ALLOCATION PATTERNS OF ORGANIC NITROGEN AND MINERAL NUTRIENTS WITHIN STEM GALLS OFDIPLOLEPIS SPINOSAANDDIPLOLEPIS TRIFORMA(HYMENOPTERA: CYNIPIDAE) ON WILD ROSES (ROSACEAE)

Abstract

AbstractConcentrations of organic N and minerals Ca, Fe, K, Mg, Na, P, and S in tissues of galls induced byDiplolepis spinosa(Ashmead) andDiplolepis triformaShorthouse and Ritchie in growth and maturation phases were compared with those in ungalled tissues of host roses and tissues distal to galls to increase our understanding of nutritional relationships between gall wasps and their host plants (Rosa blandaAiton andRosa acicularisLindley, respectively). Concentrations of N and most mineral nutrients were lower in galls than in ungalled tissues, and tissues distal to galls, suggesting that cynipids regulate rather than concentrate nutrients within their galls. Concentrations of mineral nutrients within the larvae of both species of inducers, and their parasitoids, were determined for galls in the maturation phase. Absolute amounts of most minerals in gall tissues were positively correlated with the number of inhabitants, indicating that control of translocation of nutrients to galls occurs on a per inducer basis. Concentrations of nutrients in mature larvae of parasitoids were the same as concentrations in mature larvae of inducers, which explains why parasitism of gall inducers had no influence on the concentrations or amounts of nutrients in galls. Galls ofD.triformahad greater concentrations of N and most mineral nutrients than did galls ofD.spinosa. Likewise, larvae ofD.triforma, and the parasitoids feeding onD.triforma, had greater concentrations of N and mineral nutrients than did larvae ofD.spinosaand its parasitoids. Galls of both species had different concentrations of nutrients compared with ungalled tissues and tissues distal to the galls. Galls of both species also had seasonal decreases in concentrations of nutrients. Parasitoids of each species of inducer were generally similar in mineral composition to their hosts.