l., and hence the resistance displayed by B. cereus/thuringiensis isolates to these compounds suggests an advantage to B. cereus/thuringiensis to grow in the ant cadaver. Bacteria proliferating in the ant cadaver inevitably compete for resources with the fungus. However, the B. cereus/thuringiensis isolates displayed in vitro capabilities of hemolysis, production of hydrolytic enzymes, and antagonistic effects to co-cultured nematodes and entomopathogenic fungi. Thus, co-infection with B. cereus/thuringiensis offers potential benefits to the zombie fungus in killing the host under favorable conditions for reproduction, digesting the host tissue, and protecting the cadaver from being taken over by other consumers. With these potential benefits, the synergistic effect of B. cereus/thuringiensis on O. unilateralis infection is noteworthy given the competitive relationship of these two organisms sharing the same resource.