Defense against <i><scp>P</scp>ieris rapae</i> in cabbage plants induced by <i><scp>B</scp>emisia tabaci</i> biotype B

Abstract

Abstract B emisia tabaci ( G ennadius) ( H emiptera: A leyrodidae) and P ieris rapae L . ( L epidoptera: P ieridae) are serious pests of vegetables, that can occur simultaneously on a single cabbage plant [ B rassica oleracea var. capitata L . ( B rassicaceae)]. We determined whether pre‐feeding or infestation by B . tabaci on cabbage could induce physiological and biochemical responses of the plant against P . rapae . Developmental time, length, and weight of immature P . rapae , and defense‐related plant compounds ( SOD , superoxide dismutase; POD , peroxidase; CAT , catalase; APX , ascorbate peroxidase) were measured. Development of P . rapae larvae was 21% slower on B . tabaci ‐pre‐infested plants than on plants without B . tabaci infestation. When feeding on B . tabaci ‐pre‐infested plants, 22% of P . rapae larvae pupated as compared with 83% on B . tabaci ‐free plants. Weights of P . rapae from first to fourth instars that fed on B . tabaci ‐pre‐infested plants were also reduced, whereas those of fifth instars and pupae were not. Similarly, body length of P . rapae from first to fourth instars was affected by B . tabaci pre‐infestation, whereas that of the fifth instars was not. Peroxidase and APX activities of the B . tabaci ‐pre‐infested plants increased more than SOD and CAT . Peroxidase and SOD activities of B . tabaci and P . rapae co‐infested plants increased as compared with those of P . rapae ‐infested plants; however, CAT and APX activities were not different between B . tabaci ‐ and P . rapae ‐infested plants. These results showed that B . tabaci infestation had a negative effect on P . rapae when they occurred simultaneously on the same host plant. The implications of the induced plant changes on the herbivore are discussed.