Hymenolepis diminuta: influence of metacestodes on synthesis and secretion of fat body protein and its ovarian sequestration in the intermediate host,Tenebrio molitor

Abstract

SUMMARYFemaleTenebrio molitorinfected with metacestodes ofHymenolepis diminutaexhibit elevated concentrations of female-specific proteins in their haemolymph and the origin of these has been investigated. Following a 4 hin vitroincubation with [14C]leucine, fat bodies from non-infected females secreted 13 times more protein than those from females 12 days post-infection. A comparison of the uptakein vivoof radio-isotope labelled amino acids by ovaries from non-infected and infected beetles of various ages revealed no differences; however, a 51·5% decrease in protein sequestration was detected in females 12 days post-infection. Electrophoresis of homogenates of radio-isotope labelled ovaries demonstrated that the majority of label was associated with vitellin sub-units. It is suggested that the decrease in vitellogenin sequestration associated with infection results in an increase in the haemolymph concentration of these proteins despite a concomitant reduction in their secretion by fat bodies. Both fat body synthesis and ovarian sequestration are under juvenile hormone control and it is proposed that metacestodes ofH. diminutamay cause a reduction in the concentration of this hormone in the intermediate host.