Eicosanoids play crucial roles in mediating insect immune responses. PLA2 releases arachidonic acid (AA) from phospholipids (PLs) and AA is usually used for biosynthesis of eicosanoids. However, AA is little (less than 0.05%) detected in insect PLs. In contrast, insect PLs have a lot of other C18 PUFAs (linoleic acid and linolenic acid). A new hypothesis is that AA is synthesized from C18 precursor by subsequent desaturation and elongation reactions. We predicted several fatty acyl desaturases (DESs) from Spodoptera exigua. Some specific DES inhibitors inhibited eicosanoid-mediated immune responses. Subsequent AA precursor analysis suggests that AA may be synthesized from linolenic acid via the omega-6 pathway.

• Md. Ariful Hasan(Department of Plant Medicals, Andong National University)
• Yonggyun Kim(Department of Plant Medicals, Andong National University)