Influence of Gall-Inducing Insects (Cynipini) on the Nutritional and Defensive Chemical Profile of Quercus rugosa

Analyzing the nutritional and defensive chemistry of Quercus rugosa provides insight into gall wasp interactions. Quercus rugosa is the most widely distributed white oak species in Mexico. It is the dominant canopy species in its geographic distribution range and has the largest number of associated gall wasp species (Cynipidae: Cynipini). Our main aims were to characterize the nutritional and defensive chemistry of Q. rugosa leaves and determine whether this chemistry differed between leaves with and without galls. We evaluated 60 trees from six populations of Q. rugosa in central Mexico. For each tree, we analyzed the nutritional chemistry (nitrogen, phosphorus, carbon, and carbon/nitrogen ratio) and defensive chemistry (secondary metabolites). Also, we characterized the community of cynipids in the leaf tissue of each tree. We documented 18 cynipid species, and the cynipid communities differed in composition among localities. We recorded the presence of a total of ten phenolics. The composition of nutritional and defensive chemicals differed significantly between leaves with and without galls in each locality. The nutritional and defensive chemical compounds of Q. rugosa were influenced by their associated cynipids. Our results suggest that gall-inducing cynipids influence the production of secondary metabolites in leaves with galls through the reassignment of nutritional compounds by the hosts.