Differential biochemical responses of Calliandra brevipes (Fabaceae, Mimosoidae) to galling behaviour by Tanaostigmodes ringueleti and T. mecanga (Hymenoptera, Tanaostigmatidae)

Abstract

Two species of Tanaostigmodes, T. ringueleti and T. mecanga, induce two distinct gall morphotypes in Calliandra brevipes Benth. (Fabaceae: Mimosoidae), namely a globose and a fusiform one. Secondary and primary metabolism of the two galls was compared with that of the stem tissue of the host plant. Phytochemical screening of gall samples revealed that triterpenoids were exclusive of the globose gall, and sterols exclusive of the fusiform gall, whereas saponins were absent in both galls. Flavonoid content in the globose gall was significantly lower than that in the fusiform gall. As expected, high antioxidant activity was observed in the fusiform gall, which was associated with the high flavonoid content. Protein analyses showed the presence of specific polypeptides in globose (97, 75, 34 kDa) and fusiform (40, 33 kDa) galls. Sucrose, glucose and fructose contents were 1.4–3.3 times higher in the globose-gall than in non-galled tissue, whereas in the fusiform gall, fructose content was 2-fold increased. The interactions between the host and the two Tanaostigmodes showed both similarities and differences between them, and with the non-galled tissue. Taken together, the results suggested that the two gall inducers co-inhabiting C. brevipes are capable of manipulating the primary and secondary metabolism differentially for their own benefit and, thus, the nutritive hypothesis was reinforced.