Fungal pathogens of insects

Definition

Fungi that infect and cause disease in insects, encompassing a phylogenetically diverse assemblage of entomopathogenic species that invade through the cuticle, proliferate in hemolymph or tissues, and typically kill the host to complete their life cycle. These pathogens span multiple fungal phyla, with Ascomycota (particularly Hypocreales such as Beauveria, Metarhizium, and Cordyceps sensu lato) and Entomophthoromycota (formerly Zygomycota, including Entomophthora and Zoophthora) being the most significant in terrestrial systems. Infection generally proceeds via adhesion of conidia to the exoskeleton, germination, cuticle penetration by mechanical force and enzymatic degradation, and systemic colonization; many species manipulate host behavior before death to position the cadaver for optimal spore dispersal. Fungal pathogens function as key density-dependent mortality agents in natural populations and are widely deployed as microbial biocontrol agents against pest insects.

Etymology

From Latin fungus (mushroom, fungus) + Greek pathos (suffering) + Latin insectum (insect)

Example

Metarhizium anisopliae and Beauveria bassiana are commercially formulated fungal pathogens of insects used to manage soil-dwelling scarab larvae and foliar-feeding hemipterans; in tropical forests, Ophiocordyceps species famously manipulate ant behavior, driving infected workers to bite vegetation in precise locations where the fungus produces a stalked fruiting body.

Synonyms

• Entomopathogenic fungi
• Entomopathogens

Related Terms

• Entomopathogen
• Mycosis
• Biological control
• Host manipulation
• Cuticle penetration
• Conidia
• White muscardine disease
• Green muscardine disease
• Hypocreales
• Entomophthorales
• Chytridiomycota
• Microsporidia
• nuclear polyhedrosis virus
• Bacillus thuringiensis
• Integrated Pest Management
• epizootic
• horizontal transmission
• vertical transmission
• Spore persistence

Usage Notes

Distinguished from opportunistic fungal infections (saprophytic fungi colonizing already compromised hosts) by active pathogenesis and host specificity; contrast with bacterial, viral, and protistan entomopathogens. 'Entomopathogenic fungi' is often preferred in technical literature. Microsporidia, historically treated as protozoa, are now classified as fungi and represent a distinct transmission mode (ingestion of spores) versus the contact-dependent infection typical of most fungal pathogens of insects. Field efficacy is strongly constrained by environmental humidity and temperature requirements for spore germination.