HEMOLYMPH FROM FEMALE BEETLES INFECTED WITH HYMENOLEPIS-DIMINUTA METACESTODES RETARDS THE DEVELOPMENT OF OVARIAN FOLLICLES IN RECIPIENT TENEBRIO-MOLITOR (COLEOPTERA)

Infection with developing metacestodes of the rat tapeworm, Hymenolepi s diminuta, is known to retard the accumulation of the yolk protein, v itellin, in the terminal ovarian follicles of the intermediate host, T enebrio molitor. It is probable that this is the result of competitive inhibition of juvenile hormone binding at a microsomal binding site i n the beetle follicular epithelium. Experiments were designed to test the hypothesis that inhibitor molecules were circulating in the haemol ymph of infected beetles. Whole haemolymph, collected from male or fem ale beetles at various stages post-infection, was injected into non-in fected female recipients 2 days post-emergence. Ovaries were removed 3 days later and the vitellin content of the same sized follicles measu red using an ELISA, The vitellin content of follicles from recipients of haemolymph from females infected with metacestodes at stage 1 and s tage 3-4 was significantly reduced (24 and 27.9%) compared to sham-inf ected females. However, haemolymph from females infected with mature m etacestodes did not affect the vitellin content. Results were thus com parable to those obtained by monitoring ovarian vitellin levels in fem ale T. molitor with bona fide infections. Haemolymph from infected mal es did not affect ovarian vitellin content. These results indicate tha t molecules that can modulate vitellogenesis may be present in the hae molymph of females infected with developing metacestodes but that thes e factors disappear later in infection.