Efficacy of indigenous entomopathogenic fungi for the control of the tomato leafminer Tuta absoluta (Meyrick) in Sudan.
The current study evaluated the efficacy of indigenous isolates of entomopathogenic fungi against the third larval instar of tomato leaf miner (Tuta absoluta Meirick; Lepidoptera: Gelechiidae). Four virulent isolates were subject to morphological and molecular identification and they were identified as; Beauveria bassiana isolate Hammad-R7 (Sudan) accession (MN598666); Beauveria bassiana isolate-Sud-afro-18ITS accession (MK046654); Beauveria bassiana isolate Sud-afro-2oITS accession (MK046652) and Purpureocillium lilacinum isolate Khartoum accession (MK046655). Efficacy test was done by larval dipping in the fungal suspension along with the commercial product Eco-Bb®. Mycosis test was performed to confirm the growth of fungus from the cadaver. Treated larvae died within three days after the appearance of the symptoms. The four indigenous isolates showed medium mortality responses (LT50 ranged between 4.1-4.3 days) close to or slightly even better than that induced by the commercial product ECO-Bb (LT50 4.2 days) however three of them induced superior responses (LT90 ranged between 9.5-11.7 days) to the commercial product ECO-Bb (LT90 14.4 days) at higher doses measured at the LT90. Endophytic capability of the isolates was tested by seed dipping and soil drenching methods and the fungal mycelia was detected microscopically in the leaves and stems without apparent negative effects on plant growth. The current results indicate the promising potential of these isolates in the regulation of T. absoluta.