Conidia Shelf-Life and Pathogenicity of Strains of Hirsutella citriformis Speare1 Against Diaphorina citri Kywayama2 Produced on Rice

After conidia of Hirsutella citriformis Speare produced on potato dextrose agar or rice (Oryza sativa L.) were harvested and dried, the shelf-life was evaluated after storage at room temperature. Viability and pathogenicity of conidia against Diaphorina citri Kuwayama adults also was determined. Most conidia germinated on agar at 72 hours (93.7-98.7% for INIFAP-Hir-2 and INIFAP-Hir-7 strains, respectively). Most conidia on rice were produced after 14 days of incubation -- 1.47-1.97 × 107 per gram by INIFAP-Hir-5 and INIFAP-Hir-7 strains, respectively. To evaluate shelf-life of conidia produced on rice, germination was evaluated at 0 days of storage and 72 hours of incubation on agar. Results were similar to that by conidia cultivated on agar (97.7-93.0%), germination percentage decreased over time once dried and stored; after 1 week, germination decreased to 5.7-16.0%, and 30 days later, the decrease was 17.4-34.0%. Conidia produced on agar or rice did not differ significantly in pathogenicity. Results confirmed it was possible to increase production of H. citriformis conidia in rice, maintaining pathogenicity with less overall processing time.