Pathogenicity of Metarhizium anisopliae for Ceratitis capitata (Wied.) (Diptera: Tephritidae) in soil with different pesticides

This research intended to investigate if the presence of pesticides in the soil could affect the pathogenicity of Metarhizium anisopliae Metsch. (Sorokin) for Ceratitis capitata (Wied.) and assess the effect of conidia application as suspension or dry conidia. The fungicides chlorothalonyl and tebuconazol, the acaricide abamectin, the insecticide trichlorfon, and the herbicide ametrin were applied at the manufacturer-recommended doses. Soil samples were placed in glass flasks and were given the fungus as conidial suspension or dry. After pesticide application, 20 3(rd)-instar larvae were placed in the soil. The flasks were sealed with voile fabric and incubated at 27 +/- 0.5 degrees C for nine days, until adult emergence; incubation continued for four more days at room temperature. The total insect survival was significantly affected and pathogenic activity was detected from the pupa stage on. Pupa survival was reduced (P < 0.05); the same occurred during the adult phase. No effect was observed at the larval stage. The pesticides applied to the soil affected the activity of M anisopliae slightly: only in the dry conidia assay the fungicides chlorothalonyl and tebuconazole reduced (86.2% and 82.5%, respectively) the survival period of C capitata compared to the control (95.0%). The techniques used for conidia application did not influence the total insect survival rate, but conidial suspension applied on soil surface reduced survival during the pupae and adult phases.