Eusocial Structure of Macrotermes Termites and Antagonistic Potential of Fungal Biocontrol Agents against Termitomyces Fungus and Termites

Abstract

The study was conducted to investigate the mutual relationship between Macrotermes termites and their symbiotic fungus Termitomyces, focusing on their structural organization and functional roles within the mound ecosystem. Additionally, the research explored the potential of using fungal antagonists as eco-friendly biocontrol agents for sustainable termite management. Field observations were conducted on ten Macrotermes mounds and detailed data were collected from only one representative mound, which was dome-shaped with multiple ventilation holes measuring 3–6 cm in diameter, an average height of 120 cm, and an average width of 190 cm. Internal examination revealed well-organized chambers containing fungus combs with a mean fresh weight of 230.47 ± 92 g, a perimeter of 37.5 ± 5 cm, and a volume of 1793.1 ± 926 cm³, indicating advanced eusocial organization and efficient resource allocation. The isolated Termitomyces species displayed white, cottony mycelial growth with basidiomycete characteristics, including clamp connections observed microscopically. Dual culture assays with three replicates demonstrated strong antagonistic activity of Trichoderma viride against Termitomyces, achieving 83.33% inhibition of mycelial growth after 14 days. An eco-friendly substrate formulation containing tamarind seed and fenugreek seed supported maximum mycelial growth and sporulation (6.23 ± 0.3 × 10⁶ spores g⁻¹) at an optimal pH range of 5.5–6.5. T. viride colonized sterilized termite combs more effectively than wild combs, suggesting that native microbial flora restricted colonization. Laboratory bioassays revealed a significant effect (p < 0.05) of entomopathogenic fungi on termite mortality, with Paecilomyces cerevisiae causing the highest mortality (85%), followed by Metarhizium anisopliae (75%) and Beauveria bassiana (49.3%). Overall, the findings support the use of fungal-based biocontrol agents in environmentally sustainable management of Macrotermes termites.