Entomopathogenic Fungi as Mortality Agents in Insect Populations: A Review.

Area of Science:

• Ecology
• Mycology
• Entomology

Background:

• Natural enemies significantly influence insect population dynamics and evolution.
• The ecological role of insect pathogens, particularly entomopathogenic fungi (EPF), in natural ecosystems is less understood than that of predators and parasitoids.
• EPF have been extensively studied for biocontrol but their prevalence in wild insect populations remains poorly documented.

Purpose of the Study:

• To synthesize available case studies on the prevalence of EPF infections in natural insect populations.
• To examine variations in EPF prevalence across major insect taxa and fungal pathogens.
• To assess the ecological significance of EPF in natural ecosystems compared to other natural enemies.

Main Methods:

• A meta-analysis of 79 case studies reporting EPF infections in field populations.
• Data extraction on fungal prevalence, host insect species, and fungal taxa.
• Statistical analysis to compare prevalence rates among insect groups, fungal orders, and geographical regions.

Main Results:

• Data from 122 fungal species infecting 104 insect species were analyzed.
• The meta-analytic median prevalence of EPF infection was 8.2%, suggesting lower mortality impact than predators/parasitoids.
• No substantial differences in prevalence were found among major insect taxa, but moderate differences existed among fungal orders (Neozygitales highest, Eurotiales lowest).
• Overall EPF prevalence did not differ significantly between tropical and temperate regions, though specific fungal taxa showed geographical patterns.
• Temperate studies indicated a potential increase in infection prevalence towards the end of the growing season.
• Insect populations typically host diverse EPF assemblages, but infections rarely reach epidemic levels.

Conclusions:

• Entomopathogenic fungi are common in natural insect populations but rarely cause widespread mortality.
• Their ecological impact appears less significant than that of predators and parasitoids.
• Further research on multi-species fungal pathogen assemblages in natural settings is crucial for a comprehensive understanding of their role.