Evaluation of the insecticidal activity of some Turkish entomopathogenic fungal isolates against second larval stage of Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae)

In this study, the efficacy of two local isolates of the entomopathogenic fungus (EPF) Beauveria bassiana (Bals.-Criv.) Vuill. (GOPT-DYYLD, BBE2) (Hypocreales: Cordycipitaceae) and one isolate of Metarhizium brunneum (Petch) (ORP-13) (Hypocreales: Clavicipitaceae) against the second instar larvae of the tomato leafminer, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) was determined. The study was conducted in 2023 at the Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Tokat Gaziosmanpasa University. As positive controls, the commercial preparation of B. bassiana strain Bb-1 and 120 g/L Spinetoram were used. The EPF isolates were evaluated in dose-mortality assays at concentrations ranging from 1×10³ to 1×10⁹ conidia/mL-1. The EPF isolates were evaluated using two different methods: Topical application bioassays and foliar spray application bioassays. In topical application bioassays, at a dose of 1×10⁸ conidia/mL-1 on the 5th day, GOPT-DYYLD caused 69.8% mortality, BBE2 45.8%, ORP-13 29.2%, while B. bassiana strain Bb-1 caused 72.9% mortality and 120 g/L Spinetoram caused 96.9% mortality. In foliar spray application bioassays, at a dose of 1×10⁸ conidia/mL-1 on the 5th day, GOPT-DYYLD caused 76.04% mortality, BBE2 54.2%, and ORP-13 24.5%. Promising results were obtained in the control of tomato leaf miner using the GOPT-DYYLD and BBE2 isolates.