Influence of parasitism by Glyptapanteles liparidis (Hym., Braconidae) on the haemolymph carbohydrate and glycogen content of its host larva, Lymantria dispar (Lep., Lymantriidae)

Abstract

Abstract: Parasitism of the gregarious endoparasitic braconid, Glyptapanteles liparidis, reduced markedly the hae‐molymph trehalose level of its host larva, Lymantria dispar, when the parasitoid larvae had reached their final endo‐phageous second instar. The extent of the trehalose decrease was dependent on the time of parasitization and therefore on the host stage in which the second instar parasitoids developed. The haemolymph glucose content amounted to 5–10% of the trehalose level during the feeding period of unparasitized larvae and only rose before moulting. The level was significantly reduced in hosts at the end of the endophageous development of the parasitoid larvae as well as in hosts which contained parasitoid larvae moulting from the first to the second instar. Only in newly moulted third instar hosts parasitized during premoult to the second instar a markedly lower glycogen content was found than in unparasitized gypsy moth larvae. On the other hand, the mean glycogen level of final fifth midinstar hosts was significantly elevated compared to unparasitized larvae, when they were parasitized one stage later, during the premoult period to the third instar. The number of parasitoids per host, however, did not significantly influence the host's carbohydrate level.