Pathogenicity of Steinernema feltiae and endophytic microorganisms against european corn borer

Ciljevi istraživanja su utvrditi prirodni mortalitet gusjenica kukuruznog moljca (Ostrinia nubilalis Hbn.), prirodne populacije populacije endofitskih mikroorganizama u gusjenicama te potencijal entomopatogenih nematoda Steinernema feltiae u suzbijanju ovog štetnika. Disekcija stabljika kukuruza je obavljena u rujnu 2018. godine, te su prikupljene gusjenice kukuruznog moljca. U laboratorijskim uvjetima, praćen je prirodni mortalitet gusjenica tijekom sedam dana, a diskecijom gusjenica uzeti su brisevi i uzgojene populacije endofitskih organizama. Patogenost entomopatogenih nematoda S. feltiae ISO16 testirana je tijekom 7 dana na filter papiru u koncentracijama od 10, 50 i 100 nematoda po gusjenici kukuruznog moljca. Prirodni mortalitet je iznosio tek oko 2%. S. feltiae su imale visoku učinkovitost od 95% u suzbijanju gusjenica kukuruznog moljca u tretmanu od 100 nematoda po gusjenici. Na PDA podlogama su se razvili endofitski mikroorganizmi tj. gljive iz rodova Fusarium, Mucor i razne populacije endofitskih bakterija. Ovim pokusom je utvrđeno da su gusjenice kukuruznog moljca u vrlo dobrom zdravstvenom stanju u polju i otporne na utvrđene populacije Fusarium i Mucor gljiva.The aims of this study were to evaluate natural European Corn Borer (ECB; Ostrinia nubilalis Hbn.), mortality, natural populations of endophyitic microorganisms from ECB larval gut, and pathogenicity of entomopathogenic nematodes Steinernema feltiae against this pest. ECB larvae were collected upon dissection of maize stalks in September 2018. Natural larval mortality was monitored during 7 days under laboratory conditions. Endophytic microorganisms were isolated from larval gut after dissection and reared on PDA. Natural larval mortality was low, only 2%. Pathogenicity of S. feltiae ISO16 against ECB larvae was tested for seven days on filter paper tretated with different concentrations of nematodes (10, 50 and 100 nematodes per insect). Nematodes S. feltiae in concentration of 100 nematodes per insect caused 95% of larval mortality. Fungi belonging to the genera Mucor and Fusarium, as well as many bacterial colonies were identified on PDA. The conclusion is that natural population of ECB larvae are in good health conditions, and resistant to identified Fusarium and Mucor fungi. The entomopathogenic nematodes proved its high efficiency against this important pest