Knock-down of Uba2^HM05055 in the fat body (under the control of Scer\GAL4^Lsp2.PH does not yield strong fat body defects such as loss of tissue integrity but results in a weak but reproducible differentiation and aggregation of blood cells in the hemocoel. In contrast expression in blood cells and the fat body under the control of Scer\GAL4^Cg.PA or in the hemocoel alone under the control of Scer\GAL4^Hml.PG significantly promotes infiltration and tumorigenesis upon L.victoriae parasitic wasp infection. Approximately 60% of Scer\GAL4^Cg.PA>Uba2^HM05055 animals develop microtumors whereas parental genotypes are not tumorous in third-instar larval stages.