Submitted to: Biochimica et Biophysica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2006
Publication Date: 11/1/2006
Citation: Stanley, D.W. 2006. The non-venom insect phospholipases A2. Biochimica et Biophysica Acta. 1761:1383-1390.
Interpretive Summary: Application of classical insecticides has introduced severe problems in agricultural sustainability. The concept of biological control of insects is a useful alternative to classical insecticides. Biological control is based on the idea that direct application of some 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. We have discovered a target enzyme responsible for starting insect cellular immune reactions. More recent work indicates some pathogens have usurped this target. They disable insect immunity by inhibiting the enzyme. Insects infected with these pathogens quickly succumb to infection because they lack immune defense mechanisms. Moreover, this enzyme is also important in other areas of insect biology, such as digestion. In this paper I identify the significance of this enzyme with respect to the biological control of insects and with respect to insect digestion. 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 enhancing long-term sustainability of agriculture.
Technical Abstract: Phospholipases A2 (PLA2s) are responsible for releasing the fatty acid moiety from the sn-2 position of phospholipids. These enzymes are virtually ubiquitous proteins known from all major biological taxa. Various PLA2s act in a wide array of biological processes, including digestion of dietary lipids, cellular homeostasis, intra- and intercellular signaling, host defense and at least a few ecological interactions. PLA2 activities have been recorded in a small number of insect species, which can be taken to represent the broad group, Insecta. Within insects, PLA2s act in functions expected from the background on these enzymes. So far, we know PLA2s act in lipid digestion, cellular host defense signaling, reproduction and in organismal-level metabolism. Additional PLA2 actions are certain to emerge. This is the first article devoted to assembling the known information on insect PLA2s. I review the scant information available on the biological actions of PLA2s in insects, relate new findings on insect pathogens that disrupt insect immune functions by inhibiting PLA2s and mention the few reports of sequence information on insect PLA2s. Finally, I offer a brief prospectus on future research into insect PLA2s. There are two overarching points in this paper. One, because of the diversity of insect species it is possible that new groups of PLA2s will be found in insect systems, and two, some of the findings on insect PLA2s will have meaningful practical significance.