Fusarium phytopathogens as insect mutualists

Abstract

As vectors of numerous plant pathogens, herbivorous insects play a key role in the epidemiology of plant disease. But how phytopathogens impact the metabolism, physiology, and fitness of their insect vectors is often unexplored within these tripartite interactions. Here, we examine the diverse symbioses forged between insects and members of the ascomycete fungal genus Fusarium. While Fusarium features numerous plant pathogens that are causal to diseases such as wilts and rots, many of these microbes also engage in stable mutualisms across several insect clades. Matching a diversity in symbiont localization and transmission routes, we highlight the various roles fusaria fulfill towards their insect hosts, from upgrading their nutritional physiology to providing defense against natural enemies. But as the insect partner is consistently herbivorous, we emphasize the convergent benefit Fusarium derives in exchange: propagation to a novel host plant. Collectively, we point to the synergy arising between a phytopathogen and its insect vector, and the consequences inflicted on their shared plant.

Assessing the structure and diversity of fungal community in plant soil under different climatic and vegetation conditions

“…In addition, Trichoderma , known for various plant beneficial effects, including protection (of plants) from pathogenic microorganisms ( Sharma et al, 2017 ) and disease ( Woo et al, 2023 ), was found to be a dominant fungal genus in Fujian. On the other hand, certain types of Fusaria , a dominant fungal genus identified in the Xinjiang soil samples, are plant pathogens ( Berasategui et al, 2023 ). However, some Fusaria may have beneficial functions, such as organic matter decomposition and nutrient cycling ( Mukjang et al, 2022 ).…”

Cladosporium—Insect Relationships

“…Clearly, the possible epidemiological role of some insects as occasional vectors of plant pathogenic species must be taken into careful consideration, even if the impact of Cladosporium spp. as plant pathogens is generally lower than other insect-associated fungi such as Fusarium [236].…”

Fights on the surface prior to fungal invasion of insects

“…Many insect herbivores are also the vectors of plant diseases, including phytopathogenic fungi. For example, different Fusarium species have been frequently found as the mutualists of beetles and caterpillars, which benefits disease transmission [ 27 ]. The mycobiome analysis of the tortoise beetle Chelymorpha alternans revealed that this insect can be inhabited by Fusarium oxysporum throughout its lifecycle, including the conspicuous coating of beetle pupae by the fungus to confer defense against predators [ 28 ].…”