Qualitative evaluation of damage by Epiblema strenuana (Lepidoptera : Tortricidae) to the weed Parthenium hysterophorus (Asteraceae)

The North American Epiblema strenuana (Walker) may prove to be an important agent for the control of the weed Parthenium hysterophorus L. in Australia . In this article we report time-related changes in the galled shoots of P. hysterophorus consequent to attack by E. strenuana. In addition to many st ructural adjustments involving tissue regeneration, the host plant shows a number of metabolic alterations as a result of its response to galling by t he moth larva. Through histochemical localization we demonstrate how the pl ant synthesizes some of the kev metabolites facilitating the nutritional re quirements of the larva and displays compensatory behavior to neutralize th e stress induced by larval feeding. As the larva prepares for pupation, hos t-plant metabolism changes abruptly, by accumulating polyphenolic materials in the translocatory cells and ultimately blocking them. This event coinci des with a modest decline in gall mass that was previously increasing with larval mass. The ability of the moth to damage the growth point, phloem, an d the associated parenchyma, making them nonfunctional, and induce the plan t to lose vigor, indicates that it is a potential biocontrol agent.