Endophytic Colonization of Cotton by Fungal Entomopathogens for Effective Pest Management

Plants commonly harbor a diversity of fungi as asymptomatic endophytes that can provide protection from a range of biotic and abiotic stressors.  Included among these fungal endophytes are several species known to be insect pathogens (entomopathogens).  Several fungal entomopathogens (e.g. Beauvaria bassiana and Lecanicillium lecanii) can be both isolated from as well as inoculated to live systemically within a broad range of plants. Importantly, recent findings indicate the presence of entomopathogenic fungal endophytes can negatively affect the survival, reproduction and performance of both sucking and foliage feeding insect pests across a range of important crop plants including cotton (Gossypium hirsutum). In order to assess the diversity of fungal endophytes in cotton and potentially identify any natively occurring endophytic entomopathogens, we conducted a survey of fungal endophyte community composition across the growing season at multiple sites in Texas. Our survey revealed a number of candidate endophytes with known anti-insect and nematode effects to be further evaluated as potential tools in cotton pest management.  In addition to identifying potential endophytic agents, we also tested several seed, soil and foliar inoculation protocols to improve the frequency of endophytic colonization of cotton seedlings by B. bassiana.  Our results suggest that seed treatments of fungal conidia in a basal media mixed with an inert coagulant could provide an efficient means of inoculation during germination in the soil that is particularly suited for the endophytic protection of early season cotton.