Efficacy of Metarhizium brunneumand Beauveria bassianaisolates against the European tent caterpillar, Malacosoma neustriaLinnaeus, 1758 (Lepidoptera: Lasiocampidae)

Background: The European tent caterpillar Malacosoma neustriaLinnaeus, 1758 (Lepidoptera: Lasiocampidae), a worldwide pest, feeds on a wide variety of woody and shrub-like plants in its larval stage and causes extensive economic losses. In the fight against this species, environmentally friendly biological control methods should be preferred instead of chemical control. The aim of this study was to evaluate the efficacy of entomopathogenic fungi (EPF) Metarhizium brunneum(ORP-13) and Beauveria bassiana(GOPT-301-2) isolates against the fourth instar larvae of M. neustriaunder laboratory conditions. Results: M. neustriaeggs were collected from the Kızılırmak Delta of Samsun Province, Turkey, and the fourth instar larvae were used in the experiment. Larvae in the control group were fed on sterilized leaves of Eleagnus rhamnoides. Both fungal isolates were applied onto the larvae at 2 ml for each concentration (1 × 10⁶, 1 × 10⁷, and 1 × 10⁸conidia ml⁻¹). Ten larvae were placed in each group, and sterilized E. rhamnoidesleaves were offered to the larvae. The study was carried out in 9 replicates for each group, and the larvae were observed for 14 days. As a result of the study, it was found that the survival rates of the larvae decreased as concentration increased. It was determined that both isolates caused 100% mortality at 1 × 10⁸conidia ml⁻¹concentration. The lowest LC₅₀value was found in larvae exposed to the ORP-13 isolate. Conclusion: It has been suggested that M. brunneumand B. bassianaisolates were virulent for M. neustrialarvae and can be used for biological control of this species.