Nodulation is the first step of the cellular defense reactions to bacterial infections in insects. In the present study, injecting larvae of the European corn borer, Ostrinia nubilalis, with eicosanoid biosynthesis inhibitors, immediately prior to intrahemocoelic injections of the bacterium, Serratia marcescens, sharply reduced the nodulation response to bacterial challenges. | Turk J Agric For 27 (2003) 269-275 © TÜB‹TAK The Role of Eicosanoids on Nodulation Reactions to Bacterium Serratia marcescens in Larvae of Ostrinia nubilalis Hasan TUNAZ*, Ali Arda IfiIKBER, Mehmet Kubilay ER Kahramanmarafl Sütçü ‹mam University, Faculty of Agriculture, Department of Plant Protection, Kahramanmarafl - TURKEY Received: Abstract: Nodulation is the first step of the cellular defense reactions to bacterial infections in insects. In the present study, injecting larvae of the European corn borer, Ostrinia nubilalis, with eicosanoid biosynthesis inhibitors, immediately prior to intrahemocoelic injections of the bacterium, Serratia marcescens, sharply reduced the nodulation response to bacterial challenges. Separate treatments with specific inhibitors including dexamethasone (a phospholipase A2 inhibitor), indomethacin (a cyclooxygenase inhibitor) and phenidone (a dual cyclooxgenase/lipoxygenase inhibitor) also impaired the ability of European corn borers to form nodules in reaction to bacterial challenges. The inhibitory influence of phenidone was apparent within 30 mins after infection, and nodulation was significantly reduced, relative to the control insects, over following 4 h. These findings support the hypothesis that eicosanoids act in nodulation reactions to bacterial infections in European corn borers. Key Words: Insect cellular immunity; nodulation; Ostrinia nubilalis Ostrinia nubilalis’in Larvalar›nda Serratia marcescens Bakteriyal ‹nfeksiyonuna Karfl› Oluflan fi›r›nga ile Nodülasyon Reaksiyonunda Eikosanoidlerin Rolü Özet: Nodülasyon reaksiyonu bakteri infeksiyonlar›na karfl› böcekleri koruyan ilk hücresel reaksiyondur. Yap›lan bu çal›flmada m›s›r kurdu larvalar›na fl›r›nga ile eicosanoid biyosentezini engelleyen kimyasallar injekte edildikten sonra ayn› larvalara fl›r›nga ile bakteri, Serratia marcescens, verilmesi bu böceklerde nodülasyon oluflumunu önemli derecede azaltm›flt›r. Bunun yan› s›ra yine eicosanoid biyosentezi .