THE EffECTS of DiffEREnT fungiCiDES on THE ViAbiliTy of EnTomopATHogEniC nEmAToDES Steinernema feltiae (filipjEV), S. carpocapsae WEiSER, AnD Heterorhabditis downesi SToCk, gRiffin & buRnEll (nEmAToDA: RHAbDiTiDA) unDER lAboRAToRy ConDiTionS

habditid nematodes of the Steinernematidae and Heterorhabditidae family are lethal to a broad range of economically important insect pests (Journey and Ostlie, 2000). Entomopathogenic nematodes (EPN) are often applied to sites and ecosystems that routinely receive other inputs that may interact with nematodes, including chemical pesticides, fertilizers, and soil amendments (De Nardo and Grewal, 2003). To save time and money, it is often beneficial to determine if a pesticide can be tankmixed or applied simultaneously with another pesticide. In addition, the compatibility of an agent with integrated pest management (IPM) and integrated production (IP) systems must be evaluated (Grewal, 2002). EPN infective juveniles (IJ) can tolerate short-term exposure (2-24 h) to many chemical and biological insecticides, fungicides, herbicides, fertilizers, and growth regulators, which can be tank-mixed and applied together (Krishnayya and Grewal, 2002; De Nardo and Grewal, 2003). However, generalizations cannot be applied because the nematode’s susceptibility depends on several factors, including the species, strain, agrochemical formulation and application dose (Grewal, 2002). Biological control agents are used to control a wide range of foliar insect pests (Trdan et al., 2007; Laznik et al., 2010a). When applied under conducive conditions, nematodes can be as effective as chemical insecticides (Trdan et al., 2007; Laznik et al., 2010a). Nematodefungicide combinations in tank mixes could offer a costeffective alternative to foliar integrated pest management (IPM) systems. However, before an ecologically integrated approach to pest management involving nematode-fungicide combinations in tank mixes can be developed for foliar application, the compatibility of nematodes with new and routinely used fungicides must be established. To increase our knowledge of the susceptibility of EPN species to agrochemicals (fungicides) and to explore the effect of their mechanism on the viability of these organisms, the aim of the present study was to select several commercial fungicides currently used in Slovenia for crop protection, evaluate their effects on the survival of IJ from native Slovenian strains of Steinernema feltiae (Filipjev) and Steinernema carpocapsae Weiser, a Hungarian strain of Heterorhabditis downesi Stock (Griffin & Burnell) and commercial ENTONEM® strains To increase our knowledge on the susceptibility of entomopathogenic nematodes (EPN) species to agrochemicals, the compatibility of the infective juveniles (IJ) of the entomopathogenic nematodes Steinernema feltiae, S. carpocapsae, and Heterorhabditis downesi with 15 chemical fungicides was investigated under laboratory conditions. The effect of direct IJ exposure to fungicides for 24 h was tested in a petri dish at 15, 20, and 25 oC. The results showed that the compatibility of S. feltiae with azoxystrobin was high, and similar findings were obtained for S. carpocapsae (strain C67) and all of the tested fungicides, except for tebuconazole + spiroxamine + triadimenol, maneb, dinocap, and copper (II) hydroxide + metalaxil-M. Nematode H. downesi (strain 3173) suffered the highest mortality rate when infective juveniles were mixed with tebuconazole + spiroxamine + triadimenol. The integration of the aforementioned agents into a pest management program is also discussed.