Compatibility of Hirsutella citriformis Gum with Entomopathogenic Fungi and Mortality of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae)

Entomopathogenic fungi (EPF) are important microbial agents for sustainable pest management. However, their effectiveness depends on compatible formulations that preserve conidial viability and biological activity. Hirsutella citriformis Speare produces an extracellular gum with potential application as a microbial formulation component. The present study evaluated its short-term compatibility with Beauveria bassiana (Balsamo) Vuillemin and Metarhizium brunneum (Petch) conidia, together with mortality associated with gum-based treatments against Bactericera cockerelli (Šulc), under greenhouse conditions. Conidia were formulated in 0.5% (w/v) gum and applied at 1 × 107 conidia mL−1. Conidial germination remained above 90% and was not affected by gum exposure. Significant treatment effects on mortality were detected for adults and nymphs, using binomial generalized linear models. B. bassiana formulation produced 75.0% and 93.56%, whereas M. brunneum produced 65.2% and 78.2% adult and nymph mortality, respectively. The gum-containing treatment, which included Tween 80, was associated with 44.9% adult and 63.0% nymph mortality. H. citriformis gum therefore showed short-term compatibility with both fungi. However, because we did not include a Tween alone control, mortality may not be specifically attributed to the gum. Further studies will evaluate the basis of this mortality and formulation performance, under storage and field conditions.