DIFFERENTIAL EXPRESSION OF THE VITELLOGENIN GENE IN THE SPRUCE TERMINAL WEEVIL FEEDING ON RESISTANT VERSUS SUSCEPTIBLE HOST TREES

Reproductive maturation and oviposition of the spruce terminal weevil (Pissodes strobi Peck) are inhibited by resistant Sitka spruce (Picea sitchensis (Bong) Carr.). Vitellogenin is an egg yolk protein precurso r which accumulates during the maturation of eggs. We describe the mol ecular cloning and characterization of a fragment of the vitellogenin gene from the spruce terminal weevil. The DNA sequence of this fragmen t has high identity to vitellogenin sequences from other insects and l ess to nematode and vertebrate vitellogenins. It hybridizes on Norther n blots to a single 6.0 kb mRNA that is expressed only in females, and only after they have commenced reproductive development. Vitellogenin gene expression is induced by treatment with juvenile hormone, and is differentially regulated in insects feeding on resistant or susceptib le trees. The effects of resistance on vitellogenin gene expression we re studied to confirm our earlier findings and to provide a sensitive bioassay for identifying resistance factors. Crown Copyright (C) 1997 Published by Elsevier Science Ltd.