Submitted to: Journal of Insect Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/28/2011
Publication Date: 2/15/2011
Citation: Buyukguzel, E., Tunaz, H., Stanley, D.W., Buyukguzel, K. 2011. Influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth, Galaleria mellonella and its ectoparasitoid, Bracon hebetor. Journal of Insect Physiology. 57:501-507. Interpretive Summary: The concept of biological control of insects is based on the idea that direct application of some of these 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. We have discovered one group of molecules that mediate insect cellular immune reactions. We also found that some common, over-the-counter, pain relievers such as aspirin, block the production of these molecules during infection in insects. The problem with novel approaches to biological control of insects, such as disabling insect immunity, is that there is no knowledge of the long-term influence of chemicals, such as aspirin, on insect life histories. In this paper we show for the first time that pain relievers such as aspirin do not exert substantial influences on life history parameters of an insect, except during reproduction. This new information will be directly useful to scientists who are working to improve the efficacy of biological control methods. The ensuing improved biological control methods enhance long-term environmental and agricultural sustainability. These enhancements will benefit agricultural producers and the people who consume their products.
Technical Abstract: Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids’ eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of pharmaceutical approaches to targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.