Parasitic Relationships between a Gall-forming InsectTomoplagia rudolphi(Diptera: Tephritidae) and its Host Plant (Vernonia polyanthes, Asteraceae)

Abstract

We studied the impact caused by Tomoplagia rudolphi Lutz & Costa Lima (Diptera : Tephritidae) on the architecture, flower production, seed germination and seed viability of its host plant Vernonia polyanthes Less (Asteraceae). We measured the gall influence on the number of lateral shoots, on the production of flower heads and on seed viability. Gall formation induced a significant increase in the number of lateral shoots modifying the host plant normal growth pattern. Galled stems produced an average of 7n3p0n45 shoots, whereas ungalled stems produced 5n6p0n60 shoots. Galling also caused a significant reduction in seed viability. Seeds of galled stems had a total percent seed germination mean of 28n4 %, while seeds of ungalled stems had a mean of 33n8 %. However, flower head production and seed germination velocity were not affected by the gall. This study showed that T. rudolphi galls influence the architecture and seed viability of its host plant.