Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2007
Publication Date: 7/29/2007
Citation: Durmus, Y., Buyukguzel, E., Terzi, B., Tunaz, H., Stanley, D.W., Buyukguzel, K. 2007. Eicosanoids mediate melantoic nodulation reactions to viral infection in larvae of the parasitic wasp, Pimpla turionellae. Journal of Insect Physiology. 54:17-24. Interpretive Summary: Application of classical insecticides has introduced severe problems in agricultural sustainability. The concept of biological control of insects is a potentially powerful alternative to classical insecticides. Biological control is based on the idea that direct application of insect-specific pathogens and parasites can reduce pest insect populations and the economic damage due to pest insects. The problem, however, is the efficiency of these organisms in biological control programs is limited by insect immune defense reactions to challenge. One approach to improving the efficiency of biocontrol agents would be to somehow disable insect immune reactions to viral, bacterial, fungal and parasitic infections. With this goal, we are investigating insect immune reactions to virus infection. In this paper we report on identification of biological signals that are responsible for stimulating insect defenses to viral infection. We show for the first time that interruption of these signals cripples the normal immune response to viral challenge in beneficial insects. This new research will be directly useful to scientists who are working to improve the efficacy of biological control methods. The ensuing improved biological control methods will benefit a wide range of agricultural producers by supporting the long-term sustainability of agriculture.
Technical Abstract: Nodulation is the predominant insect cellular immune response to bacterial and fungal infections and it can also be induced by viral infection. Treating seventh instar larvae of greater wax moth Galleria mellonella with Bovine herpes simplex virus-1 (BHSV-1) induced nodulation reactions in a dose-dependent manner. Because eicosanoids mediate nodulation reactions to bacterial and fungal infection, we hypothesized that eicosanoids also mediate nodulation reactions to viral challenge. To test this idea, we injected G. mellonella larvae with indomethacin, a nonsteroidal anti-inflammatory drug immediately prior to intrahemocoelic injection of BHSV-1. Relative to vehicle-treated controls, indomethacin-treated larvae produced significantly reduced numbers of nodules following viral infection (down from approximately 190 nodules/larva to <50 nodules/larva). In addition to injection treatments, increasing dietary indomethacin dosages (from 0.01% to 1%) were associated with decreasing nodulation (by 10-fold) and phenoloxidase activity (by 3-fold) reactions to BHSV-1 injection. We infer from these findings that COX products mediate nodulation response to viral infection in G. mellonella.