Investigation on using possibilites of some entomopathogenic nematodes against alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), and lucerne beetle, gonioctena fornicata (Brüggemann) (Coleoptera: Chrysomelidae)

Entomopathogenetic nematodes (EPNs) have more important role in biological control of the important insect pests. In this study conducted between 2016-2018, it was investigated the presence of entomopathogenic nematodes in the 15 villages (Ulaş, Taşlıçiftlik, Söngüt, Büyükbağlar, Uğrak, Tahtoba, Dayılıhacı, Çördük, Kızılköy, Bakışlı, Ballıdere, Çöreğibüyük, Gaziosmanpaşa, Günevi, Akyamaç) and 2 town (Güryıldız, Emirseyit) of Tokat province where alfalfa was cultivated intensively and the effect of the obtained entomopathogenic nematodes against Gonioctena fornicata and Hypera postica adults. For this purpose, 58 soil samples were taken and obtained 10 entomopathogenic nematod isolates. As a result of the morphological and molecular diagnosis, 8 of them were defined as Steinernema carpocapsae, others as Steinernema feltiae and Heterorhabditis bacteriophora. Dose-mortality trials were carried out with 2 isolates (Heterorhabditis bacteriophora Tokat-Songut, Steinernema carpocapsae Tokat-Ulas) selected from these and 3 isolates [Steinernema carpocapsae (Black sea isolate), Steinernema feltiae (izolat 09-31), Heterorhabditis bacteriophora (izolat 09-43)], previously identified in our country, using doses of 500, 1000 and 2000 IJs ml-1 against adults of Gonioctena fornicata ile Hypera postica in the laboratory. In addition, greenhouse-pot efficacy study was carried out with Steinernema carpocapsae Tokat-Ulas isolate, found effective in the laboratory, against last instar larvae of G. fornicata. Laboratory studies showed that all isolates had an effect 90% and more at 2,000 IJs/ml and at the end of 112 hours [except, H. postica H. bacteriophora (izolat 09-43) and H. bacteriophora Tokat-Songut isolates aginst H. postica]. In greenhouse-pot efficacy study carried out with S. carpocapsae Tokat-Ulas isolate, 94% effect was observed. According to the results, G. fornicata adults were susceptible to all isolates used in the study and H. postica adults were susceptible to isolates; Steinernema carpocapsae (Black sea isolate), S. feltiae (isolate 09-31) and S. carpocapsae Tokat-Ulas. With these isolates, more detailed studies should be conducted in greenhouse and field conditions.