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In this study, the objective was to determine the efficacy of entomopathogenic fungi on the Colorado potato beetle Leptinotarsa decemlineata Say. (Coleoptera: Chrysomelidae). To reach this goal, surveys were conducted in potato fields, and dead L. decemlineata and soil samples were collected to isolate entomopathogenic fungi. Pathogenicity tests were carried out using 30 entomopathogenic fungi that were obtained as a result of the analyses. According to the biological activity results, EP-1 isolate was identified and diagnosed as having 75% efficacy against L. decemlineata. Beauveria bassiana (EP-1), was identified as the most effective isolate. In the dose determination studies, 106, 107, and 108 conidia ml/l doses of B. bassiana's most effective isolate were used. The experiments were set up with five replications for each dose and control group. The spore suspension of the entomopathogenic fungus was sprayed on fully-grown potato plants cultivated in pots, targeting mature and 2nd or 3rd instar L. decemlineata. The number of live individuals was recorded on the 1st, 3rd, 5th, 7th, and 9th days after application to calculate the percentage of mortality. The most effective dose of B. bassiana isolate was determined to be 85% mortality on the 7th day after application with a dose of 108 conidia ml/l. According to the obtained data, it was observed that the mortality rates increased with the increase in dose on the 1st, 3rd, 5th, 7th, and 9th days after application. The highest impact was observed in applications with a dose of 108 conidia ml/l. In conclusion, the entomopathogenic fungus B. bassiana isolate, which is less harmful to humans and the environment, is considered suitable for use as a biological control agent against L. decemlineata.
Semiha Yüceer (Tue,) studied this question.