Touray et al. Tri-trophic Interactions of Sancassania polyphyllae with Fungal Biocontrol Agents.csvTri-trophic Interactions of soil mite Sancassania polyphyllae (Acari: Acaridae) with Fungal Biocontrol Agents

Mycophagous invertebrates can significantly impact the efficacy of fungal biocontrol agents, yet the interaction between these agents and <em>Sancassania</em> <em>polyphyllae</em> (Acari: Acaridae), commonly found in soil ecosystems, remains poorly understood. Our study demonstrates that <em>S. polyphyllae </em>mites feed on fungus-infected insect cadavers as well as the mycelium and spores of <em>Trichoderma afroharzianum</em> and <em>Metarhizium brunneum </em>in pure cultures. Mite feeding activity was greater on <em>Trichoderma</em> than <em>Metarhizium</em>  pure cultures, possibly due to <em>Metarhizium</em>'s acaricidal effects, which impacted mite activity. Furthermore, mite feeding on fungus-infected insect cadavers caused visible damage to the integument. This feeding behavior significantly impacted fungal sporulation, a key factor in biocontrol efficacy. In both the <em>M. brunneum</em>-infected <em>Galleria</em> groups and the <em>T. afroharzianum</em>-infected <em>Galleria</em> groups, mite numbers increased over time, peaking around 9 to 11 days post-infection (dpi) before slightly declining or plateauing. Notably, the fungi-infected insect tissue consistently exhibited significantly higher mite numbers than the pure cultures group at several time points. In dual-culture assays, <em>S. polyphyllae </em>mites preferentially fed on <em>Fusarium oxysporum</em> over <em>T. afroharzianum</em>. The presence of <em>Fusarium</em> may influence mite behavior and potentially reduce their impact on <em>Trichoderma</em>. This preference, possibly nutritional, requires further investigation. Consequently, <em>Trichoderma</em>'s suppression of <em>Fusarium</em> in soil could significantly impact the food resources available to soil-dwelling mites like <em>S. polyphyllae. </em>Further research is needed to determine the nutritional basis of this feeding preference.