Determination of the efficacy of some entomopathogenic nematodes against Tuta absoluta (Meyrick 1917) (Lep:Gelechiidae) in laboratory conditions

In this study, the efficacy of three different entomopathogenic nematode species, Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora, which was obtained from e-nema and used commercially in Europe, was investigated against Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) in laboratory conditions. The entomopathogenic nematodes were applied with different dosages to the third instar larvae of T. absoluta outside the leaves, the last instar larvae inside the mines of the leaves and to the pupae stages. The mortality rates of the third instar larvae of T. absoluta outside the leaves were determined by using 8 different dosages, 1, 2, 5, 10, 15, 20, 25, 40 IJs/larva of each entomopathogenic nematode species. The mortality rates were found between 17.46-95.24 % for S. feltiae, 28.79-99.39 % for S. carpocapsae and 21.21-74.24 % for H. bacteriophora. According to the results, S. feltiae and S. carpocapsae caused similar mortalities at the given dosages while H bacteriophora had low efficacy compared to those two species. There was an increase in the mortality rates of the third instar larvae of T. absoluta outside the leaves in terms of all nematode species with increasing dosages. The values of LD50 for S. feltiae, S. carpocapsae and H. bacteriophora were 6.252, 7.132 and 21.677, respectively. As a result of this evaluation, the LD50 dosage of S. feltiae, the most efficient nematode strain, was used against the larva of T. absoluta inside the mines of the leaves and against pupae. Finally, S. feltiae was lead to low mortality both the larvae inside the mines (19 %) and the pupae stages (7 %). These results revealed that entomopathogenic nematodes could be used only for the control of T. absoluta larvae outside the leaves. Keywords: Steinernema, Heterorhabditis, Tuta absoluta, efficacy, tomatoes