JH biosynthesis and degradation in parasitized host larvae
Abstract
Our previous investigations on the endocrine interaction between gypsy moth larvae (Lymantria dispar) as host and the endoparasitic wasp Glyptapanteles liparidis showed that parasitism increased the juvenile hormone (JH) titre of the host, but also induced a change in the predominant JH homologue. Due to the high content of JHs, the development of the host larva is arrested before parasitoid emergence, apparently in order to prevent further energy consuming moults and the pupation of the host. In host hemolymph, this rise in JH is at least partly explained by a low activity of the hormone specific degrading enzyme, the juvenile hormone esterase (JHE). However, it remains unclear why parasitism leads to this drastic change in the composition of the JH homologues, too. Thus, the aim of the proposed project is to determine the origin of the elevated JH haemolymph titre in parasitized host larvae and to study its metabolism in host tissues. We will check in vitro a potential release of JH III by the parasitoid larvae and a possible influence of parasitism on the hormone secreting activity of the corpora allata from parasitized and unparasitized gypsy moth larvae. To support the results of the in vitro studies and to investigate the role of the parasitoid and its associated factors (venom and polydnavirus, teratocytes) on the JH composition in the host haemolymph, we will implant or inject these components in unparasitized gypsy moth larvae which will be immune-suppressed by pseudoparasitism or by chemicals. Changes in JH titre caused by the single factors will be recorded in vivo by a highly sensitive physicochemical method with GC-MS. Although parasitism reduces the activity of JHE in the host haemolymph, no data are available on JH degradation in other insect tissues. Therefore, our research will focus on the significance of cellular JHE and JH epoxide hydrolases (JH-EH) in JH cleavage of fat body, integument and midgut. This study will give new insights in JH metabolism of insect tissues and will extend our knowledge of endocrine regulation processes influenced by parasitism.
keywords Lymantria dispar Glyptapanteles liparidis host-parasitoid interactions juvenile hormone metabolism JH degrading enzymes
Publikationen
Host manipulation by the endoparasitic wasp Glyptapanteles liparidis
Autoren: Schafellner, C Jahr: 2008
Conference & Workshop proceedings, paper, abstract
Inhibition of juvenile hormone esterase activity in Lymantria dispar larvae parasitized by Glyptapanteles liparidis
Autoren: Schopf, A; Schafellner, C; Marktl, RC Jahr: 2007
Conference & Workshop proceedings, paper, abstract
Juvenile hormone esterase – a key enzyme for host-parasitoid interactions
Autoren: Schafellner, C Jahr: 2007
Conference & Workshop proceedings, paper, abstract
Juvenile hormone esterase from Lymantria dispar – a key enzyme for regulation of host-parasitoid development
Autoren: Schafellner, C; Nussbaumer, C; Schopf, A Jahr: 2006
Conference & Workshop proceedings, paper, abstract
Project staff
Axel Schopf
Univ.-Prof. i.R. Dr.phil. Axel Schopf
axel.schopf@boku.ac.at
Project Leader
01.04.2002 - 31.03.2004
Christa Schafellner
Priv.-Doz. Dr.phil. Christa Schafellner
christa.schafellner@boku.ac.at
Tel: +43 1 47654-91619
Project Staff
01.04.2002 - 31.03.2004